Human Adipose-Derived Mesenchymal Stromal/Stem Cells Remain Viable and Metabolically Active Following Needle Passage

Objective To assess the biological effects of passage through clinically relevant needles on the viability and metabolic activity of culture-expanded, human adipose tissue–derived mesenchymal stromal/stem cells (AMSCs). Design Prospective observational pilot study. Setting Academic medical center. Participants Patient-derived clinical-grade culture expanded AMSCs. Interventions AMSCs were passed through syringes without a needle attached (control), with an 18-gauge (25.4-mm) needle attached and with a 30-gauge (19-mm) needle attached at a constant injection flow rate and constant cell concentrations. Each injection condition was completed in triplicate. Main Outcome Measures Cell number and viability, proliferative capacity, metabolic activity, and acute gene expression as measured by cell counts, mitochondrial activity, and quantitative real time reverse-transcription polymerase chain reaction on day 0 (immediately), day 1, and day 4 after injection. Results AMSC viability was not significantly affected by injection, and cells proliferated normally regardless of study group. Postinjection, AMSCs robustly expressed both proliferation markers and extracellular matrix proteins. Stress-response mRNAs were markedly but transiently increased independently of needle size within the first day in culture postinjection. Conclusions Human, culture-expanded AMSCs maintain their viability, proliferative capacity, and metabolic function following passage through needles as small as 30-gauge at constant flow rates of 4 mL/min, despite an early, nonspecific stress/cytoprotective response. These initial findings suggest that culture-expanded AMSCs should tolerate the injection process during most cell-based therapeutic interventions.