Hidrogel de quitosana em diferentes graus de desacetilação na cicatrização de feridas cutâneas de ratas diabéticas

• Autor(a) principal: Souza, Taís Andrade Dias de
• Data de Publicação: 2016
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/5969
• topic: Angiogênese; Diabetes mellitus; Membrana córioalantoide; Quitina; Reparo cutâneo; Angiogenesis; Chitin; Chorioallantoic membrane; Diabetes mellitus; Skin repair; PATOLOGIA ANIMAL::PATOLOGIA CLINICA ANIMAL

Impaired wound healing is one of the main complications of diabetes. It is related to high blood glucose levels that cause metabolic and cellular changes, making the tissue repair process difficult, with long and costly treatment. Chitosan has been investigated for its biological activity when in contact with tissue. However, further elucidation about the mechanisms of chitosan’s action on the wound healing is needed, as well as how its physico-chemical and handling characteristics can offer better performance for the treatment of diabetic wounds. This study aimed to develop and characterize a chitosan hydrogel, and evaluate its angiogenic potential and healing activity in skin wounds of experimentally-induced diabetic rats. To obtain 80, 85 and 90% deacetylation degree, a deacetylation protocol was conducted in basic medium and high temperature. After hydrogels preparation, they were evaluated for pH, viscosity, organoleptic properties, microbiological contamination, and antimicrobial activity for 60 days and stored at room temperature and under refrigeration. The angiogenic potential of each formulation was investigated by the chorioallantoic membrane assay of embryonated chicken eggs, determining the vascular area by fresh analysis and vascular density by histological evaluation. The healing activity of chitosan gels was determined by the treatment of skin wounds promoted at the dorsal region of experimentally-induced diabetic female rats, evaluated at the periods of three, 7 and 14 days postoperatively. The following parameters were investigated: wound contraction rate, microscopic changes in the epidermis and dermis by hematoxylin-eosin, angiogenic activity, and cell proliferation by immunohistochemistry. The methodology used to deacetylation of the chitosan was considered appropriate, and the degrees of deacetylation pretended were obtained. During the 60 days of evaluation, there was a significant change only in the viscosity of samples kept at room temperature and refrigeration was considered the best form of storage. The angiogenic activity of chitosan gels was positive with an increase in the area and vascular density of the chorioallantoic membrane. The higher the degree of deacetylation, the greater the angiogenic response observed, therefore, the 90% deacetylation hydrogel showed the best performance in this analysis. In the treatment of skin wounds in diabetic rats, the chitosan hydrogels increased the rate of contraction of the wounds, had greater angiogenesis indexes, cell proliferation and collagen production resulting in faster healing compared to the control group. Hydrogel higher’s degree of deacetylation seems to optimize the biological activity of the polymer.