A Histopathological Study of Induced Open Wounds Treated With Urinary Bladder Submucosa Scaffold in Rabbits

Treating various wounds is one of the challenges that researchers are working on to find innovative ways to shorten and accelerate healing. Various materials have been used for this purpose, including those from the submucosal layer of certain animals, such as the calf bladder used in this study. Since extracellular matrix (ECM) contains many components that are important for the healing process, such as collagen, laminin, and hyaluronic acid, it has the potential to accelerate wound healing. The study used twelve adult rabbits. After surgical preparation, a 2 × 2 cm square wound was made on each side of the animal's body behind the costal arch in the upper abdomen. The wound on the right side was washed with normal saline only as a control group, and the wound on the left side was treated with a dry decellularized ECM. Fresh urinary bladders were collected from slaughtered calves and prepared through mechanical and chemical processes for decellularization. Excess collagenous connective and adipose tissues were removed from the bladder's external surfaces. The submucosal layer, tunica serosa, and tunica muscular were carefully removed using a knife. The resulting sheet of submucosal bladder was then soaked in phosphate-buffered saline (PBS) at a pH of 7.4, which contained penicillin (100 IU/mL), streptomycin (100 μg/mL), and amphotericin (100 μg/mL). The decellularized bladder matrix (UBM) was treated with a mixture of 0.1% peracetic acid (PAA) and 4% ethanol, shaking the solution for 2 h at room temperature. The wound was covered with a sterile gauze until the seventh postwounding day (PWD), when the wound was measured, and samples were collected for histopathological examination. Additional samples were collected for histopathological examination at the 14th and 21st PWDs. Visual inspection, wound size measurement, and histopathological examination of both groups revealed that the ECM scaffold had a significant effect on accelerating healing compared with the control group starting from the seventh PWD. The percentage of wound contraction was clearly in favor of the treatment group compared to that of the control group. At the end of the experiment, the epidermal layer and rete ridge were completely thick, with fibroplasia of the dermal layer in the treated group, while in the control group, there was fibrosis in the subcutaneous tissue, and granulation tissue consisting of blood vessels, fibroblasts, and collagen fibers infiltrated with mononuclear cells, but there was no rete bridge. In conclusion, the use of ECM scaffolds plays an important role in accelerating wound healing, making its use advantageous in open wounds.