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Abstract: Cryopreservation is a fundamental technology in biomedical research, regenerative medicine, and tissue engineering, enabling the long-term storage of cells, tissues, and organs. However, its effectiveness is limited by challenges such as intracellular ice formation, cryoprotectant toxicity, and reduced post-thaw viability. This review explores the crucial role of encapsulation in enhancing cryopreservation efficiency, with a focus on recent advances in materials science, bioengineering, and cryobiology. Emerging technologies, such as nanotechnology and stimuli-responsive polymers, are transforming encapsulation strategies. Innovations such as microfluidic systems offer precise control over cooling rates and cryoprotectant distribution, thereby mitigating conventional limitations. The review also addresses current obstacles related to scaling up encapsulation processes and ensuring the long-term biocompatibility and stability of preserved specimens. By synthesizing recent findings, this work provides a comprehensive resource for researchers and clinicians seeking to enhance biopreservation techniques and their applications in contemporary medicine and biotechnology. Finally, the review identifies critical knowledge gaps that must be addressed to improve the efficacy of cryopreservation strategies and advance their clinical translation.
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Key words:
- cryopreservation /
- encapsulation /
- hydrogels /
- biomaterials /
- tissue engineering /
- regenerative medicine /
- nanotechnology /
- smart polymers
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Figure 2. Overview of encapsulation techniques for cryopreservation
(A) Schematic of a capillary microfluidics-based core-shell device, in which cells are encapsulated in droplets using a tube-in-tube system and cross-linked in CaCl2 solution to form stable microcapsules. (B) Illustration of stem cell encapsulation and vitrification using quartz microcapillaries and plastic straws, including cryomicroscopy to monitor ice formation inhibition. Insets show alginate hydrogel microdroplets and stem cell-laden capsules. (C) Diagram of an electrostatic spraying system used to generate core-shell microcapsules and monitor vitrification in a water bath. (D) Schematic of a centrifugal platform used to fabricate core-shell structures and hydrogel beads/fibers. (E) Characterization of microcapsule formation as a function of oil flow rate, demonstrating control over microcapsule diameter and shell thickness. (F) Fluorescence microscopy images and size distribution of electrostatically sprayed microcapsules. (G) Microscopic evaluation of encapsulation efficiency for murine embryonic stem cells and human adipose-derived stem cells. (H) Morphological characterization and size distribution of hydrogel fibers and capsules generated via centrifugal techniques. (I) Comparison of perivascular Adipose-Derived Stem Cell (pADSC) viability among fresh, CPA-treated, and cryopreserved samples. (J) Viability assessment of encapsulated versus non-encapsulated stem cells before and after vitrification. (K) Cell viability comparison between conventional slow freezing and core-shell encapsulation methods for HUVECs. (L) Short-term viability analysis of cells encapsulated in simple hydrogel beads/fibers versus core-shell microcapsules. All panels reproduced with permission: Figure (A, E, I)[40], (B, G, J)[41], (C, F, K)[37], (D, H, L)[42]. * indicates P < 0.05, ** indicates P < 0.01.
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