Microvascular injuries can have systemic physiological effects that exacerbate other injuries and pose a danger to life. Reliable in vitro microvascular models are required to enhance understanding of traumatic injuries. This research aims to develop and optimise a three-dimensional (3D) hydrogel construct for the formation and long-term stability of an in vitro microvascular model for trauma research. First, we develop a 3D hydrogel scaffold using a physiologically relevant cell type to enable the formation of a durable microvascular endothelial network and validate it against the gold standard: HUVECs. Then, we explore the impact of modifying the hydrogel composition, specifically fibrinogen source and concentration, medium, and crosslinking ratio, on scaffold material properties and, consequently, the formation of endothelial networks, their architecture, and long-term integrity. Our results demonstrate that 3D hydrogel scaffolds are crucial for maintaining network stability beyond the initial 24 h. For trauma research applications, the material properties and mechanical behaviour of the hydrogels are critical. Microrheometry revealed that fibrinogen concentration significantly influences gelation times, absorbance rate, storage modulus (G'), loss modulus (G"), and complex viscosity, while also reducing creep compliance. Our multi-pronged approach to engineering microvasculature constructs revealed that variations in hydrogel composition, including fibrinogen concentration and source, crosslinking ratio and choice of medium, strongly affect the hydrogel material characteristics and, in turn, the resulting microvascular networks. Hydrogels made with high concentrations of human fibrinogen, a 200:10:1 crosslinking ratio, and endothelial basal medium (EBM) or EBM supplemented with VEGF performed best, demonstrating superior long-term network stability. The microvasculature construct developed here could be used as a potential platform for studying traumatic injuries, as well as testing interventions aimed at improving recovery and mitigating damage.

To reduce costs and delays related to developing new and effective drugs, there is a critical need for improved human liver tissue models. Here we describe an approach for 3D bioprinting functional human liver tissue models, in which we fabricate disc-shaped structures (discoids) 200 μm in thickness and 1-3 mm in diameter from mixtures of cells and collagen-1, embedded in a highly permeable support medium made from packed polyethylene glycol (PEG) microgels. We demonstrate that the method is precise, accurate, and scalable; up to 100 tissues/h can be manufactured with a variability and error in diameter of about 4 %. Histologic and immunohistochemical evaluation of printed discs reveal self-organization, cell cohesion, and key liver marker expression. Over the course of three weeks in culture, the tissues stably synthesize albumin and urea at high levels, outperforming spheroid tissue models. We find the tissues express >100 genes associated with molecular absorption, distribution, metabolism, and excretion (ADME) at levels within the range of human liver. The liver tissue models exhibit enzymatic formation of metabolites after exposure to multiple test compounds. Together, these results demonstrate the promise of 3D printed discoids for pharmacological and toxicological applications.

Self-activating and microenvironment-responsive biomaterials for tissue regeneration would address the escalating need for bone grafting, but remain challenging. The emergence of microbial living therapeutics offers vast potential in regenerative medicine, as genetically engineered probiotics possess efficient stimuli-responsiveness and tunable biological functions. Here, using elevated endogenous nitric oxide (NO) signals as a biological trigger in bone fracture injuries, a Living Responsive Regenerative Medicine (LRRM) strategy for in situ bone defect repair through real-time controlled release of bone morphogenetic protein-2 (BMP2) is proposed. The Escherichia coli Nissle 1917 (EcN) strain, genetically engineered to sense NO signals and correspondingly produce and secrete BMP2, was firstly encapsulated in gelatin methacryloyl (GelMA) microspheres and then embedded in a bulky hyaluronic acid methacryloyl (HAMA) hydrogel to form a living hydrogel device that circumvents immune attack and prevents bacterial leakage. In vivo multiple bone defect models demonstrated the efficacy of the living hydrogel in enhancing the maturation of bone callus, promoting neovascularization, and facilitating full-thickness bone union. Strategic incorporation of engineered probiotics and the bilayer-structured encapsulation system may emerge as an effective and microenvironment-responsive medicine approach for tissue regeneration.

For single ventricle congenital heart patients, Fontan surgery is the final stage in a series of palliative procedures, bypassing the heart to enable passive flow of de-oxygenated blood from the inferior vena cava (IVC) to the pulmonary arteries. This circulation leads to severely elevated central venous pressure, diminished cardiac output, and thus numerous sequelae and premature mortality. To address these issues, we propose a bioprinted pulsatile conduit to provide a secondary power source for the Fontan circulation. A multiphysics computational framework was developed to predict conduit performance and to guide design prior to printing. Physics components included electrophysiology, cardiomyocyte contractility, and fluid-structure interaction coupled to a closed-loop lumped parameter network representing Fontan physiology. A range of myocardial contractility was considered and simulated. The initial conduit design with adult ventricular cardiomyocyte contractility values coupled to a Purkinje network demonstrated potential to reduce liver (IVC) pressure from 16.4 to 9.3 mmHg and increase cardiac output by 29%. After systematically assessing the impacts of contraction duration, fiber direction, and valve placement on conduit performance, we identified a favorable design that successfully reduces liver pressure to 7.3 mmHg and increases cardiac output by 38%, almost normalizing adverse hemodynamics in the lower venous circulation. Valves at the input and output of the conduit are essential to achieve these satisfactory results; without valves, performance is compromised. However, a potential drawback of the design is the elevation of superior vena cava (SVC) pressure, which varies linearly with liver pressure reduction.

Bone tissue engineering aims to address critical-sized defects by developing biomimetic scaffolds that promote repair and regeneration. This study introduces a material extrusion-based embedded bioprinting approach to fabricate dense cellular constructs within methacrylated hyaluronic acid (MeHA) hydrogels enhanced with bioactive microparticles. Composite matrices containing human bone allograft or tricalcium phosphate (TCP) particles were evaluated for their rheological, mechanical, and osteoinductive properties. High cell viability (>95%) and uniform strand dimensions were achieved across all bioprinting conditions, demonstrating the method's ability to preserve cellular integrity and structural fidelity. The inclusion of bone or TCP particles did not significantly alter the viscosity, crosslinking kinetics, or compressive modulus of the MeHA hydrogels, ensuring robust mechanical stability and shape retention. However, bone allograft particles significantly enhanced osteogenic differentiation of human mesenchymal stem cells (hMSCs), as evidenced by increased alkaline phosphatase (ALP) activity and calcium deposition. Notably, osteogenesis was observed even in basal media, with a dose-dependent response to bone particle concentration, highlighting the intrinsic bioactivity of allograft particles. This study demonstrates the potential of combining embedded bioprinting with bioactive matrices to create dense, osteoinductive cellular constructs. The ability to induce osteogenesis without external growth factors positions this platform as a scalable and clinically relevant solution for bone repair and regeneration.

