Purpose: Recently, the local renin-angiotensin system (RAS) has attracted many researchers in many pathophysiological issues. In Orthopedics, expression of local RAS was found in bone tissues, fracture callus and arthritic synovium. The purpose of this study is to reveal immunohistological localization of the RAS components in the epiphyseal plates of mice and to analyze function of the local RAS in the processes of hypertrophic differentiation using ATDC5 chondroprogenitor cells.<br />
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Methods: The epiphyseal plates of 8-week-old mice was immunostained with antibodies to angiotensinogen, angiotensinogen converting enzyme 1 (ACE1), angiotensinII type 1 receptor (AT1R) and angiotensinII type 2 receptor (AT2R). We cultured ATDC5 in long term and evaluated the expression of angiotensinogen, ACE1, AT1R, AT2R and type 2 collagen (COL2) by real- time PCR and Western blot analysis.<br />
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Results: In the epiphyseal plates of mice, angiotensinogen and AT1R expressed in the resting chondrocytes, the proliferative chondrocytes and hypertrophic chondrocytes; however, ACE1 and AT2R expressed only in the hypertrophic chondrocytes. In ATDC5 chondroprogenitor cells, the local RAS components expressed both in proliferative and hypertrophic differentiating stages.<br />
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Conclusions: The local RAS expresses in the epiphyseal plates of mice and might play an important role in the process of hypertrophic differentiation.