The Subacromial Bursa is a Viable Source of Autologous Mesenchymal Stem Cells for Rotator Cuff Repair

• Published in: Orthopaedic journal of sports medicine 2019-07, Vol.7 (7_suppl5)
• Main Authors: Warth, Ryan J., Matre, Polina, Kozemchak, Adam, Supak, Dylan N., Huard, Johnny, Harner, Christopher D., Gregory, James M.
• Format: Article
• Language: English
• Subjects: Gene expression; Morphology; Orthopedics; Phosphatase; Rotator cuff; Sports medicine; Stem cells
• ISSN: 2325-9671; 2325-9671
• DOI: 10.1177/2325967119S00279

Objectives: Chronic rotator cuff tears still represent a significant source of morbidity and functional decline in the general population. The purpose of this study was to establish protocols for isolation and expansion of bursa-derived mesenchymal stem cells (BDSCs) and to evaluate their differentiation capacity, including tenogenesis. We hypothesized that BDSCs would be capable of multilineage differentiation (including tenogenesis) and represent an important source for autologous stem cells for patients undergoing rotator cuff repair. Methods: After IRB approval, 10 patients (ages 43-65 years) scheduled to undergo arthroscopic repair for chronic rotator cuff tears were enrolled. During diagnostic arthroscopy, subacromial bursa tissue was harvested using an arthroscopic shaver and collected by attaching the outflow tubing to a specialized specimen cup. Tissue specimens were transported to our laboratory for analysis. BDSCs were isolated via adherent culture and plated in Dulbecco’s Modified Eagle’s Medium (DMEM) supplemented with 10% Fetal Bovine Serum (FBS). Chondrogenic, adipogenic, and osteogenic induction media were used to induce differentiation. Tenogenic induction was performed using DMEM supplemented with varying concentrations of BMP-12, ascorbic acid, and human tenocyte-conditioned media. Alcian Blue staining was used to evaluate chondrogenesis, Oil Red O staining for adipogenesis, and Alkaline Phosphatase staining for osteogenesis. Gene expression markers for adipogenesis (ADIPOQ, FABP4, PPARγ), chondrogenesis (COL2A1 and SOX5), and osteogenesis (osteocalcin, osterix), along with primary antibodies to tenogenic markers (scleraxis, tenomodulin), were used to verify each cell lineage. Results: BDSCs isolated by adherent culture without collagen exhibited a spindle-shaped morphology characteristic of mesenchymal stem cells (MSCs), formed colonies, and demonstrated great expandability for six to eight passages without morphology changes (Figure 1A). After 3 weeks of culture, 95% (p