Mesenchymal stem cell-conditioned medium accelerates type 2 diabetic wound healing by targeting TNF and chemokine signaling.

Introduction: Given the crucial role of paracrine signaling in the therapeutic function of adipose tissue-derived mesenchymal stem cells (ADSCs) for skin wound repair, this study aimed to evaluate the efficacy of ADSC-conditioned medium (ACM) in enhancing type 2 diabetic (T2D) wound healing.

Methods: The effect of ACM on the viability and angiogenesis of human umbilical vein endothelial cells (HUVECs) was first evaluated using the CCK-8 assay and q-PCR analysis, respectively. Next, a T2D rat model was established through the combination of a high-fat diet and streptozotocin (STZ). Following the establishment of full-thickness skin defects in T2D rats, ACM or serum-free cultured medium was daily injected around the wound edges for 7 days. Afterward, the skin wound healing rate was analyzed, and the skin tissues were assessed by histopathological examination. The mRNA levels of TNF-α, IL-1β, IL-6, COX-2, IL-12, and IFN-γ were evaluated by q-PCR analysis. Additionally, transcriptome sequencing and immunohistochemistry were performed to reveal the potential mechanisms of ACM in T2D skin wound healing.

Results: ACM significantly enhanced HUVEC proliferation and angiogenesis while upregulating the expression of EGF, bFGF, VEGF, and KDR. In T2D rats, ACM accelerated wound closure and suppressed pro-inflammatory mediators (TNF-α, IL-1β, IL-6, COX-2, IL-12, and IFN-γ). Notably, transcriptome analysis revealed ACM-mediated downregulation of TNF and chemokine signaling pathways.

Discussion: ACM promotes diabetic wound healing through dual mechanisms: (1) stimulating vascularization by inducing growth factor expression and (2) modulating the inflammatory microenvironment by inhibiting TNF/chemokine cascades. These findings position ACM as a promising cell-free therapy for impaired wound healing in diabetes.