NASHVILLE, Tenn. — Stem cells can successfully be isolated from synovial fluid in knees with acute ACL tears or osteoarthritis at the point of care using devices designed for platelet-rich plasma processing, according to study results.
“Viable resident stem cells can be harvested from synovial fluid in an injured knee and processed with a buffy coat PRP system,” Eric A. Branch, MD, said. “This synovial fluid did yield significantly fewer [colony-forming units] CFUs/mL than adipose and bone marrow sources and, while resident stem cells can be harvested and concentrated with techniques described here, it is unclear the number of cells required for clinical application.”
During the Biologic Association Annual Summit at the American Orthopaedic Society for Sports Medicine and Arthroscopy Association of North America Combined Meeting, Branch presented results for two heterogeneous groups of patients who sustained either an acute ACL injury or had knee OA and presented to the clinic in a 24-month period.
“The amount of effusion was similar in both groups; however, patients in the OA group were older than patients in the ACL injury group”, Eric A. Branch.
Branch and colleagues collected 50-mm whole blood from each patient in a 16-mm syringe with anticoagulant, some of which was retained for complete blood count analysis and culture. In addition, researchers obtained synovial fluid and set aside some of it, as well, for complete blood count analysis and culture. They combined individual patient’s whole blood and synovial fluid into one product in an automated PRP processing device which had automated valves. A hematocrit setting of 15 on the device was used “based on the wavelength of the product,” Branch said, which was done in an attempt to take as much of the deeper portion of buffy coat as possible.
Commenting on the results, Branch said, “Flow cytometry showed more than 95% of cells expressed surface markers typical and defining of resident stem cell lineages.”
CFUs/mL were in about the 100 range in the OA group, which is similar to what is typically seen with PRP stem cell isolation, “while the synovial fluid alone was less concentrated at 42 and 56, respectively,” in the ACL and OA groups, he said.
According to Branch, study limits included a small sample size and lack of a power analysis because the study was underpowered to do one.