Multipotent adult progenitor cells improve healing of mouse burn wounds

Background & Aim Although survival rates are increasing, burn injuries remain a challenge in the field of cutaneous wound healing. Stem cells have been shown to be a potential new therapy for burns and promote wound healing through a decrease in the inflammation and increase in collagen production. Multipotent adult progenitor cells (MAPC®) are a subpopulation of bone marrow-derived stem cells with outstanding self-renewal and differentiation capacity. MAPC cells also secrete a wide range of growth factors and cytokines which have effects on cellular activities. This study aimed to examine the effects of MAPC treatment and its secretome on burn injury repair using in vitro and in vivo models. Methods, Results & Conclusion The effect of MAPC secretome on the capacity of keratinocytes, fibroblast and endothelial cells to migrate and proliferate was determined in vitro using scratch wound closure and WST1 assay respectively. Secretome-treated fibroblasts were also immunostained for collagen 1 and 3 to investigate its effect on matrix production. Additionally, second degree burns were created on the dorsal surface of mice (n=8/group) and 5 × 10 5 MAPCs in 100µl PBS were administered via intradermal injection to the wound margins, 24h post-burn injury. The burns were imaged daily until day 7, for macroscopic wound area determination, when they were collected and analysed by H&E staining to determine dermal wound width and rate of re-epithelialisation. Masson's trichrome staining was also performed to investigate the total amount of collagen deposited within the burns. Cells treated with MAPC-secretome showed improved rate of scratch closure compared to controls. The proliferation of these cells was also increased when treated with MAPC-secretome. Moreover, fibroblasts treated with MAPC-secretome deposited more collagen 1 and 3. Burns intradermally injected with MAPCs showed a significant reduction in macroscopic wound area compared with controls at day 3 and day 7. Analysis of day 7 burn tissues showed significant decrease in the dermal wound width and increased rate of reepithelialisation. Masson's trichrome staining showed that collagen deposition in the wounds was significantly elevated following MAPC cell treatment. This study demonstrates the beneficial effects of MAPC cell therapy on burn injury repair including reduced time to healing and increased collagen deposition. The beneficial effect of MAPC cells may be due in part to the factors they secrete which improve skin cell proliferation and migration as well as collagen deposition.