Activation of angiopoietin-1 signaling with engineering mesenchymal stem cells promoted efficient angiogenesis in diabetic wound healing

Background: 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.

Methods: 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 (MSC^ANG1) 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 MSC^ANG1 were assessed in primary endothelial cell cultures. Subsequently, MSC^ANG1 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.

Results: The comprehensive analysis of the temporal expression of pro- and anti-angiogenic factors revealed a consistent impairment in ANG1 expression throughout diabetic wound healing. MSC^ANG1 exhibited robust EGFP expression in 80% of cells, with overexpression and secretion of the ANG1 protein. MSC^ANG1 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 MSC^ANG1 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 MSC^ANG1-treated diabetic wounds confirmed efficient angiogenesis process. Consequently, epidermal and dermal reconstruction, as well as skin appendage regeneration were markedly accelerated in MSC^ANG1-treated diabetic wounds compared to MSC-treated wounds.

Conclusion: 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.

Angiogenesis; Angiopoietin-1; Diabetic Wound Healing; Mesenchymal stem cells; Vascular leakage.