Engineering functional cellular tissue components holds great promise in regenerative medicine. Collagen I, a key scaffolding material in bodily tissues, presents challenges in controlling its assembly kinetics in a biocompatible manner in vitro, restricting its use as a primary scaffold or adhesive in cellular biofabrication. Here we report a collagen fabrication method termed as tunable rapid assembly of collagenous elements that leverages macromolecular crowding to achieve the instant assembly of unmodified collagen. By applying an inert crowder to accelerate the liquid-gel transition of collagen, our method enables the high-throughput creation of physiological collagen constructs across length scales-from micro to macro-and facilitates cell self-assembly and morphogenesis through the generation of tunable multiscale architectural cues. With high biocompatibility and rapid gelation kinetics, the tunable rapid assembly of collagenous elements method also offers a versatile bioprinting approach for collagen over a wide concentration range, enabling the direct printing of cellular tissues using pH-neutral, bioactive collagen bioinks and achieving both structural complexity and biofunctionality. This work broadens the scope of controllable multiscale biofabrication for tissues across various organ systems using unmodified collagen.

Three-dimensional bioprinting is getting enormous attention among the scientific community for its application in complex regenerative tissue engineering applications. One of the focus areas of 3-D bioprinting is Skin tissue engineering. Skin is the largest external organ and also the outer protective layer is prone to injuries due to accidents, burns, pathologic diseases like diabetes, and immobilization of patients due to other health conditions, etc. The demand for skin tissue and the need for an off-the-shelf skin construct to treat patients is increasing on an alarming basis. Conventional approaches like skin grafting increase morbidity. Other approaches include acellular grafts, where integration with the host tissue is a major concern. The emerging technology of the future is 3D bioprinting, where different biopolymers or hybrid polymers together provide the properties of extracellular matrix (ECM) and tissue microenvironment needed for cellular growth and proliferation. This raises the hope for the possibility of a shelf skin construct, which can be used on demand or even skin can be printed directly on the wound site (in-situ printing) based on the depth and complex structure of the wound site. In the present review article, we have tried to provide an overview of Skin tissue engineering, Conventional advancement in technology, 3D bioprinting and bioprinters for skin 3D printing, different biomaterials for skin 3D bioprinting applications, desirable properties of biomaterials and future challenges.

Establishing adequate vascularization to engineered organs remains a significant challenge that must be addressed. This study presents a novel approach to fabricating viable thick metabolic tissue (>1 cm3) for applications in human physiology, fundamental biology, and medicine. We designed a tissue construct with a gyroid-shaped architecture to enable uniform flow and surface shear stress that adequately covers the inner surfaces of cell-laden constructs. The constructs (1 × 1 × 1 cm3) were fabricated using a digital light projection (DLP) printer with a cell-laden poly(ethylene glycol) (PEG)/gelatin methacryloyl (GelMA) bioink combined with human hepatocytes (HepG2), followed by coating the interconnected vascular channels with human endothelial cells (ECs). These constructs were then placed in flow chambers connected to a medium reservoir for continuous perfusion for up to 30 days. The constructs retained their original dimensions, and the cells maintained a greater than 85 % viability at all time points. Immunofluorescent staining confirmed hepatocytes and ECs using cell-specific markers (HNF4-α/albumin for hepatocytes and vWF for ECs). The EC layer effectively lined the vascular lumens, while viable hepatocyte aggregates populated the interior of the constructs. Functional assays demonstrated that the hepatocytes produced albumin and bilirubin at levels comparable to those observed in humans, validating the metabolic functionality of the hepatic tissue constructs. This study successfully developed thick, vascularized human hepatic tissue in an in vitro environment, maintaining functionality comparable to native liver cells over 30 days. The innovative gyroid design applied in these organ constructs represents a significant advancement in developing physiologically relevant in vitro vascularized organ models.

Evaporation of sessile multicomponent droplets is ubiquitous in many common processes, such as printing, cooling, and coating. The evaporation rate is not evenly distributed across the surface of the droplet. As a result, there are regions with high evaporation rates in which the more volatile part evaporates preferentially; this can induce local surface tension gradients, which, in combination with density differences, can lead to flows within the droplet originating from local concentration gradients. Current experimental methods are based on the addition of markers that can alter liquid properties. Thus, marker-free experimental evidence for the concentration fields proposed is needed. In this work, we use Raman imaging and MRI to quantify concentration gradients in 4.2 μL droplets of 90 mol% water and 10 mol% glycerol. MRI concentration maps with 33 μm resolution enable the investigation of local concentrations as close as 100 μm to the 3-phase contact line. Raman imaging allows even higher resolution and longer observation times. The results of both methods are in excellent agreement. In accordance with the simulations, an increasing glycerol content close to the 3-phase contact line was found. Close to the droplet apex, the glycerol content decreased. The horizontal and vertical concentration gradients were on the order of 1 × 10-2 mol%μm-1. These findings can be used for the development and optimization of inks, medical diagnostic devices, food processing procedures, 3D bioprinting, and many more; they might provide the experimental concentration fields sought for the optimization of simulations.

To conduct a critical review of the current applications, challenges and future directions of three-dimensional bioprinting (3DBP) in otolaryngology with a focus on surgical education, personalised implants and regenerative medicine.

Expert opinion based on a targeted literature review and clinical experience.

Translational research relevance of academic otolaryngology.

Assessment of bioprinting approaches and new materials, anatomical accuracy, overcoming limitations by pairing with enhanced technology as virtual and augmented reality.

