Deng Zhenhan, Gao Xueqin, Utsunomiya Hajime, Arner Justin W, Ruzbarsky Joseph J, Huard Matthieu, Ravuri Sudheer, Philippon Marc J, Huard Johnny
Department of Orthopaedic Surgery, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, USA.
Steadman Philippon Research Institute, Vail, CO, USA.
Bone Rep. 2022 Mar 28;16:101526. doi: 10.1016/j.bonr.2022.101526. eCollection 2022 Jun.
Previous work has shown that oral losartan can enhance microfracture-mediated cartilage repair in a rabbit osteochondral defect injury model. In this study, we aimed to determine whether oral losartan would have a detrimental effect on articular cartilage and bone homeostasis in the uninjured sides.
New Zealand rabbits were divided into 4 groups including normal uninjured (Normal), contralateral uninjured side of osteochondral defect (Defect), osteochondral defect plus microfracture (Microfracture) and osteochondral defect plus microfracture and losartan oral administration (10 mg/kg/day) (Losartan). Rabbits underwent different surgeries and treatment and were sacrificed at 12 weeks. Both side of the normal group and uninjured side of treatment groups tibias were harvested for Micro-CT and histological analysis for cartilage and bone including H&E staining, Herovici's staining (bone and cartilage) Alcian blue and Safranin O staining (cartilage) as well as immunohistochemistry of losartan related signaling pathways molecules for both cartilage and bone.
Our results showed losartan oral treatment at 10 mg/kg/day slightly increase Alcian blue positive matrix as well as decrease collagen type 3 in articular cartilage while having no significant effect on articular cartilage structure, cellularity, and other matrix. Losartan treatment also did not affect angiotensin receptor type 1 (AGTR1), angiotensin receptor type 2 (AGTR2) and phosphorylated transforming factor β1 activated kinase 1 (pTAK1) expression level and pattern in the articular cartilage. Furthermore, losartan treatment did not affect microarchitecture of normal cancellous bone and cortical bone of tibias compared to normal and other groups. Losartan treatment slightly increased osteocalcin positive osteoblasts on the surface of cancellous bone and did not affect bone matrix collagen type 1 content and did not change AGTR1, AGTR2 and pTAK1 signal molecule expression.
Oral losartan used as a microfracture augmentation therapeutic does not have significant effect on uninjured articular cartilage and bone based on our preclinical rabbit model. These results provided further evidence that the current regimen of using losartan as a microfracture augmentation therapeutic is safe with respect to bone and cartilage homeostasis and support clinical trials for its application in human cartilage repair.
先前的研究表明，在兔骨软骨缺损损伤模型中，口服氯沙坦可增强微骨折介导的软骨修复。在本研究中，我们旨在确定口服氯沙坦是否会对未受伤侧的关节软骨和骨稳态产生不利影响。
将新西兰兔分为4组，包括正常未受伤组（正常组）、骨软骨缺损对侧未受伤组（缺损组）、骨软骨缺损加微骨折组（微骨折组）和骨软骨缺损加微骨折并口服氯沙坦组（10mg/kg/天）（氯沙坦组）。兔接受不同的手术和治疗，并在12周时处死。采集正常组双侧及治疗组胫骨未受伤侧，进行Micro-CT和组织学分析，观察软骨和骨的情况，包括苏木精-伊红染色、赫罗维茨染色（骨和软骨）、阿尔辛蓝和番红O染色（软骨），以及软骨和骨中氯沙坦相关信号通路分子的免疫组织化学分析。
我们的结果显示，每天口服10mg/kg氯沙坦治疗可使关节软骨中阿尔辛蓝阳性基质略有增加，同时使3型胶原蛋白减少，而对关节软骨结构、细胞数量和其他基质没有显著影响。氯沙坦治疗也不影响关节软骨中1型血管紧张素受体（AGTR1）、2型血管紧张素受体（AGTR2）和磷酸化转化生长因子β1激活激酶1（pTAK1）的表达水平和模式。此外，与正常组和其他组相比，氯沙坦治疗对胫骨正常松质骨和皮质骨的微观结构没有影响。氯沙坦治疗使松质骨表面骨钙素阳性成骨细胞略有增加，不影响骨基质1型胶原蛋白含量，也不改变AGTR1、AGTR2和pTAK1信号分子的表达。
基于我们的临床前兔模型，作为微骨折增强治疗药物使用的口服氯沙坦对未受伤的关节软骨和骨没有显著影响。这些结果进一步证明，目前将氯沙坦用作微骨折增强治疗的方案在骨和软骨稳态方面是安全的，并支持其在人类软骨修复中的应用进行临床试验。
