Synthesis and Characterization of Exopolysaccharide Encapsulated PCL/Gelatin Skin Substitute for Full-Thickness Wound Regeneration

Abstract

Loss of skin integrity can lead to serious problems and even death. In this study, for the first time, the effect of exopolysaccharide (EPS) produced by cold-adapted yeast R. mucilaginosa sp. GUMS16 on a full-thickness wound in rats was evaluated. The GUMS16 strain's EPS was precipitated by adding cold ethanol and then lyophilized. Afterward, the EPS with polycaprolactone (PCL) and gelatin was fabricated into nanofibers with two single-needle and double-needle procedures. The rats' full-thickness wounds were treated with nanofibers and Hematoxylin and eosin (H&E) and Masson's Trichrome staining was done for studying the wound healing in rats. Obtained results from SEM, DLS, FTIR, and TGA showed that EPS has a carbohydrate chemical structure with an average diameter of 40 nm. Cell viability assessments showed that the 2% EPS loaded sample exhibits the highest cell activity. Moreover, in vivo implantation of nanofiber webs on the full-thickness wound on rat models displayed a faster healing rate when EPS was loaded into a nanofiber. These results suggest that the produced EPS can be used for skin tissue engineering applications.

Keywords: exopolysaccharide; nanofiber; tissue regeneration; wound dressing.

Figure 1

(a) FTIR spectrum, (b) TGA (blue)/DSC (black) diagram, and (c) SEM images of produced EPS.

Figure 2

SEM images (right) and fiber diameter distribution (left) of the nanofiber samples (PCL/Gel) with different EPS contents: (a) 0% EPS (b) 1% EPS (c) 2% EPS.

Figure 3

(a) Full (400–4000 cm⁻¹) and (b) magnified spectrum (900–1700 cm⁻¹) of EPS and PCL/Gel nanofibers containing different amounts of EPS. Blue and red dashed lines are the functional groups related to the PCL and gelatin portion of the nanofibers.

Figure 4

Water contact angle images (mean ± standard deviation) of (a) PCL/Gel, (b) PCL/Gel + 1% EPS, and (c) PCL/Gel + 2% EPS nanofiber web.

Figure 5

Results and statistical analysis of the cell viability examination obtained from MTT assay for PCL/Gel nanofibers containing different amounts of EPS (* p < 0.05, ** p < 0.01, *** p < 0.001).

Figure 6

(a) Macroscopic images of wound area and closure rate (from 0 to 14 days) for the control and treated groups with PCL/Gel, PCL/Gel/1% EPS, and PCL/Gel/2% EPS nanofiber samples. (b) wound closure rate was measured 15 days post-surgery.

Figure 7

Microscopic images of Hematoxylin and Eosin-stained tissues after 7- and 14-days post-surgery.

Figure 8

(a) Microscopic images of Trichrome Masson-stained tissues after 7- and 14-days post-surgery. (b) Statistical analysis according to the integrated optical density (IOD) value and mean density measured by Image-J software. Data are presented as the means ± standard deviation for at least three independent experiments. ** p < 0.01 vs. the control group, *** p < 0.01 vs. the control group.