Callus formation is related to the expression ratios of estrogen receptors-alpha and -beta in ovariectomy-induced osteoporotic fracture healing
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AbstractIntroduction
This study characterizes ovariectomized (OVX)-induced osteoporotic fracture healing with focus on estrogen receptors (ERs). Callus formation plays a critical role in fracture healing, and ERs are well-known mechanosensors in osteogenic pathways. It was hypothesized that callus formation was related to and partially determined by the difference in expression patterns of ERs in both normal and OVX-induced osteoporotic fractures.

Methods
Closed femoral fracture in SHAM and ovariectomized rats were used in this study. Weekly callus width (CW) and area (CA), endpoint mechanical properties, gene expressions of Col-1, BMP-2, ER-α, ER-β and ER-α:ER-β ratios (ER-ratios), and correlations were assessed at 2, 4 and 8 weeks post-fracture.

Results
CW and CA results confirmed that OVX-induced osteoporotic fracture was delayed at 2–4 weeks with impaired endpoint mechanical properties. Gene expressions of ER-α and ER-β were higher in the SHAM group at week 2 (p < 0.05) and later lowered at week 8; whereas the OVX group showed an opposing trend. Moderate correlation existed between ER-α and BMP-2 (0.545, p = 0.003), and ER-ratio and BMP-2 (0.601, p = 0.001), and BMP-2 to CW and CA (r = 0.709, p = 0.000 and r = 0.588, p = 0.001, respectively). ER-α and ER-β proteins expressions were confirmed by immunohistochemistry at the fracture callus in reparative progenitor cells, osteoblasts- and osteoclasts-like cells.

Conclusion
We conclude that the delayed healing rate and impaired callus quality in OVX-induced osteoporotic fracture is related to the delayed expression of ERs. A high ER-α:ER-β ratio favors callus formation.
All Author(s) ListChow SK, Leung KS, Qin L, Wei FY, Cheung WH
Journal nameArchives of Orthopaedic and Trauma Surgery
Year2014
Month10
Volume Number134
Issue Number10
PublisherSpringer
Pages1405 - 1416
ISSN0936-8051
eISSN1434-3916
LanguagesEnglish-United Kingdom
KeywordsEstrogen receptors; Fracture healing; Osteoporosis
Web of Science Subject CategoriesOrthopedics; Surgery

Last updated on 2021-22-09 at 00:51