Characterization of tendon cell cultures of the human rotator cuff.

Rotator cuff tears are common soft tissue injuries of the musculoskeletal system that heal by formation of repair tissue and may lead to high retear rates and joint dysfunction. In particular, tissue from chronic, large tendon tears is of such degenerative nature that it may be prone to retear after surgical repair. Besides several biomechanical approaches, biologically based strategies such as application of growth factors may be promising for increasing cell activity and production of extracellular tendon matrix at the tendon-to-bone unit. As a precondition for subsequent experimental growth factor application, the aim of the present study was to establish and characterize a human rotator cuff tendon cell culture. Long head biceps (LHB)- and supraspinatus muscle (SSP)- tendon samples from donor patients undergoing shoulder surgery were cultivated and examined at the RNA level for expression of collagen type-I, -II and -III, biglycan, decorin, tenascin-C, aggrecan, osteocalcin, tenomodulin and scleraxis (by Real-time PCR). Finally, results were compared to chondrocytes and osteoblasts as control cells. An expression pattern was found which may reflect a human rotator cuff tenocyte-like cell culture. Both SSP and LHB tenocyte-like cells differed from chondrocyte cell cultures in terms of reduced expression of collagen type-II (p<or=0.05) and decorin while higher levels of collagen type-I were seen (p<or=0.05). With respect to osteoblasts, tenocyte-like cells expressed lower levels of osteocalcin (p<or=0.05) as well as tenascin C, biglycan and collagen type-III. Expression of scleraxis, tenomodulin and aggrecan was similar between all cell types. This study represents a characterization of tenocyte-like cells from the human rotator cuff as close as possible. It helps analyzing their biological properties and allows further studies to improve production of tendon matrix and osteofibroblastic integration at the tendon-bone unit following tendon repair.