Tratamento da lesão dermonecrótica induzida pelo veneno de Loxosceles laeta com dapsona e células-tronco mesenquimais

Abstract

This study aimed to evaluate the effects of mesenchymal stem cells (MSC), isolated and associated with dapsone in dermonecrotics wounds in rabbits inoculated with 20g of Loxosceles laeta venom. 25 male adult rabbits, New Zealand, with an average weight of 1.0 kg were divided into five groups (n = 5). Except for the placebo group (PG), in which was only inoculated ultrapure water, in all other groups were applicated 20g of Loxosceles laeta venom in the interscapular region and treated four hours after with: phosphate buffer saline (PBS); dapsona (2mg/kg); MSCs (1,25X106) and association of dapsona and MSCs. The animals were evaluated daily and photographic records made at pre-set 50 cm for further analysis of the evolution of the wound area by morphometry. Blood samples were collected immediately before the application of poison and 3, 6, 9 and 12 days for evaluation and monitoring of hematological and biochemical parameters, including protein concentrations. After 12 days the animals were euthanized and skin samples (5cmx6cm) around the lesion were removed and fixed in paraformol for subsequent histological analysis. In Blood cell count, mild anemia and leukocytosis was observed (p< 0.05) three days after inoculation of the poison, except in the group which we associated dapsona e MSC where leukocytosis was not observed. In protein profile, there was a significant increase in alpha- 2 globulin (p< 0.05), 3 hours after venom inoculation, except in the group receiving dapsone. After evaluating the rate of wound contraction, we observed that MSC isolated or in association with dapsone, showed faster tissue repair when compared to other types of treatment. Histologically it was observed that the animals that received PBS showed extensive areas of necrosis, ulcers, intense neutrophilic infiltrate and mineralization. Animals treated with dapsone, MSCs and with the association between the therapies had fewer significant lesions with areas of mineralization and angiogenesis. Moreover, we observed a higher collagen deposition, mainly due to collagen type III, in the group that received dapsona + MSCs when compared with PG (p < 0.05). We conclude that therapy with MSCs, particularly when associated with dapsone should be considered as a future therapy for cutaneous loxoscelism.