Effects of cryopreservation on human mesenchymal stem cells attached to different substrates

There is a need to preserve cell-seeded scaffolds or cell-matrix constructs for tissue-engineering and other applications. Cryopreservation is likely to be the most practical method. The aim of this study was to investigate how cryopreservation affects cells attached to different substrates and how they respond differently from those in suspension. Human mesenchymal stem cells (hMSCs) were studied for their close relevance to tissue-engineering and stem cell therapy applications, in particular how cryopreservation affects cell adherence, cell growth and the viability of hMSCs attached to different substrates, including glass, gelatin, matrigel and a matrigel sandwich. The effects of cryopreservation on F-actin organization, intracellular pH and mitochondrial localization of the adherent hMSCs were further investigated. It was found that cells attached to a glass surface could hardly survive the common cryopreservation protocol using 10% DMSO and a 1°C/min cooling rate. By contrast, cells attached to gelatin and matrigel could survive to a greater extent. Furthermore, cryopreservation affected the potential of cell attachment and proliferation, resulted in distortion of F-actin, led to alteration of intracellular pH of the hMSCs for all tested substrates and caused a change in the mitochondrial localization of hMSCs on a matrigel substrate and in a matrigel sandwich. Our results showed that cell attachment and cell viability could be improved by changing the interaction between cell and substrate through modification of the substrate properties, which has implications for scaffold design if cell-seeded scaffolds or engineered tissues need to be cryopreserved.