Cord blood-derived platelet concentrates as starting material for new therapeutic blood components prepared in a public cord blood bank: from product development to clinical application

Abstract

Background - There are many advantages to using cord blood (CB) as a source of therapeutic platelet and plasma derivatives for regenerative medicine. These include availability, universal use, young donor source, and virally safe biological material, rich in tissue regenerative factors.
Materials and methods - We aimed to validate a bioprocess design for the production of cord blood-derived platelet concentrates (CBPC) in a public Cord Blood Bank (CBB). CBPC was defined as a product of 10±5 mL, 1,000±200×10⁹/L total platelets, free of erythrocytes and leukocytes. A total of 300 CB units were centrifuged in two steps to enrich for platelets, in compliance with Good Manufacturing Practice. The samples were tested for the degree of platelet activation present, and the levels of growth factor were analysed to evaluate their potential function. CBPC were then activated after thawing with 10% calcium gluconate to generate platelet gels (CBPG) to treat patients with diabetic foot ulcers.
Results - After processing, 84% of the products fulfilled the acceptance criteria. Final products contained 1,017±149×10⁶ platelets/mL in 10±3mL of plasma. Platelet recovery was 50±9%. The methods described here ensure depletion of white and red blood cells down to a residual concentration of 0.2±0.1×10⁶/mL and 0.03±0.02×10⁶/mL, respectively. Platelets showed low levels of activation during processing, but were significantly activated after thawing, as indicated by an increase in CD62p expression. The growth factors EGF, VEGF, bFGF, PDGF AB/BB and TGF-β1 were at concentrations of 1,706±123 pg/mL; 1,602±227 pg/mL; 314±26 pg/mL; 30±1.5 ng/mL;
24±2 ng/mL (mean±standard error of mean), respectively. For clinical evaluation, a total of 21 CBPG were applied in 3 patients, with no reported adverse events and improvement of ulcers in all of them.
Discussion - We designed and validated a highly reproducible, closed system method to manufacture high quality CBPC suitable for clinical applications using CB units not suitable for transplantation in a public CBB.