There is a need of an effective and non-toxic method for cryopreservation of cells and tissues for research and in clinical practice. In particular, stem cell transplantation and banking, as well as fertility treatment would be mostly impossible without effective cryopreservation methods. My PhD project focuses on application of a novel method of cryopreservation to two types of tissue: human haematopoietic stem cells (HSCs) and pancreatic islets. HSCs are used for treatment of leukaemias and other haematological malignancies, but are in most cases transplanted after a variable period of cryopreservation due to logistical aspects (such as time needed for donor screening, transport or quality control of the cells). Pancreatic islets can provide an effective treatment for patients with type I diabetes, but cannot be preserved effectively beyond approximately 72 hours due to lack of an effective cryopreservation method.
Cells must be frozen in cryoprotectant solutions to prevent the damage caused by creation of ice crystals. Dimethyl sulphoxide (DMSO) is currently the most widely used cryoprotectant, despite its known cellular toxicity, low efficacy for cryopreservation of cell clusters and toxicity to patients after transplantation. There is, therefore, a need to develop a non-toxic alternative to DMSO. One such alternative is trehalose, a natural disaccharide that has been shown to protect various plants, invertebrates and fish living in cold areas and also to enable effective cryopreservation of some cells in the laboratory. However, the cell membrane is impermeable to trehalose and, used alone, it can only provide extracellular protection for cells. A polymer developed by the Department of Chemical Engineering and Biotechnology, which can disrupt the cell membrane to allow trehalose to enter the cells, is a promising solution. The aim of my PhD project, therefore, is to develop and optimise a protocol for cryopreservation of human HSCs and pancreatic islets using this polymer and trehalose, as an alternative to DMSO. If successful, this method could be further optimised for cryopreservation of other valuable cell types and ultimately used clinically.