The effect of a self‐assembling peptide nanofiber scaffold (peptide) when used as a wound dressing for the treatment of deep second degree burns in rats

Abstract

RADARADARADARADA (RADA16-I) peptide, consisting of 16 alternating hydrophobic and hydrophilic (also alternating negative and positive charges) amino acids, forms extremely stable beta-pleated sheet structure and then self-assembles into nanofibers to produce high-order interwoven nanofiber scaffold hydrogel. To investigate its therapeutic effects, a burn model of partial thickness-deep dermal injury (the deep second degree burns) was performed at the dorsal skin of female Sprague-Dawley rats with an electrical scalding machine. The wounds treated with either RADA16-I or control materials were carefully examined at morphological, histological and cellular levels. We found that RADA16-I can advance the time of eschar appearance and the time of eschar disappearance both by 3-5 days, and speed up wound contraction by 20-30% compared with contrast groups (chitosan, poly(DL)-lactic acid (PDLA), collagen I and the blank) without obvious edema. Immunohistochemical studies showed that both FGF and EGF were obviously expressed in nascent tissue such as epidermis and glands when wounds were treated with the RADA16-I after injury. When peptide stock solution was diluted from 10 to 0.17 mg/mL, atomic force microscopy (AFM) observation showed that the shape of peptide nanofibers changed from the globular-pieces-clustered filaments with 4.8 +/- 0.38 nm in height, 61.6 +/- 6.10 nm in width and 708 +/- 80.2 nm in length, to general filaments with 1.4 +/- 0.36 nm, 17.5 +/- 1.13 nm and 1108 +/- 184 nm. The nanofiber surface porosity gradually decreased from 49-70% to 12-28%. These characteristics contribute to wound healing by offering an "ideal dressing" moist healing microenvironment and a nanofiber 3D scaffold. These results suggest that the self-assembling peptide might be a promising wound dressing with being simple, effective, and affordable.