Patient Body Mass Index Has No Direct Effect on The Characteristics of Primary Tenocytes Derived from Torn Rotator Cuffs

Background. Obesity is associated with an increased risk of rotator cuff tears and impaired tendon healing after surgery. This study aimed: 1) to investigate the influence of patient body mass index (BMI) on cellular function in tenocytes derived from diseased torn human rotator cuff; 2) to determine if BMI altered the response of tenocytes to tenogenic growth factors. Methods. Tenocytes were isolated from torn supraspinatus tendons of patients undergoing rotator cuff surgery. Tenocyte growth and collagen production were determined by alamarBlue and Sirius red assays, respectively, at baseline and in the presence of IGF-1, TGF-beta and PDGF after 72 hours. Changes in the relative expression of genes important in tenocyte, chondrocyte and osteoblast biology were determined using real-time PCR. Correlation analyses were performed between patient BMI and tenocyte function and gene expression. Results. BMI had no direct effect on tenocytes with no significant correlations between patient BMI and cellular behaviour, gene expression or response to growth factor treatment. Higher cellular growth and collagen production were observed in response to PDGF and TGF beta treatment, while IGF-1 had minimal effect. TGF-beta was associated with higher expression of tenocyte-related genes, collagen Ia and scleraxis, while PDGF resulted in higher expression of adipose marker, PPAR-gamma, suggesting it may be promoting de-differentiation from a tenocytic phenotype. Conclusions. In summary, BMI does not influence tenocyte growth, collagen synthesis or gene expression profile ex vivo. These findings have significant clinical implications, as they suggest that growth factor treatment will be effective in patients independent of BMI.