Breaking the vicious cycle of impaired angiogenesis and chronic inflammation in diabetic wounds: a bioengineered microneedle system delivering RGD-modified M2 exosomes.

Abstract

Background: Persistent local tissue hypoperfusion and chronic inflammation are central challenges in diabetic wound management. The development of effective therapeutic strategies to mitigate prolonged inflammation and enhance tissue vascularization is crucial for accelerating diabetic wound healing. This study aimed to develop soluble microneedle materials that simultaneously target both aspects to improve the clinical prognosis of diabetic wounds.

Methods: A stable macrophage cell line overexpressing basic fibroblast growth factor (bFGF) was established using lentiviral transfection. After M2 polarization was induced with interleukin-4 (IL-4) and IL-10, exosomes were isolated via ultracentrifugation and surface-functionalized with arginine-glycine-aspartic acid (RGD)-targeting peptides. The reparative effects of these exosomes on human umbilical vein endothelial cells (HUVECs) with high glucose-induced injury were evaluated using scratch test, 5-ethynyl-2'-deoxyuridine (EdU) staining, and cell counting kit-8 assays. A delivery system based on soluble hyaluronic acid microneedles (MNs) loaded with engineered exosomes was then developed. Its therapeutic efficacy was evaluated in a diabetic wound mouse model, and the underlying mechanisms were explored via ribonucleic acid (RNA) sequencing.

Results: Targeted engineered exosomes (TE-Exos) derived from bFGF-overexpressing M2 macrophages with surface RGD modification were successfully prepared. Assays revealed that TE-Exos exhibited specific targeting to HUVECs with high glucose-induced injury and significantly enhanced cellular proliferation, migration, and tube formation. Furthermore, the polarization ratio of macrophages improved after TE-Exos treatment. In vivo, the MN-mediated delivery of TE-Exos markedly accelerated diabetic wound healing by enhancing re-epithelialization, collagen deposition, and angiogenesis. Furthermore, the treatment modulated the wound microenvironment by reducing the infiltration of proinflammatory M1 macrophages while increasing the proportion of reparative M2 macrophages. RNA sequencing analysis indicated that the therapeutic effects were mediated primarily through the inhibition of excessive inflammation and the activation of angiogenesis-related signaling pathways.

Conclusions: This innovative strategy breaks the vicious cycle of impaired angiogenesis and chronic inflammation in diabetic wounds through a synergistic mechanism involving 'angiogenesis, inflammation regulation, and precise delivery'. The combination of targeted exosome engineering with an MN delivery system not only overcomes the limitations of conventional growth factor therapies but also enables intelligent modulation of the wound microenvironment, offering novel theoretical insights and practical approaches for clinical translation.