Generation of a bank of clinical-grade, HLA homozygous iPSC lines with high coverage of the Spanish population

Abstract

Background: Induced Pluripotent Stem Cells (iPSC) derived cell therapies are an interesting new area in the field of regenerative medicine. One of the approaches to decrease costs of iPSC derived therapies is the use of allogenic homozygous human leukocyte antigen (HLA) matched donors to generate iPSC lines and to build up a clinical grade iPSC bank covering high percentage of the Spanish population. Methods: The Spanish Stem Cell Transplantation Registry was screened for cord blood units (CBUs) homozygous for the most common, HLA-A, -B and DRB1 haplotypes. 7 donors were selected with haplotypes covering 21.37% of the haplotypes of the Spanish population. CD34 positive hematopoietic progenitors were isolated from the mononuclear cell fraction of frozen cord blood units from each donor by density gradient centrifugation and further by immune magnetic labelling and separation using purification columns. Purified CD34+ cells were reprogrammed to iPSCs by transduction with CTS CytoTune-iPS 2.1 Sendai Reprogramming Kit. Results: The generated iPSCs from the 7 donors were expanded, characterized, banked, and registered. Master Cell Banks (MCB) and Working Cell Banks (WCB) from the iPSCs of each donor were produced under GMP conditions in qualified clean rooms. Conclusions: Here we present the first, clinical-grade, iPSC haplobank in Spain made from CD34+ cells from seven cord blood units homozygous for the most common HLA-A, -B and -DRB1 haplotypes within the Spanish population. We describe their generation by transduction with Sendai viral vectors and their GMP-compliant expansion and banking. These haplolines will constitute starting materials for advanced therapy medicinal product development.