Wound healing treatment using insulin within polymeric nanoparticles in the diabetes animal model

The aim of this work was to prepare chitosan nanoparticles containing insulin and to evaluate its therapeutic activity during wound healing in diabetic rats. The hypothesis that guided this study was that the combination of insulin within chitosan nanoparticles could stimulate the signaling pathway for wound healing. The chitosan nanoparticles were prepared by the ionotropic gelation method presenting average size of 183.3 ± 8.32 nm, polydispersity index (PDI) 0.397 ± 0.07 and zeta potential of 33.7 ± 2.45 mV for empty chitosan nanoparticles (EC) and 245.9 ± 25.46 nm and PDI 0.463 ± 0.01, and zeta potential of 39.3 ± 4.88 mV for chitosan nanoparticles containing insulin (IC). The insulin association efficiency was 97.19% ± 2.18. These nanoparticles and free insulin (FI) were incorporated within a hydrogel (Sepigel®) for topical application in the wound of 72 diabetic rats distributed in four groups: Sepigel® (S, control), free insulin (FI), empty chitosan nanoparticles (EC), and chitosan nanoparticles containing insulin (IC). The animals in each group were reorganized into three subgroups (n = 6) to assess their clinical signs after days 3, 7, and 14 from the beginning of treatments. Intense fibroplasias were observed in the free or insulin-chitosan nanoparticles groups. In the latter, a large number of blood vessels were observed at day 7th. Our data indicated that both empty and insulin-containing chitosan nanoparticles were able to stimulate inflammatory cell proliferation, and angiogenesis, followed by wound maturation.