A single-dose of PDGFB circular RNA enables sustained growth factor expression to accelerate diabetic wound healing

Diabetic foot ulcer (DFU) is one of the most serious complications of diabetes and lack effective treatment options. Although platelet-derived growth factor-B (PDGFB) has been approved for the treatment of diabetic wounds, it is difficult to sustainably deliver PDGFB to the wound site of DFU owing to its poor stability and easy degradation. To address these limitations, we developed a lipid nanoparticle (LNP)-encapsulated PDGFB circular RNA (LNP-circPDGFB) formulation designed to achieve sustained local expression and release of PDGFB for enhanced diabetic wound healing. The therapeutic circRNA was synthesized via in vitro transcription (IVT), followed by microfluidic encapsulation into ionizable LNPs to generate LNP-circPDGFB. LNP-circPDGFB facilitated highly efficient and prolonged expression of PDGFB both in vitro and in vivo. It exhibited pleiotropic effects by promoting the proliferation and migration of vascular endothelial cells and fibroblasts, as well as the angiogenesis of vascular endothelial cells. In diabetic mice, a single administration of LNP-circPDGFB could significantly accelerate diabetic wound healing and improved histopathological outcomes without obvious immunogenicity. Single cell RNAseq results also highlighted the potential of LNP-circPDGFB to promote proliferation, migration and extracellular matrix deposition of fibroblasts and vascular repair and angiogenesis of vascular endothelial cells. Taken together, we established LNP-circPDGFB as a promising "single-dose, long-acting" therapeutic platform for DFU treatment, addressing key limitations of current therapies. By leveraging the stability of circRNA and efficient LNP delivery, this approach not only enhances diabetic wound healing but also offers a versatile framework for protein delivery in regenerative medicine.