With the development of tissue engineering and regeneration medicine, decellularized extracellular matrix (dECMs) has raised a lot of attention as they can provide a natural biochemical environment, availability, and lack of immunogenicity in host tissues. In addition, biologically active molecules, such as growth factors and cytokines can be maintained in the decellularized matrix. Therefore, extracellular matrix (ECM)-based scaffolds are considered as the most similar scaffold to the original tissue. ECMs have been widely used in the field
The successful rewarming of cryopreserved organs has always been a big challenge for the cryopreservation technology aimed at improving the shortage of available organs for transplantation. The traditional water bath rewarming produces more obvious devitrification and thermal stress damages, resulting in negative effects on the organ structure and physiological function. Nanowarming technology via induction heating of iron oxide nanoparticles for rewarming large-volume frozen biosamples is a promising strategy to overcome related problems. In this study, Fe 3 O 4 nanoparticles modified with carboxylic acid are used for nanowarming to rewarm the whole frozen kidney. The key steps including loading and elution of the cryoprotectant and magnetic nanoparticles (mNPs), vitrification of large-volume samples, and nanowarming of the whole kidney are explored in detail to achieve whole kidneys with a more integrated structure. Compared with water bath thawing, the nanowarming method could reduce the maximum thermal stress of the whole kidney by 2 orders of magnitude and has enough rewarming rate to avoid the devitrification phenomenon, so as to obtain a lower cell apoptosis rate, a more integrated vascular network, and a lower residual amount of mNPs inside the kidneys after elution. The optimization of the nanowarming method for the whole kidney could provide effective guidance for the large organ cryopreservation in clinical transplantation.
Droplet-based vitrification is considered to be a promising cryopreservation method, which achieves high cell viability through high cooling rates and low concentrations of cryoprotective agents (CPAs). However, the droplet vitrification cryopreservation process needs in-depth research, such as the balance of the CPA concentration and the cooling rate, the CPA loading process, and the droplet encapsulation method. Here, we developed a chip with a high cooling rate for vitrification droplet encapsulation and provided a new method for continuous loading of low-concentration CPA droplets by evaporation. The results showed that the CPA droplet volume decreased exponentially with the evaporation time, and the larger the initial droplet size, the longer the evaporation time to achieve the critical vitrification concentration. There was no significant difference in the viability of MSCs, NHEK, and A549 cells between the evaporation loading vitrification method and the traditional slow freezing method, but the former was easier to operate and can balance the cooling rate and concentration by controlling the evaporation time. Moreover, a theoretical model was proposed to predict the CPA concentration inside the microdroplets dependent on the evaporation time. The current work provides a potential method to load low-concentration CPAs for cell vitrification preservation, which is more beneficial for cell therapy and other regenerative medicine applications.
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