Investigation into the Influence of Temperature on the Cryopreservation of Mesenchymal Stem Cells

Abstract

Mesenchymal Stem Cells (MSCs) are utilised in regenerative medicine due to their multilineage differentiation potential, ease of isolation, capacity for in vitro expansion and wide-spread availability in the adult tissues. Their therapeutic applications have been widely demonstrated. In order to facilitate their transition from a bench to bedside therapeutic, on-demand availability of cells is required. Cryopreservation is thus a crucial element in achieving this goal as it permits the long term stabilisation of biological cells. For successful cryopreservation, ultra-low temperatures are needed. However, uncontrolled elevated temperatures cannot be avoided in certain situations. The work presented in this thesis focuses on the investigation of the influence of temperature elevation on the cryopreservation of MSCs. This thesis comprises of three separate components. The first section examines the temperature variations of cryopreserved stem cells during transportation, using conventional solid CO2 as the cryogenic agent. It was observed that significant temperature variations can occur using this method of transportation. The second study investigates the effects of temperature elevations of cryopreserved MSCs derived from rats. A multiple regression model composed of two exponentials is proposed to approximate the detrimental effects on cell viability. It demonstrates that temperature elevations have an imminent detrimental effect on cell viability. The topic is further elaborated in a subsequent study which uses human-derived MSCs as well as a larger sample set. In addition, an active learning sampling strategy in conjunction with Gaussian process data model is presented which attempts to maximise the information return from the experiments. This study demonstrates the existence of a 'lethal' region causing the highest detrimental effect to cell viability.