Abstract:Due to the relevance of the critical cooling rate, Rc, for glasses, Barandiarán and Colmenero (BC) developed a method for calculating Rc as a function of the crystallization temperature on cooling obtained from thermal analysis. The critical cooling rate is obtained by the extrapolation method to conditions of infinity undercooling. However, for polymers, there is a strong reason for modifying the original BC method. In this case, the extrapolation must be extended only to the undercooling associated to the gl… Show more
“…In the cryopreservation process, both cooling and warming rates should exceed the critical cooling rate (CCR) 17 and critical warming rate (CWR) 18 to avoid failure of vitrification, resulting in cell damage caused by ice crystal growth 19 . In large scale cryopreservation, one of the major technological barriers is achieving the CWR to avoid devitrification, because the conventional method of rewarming is performed by immersing vitrified cells in a water bath at 37 °C to avoid cellular damage caused by overheating.…”
Scale-up of production is needed for industrial applications and clinical translation of human induced pluripotent stem cells (hiPSCs). However, in cryopreservation of hiPSCs, successful rewarming of vitrified cells can only be achieved by convective warming of small volumes (generally 0.2 mL). Here, we present a scalable nano-warming technology for hiPSC cryopreservation employing inductive heating of magnetic nanoparticles under an alternating magnetic field. The conventional method by water bath heating at 37 °C resulted in a decrease of cell viability owing to devitrification caused by slow warming of samples with large volumes (≥ 20 mL). Nano-warming showed uniform and rapid rewarming of vitrified samples and improved viability of hiPSCs in the 20-mL system. In addition to single cells, hiPSC aggregates prepared using a bioreactor-based approach were successfully cryopreserved by the nano-warming technique. These results demonstrate that nano-warming is a promising methodology for cryopreservation in mass production of hipScs. Pluripotent stem cells, including human embryonic stem cells (hESCs) and induced pluripotent stem cells (hiP-SCs), are a promising cell source for regenerative medicine because of their unlimited proliferation potential and differentiation capability 1,2. The first patient was treated with an hESC-based cellular therapy product in a clinical trial for spinal cord injury in 2010 3. In 2014, the first patient received hiPSC-derived retinal pigment epithelial cells for macular degeneration 4. Although pluripotent stem cells have been generated at laboratory scale, large scale production processes by standardized and economically viable procedures and technologies will be required 5. One of the challenges in large scale expansion of pluripotent stem cells is suspension culture of cell aggregates in stirred bioreactors 6,7 in which single cells form cell aggregates in the presence of the small molecule Y27632 (Rho-associated coiled-coil kinase inhibitor) 8. Furthermore, bioreactor-based suspension culture of pluripotent stem cells can be used for large scale induction of functional cells such as iPSC-derived cardiomyocytes 9. In addition, a recent report suggests that cell aggregates can be used as building blocks for tissue engineering 10. One bottleneck in manufacturing pluripotent stem cells is robust cryopreservation, and large-scale cell cryopreservation will be mandatory for industrial applications and clinical translation. Cryopreservation is classified into two distinct methods: slow freezing and vitrification. In vitrification methods, cryoprotectant solutions with high cryoprotectant concentrations are used, and cells are rapidly frozen by direct immersion of the container in liquid nitrogen. Originally, vitrification methods were developed for cryopreservation of oocytes and embryos 11. Fujioka et al. developed DAP213, a cryoprotectant solution containing dimethyl sulfoxide (DMSO) for primate ESCs, and succeeded in cryopreservation of ESCs by vitrification of a 0.2-mL scale 12. H...
“…In the cryopreservation process, both cooling and warming rates should exceed the critical cooling rate (CCR) 17 and critical warming rate (CWR) 18 to avoid failure of vitrification, resulting in cell damage caused by ice crystal growth 19 . In large scale cryopreservation, one of the major technological barriers is achieving the CWR to avoid devitrification, because the conventional method of rewarming is performed by immersing vitrified cells in a water bath at 37 °C to avoid cellular damage caused by overheating.…”
Scale-up of production is needed for industrial applications and clinical translation of human induced pluripotent stem cells (hiPSCs). However, in cryopreservation of hiPSCs, successful rewarming of vitrified cells can only be achieved by convective warming of small volumes (generally 0.2 mL). Here, we present a scalable nano-warming technology for hiPSC cryopreservation employing inductive heating of magnetic nanoparticles under an alternating magnetic field. The conventional method by water bath heating at 37 °C resulted in a decrease of cell viability owing to devitrification caused by slow warming of samples with large volumes (≥ 20 mL). Nano-warming showed uniform and rapid rewarming of vitrified samples and improved viability of hiPSCs in the 20-mL system. In addition to single cells, hiPSC aggregates prepared using a bioreactor-based approach were successfully cryopreserved by the nano-warming technique. These results demonstrate that nano-warming is a promising methodology for cryopreservation in mass production of hipScs. Pluripotent stem cells, including human embryonic stem cells (hESCs) and induced pluripotent stem cells (hiP-SCs), are a promising cell source for regenerative medicine because of their unlimited proliferation potential and differentiation capability 1,2. The first patient was treated with an hESC-based cellular therapy product in a clinical trial for spinal cord injury in 2010 3. In 2014, the first patient received hiPSC-derived retinal pigment epithelial cells for macular degeneration 4. Although pluripotent stem cells have been generated at laboratory scale, large scale production processes by standardized and economically viable procedures and technologies will be required 5. One of the challenges in large scale expansion of pluripotent stem cells is suspension culture of cell aggregates in stirred bioreactors 6,7 in which single cells form cell aggregates in the presence of the small molecule Y27632 (Rho-associated coiled-coil kinase inhibitor) 8. Furthermore, bioreactor-based suspension culture of pluripotent stem cells can be used for large scale induction of functional cells such as iPSC-derived cardiomyocytes 9. In addition, a recent report suggests that cell aggregates can be used as building blocks for tissue engineering 10. One bottleneck in manufacturing pluripotent stem cells is robust cryopreservation, and large-scale cell cryopreservation will be mandatory for industrial applications and clinical translation. Cryopreservation is classified into two distinct methods: slow freezing and vitrification. In vitrification methods, cryoprotectant solutions with high cryoprotectant concentrations are used, and cells are rapidly frozen by direct immersion of the container in liquid nitrogen. Originally, vitrification methods were developed for cryopreservation of oocytes and embryos 11. Fujioka et al. developed DAP213, a cryoprotectant solution containing dimethyl sulfoxide (DMSO) for primate ESCs, and succeeded in cryopreservation of ESCs by vitrification of a 0.2-mL scale 12. H...
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