Sand-Mediated Ice Seeding for Serum-Free hiPSC Cryopreservation
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Solution Overview
Problem
Current cryopreservation methods for human induced pluripotent stem cells (hiPSCs) face challenges such as low survival rates, toxicity from cryoprotectants like DMSO, risk of spontaneous differentiation, and ethical concerns with fetal bovine serum, making it difficult to scale up for high-volume cell banking while maintaining high viability and pluripotency.
Innovation Solution
A method using sand-mediated ice seeding in cryovials, where sand particles immobilized on the inner plastic surface induce controlled ice nucleation above −10°C, allowing for serum-free cryopreservation with reduced DMSO concentration, enhancing cell survival and pluripotency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional slow-freezing method with DMSO and FBS is used, then cell survival rate is improved, but toxicity from DMSO and risk of spontaneous differentiation increase
Solution Approach 1:
The patent removes fetal bovine serum (FBS) from the cryopreservation medium, replacing it with a serum-free formulation. This extraction eliminates the harmful factors associated with FBS (spontaneous differentiation, xenogeneic pathogens) while maintaining cell survival through alternative protective mechanisms involving sand-mediated ice seeding and optimized CPA composition
Solution Approach 2:
The patent changes the concentration parameters of cryoprotectants, specifically using reduced DMSO concentration (5% instead of conventional 10%) combined with alternative CPAs like sugars. This parameter adjustment reduces toxicity while maintaining protective effects through controlled ice nucleation at higher temperatures
2Reliability
If high concentration of DMSO is used for cryopreservation, then cell protection during freezing is improved, but cell toxicity and epigenetic changes increase
Solution Approach 1:
The patent changes the concentration parameter of DMSO from conventional 10% to 5%, and introduces alternative cryoprotectants such as sugars. This parameter modification reduces the harmful epigenetic effects and cellular process changes while maintaining freezing protection through a different chemical composition
Solution Approach 2:
The patent uses a composite cryopreservation medium containing multiple components including reduced DMSO, sugars, and other compatible cryoprotectants. This composite formulation provides synergistic protection during freezing while minimizing the toxic effects associated with high concentrations of single agents like DMSO
3Reliability
If controlled ice nucleation above -10°C is achieved through sand-mediated seeding, then cell survival is improved, but device complexity increases
Solution Approach 1:
The patent introduces sand particles as an intermediary substance that mediates ice nucleation. These particles, when coated on the inner surface of cryovials, serve as nucleation sites that trigger controlled ice formation at temperatures above -10°C, thereby improving cell survival without requiring complex external cooling systems
Solution Approach 2:
The patent applies sand coating to the cryovial surfaces in advance before cell loading. This preliminary action prepares the device with pre-positioned nucleation sites, enabling controlled ice formation during subsequent freezing without requiring complex real-time control systems or specialized equipment
4Reliability
If sand coating is applied to cryovial inner surface, then controlled ice nucleation is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent uses sand particles, which are inexpensive and readily available, to coat the cryovial surfaces. This approach replaces complex manufactured nucleation structures with a simple, cheap coating that can be applied through straightforward processes, minimizing manufacturing complexity while achieving reliable controlled ice nucleation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method achieves high viability (up to 90%) and pluripotency of hiPSCs post-thaw, with reduced toxicity and cost-effectiveness, facilitating widespread application in cell-based medicine and conservation.
Implementation Method 1
sand particles immobilized on the inner plastic surface induce controlled ice nucleation above -10°C
Data Source
AI summary
Human induced pluripotent stem cells (hiPSCs) possess tremendous potential for tissue regeneration and banking hiPSCs by cryopreservation for their ready availability is crucial to their widespread use. However, contemporary methods for hiPSC cryopreservation are associated with both limited cell survival and high concentration of toxic cryoprotectants and/or serum. The latter may cause spontaneous differentiation and introduce xenogeneic factors, which may compromise the quality of hiPSCs. Here, sand from nature is discovered to be capable of seeding ice above −10° C., which enables cryopreservation of hiPSCs with no serum, minimized cryoprotectant, and high cell survival. Furthermore, the cryopreserved hiPSCs retain high pluripotency and functions judged by the pluripotency marker expression, cell cycle analysis, and capability of differentiation into the three germ layers. This unique sand-mediated cryopreservation method may greatly facilitate the convenient and ready availability of high-quality hiPSCs and probably many other types of cells/tissues for the emerging cell-based translational medicine.