Chenglong Li

Vascular insufficiency is associated with the pathogenesis and therapeutic outcomes of diabetic foot ulcers (DFU). While mesenchymal stem cells (MSCs) hold potential for DFU treatment, further enhancement in promoting angiogenesis in the challenging DFU wounds is imperative. The differential expression of pro- and anti-angiogenic factors during both normal and diabetic wound healing was compared using quantitative PCR. MSCs derived from the umbilical cord was prepared, and the engineered MSC (MSCANG1) overexpressing both the candidate pro-angiogenic gene, angiopoietin-1 (ANG1), and green fluorescent protein (GFP) was constructed using a lentiviral system. The pro-vascular stabilizing effects of MSCANG1 were assessed in primary endothelial cell cultures. Subsequently, MSCANG1 was transplanted into streptozotocin (STZ)-induced diabetic wound models to evaluate therapeutic effects on angiogenesis and wound healing. The underlying mechanisms were further examined both in vitro and in vivo. The comprehensive analysis of the temporal expression of pro- and anti-angiogenic factors revealed a consistent impairment in ANG1 expression throughout diabetic wound healing. MSCANG1 exhibited robust EGFP expression in 80% of cells, with overexpression and secretion of the ANG1 protein. MSCANG1 notably enhanced the survival and tubulogenesis of endothelial cells and promoted the expression of junction proteins, facilitating the establishment of functional vasculature with improved vascular leakage. Although MSCANG1 did not enhance the survival of engrafted MSCs in diabetic wounds, it significantly promoted angiogenesis in diabetic wound healing, fostering the establishment of stable vasculature during the healing process. Activation of the protein kinase B (Akt) pathway and suppression of proto-oncogene tyrosine kinase Src (Src) activity in MSCANG1-treated diabetic wounds confirmed efficient angiogenesis process. Consequently, epidermal and dermal reconstruction, as well as skin appendage regeneration were markedly accelerated in MSCANG1-treated diabetic wounds compared to MSC-treated wounds. Treatment with MSCs alone promotes angiogenesis and DFU healing, while the engineering of MSCs with ANG1 provides substantial additional benefits to this therapeutic process. The engineering of MSCs with ANG1 presents a promising avenue for developing innovative strategies in managing DFU.

Introduction: Mesenchymal stem cells (MSCs) have been introduced as a promising treatment for diabetic wounds. The effects of stem cell therapy are thought to be caused by bioactive molecules secreted by stem cells. Stem cell-based gene therapies can target bioactive molecules. Therefore, treatment using conditioned medium (CM) derived from genetically engineered stem cells has been proposed as an alternative option for diabetic ulcer care. Methods: MSCs derived from human umbilical cords were obtained and engineered to overexpress the angiogenin-1 gene (MSCs^Ang1) through plasmid transfection. This study extracted conditioned medium from MSCs (MSC-CM) or MSCs^Ang1(MSC^Ang1-CM) for wound treatment applications. Via in vitro experiments, the proangiogenic effects of MSC^Ang1-CM were assessed via the migration and tube formation of human umbilical vein endothelial cells (HUVECs). Furthermore, the efficacy of MSC^Ang1-CM in promoting wound healing, re-epithelialization, hair follicle, and angiogenesis was evaluated via a diabetic mouse skin defect model. Results: In vitro assays demonstrated that MSC^Ang1-CM significantly enhanced HUVECs’ functions, including migration and tube formation. In vivo assays revealed that MSC^Ang1-CM exhibited notable advancements in healing speed, re-epithelialization, hair follicle, and angiogenesis. Conclusion: These results indicate that MSC^Ang1-CM can promote wound healing in diabetic mice and make the vascular structure in regenerated tissues more stable without inducing tissue fibrosis, providing a new therapeutic strategy for treating diabetic skin wounds. This provides a valuable theoretical basis for further research on regenerative medicine and cell therapy.