Tendinopathy is a prevalent and debilitating musculoskeletal disorder. Uncertainty remains regarding its pathophysiology, but it is believed to be a combination of inflammation, damage, degenerative changes, and unsuccessful repair mechanisms. Cell-based therapy is an emerging regenerative medicine modality that uses mesenchymal stem cells (MSCs), their progeny or exosomes to promote tendon healing and regeneration. It is based on the fact that MSCs can be differentiated into tenocytes, the major cell type within tendons, and facilitate tendon repair. Photobiomodulation (PBM) is a non-invasive and potentially promising therapeutic technique that utilizes low-level light to alter intracellular processes and promote tissue healing and regeneration. Recent studies have examined the potential for PBM to improve MSC therapy use in tendinopathy by promoting viability, proliferation, and differentiation. As well as enhance tendon regeneration. This review focuses on Photobiomodulation and MSC therapy applications in regenerative medicine and their potential for tendon tissue engineering.

To identify the optimal photobiomodulation (PBM) parameters using molecular, histological, and erectile function analysis in cavernous nerve injury.

A cavernous nerve injury was induced in 8-week-old C57BL/6J male mice that were subsequently divided randomly into age-matched control groups. Erectile function tests, penile histology, and Western blotting were performed 2 weeks after surgery and PBM treatment.

The PBM treatment was administered for five consecutive days with a light-emitted diode (LED) device that delivers 660 nm±3% RED light, and near infra-red 830 nm±2% promptly administered following nerve-crushing surgery and achieved a notable restoration of erectile function approximately 90% of the control values. Subsequent in-vitro and ex-vivo analyses revealed the regeneration of neurovascular connections in both the dorsal root ganglion and major pelvic ganglion, characterized by the sprouting of neurites. Furthermore, the expression levels of neurotrophic, survival, and angiogenic factors exhibited a substantial increase across all groups subjected to PBM treatment.

The utilization of PBM employing LED with 660 nm, 830 nm, and combination of both these wavelengths, exhibited significant efficacy to restore erectile function in a murine model of cavernous nerve injury. Thus, the PBM emerges as a potent therapeutic modality with notable advantages such as efficacy, noninvasiveness, and non-pharmacological interventions for erectile dysfunction caused by nerve injury.

Novel methods and technologies that improve mesenchymal stem cells (MSCs) proliferation and differentiation properties are required to increase their clinical efficacy. Photobiomodulation (PBM) and low-intensity pulsed ultrasound (LIPUS) are two strategies that can be used to enhance the regenerative properties of dental MSCs. This study evaluated the cytocompatibility and osteo/odontogenic differentiation of dental pulp, periodontal ligament, and gingival MSCs after stimulation by either PBM or LIPUS and their combined effect. MTT assay, cell migration assay, osteo/odontogenic differentiation by AR staining and ALP activity, and expression of osteo/odontogenic markers (OPG, OC, RUNX2, DSPP, DMP1) by RT-qPCR were evaluated. Statistical analysis was performed using ANOVA, followed by Tukey's post hoc test, with a p-value of less than 0.05 considered significant. The results showed that combined stimulation by PBM and LIPUS resulted in significantly the highest viability of MSCs, the fastest migration, the most dense AR staining, the most increased ALP activity, and the most elevated levels of osteogenic and odontogenic markers. The synergetic stimulation of PBM and LIPUS can be utilized in cell-based regenerative approaches to promote the properties of dental MSCs.

Osteoporosis and other degenerative bone diseases pose significant challenges to global healthcare systems due to their prevalence and impact on quality of life. Current treatments often alleviate symptoms without fully restoring damaged bone tissue, highlighting the need for innovative approaches like stem cell therapy. Adipose-derived mesenchymal stem cells (ADMSCs) are particularly promising due to their accessibility, abundant supply, and strong differentiation potential. However, ADMSCs tend to favor adipogenic pathways, necessitating the use of differentiation inducers (DIs), three-dimensional (3D) hydrogel environments, and photobiomodulation (PBM) to achieve targeted osteogenic differentiation. This study investigated the combined effects of osteogenic DIs, a fast-dextran hydrogel matrix, and PBM at specific wavelengths and fluences on the proliferation and differentiation of immortalized ADMSCs into osteoblasts. Near-infrared (NIR) and green (G) light, as well as their combination, were used with fluences of 3 J/cm2, 5 J/cm2, and 7 J/cm2. The results showed statistically significant increases in alkaline phosphatase levels, a marker of osteogenic differentiation, with G light at 7 J/cm2 demonstrating the most substantial impact on ADMSC differentiation. Calcium deposits, visualized by Alizarin red S staining, appeared as early as 24 h post-treatment in PBM groups, suggesting accelerated osteogenic differentiation. ATP luminescence assays indicated increased proliferation in all experimental groups, particularly with NIR and NIR-G light at 3 J/cm2 and 5 J/cm2. MTT viability and LDH membrane permeability assays confirmed enhanced cell viability and stable cell health, respectively. In conclusion, PBM significantly influences the differentiation and proliferation of hydrogel-embedded immortalized ADMSCs into osteoblast-like cells, with G light at 7 J/cm2 being particularly effective. These findings support the combined use of 3D hydrogel matrices and PBM as a promising approach in regenerative medicine, potentially leading to innovative treatments for degenerative bone diseases.