Abstract 23 HLA-Homozygous iPSC from Cord Blood for the Generation of Cardiomyocytes for Allogeneic Cell Therapy to the Heart

INTRODUCTION: Based on a previous grant on HLA-homozygous (HLAh) iPS-GMP (and ATMP conform) generation from allogeneic licensed cord blood (CB) units, the Düsseldorf CBB could provide the most frequent HLA-types for reprogramming (Liedtke et al. 2020). These HLAh iPSC provide the basis for the generation of cardiomyocytes from iPSC. Patients with acute heart failure or cardiomyopathies have limited options of treatment. iPSC technology allows for de novo generation of functional heart muscle in vitro, enabling the implementation of new therapy concepts for heart regeneration. OBJECTIVES: The GMP-grade iPSC-lines are the backbone for the granted EU project (HEAL (101056712) on iPSC-cardiomyocyte aggregate manufacturing for allogeneic cell therapy. Besides GMP-compliant up-scaled cell production of cardiomyocytes, the project is designed to overcome many of the scientific, safety and regulatory hurdles necessary to initiate a first-in-man clinical HLAh-based heart regeneration study. METHODS: After CD34(+) selection/short expansion of CD34, cells were reprogrammed by GMP-conform plasmids and stored in a master cell bank with most frequent HLA-haplotypes. All iPSC lines were tested extensively for genetic stability, mycoplasma, virus markers, endotoxins and microorganisms. The differentiation into cardiomyocytes was performed in correspondence to the Wnt modulation, i.e. first activating Wnt pathway and then inhibiting the pathway with the addition of small molecules (Halloin et al. 2019). For the up-scaled production, a 3D-cardiomyocyte aggregate culture in large stirred tank bioreactors (STBR) was applied. Cryopreservation using controlled rate freezing was adapted to tissue freezing. RESULTS: Selection of the most frequent homozygous haplotypes facilitated the production of HLAh iPSC lines for differentiation into cardiomyocytes. Efficient progress had been made for the improvement of STBR platform for sufficient production of cardiomyocytes, enabling the differentiation with a purity of up to 95%, measured via cardiac troponin T (cTnT). DISCUSSION: Although high yields of cardiomyocytes in a GMP-compliant process is getting more achievable by using STBRs, the safety and regulatory hurdles are still a major problem. For safety testing, toxicology, tumorigenicity assays will be performed in mice and in pig models. This will enable the prediction of arrhythmia-related risks. For a safe distribution of the finally released cell product optimization of cryopreservation of cardiomyocytes aggregates will be performed. Disclaimer: Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Health and Digital Executive Agency (HADEA). Neither the European Union nor the granting authority can be held responsible for them.