Significance: 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.Aim: We aim to discuss the PBM and 3D tissue engineered constructs to define the fields of interest for PBM applications in tissue engineering.Approach: 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.Results: 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.Conclusions: 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.
One of the promising approaches to the treatment of injured tissue is the application of bioengineering techniques based on the introduction of cells into the damage area. An application of cells alone does not provide a complete replacement of the tissue defect. Therefore, scaffolds are used allowing organization of the cells into a structure, which is capable of the total reproduction of the damaged tissue integrity. Great number of factors, which influence the cell behavior and tissue formation at the injury site when using scaffolds are known. Here, we analyzed the effect of structural heterogeneity of scaffolds on cellular behavior and metabolism. All scaffolds were obtained by two-photon polymerization technic. It was found that colonization of heterogeneous scaffolds was insignificant less than homogeneous ones. However, there were not dead cells on heterogeneous matrix. We found that the level of free and bound NAD(P)H for the cells on the heterogeneous and homogeneous scaffolds was differ. This can indicate a different contribution of glycolysis and oxidative phosphorylation intensity in stem cells seeded on two types of scaffolds.
Significance: Currently, various scaffolds with immobilized cells are widely used in tissue engineering and regenerative medicine. However, the physiological activity and cell viability in such constructs might be impaired due to a lack of oxygen and nutrients. Photobiomodulation (PBM) is a promising method of preconditioning cells to increase their metabolic activity and to activate proliferation or differentiation.
Aim: Investigation of the potential of PBM for stimulation of cell activities in hydrogels.
Approach: Mesenchymal stromal cells (MSCs) isolated from human gingival mucosa were encapsulated in modified fibrin hydrogels with different thicknesses and concentrations. Constructs with cells were subjected to a single-time exposure to red (630 nm) and near-infrared (IR) (840 nm) low-intensity irradiation. After 3 days of cultivation, the viability and physiological activity of the cells were analyzed using confocal microscopy and a set of classical tests for cytotoxicity.
Results: The cell viability in fibrin hydrogels depended both on the thickness of the hydrogels and the concentration of gel-forming proteins. The PBM was able to improve cell viability in hydrogels. The most pronounced effect was achieved with near-IR irradiation at the 840-nm wavelength.
Conclusions: PBM using near-IR light can be applied for stimulation of MSCs metabolism and proliferation in hydrogel-based constructs with thicknesses up to 3 mm.
Photobiomodulation (PBM) using nonionizing light sources, including lasers, light-emitting diodes, and/or broadband light, in the visible (400 to 700 nm) and near-infrared (700 to 1100 nm) electromagnetic spectrum, has been successfully exploited for multiple therapeutic purposes. We analyzed the effects of red and infrared irradiation on neuroblastoma cells in an in vitro rotenone model of Parkinson’s disease. Cell viability was assessed by colorimetric assay for metabolic activity (MTT test), and the oxygen consumption rate was analyzed using a Seahorse analyzer. Low doses of rotenone slightly, but not significantly, suppressed oxygen consumption and did not affect cell viability within 2 hours of treatment. PBM stimulated mitochondrial respiration overcoming rotenone-induced inhibition. At high doses (50 μM), rotenone moderately suppressed cell viability, which was reversed by PBM. Thus, preliminary treatment with red and infrared radiation improves cell viability and enhances mitochondrial oxygen consumption in an in vitro rotenone model of Parkinson’s disease.
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