3DBP is fast becoming an asset to otolaryngology. These stereolithography (SLA) models facilitate the use of high-fidelity temporal bone models for surgical simulation and training. Functional outcomes of patient-specific implants for ossiculoplasty and cochlear implantation are promising, albeit mostly in preclinical settings. Educators have turned to virtual and augmented reality platforms to improve classroom experiences. But significant hurdles remain, including biocompatibility, the cost of high-resolution technologies and regulatory impediments to clinical translation.

Numerous studies have reported on the transformative potential of 3DBP for surgical planning, education implementation of personalised treatment in otolaryngology. A balanced assessment of both its current limitations and future promise is essential for ethical integration. The translation of this technology into routine practice will require multidisciplinary collaboration and rigorous validation through clinical trials.

V.

3D bioprinting is an emerging technique in tissue engineering that is advantageous for fabricating intricate tissues. However, challenges arise in bioprinting functional, implantable tissues. Commonly utilized hydrogel bioinks, while offering desirable printability and a cell-friendly environment, often lack the mechanical robustness necessary for post-printing maturation, handling, and implantation. These limitations are particularly relevant for bone tissue. Treatment of bone loss resulting from trauma or infection poses a significant clinical challenge. While surgical interventions exist, they frequently lead to complications and limited outcomes. Thus, a strategy to enhance the mechanical integrity of bioprinted constructs compatible with cells is needed. This study presents a novel hybrid bioprinting approach to create mechanically robust, vascularized bone tissue. A reinforcing bioink composed of a poly(lactic-co-glycolic) acid (PLGA), hydroxyapatite (HA), and polyethylene-glycol microparticles blend, which is thermosensitive due to a reduced glass transition temperature (∼36 °C), enabling sintering at physiological conditions is co-printed with a cell-laden, ECM-based hydrogel. The microparticles sinter at 37 °C, forming a porous, stiff scaffold. The hybrid bioprinted constructs demonstrate high cell viability, vascular network formation, and osteogenic differentiation. In vivo implantation in a rat femoral defect reveals superior bone regeneration compared to acellular controls. This study highlights the potential of hybrid bioprinting for creating tissues exhibiting high cell viability and enhanced mechanical properties, allowing for their handling and implantation.

Biopolymer-based fibrous aggregate materials (BFAMs) have gained increasing attention in biomedicine due to their excellent biocompatibility, processability, biodegradability, and multifunctionality. Especially, the medical applications of BFAMs demand advanced structure, performance, and function, which conventional trial-and-error methods struggle to provide. This necessitates the rational selection of materials and manufacturing methods to design BFAMs with various intended functions and structures. This review summarizes the current progress in raw material selection, structural and functional design, processing technology, and application of BFAMs. Additionally, the challenges encountered during the development of BFAMs are discussed, along with perspectives for future research offered.

3D printing offers a significant advantage in creating bioengineering scaffolds for patient-specific treatments of bony defects. In this study, a 3D-printed polycaprolactone (PCL)/sphene (SP, CaTiSiO5) scaffold coated with zein/ZnO was fabricated to provide a suitable environment for bone regeneration. SP nanoparticles were synthesized using a mechanochemical method and characterized by SEM-EDS, FTIR, and XRD. 0-30 wt % of prepared SP nanoparticles was used to fabricate 3D-printed PCL-based scaffolds. Incorporation of SP into PCL scaffolds (up to 20 wt %) significantly increased compressive strength (from 37.5 to 65.2 MPa) and modulus (from 0.33 to 0.63 MPa). In vitro bioactivity evaluation in simulated body fluid demonstrated the apatite formation ability of PCL/SP scaffolds, as confirmed by SEM-EDS analysis. Compared to PCL/SP, the zein/ZnO-modified scaffold showed increased surface hydrophilicity and significantly higher values of bactericidal potency against S. aureus and E. coli. Additionally, MTT assay, cell attachment, and alkaline phosphatase activity revealed that zein and ZnO coexistence on PCL/SP scaffolds resulted in significantly higher cell proliferation, improved cell adhesion, and enhanced osteogenic differentiation of MG-63 cells compared to unmodified samples. Overall, zein/ZnO-modified 3D-printed PCL/SP nanocomposite scaffolds with desirable physicochemical, mechanical, and biological characteristics can serve as superior platforms for bone regeneration applications.

Despite recent advancements in technology for the treatment of type 1 diabetes (T1D), exogenous insulin delivery through automated devices remains the gold standard for treatment. This review will explore progress made in pancreatic islet bioengineering within the field of beta-cell replacement for T1D treatment.

First, we will focus on the use of decellularized extracellular matrices (dECM) as a platform for pancreatic organoid development. These matrices preserve microarchitecture and essential biochemical signals for cell differentiation, offering a promising alternative to synthetic matrices. Second, advancements in 3D bioprinting for creating complex organ structures like pancreatic islets will be discussed. This technology allows for increased precision and customization of cellular models, crucial for replicating native pancreatic islet functionality. Finally, this review will explore the use of stem cell-derived organoids to generate insulin-producing islet-like cells. While these organoids face challenges such as functional immaturity and poor vascularization, they represent a significant advancement for disease modeling, drug screening, and autologous islet transplantation.

These innovative approaches promise to revolutionize T1D treatment by overcoming the limitations of traditional therapies based on human pancreatic islets.

Conventional in vitro models fail to accurately mimic the tumor in vivo characteristics, being appointed as one of the causes of clinical attrition rate. Recent advances in 3D culture techniques, replicating essential physical and biochemical cues such as cell-cell and cell-extracellular matrix interactions, have led to the development of more realistic tumor models. Bioprinting has emerged to advance the creation of 3D in vitro models, providing enhanced flexibility, scalability, and reproducibility. This is crucial for the development of more effective drug treatments, and glioblastoma (GBM) is no exception. GBM, the most common and deadly brain cancer, remains a major challenge, with a median survival of only 15 months post-diagnosis. This review highlights the key components needed for 3D bioprinted GBM models. It encompasses an analysis of natural and synthetic biomaterials, along with crosslinking methods to improve structural integrity. Also, it critically evaluates current 3D bioprinted GBM models and their integration into GBM-on-a-chip platforms, which hold noteworthy potential for drug screening and personalized therapies. A versatile development framework grounded on Quality-by-Design principles is proposed to guide the design of bioprinting models. Future perspectives, including 4D bioprinting and machine learning approaches, are discussed, along with the current gaps to advance the field further.

