Histological and immunohistochemical assessment of skin wound defect healing using biodegradable tissue-engineered products in deep frostbite

Background. The development of new modifications of biodegradable tissue-engineered products (BTEP) for the treatment of deep frostbite remains highly relevant in the field of critical temperature medicine. One of the key regulators of cell proliferation, migration, tissue remodeling, fibrogenesis, and regeneration is transforming growth factor beta-1 (TGF-β1).

Objective: to perform histological and immunohistochemical (IHC) assessment of wound defect healing after deep skin frostbite in an experiment using standard therapy and in combination with BTEP implantation.

Material and methods. The study was conducted on 50 male Wistar rats. Deep contact frostbite of the dorsal skin (grade III) was modeled in rats of the control and experimental groups, after which the control group received standard frostbite therapy, while the experimental group additionally received BTEP implantation. The animals were removed from the experiment on days 7 and 14. The morphology of the wound defect in skin specimens was assessed using hematoxylin-eosin staining. TGF-β1 expression was evaluated by the IHC method as the percentage of protein-expressing dermal cells.

Results. On day 7, the experimental group showed active ingrowth of dermal fibers into the BTEP implantation zone and the formation of a moderate perifocal vascular network with signs of spasm. By day 14, a branched microcirculatory bed had formed without signs of congestive insufficiency. According to IHC analysis, the TGF-β1 expression level in the comparison group on days 7 and 14 was 5.84-fold (p=0.012) and 5.56-fold higher (p=0.025), respectively, than in the intact group. In the experimental group, the protein level was elevated on day 7 (3.38-fold, p=0.028), whereas no significant differences were detected on day 14 (p=0.116). TGF-β1 expression in the experimental group was significantly lower than in the comparison group both on day 7 (1.73-fold, p=0.024) and on day 14 (5.13-fold, p=0.017). Moreover, in the experimental group, the protein level decreased 3.12-fold by day 14 relative to day 7 (p=0.031), whereas in the comparison group there was no dynamics (p=0.213).

Conclusion. The use of BTEP not only ensures structural replacement of the defect but also regulates the molecular mechanisms of the wound process in deep frostbite, preventing the formation of a coarse scar through the control of TGF-β1 expression.

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