Curcumin nanoparticles incorporated collagen-chitosan scaffold promotes cutaneous wound healing through regulation of TGF-β1/Smad7 gene expression.

Wound healing is a tissue regeneration process which is regulated by a complex interaction of multiple growth factors, primarily transforming growth factor-β1 (TGF-β1). The natural antagonist of transforming growth factor-β (TGF-β) signaling is Smad7. It has been shown that curcumin (an antioxidant) and some biocompatible polymers like collagen and chitosan enhance cutaneous wound healing. In this study, three scaffolds made with curcumin-nanoparticles (CNs) and using collagen and chitosan with various ratios of collagen and chitosan were used for evaluation of wound healing activity on full thickness punch wound model using male Wistar rats. The wound healing in terms of histology and morphology was assessed at different time points post-wounding and the expression pattern of TGF-β1 and Smad7 was studied. CNs incorporated collagen-chitosan scaffolds significantly accelerated the healing of the wounds, as revealed by a significant change in the wound area, the epidermal thickness, the density of granulation tissue, the number of new vessels and a higher collagen content compared to the control group. However, blank collagen-chitosan scaffolds did not cause any significant change in the above parameters, except for epidermal thickness compared to the control group. Incorporation of CNs into collagen-chitosan scaffold changed expression of TGF-β1 and Smad7 mRNAs in the healing wounds compared to the control group. Indeed, blank collagen-chitosan scaffold did not cause any significant up-regulation either in TGF-β1 mRNA expression or in Smad7 mRNA expression (except for day 3 post-wounding), compared to the control group. This study indicates that topical application of CNs-incorporated collagen-chitosan scaffold promotes wound healing via a regulatory effect on the expression of TGF-β1 and Smad7 mRNA in the cutaneous wound-healing model.