Objective        To investigate the differential expression of bone morphogenetic protein-1 (BMP-1) in i

njured anterior cruciate ligament (ACL) and medial collateral ligament (MCL) fibroblasts induced by TGF-β

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and to find out the differences between the poorly self-healing ACL and well functionally self-healing MCL fibroblasts.       Methods        Fibroblasts were primarily cultured from clinical ACL and MCL samples

and then given 12% mechanical stretch injury and treated by 1

5 and 50 ng/ml TGF-β

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for 2 h

or by 5 ng/ml TGF-β

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for 2

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12 and 24 h respectively at the same time. The expression of BMP-1 in the above treated and untreated fibroblasts were detected by reversed-transcript PCR and real-time quantitative PCR.  Western blotting was used to detect the expression of BMP-1 in the injured fibroblasts induced by 5 ng/ml TGF-β

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for 48 h.       Results      TGF-β

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treatment resulted in an increased mRNA expression of BMP-1 in the injured fibroblasts in a dose-depended manner

especially in the cells from MCL than in those from ACL (about 1 times higher

P0.05). Compared with the fibroblasts without TGF-β

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treatment

5 ng/ml TGF-β

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treatment for 24 h made the expression of BMP-1 reach the summit  in ACL (6.1 folds higher

P0.05) and in MCL (9.84 folds higher

P0.05). Compared with the control

the protein expression of BMP-1 were elevated to 2.32 and 3.84 folds higher in ACL and MCL respectively after 5 ng/ml TGF-β

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treatment for 48 h (P0.01).       Conclusion      TGF-β

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affects the expression of BMP-1 in the injured fibroblasts

and then directly affects activities of lysyl oxiadse in the extracellular matrix

implying its potential significant value and clinical usage in repair of injured ACL.