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Bischof, J. C.

Publications and source records attributed to Bischof, J. C..

3 recordsLinked to original sources

Cryoaerosolization Enables Scalable Vitrification-Based Cell Cryopreservation

Cell therapies hold transformative potential for treating cancer, neurologic disorders, organ failure, diabetes, and other conditions, but their widespread clinical deployment is constrained by the lack of scalable cryopreservation methods that maintain high post-thaw viability. Current standard practice using slow freezing can lead to cell death and impaired cell function. Vitrification offers an alternative by cooling samples rapidly enough to bypass ice formation entirely, better preserving cell structure and function. The high cooling and warming rates required for vitrification have previously been achieved by quenching microliter-scale samples directly into convective cooling and warming baths. Here, we present a cryopreservation platform that overcomes the throughput limitations of existing systems by combining a vibrating orifice aerosol generator with an impinging conical nozzle to generate and confine micrometer-scale droplets mid-flight in liquid nitrogen. This approach mitigates cooling losses due to the inverse Leidenfrost effect, increasing cooling and warming rates by nearly an order of magnitude compared to conventional droplet vitrification, while improving throughput by two orders of magnitude. To test the efficacy of this system, we cryoaerosolized and rewarmed human induced pluripotent stem cells, porcine red blood cells, and human dermal fibroblasts using only 190-25 wt% (2.5-3.7 M) permeating cryoprotective agent, achieving >90% post-thaw viability for HDFs and hiPSCs and 94% recovery for RBCs, with retained colony-forming capacity additionally demonstrated in hiPSCs. This work demonstrates the first scalable vitrification-based cryopreservation method capable of achieving both high cooling ({approx} 200, 000 K min-1) and warming rates ({approx} 1, 000, 000 K min-1) while maintaining the high-throughput processing required ([≥]100 mL h-1) for next-generation cell therapies. Significance StatementCell therapies require robust long-term storage methods to enable widespread clinical deployment. Current approaches utilizing refrigeration or small-scale vitrification cannot meet the scalability and viability requirements for next-generation therapeutics. In this work we demonstrate a cryoaerosolization process that achieves both ultra-rapid cooling rates (>200,000 {degrees}C min-1) and high throughput (>100 mL h-1) by generating micrometer-scale droplets and spraying in a liquid nitrogen impingement stream. Using only as little as 19 wt% cryoprotectant, we achieved >90% cell viability and maintained function, comparable to low-throughput methods, but at two orders of magnitude higher processing rates. We also introduce a just-in-time CPA loading approach that reduces toxicity exposure. This technique enables scalable vitrification-based cryopreservation of large-volume cell products.

bioengineering↗

Vitrification and rapid rewarming of precision-cut liver slices for pharmacological and biomedical research

Background and AimsHigh-throughput in vitro pharmacological toxicity testing is essential for drug discovery. Precision-cut liver slices (PCLS) provide a robust system for screening that is more representative of the complex 3D structure of the whole liver than isolated hepatocytes. However, PCLS are not available as off-the-shelf products, significantly limiting their translational potential. Cryopreservation could solve this bottleneck by effectively preserving PCLS indefinitely until their time of use. Conventional cryopreservation (slow cooling in DMSO-forming ice) results in poor PCLS viability and function and, therefore, has proven unsuitable. Here, we explore an "ice-free" cryopreservation approach called vitrification and focus on culturing and assessing PCLS for 3 days post-vitrification and rewarming, given that most acute drug toxicity tests are conducted over 24h. MethodsRat liver slices were diffusively loaded with a cryoprotective agent (CPA) cocktail consisting of EG and Sucrose. The CPA-loaded PCLS were placed on a polymer cryomesh, vitrified in liquid nitrogen (LN2), and rapidly rewarmed in CPA. The vitrified and rewarmed PCLS were subsequently cultured in a controlled volume of serum-free, chemically defined media for 3 days. ResultsThe cryopreserved PCLS maintained high viability, morphology, function, enzymatic activity, and drug toxicity response. Results show that the vitrified PCLS perform comparably to untreated controls and significantly outperform conventionally cryopreserved PCLS in all assessments (p < 0.05). ConclusionsRapid vitrification and rewarming of PCLS using cryomesh enabled successful preservation and culture. This approach maintained high viability, function, enzymatic activity, and drug response for 3 days in culture, similar to controls. Impact and ImplicationsThe implications of using vitrification to store PCLS are extensive. This technology provides an exciting opportunity for the development of an "off-the-shelf" cold supply chain of human PCLS from organs declined for transplant, which are sliced, cryopreserved, and stored in a repository and available for on-demand shipping for industrial and academic biomedical research. This would also allow PCLS to become a scalable, reproducible, wide-ranging, and population-representative source of tissue that can accurately mimic in-vivo conditions of the human liver. These transformative technologies could revolutionize our practice in studying not just the metabolism of drugs but also increase our capacity to study the zonal progression of many liver diseases and conduct other exciting biomedical research.

bioengineering↗

Physical vitrification and nanowarming at human organ scale to enable cryopreservation

Organ banking by vitrification could revolutionize transplant medicine. However, vitrification and rewarming have never been demonstrated at the human organ scale. Using modeling and experimentation, we tested the ability to vitrify and rewarm 0.5 - 3 L volumes of three common cryoprotective agent (CPA) solutions: M22, VS55, and 40% EG+0.6M Sucrose. We first demonstrated our ability to avoid ice formation by convectively cooling faster than the critical cooling rates of these CPAs while also maintaining adequate uniformity to avoid cracking. Vitrification success was then verified by visual, thermometry, and x-ray CT inspection. M22 and EG+sucrose were successfully vitrified in 0.5 L bags, but only M22 was vitrified at 3 L. VS55 did not vitrify at any tested volumes. As additional proof of principle, we successfully vitrified a porcine liver ([~]1L) after perfusion loading with 40% EG+0.6M Sucrose. Uniform volumetric rewarming was then achieved in up to 2 L volumes (M22 with [~]5 mgFe/mL iron-oxide nanoparticles) using nanowarming, reaching a rate of [~]88 {degrees}C/min with a newly developed 120 kW radiofrequency (RF) coil operating at 35kA/m and 360kHz. This work demonstrates that human organ scale vitrification and rewarming is physically achievable, thereby contributing to technology that enables human organ banking.

bioengineering↗