Effects of oral losartan administration on homeostasis of articular cartilage and bone in a rabbit model

Zhenhan Deng; Xueqin Gao; Hajime Utsunomiya; Justin W Arner; Joseph J Ruzbarsky; Matthieu Huard; Sudheer Ravuri; Marc J Philippon; Johnny Huard

doi:10.1016/j.bonr.2022.101526

Effects of oral losartan administration on homeostasis of articular cartilage and bone in a rabbit model

Bone Rep. 2022 Mar 28:16:101526. doi: 10.1016/j.bonr.2022.101526. eCollection 2022 Jun.

Authors

Zhenhan Deng¹, Xueqin Gao^{1

2}, Hajime Utsunomiya², Justin W Arner², Joseph J Ruzbarsky^{2

3}, Matthieu Huard², Sudheer Ravuri², Marc J Philippon², Johnny Huard^{1

2}

Affiliations

¹ Department of Orthopaedic Surgery, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, USA.
² Steadman Philippon Research Institute, Vail, CO, USA.
³ The Steadman Clinic, Aspen, CO, USA.

Abstract

Background and aims: 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.

Methods: 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.

Results: 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.

Conclusion: 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.

Keywords: 2D, 2 dimension; 3D, 3 dimension; AGTR1, angiotensin II receptor type 1; AGTR2, angiotensin II receptor type 2; ARRIVE, Animal Research: Reporting of In Vivo Experiments; AT1, angiotensin type 1; AngII, angiotensin II; Articular cartilage; BV, bone volume; BV/TV, bone volume/total volume; Bone; Col1, collagen type I; Col3, collagen type 3; Ct.Th, cortical thickness; DMM, destabilization of the medial meniscus; EDTA, ethylenediaminetetraacetic acid disodium dihydrate; H&E, Hematoxylin &eosin; Homeostasis; Losartan; Micro-CT, Micro-computer tomography; Microfracture; OCN, osteocalcin; RA, rheumatoid arthritis; RAS, rennin-angiotensin system; SMAD7, mothers against decapentaplegic homolog 7; Tb.N, trabecular number; Tb.Sp, trabecular seperation; Tb.Th, trabecular thickness; pSMAD2/3, phosphorylated mothers against decapentaplegic homolog; pTAK1, phosphorylated transforming growth factor β (TGF-β)-activated kinase 1.