Summary

Viable stem cells are mobilized to the post-injury effusion at the time of cruciate ligament injury and can be found in the by- product waste of cruciate ligament surgery.

Abstract

Purpose

The purpose of this study was to examine the number of viable stem cells contained in the post-injury effusion fluid and the waste by-products of arthroscopic cruciate ligament surgery.

Methods

This study included patients over 18 years of age with acute (<5 weeks old) cruciate ligament injuries requiring arthroscopic surgery. The post-injury effusion fluid (effusion fluid), fatpad and cruciate ligament stump debridement tissue (by-product tissue), and arthroscopic fluid collected during fatpad/stump debridment (by-product fluid) were collected at the time of surgery from 30 individuals. Specimens were analyzed, investigating cell viability, nucleated cell counts, cell concentrations, colony forming unit assays, and flow cytometry at an independent facility. Samples from the first 20 individuals were collected in small specimen containers, and samples from the last 10 individuals were collected in larger specimen containers.

Results

Cells of the injury effusion exhibited the greatest viability, 86.4±1.31%, when compared to the by-product tissue and by-product fluid (p = 0.0001, p = 0.0001). Culture analysis of fibroblast colony forming units (CFU-F), found on average 1916±281 progenitor cells in the effusion fluid, 2488 ± 778 progenitor cells in the by-product tissue, and 2357±339 progenitor cells in the by-product fluid. Harvest with a small volume container consistently produced more colony forming units than harvest with a large volume container. Flow cytometry confirmed the presence of immature cells and the presence of cells with markers typically expressed by known stem cell populations.

Conclusions

Viable stem cells are mobilized to the post-injury effusion at the time of cruciate ligament injury and can be found in the by- product waste of cruciate ligament surgery.

Clinical Relevance: Methodology around effusion fluid and by-product tissue capture during cruciate ligament surgery should be investigated further. Cell amounts available from these tissues with current technologies are not sufficient for immediate evidence-based clinical application.