Methods for encapsulation and storage of human stem cells in three dimensional alginate aggregates

Stem cells are at the centre of biomedical research: besides improving the basic understanding of human development and cellular differentiation processes, stem cells hold the unique potential for novel therapies of degenerative diseases. Future therapies, however, will have to build on a readily available, reliable and safe supply of high-quality stem cells or stem cell-derived progeny. Isolation, identification and culture of stem cells are not standardized between laboratories, and reproducibility of protocols is limited. Hence, the aim of this work is to determine optimal methods for stem cell storage and cryopreservation that ensure survival of stem cells without affecting their proliferation characteristics and differentiation potential. The increasing interest of biomedicine in cell-matrix constructs promotes the development of new culture techniques and increases interest in cryopreservation of these constructs for retrospective investigations, pooling and stock keeping. Immobilized cells were used in many ways as model systems for tissue, e.g. to test the effects of a 3D environment on mitosis, apoptosis or differentiation of stem cells. As proof of concept, different human stem cells (human embryonic stem cells, human adult stem cells) have been encapsulated in ultra high viscosity alginate and the effects on viability have been investigated over several days. Besides, encapsulation offers the possibility to protect sensitive cells during cryopreservation. Therefore, this work also aims to evaluate the possible improvement of cryopreservation results using ultra high viscosity alginate