Bone tissue content of TGF-beta2 changes with time in human heterotopic ossification after total hip arthroplasty.

Transforming growth factor beta isoforms (TGF-beta(1), TGF-beta(2), and TGF-beta(3)) most likely play a role in bone physiology, but little is known about their relative importance in normal as well as in heterotopic bone. This study focused on possible differences in the localization and relative content of different TGF beta isoforms in heterotopic ossifications (HO) by comparing HOs, which have developed less than 17 months (immature HOs) with those developed 3-9 years (mature HOs). The HOs were harvested after total hip arthroplasty (THA) during revision surgery. The HO samples were decalcified, embedded in paraffin and sectioned. Azan staining was used to evaluate histological structure of the ossifications and immunohistochemical analysis was performed to estimate the localization of three TGF beta isoforms in the HOs. Comparison of different TGF beta isoforms in the immature and the mature ossifications showed that the content of TGF-beta(2) was decreased by almost three times in the mature HO as compared to the immature HO (p = 0.0064). The proportions of other isoforms in HOs did not differ significantly. This study shows that the relative importance of TGF betas change with HO development.