More than 5 % of people worldwide suffer from hearing disorders. Ototoxic drugs, aging, exposure to loud sounds, rupture, subperichondrial hematoma, perichondritis, burns and frostbite and infections are the main causes of hearing loss, some of which can destroy the cartilage and lead to deformation. On the other hand, disorders of the external ear are diverse and can range from dangerous neoplasms to defects that are not acceptable from a cosmetic standpoint. These issues include injuries, blockages, dermatoses, and infections, and any or all of them may be bothersome to the busy doctor. Using an implant or hearing aid is one of the treatment strategies for deafness. However, these medical devices are not useful for every eligible patient. With the right therapy, many of these issues are not life-threatening and can be treated with confidence in a positive outcome. As medical research and treatment have advanced dramatically in the past ten years, tissue engineering (TE) has emerged as a promising method to regenerate damaged tissue, raising the prospect of a permanent cure for deafness. Decellularization is now seen as a promising development for regenerative medicine, and an increasing number of applications are being found for acellular matrices. Studies on decellularization show that natural scaffolds made from decellularized tissues can serve as a suitable platform while preserving the main components, and the preparation of such scaffolds will be an important part of future bioscience research. It can have wide applications in regenerative medicine and TE. This review intends to give an overview of the status of research and alternative scaffolds in inner and outer ear regenerative medicine from both a preclinical and clinical perspective for ear disorders in order to show how ongoing TE research has the potential to advance and enhance novel disease treatments.

From the pioneering days of cell therapy to the achievement of bioprinting organs, tissue engineering, and regenerative medicine have seen tremendous technological advancements, offering solutions for restoring damaged tissues and organs. However, only a few products and technologies have received United States Food and Drug Administration approval. This review highlights significant progress in cell therapy, extracellular vesicle-based therapy, and tissue engineering. Hematopoietic stem cell transplantation is a powerful tool for treating many diseases, especially hematological malignancies. Mesenchymal stem cells have been extensively studied. The discovery of induced pluripotent stem cells has revolutionized disease modeling and regenerative applications, paving the way for personalized medicine. Gene therapy represents an innovative approach to the treatment of genetic disorders. Additionally, extracellular vesicle-based therapies have emerged as rising stars, offering promising solutions in diagnostics, cell-free therapeutics, drug delivery, and targeted therapy. Advances in tissue engineering enable complex tissue constructs, further transforming the field. Despite these advancements, many technical, ethical, and regulatory challenges remain. This review addresses the current bottlenecks, emphasizing novel technologies and interdisciplinary research to overcome these hurdles. Standardizing practices and conducting clinical trials will balance innovation and regulation, improving patient outcomes and quality of life.

Currently, bioactive composite scaffolds provide an ideal regenerative microenvironment for cartilage tissue engineering. However, the dominant regulatory role of the microenvironment in cartilage regeneration fate remains elusive, such as in situ auricle, ex situ subcutaneous, and osteogenic regions. Therefore, investigating the influence of distinct microenvironments on cartilage regeneration and long-term outcomes is important. In this study, a universal composite scaffold is developed combining 3D-printed poly(lactic-co-glycolic acid) frameworks with cartilage-specific matrix hydrogels and then systematically explored the crucial role of the microenvironment in determining the fate of cartilage regeneration. These results indicate that the in situ auricular microenvironment effectively promotes the maturation of the regenerative cartilage and maintains its chondrogenic phenotype. In contrast, ex situ subcutaneous microenvironment leads to chondrogenic phenotype loss owing to intense immune-inflammatory responses and vascularization conditions. In the osteogenic microenvironments of cranial sites, although autologous chondrocytes show good cartilage regenerative quality within 12 weeks, they are gradually replaced by regenerative bone, ultimately achieving successful cranial defect repair. Interestingly, these findings provide critical theoretical foundations for revealing the long-term outcomes of engineered cartilage and offer practical guidance for optimizing cartilage regeneration strategies in various microenvironments.

Heterogeneity and the absence of a tumor microenvironment (TME) in traditional patient-derived organoid (PDO) cultures limit their effectiveness for clinical use. Here, Embedded Bioprinting-enabled Arrayed PDOs (Eba-PDOs) featuring uniformly arrayed colorectal cancer (CRC) PDOs within a recreated TME is presented. This model faithfully reproduces critical TME attributes, including elevated matrix stiffness (≈7.5 kPa) and hypoxic conditions found in CRC. Transcriptomic and immunofluorescence microscopy analysis reveal that Eba-PDOs more accurately represent actual tissues compared to traditional PDOs. Furthermore, Eba-PDO effectively capture the variability of CEACAM5 expression-a critical CRC marker-across different patients, correlating with patient classification and differential responses to 5-fluorouracil treatment. This method achieves an uniform size and shape within PDOs from the same patient while preserving distinct morphological features among those from different individuals. These features of Eba-PDO enable the efficient development of a label-free, morphology-based predictive model using supervised learning, enhancing its suitability for clinical applications. Thus, this approach to PDO bioprinting is a promising tool for generating personalized tumor models and advancing precision medicine.

Substantial progress in aging research continues to deepen our understanding of the fundamental mechanisms of aging, yet there is a lack of interventions conclusively shown to attenuate the processes of aging in humans. By contrast, replacement interventions such as joint replacements, pacemaker devices and transplant therapies have a long history of restoring function in injury or disease contexts. Here, we consider biological and synthetic replacement-based strategies as aging interventions. We discuss innovations in tissue engineering, such as the use of scaffolds or bioprinting to generate functional tissues, methods for enhancing donor-recipient compatibility through genetic engineering and recent progress in both cell therapies and xenotransplantation strategies. We explore synthetic approaches including prostheses, external devices and brain-machine interfaces. Additionally, we evaluate the evidence from heterochronic parabiosis experiments in mice and donor-recipient age-mismatched transplants to consider whether systemic benefits could result from personalized replacement approaches. Finally, we outline key challenges and future directions required to advance replacement therapies as viable, scalable and ethical interventions for aging.

