Characterization and Evaluation of Carboxymethyl Cellulose-Based Films for Healing of Full-Thickness Wounds in Normal and Diabetic Rats

Abstract

Artificial skin substitute made of polymeric films are of great demand in the field of skin tissue engineering. We report here the fabrication of carboxymethyl cellulose (CMC) and poly(ethylene glycol) (PEG) blend films by solution casting method for wound healing applications. The physicochemical characteristics and the thermal stability of the films were analyzed. The surface morphology shows crystalline structures with large hexagonal-like platelet crystals of CMC on the surface of the films. Pure CMC films exhibited higher tensile strength than the CMC/PEG blend films. The swelling ratio (SR) of the films was influenced by the pH of Tris-HCL buffer (2.0, 5.0, and 7.0), which increased with increase in pH. The hemocompatibility assay and cytotoxicity test using NIH 3T3 fibroblast cells showed that the films were biocompatible. To evaluate the wound healing efficacy, the films were applied in full-thickness wounds created in normal and diabetic Wistar albino rats. The wounds healed faster with pure CMC film compared to blend films in both normal and diabetic rats, evidenced by intensive collagen formation in histopathological analysis. Thus, the films have potential application in skin regeneration, thereby to restore the structural and functional characteristics of the skin.

Figure 1

(a) X-ray diffraction patterns of the films. CMC and PEG peaks are indexed as (•) and (Δ), respectively. (b) Fourier transform infrared (FTIR) spectra; (c) differential scanning calorimeter (DSC) curves; and (d) thermogravimetric analyzer (TGA) traces of the films.

Figure 2

Stress vs strain curves of the films. The maximum tensile stress, ultimate tensile strength, and Young’s modulus were calculated from the stress–strain curves.

Figure 3

Scanning electron microscopy (SEM) images of (a) CMEG00, (b) CMEG25, and (c) CMEG50 showing platelet-like crystals (magnification level: 5000×).

Figure 4

Swelling ratio of the films in Tris buffer of pHs 2.0, 5.0, and 7.0 at 37 °C after 12 h (*p < 0.05, **p < 0.01, ***p < 0.001, ns = not significant).

Figure 5

Scanning electron microscopy images of the red blood cells adhered to the films: (a) CMEG00; (b) CMEG25, and (c) CMEG50 after hemocompatibility test (magnification level: 15 000×).

Figure 6

Photographs of the wound area in normal and diabetic rat models on days 0, 8, and 16 postsurgery, showing gradual healing of wound with time. The wound in normal healthy rat healed completely on 16th day (as marked by black circles), whereas in control and diabetic rats, the wound still persisted. The scale bar is 1 cm.

Figure 7

Percentage of wound closure in normal (unfilled symbols) and diabetic (filled symbols) rats on days 8, 12, and 16 compared individually. CMEG00, CMEG25, and CMEG50 films are represented as (◊), (□), and (Δ) respectively.

Figure 8

H&E staining of the wound sections collected on days 8 and 12 in normal and diabetic rat models. Control group is untreated open wounds, and experimental group is treated with three different films: CMEG00, CMEG25, and CMEG50.

Figure 9

Masson’s trichrome staining for histological sections on days 8 and 12 in normal and diabetic rat models. Original magnification 400× (the scale bar is 100 μm). Control group is untreated open wounds, and experimental group is treated with three different films: CMEG00, CMEG25, and CMEG50.