This position paper reviews the various effects of combination therapy by photobiomodulation therapy (PBMT) and stem cells, on different parts of the body. The aim of this paper is to reach consensus on recommendations for the parameters of PBMT regarding its application on stem cells. A significant number of studies involving PBMT, and stem cells have been published. The advantages of this combination therapy on tissue regeneration, cell differentiation and proliferation, and healing have been reported in many studies. Due to the diverse nature of study designs used with respect to light parameters, as well as a lack of well designed, ethically approved clinical trials, clinicians may benefit from suggested guidelines for clinical application based on data obtained from previous studies. These guidelines would also help researchers in designing future studies. An in-depth review of literature on the effect of PBMT on stem cells at a molecular, cellular and tissue specific level was performed, using experts in each field of PBMT. Depending on the number of studies in each field, recommendations are presented which can suggest further studies on stem cells and PBMT. PBMT has diverse applications on stem cells. Both in-vivo and in-vitro studies represent the effectiveness of PBMT in conjunction with stem cell therapy in cell proliferation, differentiation, tissue regeneration, wound healing, angiogenesis, and treatment of different diseases. However, there is a considerable lack of clinical studies in all the reviewed fields. In each category, we attempted to recommend a PBMT protocol based on information from literature, experience, and expertise. Protocols for PBMT on stem cells were reviewed in each field of medicine, and recommendations were made for further clinical studies. Not surprising, the main wavelengths used in PBMT studies in relation to stem cells, were in the range of 630-660 nm, and 800-890 nm. However, other laser parameters are in a very wide range of difference, depending on the tissue that PBMT was applied or the aim of its application.

Photobiomodulation (PBM) has widely been used to effectively treat complications associated with cancer treatment, including oral mucositis, radiation dermatitis, and surgical wounds. However, the safety of PBM against cancer still needs to be validated as the effects of PBM on cancer cells and their mechanisms are unclear. The current study investigated the wavelength-dependent PBM effects by examining four different laser wavelengths (405, 532, 635, and 808 nm) on B16F10 melanoma tumor cells. In vitro tests showed that PBM with 808 nm promoted both proliferation and migration of B16F10 cells. In vivo results demonstrated that PBM with 808 nm significantly increased the relative tumor volume and promoted angiogenesis with overexpression of VEGF and HIF-1α. In addition, PBM induced the phosphorylation of factors closely related to cancer cell proliferation and tumor growth and upregulated the related gene expression. The current result showed that compared to the other wavelengths, 808 nm yielded a significant tumor-stimulating effect the malignant melanoma cancer. Further studies will investigate the in-depth molecular mechanism of PBM on tumor stimulation in order to warrant the safety of PBM for clinical cancer treatment.

Introduction: The purpose of this study is to achieve a significant increase in the proliferative activity of mesenchymal stem cells (MSCs) of the bone marrow (BM) at early passages after laser exposure to a suspension of these cells and to estimate the effect of light and heat components of laser radiation on the proliferation of BM MSCs. Methods: The studies were performed on rats BM MSCs. MSC suspension was placed into the wells and heated by using laser radiation (980 nm wavelength) or a water bath at 70 °C providing similar temperature dynamics. The studies were carried out in 3 comparison groups: (1) control suspension of MSCs, which was not subjected to heating in a water bath or laser exposure; (2) MSC suspension, which was heated for in a water bath; and (3) suspension of MSCs, which was subjected to laser exposure. The exposure times for the 2nd and 3rd experimental groups were 10- 50 seconds. Results: Under optimal parameters of laser action on the suspension of BM MSCs, a six-fold increase in the number of BM MSCs colonies was registered compared to the control. The role of the light and heat components of laser exposure to MSCs was determined by comparable heating of a suspension of BM MSCs in a water bath, at which only a twofold increase in the number of colonies was maximally obtained. Conclusion: The increase in the MSC proliferation activity occurs due to their Thermo-Photobiomodulation. The result obtained is important for practical use in cell transplantation in the treatment of traumatic injuries of bone, cartilage, and tendon tissues when a rapid and multiple increase in the initial number of autologous BM MSCs is required.

The method of photobiomodulation (PBM) has been used in medicine for a long time to promote anti-inflammation and pain-resolving processes in different organs and tissues. PBM triggers numerous cellular pathways including stimulation of the mitochondrial respiratory chain, alteration of the cytoskeleton, cell death prevention, increasing proliferative activity, and directing cell differentiation. The most effective wavelengths for PBM are found within the optical window (750 to 1100 nm), in which light can permeate tissues and other water-containing structures to depths of up to a few cm. PBM already finds its applications in the developing fields of tissue engineering and regenerative medicine. However, the diversity of three-dimensional (3D) systems, irradiation sources, and protocols intricate the PBM applications.

We aim to discuss the PBM and 3D tissue engineered constructs to define the fields of interest for PBM applications in tissue engineering.

First, we provide a brief overview of PBM and the timeline of its development. Then, we discuss the optical properties of 3D cultivation systems and important points of light dosimetry. Finally, we analyze the cellular pathways induced by PBM and outcomes observed in various 3D tissue-engineered constructs: hydrogels, scaffolds, spheroids, cell sheets, bioprinted structures, and organoids.

Our summarized results demonstrate the great potential of PBM in the stimulation of the cell survival and viability in 3D conditions. The strategies to achieve different cell physiology states with particular PBM parameters are outlined.

PBM has already proved itself as a convenient and effective tool to prevent drastic cellular events in the stress conditions. Because of the poor viability of cells in scaffolds and the convenience of PBM devices, 3D tissue engineering is a perspective field for PBM applications.

This paper deals with the effect of photobiomodulation (PBM) on Daphnia magna S. and their sensitivity to cadmium sulfate, a known high toxic pollutant. In a first series of experiments, the effect of different He-Ne laser fluences irradiation (range 0.9-4300 mJ cm^-2 ) on the fertility of both parent and filial generations (F1-F3) of the crustacean was studied. It was found that PBM in some cases significantly influenced the fertility of both irradiated crustaceans and their nonirradiated offspring. By selecting two fluences (9 ± 2 mJ cm^-2 reducing fertility and 4.3 ± 0.9 J cm^-2 increasing it), the effect of these on toxicity of cadmium sulfate was evaluated. These experiments have shown that prior irradiation with low-intensity light of a helium-neon laser with 632.8 nm wavelength can change the sensitivity of aquatic organisms to toxin cadmium sulfate. The degree and direction of changes depend on the toxicant concentration and the irradiation dose.