Comparison of Preparation Techniques for Isolating Subacromial Bursa-Derived Cells as a Potential Augment for Rotator Cuff Repair

To identify an effective, nonenzymatic method for maximizing the yield of subacromial bursa-derived nucleated cells for augmenting rotator cuff repair. Subacromial bursa (minimum 0.2 g) was collected prospectively over the supraspinatus from patients (n = 7) with at least one full-thickness tendon tear undergoing arthroscopic primary rotator cuff repair. Samples were processed and analyzed prospectively using 4 different methods: (1) mechanical digestion with scissors (chopping), (2) collagenase digestion, (3) mechanical digestion with a tissue homogenizer, and (4) whole tissue with minimal manipulation. Tissue from each method were plated and cultured in a low oxygen tension, humidified incubator for 7 days. Following incubation, cellularity was assessed with nucleated cell count using a Coulter Counter. Flow cytometry was performed on the non-enzymatic method that demonstrated the greatest cell count to confirm the presence of mesenchymal stem cells (MSCs). The Kruskal–Wallis H test and post hoc Dunn's test were used for statistical analysis. Following incubation, mean nucleated cell counts (cells/mL) were (1) 102,681 ± 73,249 for chopping, (2) 76,190 ± 66,275 for collagenase, (3) 31,686 ± 29,234 for homogenization, and (4) 11,162 ± 4016 for whole tissue. There was no significant difference between chopping and collagenase (P = .45) or between homogenization and collagenase (P = .52). Both chopping (P = .003) and collagenase (P = .03) produced significantly more cells when compared with whole tissue. Flow cytometry confirmed the presence of MSC markers on samples processed by chopping. Mechanical isolation of subacromial bursa-derived cells using a chopping technique demonstrated similar nucleated cell count compared with collagenase, along with the confirmed presence of MSCs. This study demonstrated a nonenzymatic, mechanical method for isolating subacromial bursa-derived cells to potentially augment rotator cuff repair. Further clinical studies are required to assess its possible advent in the tendon–bone healing process.