Efficient delivery of VEGF-A mRNA for promoting diabetic wound healing via ionizable lipid nanoparticles.

Diabetes is often accompanied by chronic non-healing wounds, and vascularendothelial growth factor A (VEGF-A) is crucial in the treatment of chronic diabetic wounds. However, the application of VEGF-A protein in clinic is limited due to poor absorption and short half-life of protein macromolecule. Herein, we employed an emerging protein replacement therapy by delivering VEGF-A mRNA into the body to express the desired protein to accelerate diabetic wound healing. Primarily, VEGF-A mRNA was synthesized by an in vitro transcription (IVT) method and encapsulated with an ionizable lipid-mediated nanoparticles (LNP) delivery system via a microfluidic method. The resultant LNP/VEGF-A mRNA were characterized by using dynamic light scattering (DLS) and transmission electron microscope(TEM). The nanoparticles have regular spherical morphology with an average particle size of 101.17 nm, a narrow polydispersity (PDI) of 0.17 and negative Zeta potential of -3.05 mV. The bioactivities of the nanoparticles formulation were evaluated against HUVEC cells through cell proliferation, migration and tube formation assays. It was found that the LNP/VEGF-A mRNA nanoparticles could promote endothelial cell proliferation. In addition, they exhibited successful mRNA delivery and high VEGF-A protein expression in vitro and in vivo by means of Western Blot assay and in vivo imaging system (IVIS). Finally, C57BL/6 diabetic mice model was established and intradermally treated with the LNP/VEGF-A mRNA nanoparticles. It was found that the LNP/VEGF-A mRNA treated wounds were almost healed after 14 days with an average wound area of 2.4 %, compared with the PBS group of 21.4 %. Apparently, the nanoparticles formulation was able to significantly expedite diabetic wound healing. The histological analysis containing H&E, Masson's trichrome staining and CD31 further confirmed the healing efficacy and low toxicity of the formulation. Taken together, the LNP/VEGF-A mRNA nanoparticles can be taken up by cells to express protein effectively and improve diabetic wound healing, which might have potential application in the treatment of chronic diabetic wounds as a protein replacement therapy.