Avaliação da proliferação pancreática induzida por implante de matriz sintética em animais diabéticos tratados com insulina

Abstract

Pancreatic disorders such as pancreatitis, pancreatic cancer, and diabetes mellitus may result in severe pancreatic dysfunctions. Study models have been developed in order to provide the understanding of the pancreatic regeneration process to aid in therapeutic strategies. The development of these models is highly relevant for understanding pancreatic regeneration and how pancreatic cells can be generated from pre-existing ones; however, the mechanism of cell proliferation and organization is still not well elucidated. In this study, we used a synthetic polyether-polyurethane matrix to induce the proliferation of pancreatic parenchyma in vivo in diabetic C57BL/6 mice. After chemical induction of diabetes (STZ), the animals were divided into three groups, with only one group (G2) receiving daily subcutaneous insulin treatment to evaluate the influence of glycemia on pancreatic proliferation. Two groups (G1 and G2) received synthetic matrices surgically placed adjacent to the native pancreas and removed 30 days after implantation. In this matrix, pancreatic components (acini, ducts, and islets), blood vessels, and inflammatory markers were analyzed. Clinical analyses showed an improvement in the metabolism of insulin-treated animals, which showed a recovery of initial weight, a decrease in glycemic levels, and an improvement in the GTT test. Morphometric analyses by H&E and immunohistochemistry were performed to evaluate the newly formed intra-implant tissue. After 30 days, the matrices were filled with clusters of pancreatic parenchyma (acini, ducts, and islet-like structures), inflammatory cells, fibroblasts, extracellular matrix components, and blood vessels. However, analyses showed that the insulin-treated group had a larger intra- implant proliferation area and a higher number of acini per field. Both groups had islet cells positive for insulin and glucagon, as well as ductal and acinar cells positive for KI- 67 and PDX1 in the intra-implant pancreatic tissue. The insulin-treated group showed an increase in all these analyses, except for the number of acinar cells positive for KI- 67. Analyses of the angiogenesis process in the intra-implant pancreatic tissue by histology and immunobiochemical methods showed an increase in the number of vessels but a decrease in VEGF levels. Additionally, an increase in various inflammatory markers and a decrease in the expression of adhesion molecules (N- CAD and E-CAD) were observed in this group. The study model demonstrated potential in proliferating exocrine (acini, ducts) and endocrine (islets) components and allowed the evaluation of molecules and cells involved in pancreatic proliferation in adult pancreatic tissue under high metabolic demand conditions, presenting better results when the animals were in normalized glycemic conditions.