We evaluated the expression of several genes involved in tissue remodelling and bone development in patients with calcifi c tendinopathy of the rotator cuff. Biopsies from calcifi ed and non-calcifi ed areas were obtained from 10 patients (8 women and 2 men; average age: 55 years; range: 40-68) with calcifi c tendinopathy of the rotator cuff. To evaluate the expression of selected genes, RNA extraction, cDNA synthesis and quantitative polymerase chain reaction (PCR) were performed. A signifi

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... tly increased expression of tissue transglutaminase (tTG)2 and its substrate, osteopontin, was detected in the calcifi c areas compared to the levels observed in the normal tissue from the same subject with calcifi c tendinopathy, whereas a modest increase was observed for catepsin K. There was also a signifi cant decrease in mRNA expression of Bone Morphogenetic Protein (BMP)4 and BMP6 in the calcifi c area. BMP-2, collagen V and vascular endothelial growth factor (VEGF) did not show signifi cant differences. Collagen X and matrix metalloproteinase (MMP)-9 were not detectable. A variation in expression of these genes could be characteristic of this form tendinopathy, since an increased level of these genes has not been detected in other forms of tendon lesions.