Efeito regenerativo do óleo de pequi (Caryocar brasiliense) em transplantes heterólogos de scaffolds de pele suína em camundongos Balb/C

Abstract

The use of porcine skin acellular matrix (scaffold) has been a strategy to overcome the scarcity of skin for transplantation. In addition, the use of natural products can be an important ally to increase the success of these transplants. In this context, pequi (Caryocar brasiliense) stands out for having anti-inflammatory and healing actions, being able to modulate and accelerate tissue regeneration. To evaluate the regenerative potential of pequi oil, heterologous porcine scaffold transplantation was performed in Balb/C mice, which were treated (Treated) or not (Control) topically with pequi oil, and sacrificed on days 3, 10 and 30 after the surgical procedure. The peripheral blood of the animals was collected for leukocyte quantification. In addition, a fragment of the transplanted region was collected, fixed and histologically processed to perform several histopathological analyzes using hematoxylineosin and toluidine blue staining, in addition to picrosirius-polarization and immunohistochemistry techniques. The quantification of leukocytes revealed that treatment with pequi oil significantly increases the amount of neutrophils, eosinophils and monocytes (p ≤ 0.05) in the bloodstream. The evaluation of the transplanted scaffold showed that the animals treated with pequi oil had a greater infiltration of cells into the scaffold (p ≤ 0.001) and a lower cell density (resident cells and leukocytes; p ≤ 0.01) after 3 days, when compared to control animals. The morphometry of the newly formed epithelium (30 days) showed a significantly higher epithelial height in the animals in the Treated group (p ≤ 0.001) compared to the Control group. In the host tissue, underlying the scaffold, from animals treated with pequi oil, a significantly greater amount of myofibroblasts was observed in 3 days (p ≤ 0.05), a smaller number of polymorphonuclear cells in 10 days (p ≤ 0.05), and greater number of degranulated mast cells and collagen in 30 days (p ≤ 0.001 and p ≤ 0.05, respectively) when compared to the control group. In addition, after 3 days, a trend towards an increase in the number of blood vessels was observed in the animals in the Treated group when compared to the Control group. Still, through immunohistochemistry, it was verified that the expression of annexin A1 protein in the newly formed epithelium is significantly lower in the Treated group in 30 days (p ≤ 0.001) when compared to the Control group. Together, all these data confirm the pro-regenerative, anti-inflammatory and pro-angiogenic actions of pequi oil, because it was able to accelerate scaffold repopulation, increasing cell density and infiltration; control the transmigration of leukocytes, reducing the inflammatory infiltrate in the tissue; increase the amount of myofibroblasts and blood vessels at the beginning of the tissue repair process; contributing respectively to the acceleration of wound closure and angiogenesis. In addition, pequi oil acts in the final phase of wound repair, by modulating mast cells, AnxA1 and collagen deposition. Thus, the present study reveals, for the first time in the literature, the promising potential of pequi oil in increasing the success of heterologous skin transplants.