Effects of Changes in Mechanical Loading on Endochondral Bone Formation in Hindlimb-suspended Rats.
- Author:
Kun Bo PARK
1
;
Sun Young JOO
;
Sun Young KONG
;
Ho Jung KANG
;
Jae Hyun PARK
;
Hyun Woo KIM
Author Information
1. Department of Orthopaedic Surgery, Yonsei University College of Medicine, Seoul, Korea. pedhkim@yumc.yonsei.ac.kr
- Publication Type:Original Article
- Keywords:
Mechanical loading;
Endochondral bone formation;
Hindlimb-suspended rats
- MeSH:
Animals;
Apoptosis;
Biotin;
Bone Development;
Bromodeoxyuridine;
Chondrocytes;
Growth Plate;
Hindlimb;
Immunohistochemistry;
In Situ Nick-End Labeling;
Kinetics;
Lifting;
Models, Animal;
Osteogenesis*;
Rats*;
Rats, Sprague-Dawley;
Stress, Mechanical;
Tail;
Weight-Bearing;
Weightlessness
- From:Korean Journal of Aerospace and Environmental Medicine
2005;15(3):100-105
- CountryRepublic of Korea
- Language:Korean
-
Abstract:
BACKGROUND: To examine the effects of changes in mechanical loading on endochondral bone formation, a simulated rat model of weightlessness was introduced and the changes in the growth plate were evaluated. METHODS: Unloading condition on the hindlimb of Sprague-Dawley rats was created by fixing a tail and lifting the hindlimb. Six rats aged 6 weeks old were assigned to each group of unloading and reloading with their control group. Unloading was maintained for three weeks, and then reloading was applied for another one week afterwards. Histomorphometry for the assessment of vertical length of the growth plate, 5-bromo-2'-deoxyuridin (BrdU) immunohistochemistry for cellular kinetics, and biotin nick end labeling TUNEL assay for chondrocytes in the growth plate were performed. RESULTS: The vertical length of the growth plate and the proliferative potential of chondrocytes were decreased in the unloading group than those of the control group. Inter-group differences were more significant in the proliferative and hypertrophic zones. Reloading increased the length of growth plate and proliferative potential of chondrocytes as evidenced by the increase of the ratio of positive BrdU stained cells. However, the apoptotic changes in the growth plate were not affected by the alterations of the weight bearing. CONCLUSION: Alterations in the weight bearing induced changes in the chondrocytic proliferative potential of the growth plates and had no effect on the apoptosis occurrence. This may suggest that deprived weight bearing due to various clinical situations hamper normal longitudinal bone growth. Further studies regarding the factors for reversibility of chondrocytic proliferation upon variable mechanical stresses are needed.
