Role of mononuclear stem cells and decellularized amniotic membrane in the treatment of skin wounds in rats

Stem cells (SC) and amniotic membrane (AM) are recognized for their beneficial impacts on the healing of cutaneous wounds. Thus, this study evaluated the capacity of tissue repair in a skin lesion rat model. Forty Wistar rats were randomized into four groups: group I - control, with full-thickness lesions on the back, without SC or AM; group II-injected SC; group III - covered by AM; group IV-injected SC and covered by AM. Lesion closure was assessed using contraction rate (Cr). Histochemical and immunohistochemical analyses were performed, and collagen, elastic fibers, fibroblast differentiation factor (TGF-beta), collagen remodeling (MMP-8), and the number of myofibroblasts and blood vessels (alpha-SMA) were evaluated. On the 7(th) postoperative day, Cr 1(st)-7(th) day levels were higher in groups III and IV. However, on the 28(th) day, Cr 1(st)-28(th) day were higher in the control group. Picrosirius staining showed that type I collagen was predominant in all groups; however, the SC + AM group obtained a higher average when compared to the control group. Elastic fiber analysis showed a predominance in groups that received treatment. Groups II and IV showed the lowest expression levels of TGF-beta and MMP-8, and alpha-SMA was significantly lower in group IV. The application of SC and AM accelerated the initial healing phase, probably owing to their anti-inflammatory effect that favored early formation of collagen and elastic fibers.