In vitro biological model technology has become a cornerstone of modern biological research, driving advancements in drug screening, physiological and pathological studies, and tissue implantation applications. The natural basement membrane (BM), a homogeneous structure, provides critical physical and biological support for tissues and organs. To replicate its function, researchers have developed biomimetic BMs using advanced fabrication technologies, which are increasingly applied to in vitro models. This review explores the materials, preparation techniques, and applications of biomimetic BMs across various biological models, highlighting their advantages and limitations. Additionally, it discusses recent progress in the field and identifies current challenges in achieving BM simulations that closely mimic native structures. Future directions and recommendations are provided to guide the development of high-performance biomimetic BM materials and their manufacturing processes.

Osteoarthritis (OA) is the most prevalent degenerative joint disease worldwide, imposing a substantial global disease burden. However, its pathogenesis remains incompletely understood, and effective treatment strategies are still lacking. Organoid technology, in which stem cells or progenitor cells self-organise into miniature tissue structures under three-dimensional (3D) culture conditions, provides a promising in vitro platform for simulating the pathological microenvironment of OA. This approach can be employed to investigate disease mechanisms, carry out high-throughput drug screening and facilitate personalised therapies. This review summarises joint structure, OA pathogenesis and pathological manifestations, thereby establishing the disease context for the application of organoid technology. It then examines the components of the arthrosis organoid system, specifically addressing cartilage, subchondral bone, synovium, skeletal muscle and ligament organoids. Furthermore, it details various strategies for constructing OA organoids, including considerations of cell selection, pathological classification and fabrication techniques. Notably, this review introduces the concept of intelligent manufacturing of OA organoids by incorporating emerging engineering technologies such as artificial intelligence (AI) into the organoid fabrication process, thereby forming an innovative software and hardware cluster. Lastly, this review discusses the challenges currently facing intelligent OA organoid manufacturing and highlights future directions for this rapidly evolving field. By offering a comprehensive overview of state-of-the-art methodologies and challenges, this review anticipates that intelligent, automated fabrication of OA organoids will expedite fundamental research, drug discovery and personalised translational applications in the orthopaedic field.

To achieve successful bone tissue engineering (BTE), it is necessary to fabricate a biomedical scaffold with appropriate structure as well as favorable composition. Despite a broad range of studies, this remains a challenge, highlighting the need for a better understanding of how structural features (e.g., pore size) and scaffold composition influence mechanical and physical properties, as well as cellular behavior. Therefore, the objective of this study was to characterize physical properties (swelling, degradation), mechanical properties (compressive modulus), and cellular behavior in relation to varying compositions (referred to composite and hybrid scaffolds) as well as varying pore sizes in three-dimensional (3D) printed scaffolds. Composite scaffolds were fabricated from polycaprolactone (PCL) and two different graphene oxide (GO) (3% and 9% (w/v)) concentrations. Additionally, hybrid scaffolds were fabricated by impregnating 3D printed scaffolds in a hydrogel blend of alginate/gelatin. Pore sizes of 400, 1000, and 1500 μm were investigated in this study to assess their effect on the scaffold properties. Our findings showed that swelling and degradation properties were enhanced by (I) the addition of GO as well as introduction of both hydrogel and highest concentration of GO (9% (w/v) GO) into the polymeric matrix of PCL, and (II) increasing the pore size within the scaffolds. Mechanical testing revealed that compressive elastic modulus increased with decreasing pore size, incorporation of GO, and increasing GO content into the matrix of PCL. Although our investigated scaffolds with various pore sizes did not show comparable elastic moduli to that of cortical bone, they exhibited an elastic modulus range (∼31-48 MPa) matching that of trabecular bone. The highest compressive modulus (∼48 MPa) was observed in scaffolds of PCL/9% (w/v) GO (composite scaffolds) with the pore size of 400 μm. Cell viability assay demonstrated high MG-63 cell survival (greater than 70%) in all composite and hybrid scaffolds (indicating scaffold biocompatibility) except PCL/3% (w/v) GO scaffolds. The findings of this study contribute to the field of BTE by providing scaffold design insights in terms of pore size and composition.

Severe skeletal muscle injuries involving substantial tissue loss can significantly impair muscle strength and functionality, reducing the quality of life for affected individuals. Such injuries, termed volumetric muscle loss, require extensive clinical intervention, as the body's innate healing mechanisms are insufficient to regenerate functional muscle. The current standard of care primarily involves autologous muscle tissue transfer, with some consideration of acellular synthetic constructs. However, both approaches have limited therapeutic efficacy, presenting challenges such as donor-site morbidity, infection risks, and suboptimal functional recovery. Over the past decade, skeletal muscle tissue engineering (SMTE) has emerged as a promising strategy for regenerating functional muscle through bioengineered constructs. Advanced biofabrication techniques, including bioprinting, have further enabled the development of synthetic constructs that closely mimic native muscle architecture. Given these advancements, a critical review of recent therapeutic strategies, their achievements, and limitations is necessary. This review examines the spectrum of bioengineered constructs developed from various biomaterials and evaluates their therapeutic potential. Special emphasis is placed on 3D bioprinting strategies and their role in creating physiologically relevant constructs for functional muscle restoration. In addition, the integration of machine learning in optimizing construct design, predicting cellular behavior, and enhancing tissue integration is discussed. The review indicates that despite significant progress in SMTE, key challenges remain, including replicating the complex structural organization of muscle tissue, minimizing fibrosis, and achieving vascularization and innervation to regenerate functional, strengthened muscle. Future research should address these barriers while prioritizing the development of translational, clinically relevant regenerative constructs. In addition, efforts should focus on advancing scalable, construct-based regenerative treatments that are readily available at the point of care and easily managed in surgical settings.

Cancer has rapidly emerged as a leading global cause of premature mortality, with significant economic implications projected to reach USD 25.2 trillion from 2020 to 2050. Among the various types of cancer, primary bone cancers, though uncommon, are projected to see nearly 4000 new cases diagnosed in the United States in 2024. The complexity of treating bone cancer arises from its rarity, diversity, and the challenges associated with surgical interventions, metastatic spread, and post-operative complications. Advancements in bone tissue engineering (BTE) have introduced innovative therapeutic approaches to promote bone regeneration and address tumor recurrence. This interdisciplinary field integrates biomaterials, scaffolds, and gene therapy, utilizing technologies such as 3D bioprinting to create custom scaffolds that facilitate cellular activities essential for tissue regeneration. Recent developments in biodegradable, bioactive materials aim to enhance the biocompatibility and effectiveness of scaffolds, while nanotechnology presents promising avenues for targeted drug delivery and improved therapeutic outcomes. This review outlines the current landscape of BTE, highlighting scaffold fabrication techniques, the advantages of incorporating stem cell and gene therapies, and future directions, including the integration of artificial intelligence in scaffold design for personalized medicine in orthopedic oncology. This work underscores the necessity for ongoing research and innovation, aiming to improve therapeutic strategies specifically designed to address the unique challenges posed by bone sarcomas and metastatic cancers.

