Development of a Mouse Model of Ischemic Osteonecrosis

Abstract

Background Availability of a reliable mouse model of ischemic osteonecrosis could accelerate the development of novel therapeutic strategies to stimulate bone healing after ischemic osteonecrosis; however, no mouse model of ischemic osteonecrosis is currently available. Questions/purposes To develop a surgical mouse model of ischemic osteonecrosis, we asked, (1) if the blood vessels that contribute to the blood supply of the distal femoral epiphysis are cauterized, can we generate an osteonecrosis mouse model; (2) what are the histologic changes observed in this mouse model, and (3) what are the morphologic changes in the model. Methods We performed microangiography to identify blood vessels supplying the distal femoral epiphysis in mice, and four vessels were cauterized using microsurgical techniques to induce ischemic osteonecrosis. Histologic assessment of cell death in the trabecular bone was performed using terminal deoxynucleotidyl transferase mediated dUTP nick-end labeling (TUNEL) and counting the empty lacunae in three serial sections. Quantitation of osteoclast and osteoblast numbers was performed using image analysis software. Morphologic assessments of the distal femoral epiphysis for deformity and for trabecular bone parameters were performed using micro-CT. Results We identified four blood vessels about the knee that had to be cauterized to induce total ischemic osteonecrosis of the distal femoral epiphysis. Qualitative assessment of histologic sections of the epiphysis showed a loss of nuclear staining of marrow cells, disorganized marrow structure, and necrotic blood vessels at 1 week. By 2 weeks, vascular tissue invasion of the necrotic marrow space was observed with a progressive increase in infiltration of the necrotic marrow space with the vascular tissue at 4 and 6 weeks. TUNEL staining showed extensive cell death in the marrow and trabecular bone 24 hours after the induction of ischemia. The mean percent of TUNELpositive osteocytes in the trabecular bone increased from 2% ± 1% in the control group to a peak of 98% ± 3% in the ischemic group 1 week after induction of ischemia (mean difference, 96%; 95% CI, 81%-111%; p \ 0.0001). The mean percent of empty lacunae increased from 1% ± 1% in the control group to a peak of 78% ± 15% in the ischemic group at 4 weeks (mean difference, 77%; 95% CI, 56%-97%; p \ 0.0001). Quantitative analysis showed that the mean number of osteoclasts per bone surface was -015-4172-6 Clinical Orthopaedics and Related Research ® A Publication of The Association of Bone and Joint Surgeons® decreased in the ischemic group at 1, 2, and 4 weeks (p \ 0.0001, \ 0.0001, and p = 0.02, respectively) compared with the control group. The mean number of osteoclasts increased to a level similar to that of the control group at 6 weeks (p = 0.23). The numbers of osteoblasts per bone surface were decreased in the ischemic group at 1, 2 and 4 weeks (p \ 0.0001 for each) compared with the numbers in the control group. The mean number of osteoblasts also increased to a level...

IL6 receptor blockade preserves articular cartilage and increases bone volume following ischemic osteonecrosis in immature mice

“…The animal protocol for this study was approved by the Institutional Animal Care and Use Committee of the University of Texas Southwestern Medical Center. We previously developed a JIO mouse model which is only available in mice with robust incidence of osteonecrosis (ON) at almost 100 % 14 . Using this model, we surgically induced JIO of distal femoral epiphysis on immature 6week-old C57BL/6 male mice under anesthesia with isoflurane.…”

“…Terminal deoxynucleotidyl transferase mediated dUTP nick-end labeling (TUNEL) staining was performed on paraffin sections from post surgery day 1 using In Sit0075 Cell Death Detection Kit POD (Roche Applied Science) (Supplemental Figure 1, ON; n ¼ 6, sham; n ¼ 5) and day 6 (Supplemental Table), as previously reported 14 .…”

“…The purpose of this study was to determine the effects of IL6 receptor blockade using tocilizumab on JIO animal model. Here, we chose to use only available JIO mouse model which we recently established 14 and showed positive effects of tocilizumab on bone volume as well as cartilage anabolism following ischemic osteonecrosis.…”

Knee loading protects against osteonecrosis of the femoral head by enhancing vessel remodeling and bone healing

“…Osteonecrosis of the femoral head (ONFH) is a disease in which bone death occurs as a result of impairment of blood supply to the femoral head [1, 2]. There are several etiologic risk factors such as trauma [3, 4], excessive corticosteroid use [5–7], excessive alcohol intake [8], Legg-Calve-Perthes disease [9, 10], etc.…”

In vivo monitoring of activated macrophages and neutrophils in response to ischemic osteonecrosis in a mouse model

“…In order to gain a better understanding of the cellular response and the repair process following ischemic osteonecrosis, a mouse model was previously developed . In this model, cauterization of the blood vessels supplying the distal femoral epiphysis leads to complete necrosis of the cells in the bone and bone marrow at the local site, as observed by positive TUNEL‐staining as early as 24 h after surgery.…”