Large Scale Manufacturing Strategy for Production of Umbilical Cord-derived Mesenchymal Stem Cells in Support of Clinical Trials

Linetsky, E.; Lanzoni, G.; Wang, X.; Leñero, C.; Patel, A.; Ricordi, C.; Lenero, C.

Background & Aim: Mesenchymal stem cells (MSCs) have been shown to modulate hyperinflammation, promote tissue repair and secrete antimicrobial factors. MSCs have been studied in clinical trials of autoimmune diseases, inflammatory disorders, refractory GvHD and acute respiratory distress syndrome (ARDS). MSCs can be isolated and expanded from multiple tissues, including umbilical cord (UC). A number of clinical studies demonstrated safety and feasibility of UCMSCs therapy for the treatment of COVID-19 ARDS. UC-derived MSCs are easily available and can be quickly expanded to relevant numbers. UC-MSCs have an extended population doubling capacity and express low levels of class I and class II leukocyte antigen, which may reduce alloreactivity. To meet clinical manufacture demands, UC-MSC production requires an innovative, scaled-up manufacturing platform. We describe the manufacturing strategy developed in support of a double-blind, randomized, controlled UC- MSC clinical trial in subjects with COVID-19 ARDS. Methods, Results & Conclusion: UC-MSC Final Product was manufactured from the master cell bank (MCB) derived from subepithelial lining of a UC from a healthy term delivery, in cGMP conditions. Utilizing a 2D culture xenogeneic protein-free process, UC-MSC MCB was culture-expanded during 3 expansion cycles, in tissue culture treated vessels with increased surface area for each expansion, in commercially available tissue culture media supplemented with platelet lysate. Cells were harvested during log phase, at 75-80% confluence. The manufacturing process yielded ~ 300x increase in total viable cells at the end of the last expansion cycle. The Final Product was cryopreserved using a controlled rate freezer. Each subject in the treatment group received two doses of 100×106 UC-MSCs. A single UC-MSC Final Product batch was sufficient to treat all subjects randomized to the treatment group and complete the trial. The final product was tested for identity (label verification), effectiveness by viable cell dose and cell viability (>80%), safety by assessment of endotoxin (<1.65 EU/ml), Mycoplasma (negative), 14-day Sterility (negative) and purity by [Figure presented] FLOW cytometry (CD90/CD105?>90%, CD34/CD45 <10%). UC-MSC cell doses prepared for infusion produced similar results to UC-MSC Final Product when tested to confirm product identity, effectiveness, safety and purity. The developed 2D culture and expansion process can be successfully scaled up without compromising integrity of the final UC-MSC product.