Effects of allogeneic mouse adipose-derived mesenchymal stem cell-microporous sheep acellular dermal matrix on healing of wound with full-thickness skin defect in mouse and the related mechanism

Abstract

Objective: To explore the allogeneic mouse adipose-derived mesenchymal stem cell (ADSC)-microporous sheep acellular dermal matrix (ADM) on healing of wound with full-thickness skin defect in mouse and the related mechanism. Methods: One Kunming mouse was sacrificed by cervical dislocation to collect adipose tissue from inguinal region. Mouse ADSCs were isolated from the adipose tissue and cultured in vitro. Cells of the third passage were identified by cell adipogenic and osteogenic differentiation. The expressions of CD73, CD90, CD105, and CD34 were analyzed by flow cytometry. After one sheep was sacrificed, microporous sheep ADM was prepared from sheep back using decellularization method and freezing-thawing method. A 12 mm diameter, round, full-thickness skin defect wound was made on the back of each one of 36 Kunming mice. The wounds were covered by microporous sheep ADM. The mice were divided into group ADSC and control (C) group with 18 mice in each group according to the random number table after surgery. A volume of 0.2 mL DMEM/F12 culture medium containing 1×10(6) ADSCs was injected between microporous sheep ADM and wound of mice in group ADSC. While 0.2 mL DMEM/F12 culture medium was injected between microporous sheep ADM and wound of mice in group C. On post surgery day (PSD) 12 and 17, wound healing rates of mice in the 2 groups were calculated. On PSD 7, 12, and 17, wound vascularization of mice in the 2 groups was observed under reverse irradiation of backlight. On PSD 7, 12, and 17, the wound granulation tissue of mice in group ADSC was observed by hematoxylin and eosin staining. On PSD 7, the thicknesses of granulation tissue of mice in the 2 groups was measured. On PSD 12 and 17, expressions of VEGF in wounds of mice in the 2 groups were detected by immunohistochemical method. The sample number was 6 in each group at each time point in the above experiments. Data were processed with t test and analysis of variance of factorial design. Results: (1) After 7 days of adipogenic induction, lipid droplet was observed in cytoplasm using oil red O staining. After 21 days of osteogenic induction, black deposits of calcium salts were detected using silver nitrate staining. Expression rates of CD73, CD90, CD105, and CD34 in cells were 97.82%, 99.32%, 97.35%, and 5.88% respectively. The cells were identified as ADSCs. (2) The wound healing rates of mice in group ADSC on PSD 12 and 17 [(78±6)%, (98±3)%] were significantly higher than those in group C [(60±9)%, (90±4)%, t=4.26, 4.46, P<0.01]. (3) On PSD 7, no vessel obviously grew into the center of wounds of mice in the 2 groups, while the granulation tissue has covered the wounds of mice in group ADSC. On PSD 12, the vessels were more abundant in wounds of mice in group ADSC than those in group C. On PSD 17, big vessels crossing the whole wounds was observed in wounds of mice in group ADSC, while big vessels were observed without crossing the whole wounds in wounds of mice in group C. (4) The wounds were covered with thin granulation tissue on PSD 7, and the granulation tissue began to thicken on PSD 12 and were covered by epidermis on PSD 17 in wounds of mice in group ADSC. On PSD 7, the granulation tissue in wounds of mice in group ADSC [(0.62±0.05) mm] was significantly thicker than that in group C [ (0.31±0.04) mm, t=12.27, P<0.01]. (5) On PSD 12 and 17, expressions of VEGF in wounds of mice in group ADSC [(80.7±2.2), (0.98±0.03)/mm(2)] were significantly than those in group C [(59.5±2.4), (81.5±2.6)/mm(2,) t=15.95, 14.14, P<0.01]. Conclusions: Allogeneic mouse ADSC-microporous sheep ADM can accelerate angiogenesis and growth of granulation tissue, thus promoting wound healing, which may be due to the increase of expression of VEGF.