Abstract
BACKGROUND: Flap necrosis post-operation disturbs surgeons during plastic and reconstructive surgery. This is caused by hypoperfusion and subsequent ischemia-reperfusion injury, where restricted blood flow followed by restored circulation paradoxically exacerbates tissue damage. Mesenchymal stem cells, which show multidirectional differentiation, provide hematopoietic support and are involved in immune regulation and anti-fibrosis, have inspired research on improving the blood supply of flaps. METHODS: Primary human umbilical cord mesenchymal stem cells (HuMSCs), were obtained and subcultured for expansion. The cells of the third generation were incubated in a gelatin sponge. Thirty Kunming mice were randomly divided into three groups, and saline, HuMSCs, and HuMSCs-CM were injected preoperatively into the skin of the back. The vessel density was assessed on the tenth day. Forty-eight Kunming mice were divided into two groups. Group A was subdivided into the saline group, HuMSCs, and HuMSCs-CM groups and pretreated as described above. In Group B, the intervention was changed from injection to subcutaneous embedding. Random flaps were made on the back in both groups on the tenth day after pretreatment. The survival rate of the flap was calculated on the seventh day. RESULTS: HuMSCs-CM significantly increased the microvessel density on the tenth day after pretreatment. The flap survival rate was higher in the cell and CM groups, rising from approximately 13% to 60% in Group A, and to about 75% in Group B. Moreover, subcutaneous embedding of cell-carrying gelatin sponges improved flap survival compared to other interventions. CONCLUSION: Improved cell incubation conditions can enhance its utility. The application of HuMSCs and their conditioned medium promoted the survival of the flap by inducing neovasculogenesis.