Cyclosporine A impairs bone repair in critical defects filled with different osteoconductive bone substitutes

Abstract The aim of this study was to assess the influence of cyclosporine administration on the repair of critical-sized calvaria defects (CSDs) in rat calvaria filled with diverse biomaterials. Sixty animals were divided into two groups: the control (CTR) group (saline solution) and the cyclosporine (CCP) group (cyclosporine, 10 mg/kg/day). These medications were administered daily by gavage, beginning 15 days before the surgical procedure and lasting until the day the animals were euthanized. A CSD (5 mm Ø) was made in the calvaria of each animal, which was allocated to one of 3 subgroups, according to the biomaterial used to fill the defect: coagulum (COA), deproteinized bovine bone (DBB), or biphasic calcium phosphate ceramics of hydroxyapatite and β-phosphate tricalcium (HA/TCP). Euthanasia of the animals was performed 15 and 60 days after the surgical procedure (n = 5 animals/period/subgroup). Bone repair (formation) assessment was performed through microtomography and histometry, while the analyses of the expression of the BMP2, Osteocalcin, and TGFβ1 proteins were performed using immunohistochemistry. The CSDs not filled with biomaterials demonstrated lower bone formation in the CCP group. At 15 days, less bone formation was observed in the CSDs filled with DBB, a smaller volume of mineralized tissue was observed in the CSDs filled with HA/TCP, and the expression levels of BMP2 and osteocalcin were lower in the CCP group compared to the CTR group. The use of cyclosporine impaired bone repair in CSD, and this effect can be partially explained by the suppression of BMP2 and osteocalcin expression.

摘要 本研究旨在评估环孢素（cyclosporine）给药对填充不同生物材料的大鼠颅骨临界尺寸缺损（critical-sized calvaria defects, CSDs）修复的影响。将60只实验动物分为两组：对照组（CTR，生理盐水组）与环孢素组（CCP组，给药剂量为10 mg/kg/天）。两种药物均通过灌胃每日给药，于手术前15天开始给药，持续至动物安乐死当日。为每只大鼠颅骨制备直径5 mm的临界尺寸颅骨缺损（CSD），并按填充缺损的生物材料分为3个亚组：血凝块组（COA）、脱蛋白牛骨组（deproteinized bovine bone, DBB）以及羟基磷灰石与β-磷酸三钙双相磷酸钙陶瓷组（hydroxyapatite and β-phosphate tricalcium, HA/TCP）。分别于术后15天和60天对动物实施安乐死，每个亚组每个时间点取5只动物。骨修复（骨形成）评估采用显微断层扫描（microtomography）与组织计量学（histometry）完成，而骨形态发生蛋白2（BMP2）、骨钙素（Osteocalcin）及转化生长因子β1（TGFβ1）的蛋白表达分析则采用免疫组织化学法（immunohistochemistry）进行。未填充生物材料的临界尺寸颅骨缺损在环孢素组中的骨形成量更低。术后15天时，填充脱蛋白牛骨的颅骨缺损骨形成量更少，填充羟基磷灰石与β-磷酸三钙双相磷酸钙陶瓷的颅骨缺损矿化组织体积更小，且环孢素组的骨形态发生蛋白2与骨钙素表达水平较对照组更低。研究表明，环孢素的使用会损害临界尺寸颅骨缺损的骨修复，这一效应可部分通过抑制骨形态发生蛋白2与骨钙素的表达得以解释。