Effect of Needle Diameter and Flow Rate on Rat and Human Mesenchymal Stromal Cell Characterization and Viability

Introduction: Current mesenchymal stromal cell (MSC) delivery methods require infusion/implantation through needles and/or catheters. Little investigation into the effect of delivery via catheter injection has been completed. We hypothesize that injection of rat and human MSCs through various clinically relevant-sized catheters and flow rates will not affect cell viability, characterization, or function. Methods: Both rat and human MSCs were injected through 20-, 25-, and 30-gauge needles, as well through an SL-10 microcatheter at rates of 60, 120, 240, and 500 mL/h. MSC viability and apoptotic fraction was measured. MSCs were characterized 24 h after injection with flow cytometric immunophenotyping, and multilineage differentiation was completed. Results: Catheter diameter or flow rate did not affect rat MSC viability. No clinically significant decrease in human MSC viability was observed immediately after injection; however, a delayed decrease in viability was observed at 24 h. No difference in the surface markers CD11b, CD45, CD29, CD49e, CD73, CD90, CD105, and Stro-1 or the capacity for multilineage differentiation (adipogenesis, osteogenesis, and chondrogenesis) was observed for either rat or human MSCs. Conclusion: The injection of human and rat MSCs through various clinically relevant catheters and flow rates did not have a clinically significant effect on viability immediately after injection, indicating compliance with recently published Food and Drug Administration guidelines (viability >70%). Further, no changes in cell characterization or function were observed via measurement of cell surface markers and the capacity for multilineage differentiation, respectively. These results ensure the biocompatibility of MSCs with commonly used delivery methods.