As one of the 3D printing technologies, digital light processing (DLP) 3D printing technology has been widely applied in biomedical engineering. The principles and advantages of DLP 3D printing technology are compared with other 3D printing technologies, while the characteristics and applicable fields of each technique are analyzed. The applications of DLP 3D printing technology in tissue engineering, medical devices and pharmaceutical field are classified and summarized. Besides, the prospects and challenges of DLP 3D printing technology in biomedical engineering are discussed. With continuous advancement, DLP 3D printing technology will play an increasingly important role in personalized medicine and regenerative medicine.

Conventional dental materials lack the ability to promote regeneration, necessitating innovative approaches for repairing dental, oral, and craniofacial (DOC) tissues. Supramolecular materials with reversible, tunable interactions, and engineered living materials (ELMs) that mimic natural tissue dynamics, present a promising pathway towards regenerative solutions in oral medicine. This review introduces the potential of these biomaterials, focusing on their applications in oral bioprinting, therapeutic delivery, and organ-on-a-chip (OOC) systems. We discuss the integration of these technologies into clinical applications, and offer insights into future developments that may redefine oral healthcare by enabling the regeneration of complex, dynamic tissue structures and improving therapeutic outcomes in oral diseases.

Several diseases affect the female reproductive system, and both disease factors and treatments impact its integrity and function. Consequently, understanding the mechanisms of disease occurrence and exploring treatment methods are key research focuses in obstetrics and gynecology. However, constructing accurate disease models requires a microenvironment closely resembling the human body, and current animal models and 2D in vitro cell models fall short in this regard. Thus, innovative in vitro female reproductive system models are urgently needed. Additionally, female reproductive system diseases often cause tissue loss, yet effective tissue repair and regeneration have long been a bottleneck in the medical field. 3D bioprinting offers a solution by enabling the construction of implants with tissue repair and regeneration capabilities, promoting cell adhesion, extension, and proliferation. This helps maintain the long-term efficacy of bioactive implants and achieves both structural and functional repair of the reproductive system. By combining live cells with biomaterials, 3D bioprinting can create in vitro 3D biomimetic cellular models, facilitating in-depth studies of cell-cell and cell-extracellular microenvironment interactions, which enhances our understanding of reproductive system diseases and supports disease-specific drug screening. This article reviews 3D bioprinting methods and materials applicable to the female reproductive system, discussing their advantages and limitations to aid in selecting optimal 3D bioprinting strategies. We also summarize and critically evaluate recent advancements in 3D bioprinting applications for tissue regeneration and in vitro disease models and address the prospects and challenges for translating 3D bioprinting technology into clinical applications within the female reproductive system.

Organoids are rapidly self-organizing 3D in vitro cultures derived from pluripotent stem cells (PSCs) or adult stem cells (ASCs) that possess disease-like characteristics with high success rates. Due to their ability to retain tissue structure, biological phenotypes, and genetic information, they have been utilized as a novel in vitro model for disease research. In recent years, scientists have established self-organizing 3D organoids for human endometrium, fallopian tubes, ovaries, and cervix by culturing stem cells with cytokines in 3D scaffolds. The integration of organoids with animal models, organ-on-a-chip systems, and 3D printing technologies offers a novel preclinical model for exploring disease mechanisms and developing treatments. This review elaborate on the recent research progress of stem cells-formed organoids in the field of gynecology from the aspects of constructing gynecological disease organoids, drug screening and new drug development, simulation modeling, allogeneic transplantation, regenerative medicine and personalized treatment."

Facial prosthetics are an important means to rehabilitate patients with congenital or acquired facial defects. However, with a time-consuming manual workflow and workforce shortage, access to facial prosthetics is limited in Australia and worldwide, especially for rural and remote patients. Optical 3D scanning has been increasingly integrated in digitizing data. With the development of TrueDepth® camera technology on smartphones, there is increasing availability of mobile applications which can generate 3D images to improve accessibility and reduce cost. This study compares the accuracy of mobile phone applications to high resolution 3D scanners for auricular data acquisition.

We conducted a case-control study comparing the EM3D smartphone application (EM3D) with the EinScan Pro 2× Plus Shining 3D handheld scanner (EinScan) in 22 healthy participants equating to 44 ears, using CloudCompare software analysis.

On average, EM3D acquired images 2.5 minutes quicker than the EinScan. The mean absolute directional distance difference was 1.10 mm, within the accepted deviation range of 2 mm. Out of the 44 ears, only 1 ear (2.27%) did not meet the accepted value of accuracy within 2 mm. The average completeness was 85% and the overall quality of images obtained from EinScanand EM3D were 53.5% and 57.7%, respectively, through observational analysis.

Mobile iPhone applications such as EM3D are a viable alternative to 3D handheld scanners such as EinScan. This study demonstrates reliable results in accuracy, and improved results in time, cost and operational feasibility.

