Trochanteric Bursa Is a Source of Connective Tissue Progenitor Cells

Abstract

Purpose: To investigate the presence of connective tissue progenitor cells (CTPs) in the trochanteric bursa harvested over the gluteus medius muscle belly and tendon during open hip procedures. Methods: Trochanteric bursa samples from nine patients (63.1 AE 8.6 years) undergoing total hip arthroplasty for primary osteoarthritis were obtained from 2 sites: over the gluteus medius tendon at the greater trochanter and over the muscle belly. Bursal tissue was digested with collagenase and grown in culture. The nucleated cell count, cellular concentration, cellular proliferation, fluorescenceactivated cell sorting (FACS) analysis, and differentiation using immunostaining and quantitative polymerase chain reaction (PCR) were used to determine and quantify the presence of CTPs. Results: Bursa-derived CTPs were identified in all harvested samples. At t ¼ 0, there was no difference in nucleated cell count over muscle and tendon (1.69 AE 1.26 Â 10 8 and 1.41 AE 1.12 Â 10 8 cells/g, respectively; P ¼ .162). Similarly, the cellular concentration at 3 weeks was not significantly different between bursa harvested over muscle and tendon (6.61 AE 5.14 Â 10 6 and 5.58 AE 4.70 Â 10 6 cells/g, respectively; P ¼ .532). High cellular proliferation was identified for both bursal tissue overlying muscle and tendon (2.28 AE .95 and 1.66 AE 1.05, respectively; P ¼ .194). FACS analysis revealed high positivity rates (>95%) of CTP-specific surface epitopes (CD105, CD90, and CD73) and low positivity rates (<1.3%) of negative markers (CD45, CD31). Osteogenic, adipogenic, and chondrogenic differentiation potential was demonstrated with immunostaining and quantitative PCR for gene expression. Conclusions: Connective tissue progenitor cells are found in the trochanteric bursa overlying the muscle and tendon of the hip abductors.

Activated Serum Increases In Vitro Cellular Proliferation and Growth Factor Expression of Musculoskeletal Cells

“…Fresh human supraspinatus tendon and subacromial bursal tissue were obtained from primary rotator cuff repairs during arthroscopic debridement using Blakesley forceps. The tendon and bursa were cut into small fragments such that they could be digested in 2 mg/mL collagenase P (Sigma-Aldrich, St Louis, MO, USA) for 2.5 h at 37 °C, pelleted using a centrifuge, resuspended, and plated in Primaria culture dishes (Fisher Scientific, Agawam, MA, USA), as previously described [ 22 , 23 ]. The digested tissue was grown in complete culture medium containing DMEM (Gibco/Invitrogen), 10% FBS (Thermo Fischer Scientific, Waltham, MA, USA) and 0.1% penicillin/streptomycin (Thermo Fischer Scientific, Waltham, MA, USA).…”