Application oriented cryopreservation and banking of stem cells and stem cell derivates
Dr. Ina Meiser, Cryobiotechnology group manager, Fraunhofer Institute for Biomedical Engineering (IBMT)
Cryopreservation is still the only possibility to store viable cells for long periods. In general, conventional slow freezing methods are efficient enough to preserve single cells in suspension for subsequent expansion (e.g. human induced pluripotent stem cells, hiPSCs). Here, several aspects have to be taken into account for safe long-term storage regarding infrastructure and handling according to planned purpose. However, in case of preservation of adherent cells or multicellular systems that are increasingly relevant for biomedical research and application (e.g. hiPSC-derived neuronal cells), slow freezing shows major limitations. (1) Usually the adherent cells have to be enzymatically or mechanically dissociated to single cells or small aggregates prior to freezing, (2) crystallization-induced damaging mechanisms additionally disrupt cadherin- and integrin-mediated cellular contacts, and especially for hiPSC, (3) the recovered viable cell numbers is dramatically reduced compared to the control. Besides application of sophisticated scaffolds in slow freezing approaches, the method of ice-free cryopreservation (vitrification) provides the possibility to overcome these limitations, but requires skilled handling especially regarding sterile procedures, implies small sample sizes and therefore is considered as unsuitable for routine handling or bulk storage. To launch vitrification for large cell numbers and thus enabling ready-to-use cryopreserved adherent cell systems, a sophisticated multi-usage cell culture disposable covering comprehensive cell-based workflows from cultivation/differentiation to sterile vitrification will be introduced.