Human Serum Albumin Preserves Delivered Dose and Suspension Stability During Simulated Clinical Infusion of Mesenchymal Stromal Cells.

INTRODUCTION: Final formulation and infusion may alter the cell therapy dose delivered to the patient. We assessed whether human serum albumin (HSA) improves delivery and short-term stability of clinical-grade adipose tissue-derived mesenchymal stromal cells during simulated clinical infusion. METHODS: Thawed cells were diluted in sodium chloride, lactated Ringer's solution, or Plasmalyte, with or without HSA, and passed through a standardized syringe-pump-catheter setup. Samples collected before infusion, immediately after infusion, and during room-temperature hold were assessed for cell concentration, viability, recovery, debris, aggregates, image-based morphology, and post-culture expansion. RESULTS: HSA increased delivered total-cell concentration (3.05×10^6 vs 2.61×10^6 cells/mL, p < 0.001), viable-cell concentration (2.78×10^6 vs 2.27×10^6 cells/mL, p < 0.001), and viable recovery (99.8% vs 85.1%, p < 0.001). During post-infusion hold, HSA-free samples showed progressive loss of viable cells and viability, whereas HSA-containing samples remained comparatively stable. Overnight viable-cell concentration was 2.68×10^6 cells/mL with HSA versus 1.16×10^6 cells/mL without HSA, and viability was 87.8% versus 50.5%, respectively. Image-based morphology showed sustained single-cell predominance, higher single-cell counts with HSA, and a lower overnight debris-to-single-cell ratio without increased aggregate burden. CONCLUSIONS: HSA supplementation preserves delivered cell concentration, viable-cell recovery, and short-term suspension stability during simulated clinical infusion of mesenchymal stromal cells. Final formulation is therefore a practical determinant of the cell suspension delivered to the patient.