Morphometric evaluation of bone defect repair in calvarias of diabetic rats treated with desmineralized bone matrix

Abstract

Studies had demonstrated that Diabetes Mellitus helps the bone loss, being common the femurs head and/or lumbar spine osteopenia, as well as osteoporosis, furthermore it shows negative signals also during healing repair, as angiogenesis and blood suplies reduction, severe inflammatory response, collagen synthesis reduction, disorder in mineralization process and a imbalance between bone resorption by osteoclasts and matrix deposition by osteoblasts. Besides, other cells well as biochemical signals take part in this metabolism. Furthermore, os allogenic bonne grafts (MAOD), from an individual donor of the same species as the receptor but with different genotype, has been an alternative in the treatment of extensive bone defects, due to its osteoconductivity and osteoinductivity. Thus, the current study aims to determine through morphometric methods whether the MAOD improves the repair of bone defects in diabetic and normoglycemic rats. To do this, will be used 100 male Wistar rats with 90 days old divided into non diabetics group (n = 50), which will receive a dose of saline solution 0.9% and diabetic group (n = 50), which will be induced diabetes by applying a single intraperitoneal dose of streptozotocin (47 mg / kg). After 7 days, glucose index will be taken and only those rats that show 180 to 300 mg/dL will be included in diabetic group. Next, will be made a critical defect with 8 mm diameter in parietal bones, being that Treated Subgroup (n = 25/group) defects will be filled with allogenic bonne grafts obtained from donor rats of femurs those were demineralized with HCl 0.6N, and Untreated Subgroup (n = 25/group) defects will be filled only with blood clot obtained from the own animal by cardiac puncture. At the end of experimental periods of 0, 7, 14, 21 and 42 days (5 animals in each subgroup / period) the calvarias will be collected and fixed in 10% formalin and subjected to histological processing for morphometric analysis through the following parameters: a) the volume of newly formed bone tissue in both conditions (diabetes and normoglycemic) and treatment (untreated and treated with MAOD), b) the number of osteoclastos/mm2 kinetics in both conditions (diabetes and normoglycemic) and treatment (untreated and treated with MAOD). With the results of this analysis we will check if MAOD improves the bone defect repair in diabetic and normoglycemic rats and how much equal or different it is in diabetic rats.