Additive Effects of Photobiomodulation and Adipose-Derived Stem Cells on Stereology, Macrophage Polarization, and Growth Factor Expression in the Inflammatory and Proliferative Phases of Type 2 Diabetic Wound Healing in Rats

Abstract

Background: Diabetes mellitus (DM) is a global health concern, with 90% of cases diagnosed as type 2 DM (DM2). Objective: We evaluated the effects of photobiomodulation (PBM) plus adipose-derived stem (ADS) cells, alone and together, during the inflammation (day 4) and proliferation (day 8) stages of the wound healing process (WHP) in an infected ischemic wound model in DM2 rats. Stereological parameters and immunohistological assessments of M1 and M2 macrophage phenotypes, as well as mRNA expression levels of four genes, were assessed. Materials and Methods: We assigned 48 rats to 4 groups: control, PBM, ADS, and PBM+ADS. Results: On day 4, the treatment groups had significantly reduced neutrophil, macrophage, and M1 counts compared to the control group (all p < 0.001). PBM+ADS showed the greatest reduction (p < 0.001). The treatment groups had higher fibroblast and M2 counts (p < 0.001), with PBM+ADS showing the largest increase (p < 0.01). Vascular length was significantly greater in the PBM+ADS and PBM groups (p < 0.001), with PBM+ADS showing the highest increase (p < 0.001). New epidermis and dermis volumes were significantly higher in all treatment groups (p < 0.001), with PBM+ADS showing the greatest improvements (p < 0.001). On day 8, neutrophil, macrophage, and M1 counts remained significantly lower in all treated groups (p < 0.001), with PBM+ADS showing the most reduction. Fibroblasts and M2 counts remained elevated, with PBM+ADS having the highest values (p < 0.001). Vascular length, epidermis, and dermis volumes increased significantly in the PBM+ADS group (all p < 0.001). There were significant increases in basic fibroblast growth factor, vascular endothelial growth factor A, stromal cell-derived factor-1α, and hypoxia-inducible factor 1-alpha in all treatment groups (all p < 0.001), especially the PBM+ADS and PBM groups. Conclusion: Although PBM outperformed ADS in enhancing WHP in a DM2 rat model, the combination of PBM+ADS showed the best results.

Keywords: adipose-derived stem cells; diabetes mellitus; gene expression; photobiomodulation; rat; stereology; wound healing process.