Bursal Tissue Harvested During Rotator Cuff Repair Contains Viable Mesenchymal Stem Cells

Abstract

Purpose: To evaluate the effect of intraoperative ablation on the viability, distribution, phenotype, and potential for culture expansion of bursal cells harvested during arthroscopic rotator cuff surgery. Methods: Tissue was collected during primary arthroscopic rotator cuff repair on 6 healthy, randomly selected patients from a fellowship-trained surgeon’s practice between September 2020 and January 2021. There were 3 women (aged 60 ± 8 years) and 3 men (aged 61 ± 10 years). At the time of surgery, subacromial bursal tissue was subjected to no ablation, 1 second of ablation, or 3 seconds of ablation. Tissues were collected by an autograft harvesting system connected to an arthroscopic shaver and a pituitary grasper. Tissue fragments from each condition were sampled for viability testing or cell isolation. A viability kit with confocal microscopy was used to assess live and dead cells. Cell isolation consisted of collagenase digestion or placing tissue fragments onto tissue culture–treated plates that induced migration of cells out of the tissue. Cell proliferation rates were monitored and surface markers for mesenchymal stem cells (MSC) and pericytes were analyzed via multicolor flow cytometry. Results: Increased ablation time significantly reduced cell viability. The mean percentage of live cells was 55.2% ± 27.2% (range, 26%-90% live) in the control group, 46.8% ± 23.8% (range, 9.6%-69.6%, P = .045) in the short-ablation group, and 35.5% ± 19% (range, 11%-54%, P = .03) in the long-ablation group. No significant differences in population doubling level (1.6 ± 0.5 days) and population doubling time (6.7 ± 2.4 days) were observed in cells from any treatment. The surface marker profile indicated an MSC phenotype with absence of a pericyte population. Ablation or cell isolation procedure had no significant effect on the surface marker profile of isolated cells. Conclusions: Radiofrequency ablation significantly reduced the overall tissue viability but had no significant effect on cell proliferation or expression of surface markers on isolated subacromial bursal cells harvested arthroscopically. Clinical Relevance: Analysis of the viability and performance of cells harvested after the use of ablation devices using mechanical surgical collection during rotator cuff repair surgery could further our understanding of subacromial bursal tissue and its potential role in augmenting rotator cuff repair healing.