Tissue engineering (TE) aims to provide personalized solutions for tissue loss caused by trauma, tumors, or congenital defects. While traditional methods like autologous and homologous tissue transplants face challenges such as donor shortages and risk of donor site morbidity, TE provides a viable alternative using scaffolds, cells, and biologically active molecules. Textiles represent a promising scaffold option for both in-vitro and in-situ TE applications. Textile engineering is a broad field and can be divided into fiber-based textiles and yarn-based textiles. In fiber-based textiles the textile fabric is produced in the same step as the fibers (e.g. non-wovens, electrospun mats and 3D-printed). For yarn-based textiles, yarns are produced from fibers or filaments first and then, a textile fabric is produced (e.g. woven, weft-knitted, warp-knitted and braided fabrics). The selection of textile scaffold technology depends on the target tissue, mechanical requirements, and fabrication methods, with each approach offering distinct advantages. Braided scaffolds, with their high tensile strength, are ideal for load-bearing tissues like tendons and ligaments, while their ability to form stable hollow lumens makes them suitable for vascular applications. Weaving, weft-, and warp-knitting provide tunable structural properties, with warp-knitting offering the greatest design flexibility. Spacer fabrics enable complex 3D architecture, benefiting applications such as skin grafts and multilayered tissues. Electrospinning, though highly effective in mimicking the ECM, is structurally limited. The complex interactions between materials, fiber properties, and textile technologies allows for scaffolds with a wide range of morphological and mechanical characteristics (e.g., tensile strength of woven textiles ranging from 0.64 to 180.4 N/mm2). With in-depth knowledge, textiles can be tailored to obtain specific mechanical properties as accurately as possible and aid the formation of functional tissue. However, as textile structures inherently differ from biological tissues, careful optimization is required to enhance cell behavior, mechanical performance, and clinical applicability. This review is intended for TE experts interested in using textiles as scaffolds and provides a detailed analysis of the available options, their characteristics and known applications. For this, first the major fiber formation methods are introduced, then subsequent used automated textile technologies are presented, highlighting their strengths and limitations. Finally, we analyze how these textile and fiber structures are utilized in TE, organized by the use of textiles in TE across major organ systems, including the nervous, skin, cardiovascular, respiratory, urinary, digestive, and musculoskeletal systems.

Cancer is the second leading cause of death worldwide, after cardiovascular disease, claiming not only a staggering number of lives but also causing considerable health and economic devastation, particularly in less-developed countries. Therapeutic interventions are impeded by differences in patient-to-patient responses to anti-cancer drugs. A personalized medicine approach is crucial for treating specific patient groups and includes using molecular and genetic screens to find appropriate stratifications of patients who will respond (and those who will not) to treatment regimens. However, information on which risk stratification method can be used to hone in on cancer types and patients who will be likely responders to a specific anti-cancer agent remains elusive for most cancers. Novel developments in 3D bioprinting technology have been widely applied to recreate relevant bioengineered tumor organotypic structures capable of mimicking the human tissue and microenvironment or adequate drug responses in high-throughput screening settings. Parts are autogenously printed in the form of 3D bioengineered tissues using a computer-aided design concept where multiple layers include different cell types and compatible biomaterials to build specific configurations. Patient-derived cancer and stromal cells, together with genetic material, extracellular matrix proteins, and growth factors, are used to create bioprinted cancer models that provide a possible platform for the screening of new personalized therapies in advance. Both natural and synthetic biopolymers have been used to encourage the growth of cells and biological materials in personalized tumor models/implants. These models may facilitate physiologically relevant cell-cell and cell-matrix interactions with 3D heterogeneity resembling real tumors.

The growth and formation of tissues, such as skeletal muscle, involve a complex interplay of spatiotemporal events, including cell migration, orientation, proliferation, and differentiation. With the continuous advancement ofin vitroconstruction techniques, many studies have contributed to skeletal muscle tissue engineering (STME). This review summarizes recent advances in the ordered construction of skeletal muscle tissues, and evaluates the impact of engineering strategies on cell behavior and maturation, including biomaterials, manufacturing methods and training means. Biomaterials are used as scaffolds to provide a good microenvironment for myoblasts, manufacturing methods to guide the alignment of myoblasts through construction techniques, and external stimulation to further promote the myoblast orientation and maturation after construction, resulting in oriented and functional skeletal muscle tissues. Subsequently, we critically examine recent advancements in engineered composite skeletal muscle constructs, with particular emphasis on essential functionalization strategies including skeletal muscle vascularization, innervation and others. Concurrently, we evaluate emerging applications of STME in diverse translational areas such as volumetric muscle loss treatment, muscle-related disease models, drug screening, biohybrid robots, and cultured meat. Finally, future perspectives are proposed to provide guidance for rational design based on engineering strategies in STME.

Patients suffering from large bone defects are in urgent need of suitable bone replacements. Besides biocompatibility, such replacements need to mimic the 3D architecture of bone and match chemical, mechanical and biological properties, ideally promoting ossification. As natural bone mainly contains collagen type I and carbonate hydroxyapatite, a 3D-printable biomaterial consisting of methacrylated gelatin (GelMA) and nanohydroxyapatite (nHAp) would be beneficial to mimic the composition and shape of natural bone. So far, such nanocomposite hydrogels (NCH) suffered from unsatisfactory rheological properties making them unsuitable for extrusion-based 3D printing with high structural fidelity. In this study, we introduce a novel GelMA/nHAp NCH composition, incorporating the rheological modifier carbomer to improve rheological properties and addressing the challenge of calcium cations released from nHAp that hinder GelMA gelation. Leveraging its shear-thinning and self-healing properties, the NCH ink retains its shape and forms cohesive structures after deposition, which can be permanently stabilized by subsequent UV crosslinking. Consequently, the NCH enables the printing of 3D structures with high shape fidelity in all dimensions, including thez-direction, allowing the fabrication of highly macroporous constructs. Both the uncured and the UV crosslinked NCH behave like a viscoelastic solid, withG'>G″ at deformations up to 100-200 %. After UV crosslinking, the NCH can, depending on the GelMA concentration, reach storage moduli of approximately 10 to over 100 kPa and a mean Young's Modulus of about 70 kPa. The printed scaffolds permit not only cell survival but also osteogenic differentiation, highlighting their potential for bone tissue engineering.

The emergence of tissue engineering (TE) has provided new vital means for human body tissue/organ repair. TE scaffolds can provide temporary structural support for cell attachment, growth, and proliferation, until the body restores the mechanical and biological properties of the host tissues. Since native tissues are inhomogeneous and in many situations are graded structures for performing their unique functions, graded scaffolds have become increasingly attractive for regenerating particular types of tissues, which aim to offer a more accurate replication of native interactions and functions. Importantly, the advances introduced by additive manufacturing (AM) have now enabled more design freedom and are capable of tailoring both structural and compositional gradients within a single scaffold. In this context, graded TE scaffolds fabricated by AM technologies have been attracting increasing attention. In this review, we start with an introduction of common graded structures in the human body and analyse the advantages and strengths of AM-formed graded scaffolds. Various AM technologies that can be leveraged to produce graded scaffolds are then reviewed based on non-cellular 3D printing and cell-laden 3D bioprinting. The comparisons among various AM technologies for fabricating graded scaffolds are presented. Subsequently, we propose several types of gradients, structural, material, biomolecular and multi-gradients for scaffolds, and highlight the design methods, resulting mechanical properties and biological responses. Finally, current status, challenges and perspectives for AM in developing graded scaffolds are exhibited and discussed.

Extrusion is the most popular bioprinting platform. Predictions of human tissue and whole-organ printing have been made for the technology. However, after decades of development, extruded constructs lack the essential microscale resolution and heterogeneity observed in most human tissues. Extrusion bioprinting has had little clinical impact with the majority of research directed away from the tissues most needed by patients. The distance between promise and reality is a result of technology hype and inherent design flaws that limit the shape, scale and survival of extruded features. By more widely adopting resolution innovations and softening its ambitions the biofabrication field could define a future for extrusion bioprinting that more closely aligns with its capabilities.

Extrusion-based embedded 3D bioprinting, where bioinks and biomaterials are extruded within a support bath, has greatly expanded the achievable tissue architectures and complexity of biologic constructs that can be fabricated. However, significant scientific, engineering, and process-related challenges remain to recreate the full anatomic structure and physiologic function required for many therapeutic applications. This perspective explores the future advances in extrusion-based embedded 3D bioprinting that could address these challenges, paving the way for clinical translation of bioprinted tissues.

Regenerative dentistry aims to reinstate, fix, renew, and regrow tissues within the oral and craniofacial domain. Existing regenerative methods are based on insights into tissue biology or disease processes that lead to tissue degradation. However, achieving complete and functional Tissue regeneration remains a primary challenge in real-world medical scenarios.

The review focuses on the application of bioprinting techniques for rejuvenating intricate Oral and craniofacial tissues, such as craniofacial bone, periodontal ligament, cementum, dental pulp, temporomandibular joint cartilage, and whole teeth.

Bioprinting, a cutting-edge technology in regenerative dentistry, strives to create entirely new Functional tissues and organs. This approach merges principles from engineering and biology to produce three-dimensional biologically operational constructs containing bioactive substances, Living cells and cell clusters using automated bioprinters. The review summarizes the outcomes achieved through bioprinting techniques in both in vitro (laboratory experiments) and in vivo (Studies on living organisms) experiments.

The emergence of this innovative tissue engineering technology has yielded highly promising outcomes during the experimental stages.

These promising experimental results necessitate replication through human clinical trials to ascertain the viability of bioprinting techniques for mainstream clinical implementation in regenerative dentistry.

Direct ink writing is a 3D printing method that is compatible with a wide range of structural, elastomeric, electronic, and living materials, and it continues to expand its uses into physics, engineering, and biology laboratories. However, the large footprint, closed hardware and software ecosystems, and expense of commercial systems often hamper widespread adoption. This work introduces a compact, low-cost, multimaterial, and high-throughput direct ink writing 3D printer platform with detailed assembly files and instructions provided freely online. In contrast to existing low-cost 3D printers and bioprinters, which typically modify off-the-shelf plastic 3D printers, this system is built from scratch, offering a lower cost and full customizability. Active mixing of cell-laden bioinks, high-throughput production of auxetic lattices using multimaterial multinozzle 3D (MM3D) printing methods, and a high-toughness, photocurable hydrogel for fabrication of heart valves are introduced. Finally, hardware for embedded multinozzle and 3D gradient nozzle printing is developed for producing high-throughput and graded 3D parts. This powerful, simple-to-build, and customizable printing platform can help stimulate a vibrant biomaker community of engineers, biologists, and educators.

Kidney transplantation remains a pivotal treatment modality for kidney disease, yet its progress is significantly hindered by the scarcity of donor kidneys and ethical dilemmas surrounding their procurement. As organoid technology evolves and matures, the creation of bionic human kidney organoids offers profound potential for advancing kidney disease research, drug nephrotoxicity screening, and regenerative medicine. Nevertheless, current kidney organoid models grapple with limitations such as constrained cellular differentiation, underdeveloped functional structures, and a crucial absence of vascularization. This deficiency in vascularization, in particular, stunts organoid development, restricts their size, diminishes filtration capabilities, and may trigger immune inflammatory reactions through the resulting ischemic microenvironment. Hence, the achievement of vascularization within kidney organoids and the successful establishment of functional microvascular networks constitutes a paramount goal for their future progression. In this review, we provide an overview of recent advancements in biotechnology domains, encompassing organ-on-a-chip technology, biomimetic matrices, and bioprinting, with the aim of catalyzing technological breakthroughs that can enhance the vascularization of kidney organoids and broaden their applicability. These technologies hold the key to unlocking the full potential of kidney organoids as a transformative therapeutic option for kidney disease.

In this work, several gelators were employed to formulate a conducive gel phase (ionic conductivity) compatible with direct ink writing/bioprinting/robocasting (different names in the literature describe the same printing technology). The main goal of this work was to evaluate gelled phases being a mixture of background electrolyte (NaCl), redox probe (Fe(CN)63-/4-), and gel precursor (guar gum, gelatine, agarose, and agar-agar). The studied concentration of gelators ranged from 0.1 to 4% depending on the employed system. Each gelator required a customized formulation protocol. We have found that guar gum exhibits the best printing properties (lack of aggregates blocking the printing nozzle) while giving the least reproducible electrochemical results (when a glassy carbon electrode was employed as the working electrode). The study of two other gelators (agarose and gelatin) indicated significant changes in the electrochemical properties of the investigated surface as their concentration and number of voltammetric scans were varied. The best electrochemical performance was obtained for agar-agar however, this was also a gelator causing the most problems during 3D printing. Finally, we have employed six screen-printed electrodes displaying approximate properties, that were further covered with a 3D-printed conductive gelled cube (direct printing over the electrode surface). We have found that such a system allowed for a surprisingly good electroanalytical response when the model redox probe (Fe(CN)63-/4-) was considered. This work is a prelude to 3D-printed gel-based detection devices we are currently developing in our team.