Cell Cryopreservation: An Emerging Technology for Storing Living Cells at Ultra-Low Temperatures
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| Cell Cryopreservation |
Cell cryopreservation refers to the process of freezing and storing living cells at ultra-low temperatures, usually around −196°C using liquid nitrogen. At these low temperatures, any biological activity, including cell division and metabolic processes, essentially stops. This allows the cells to be preserved and maintained in a viable state for extended periods of time, in some cases indefinitely. There are many applications of cell cryopreservation in areas like reproductive medicine, biotechnology research, and gene and tissue banking.
Methods of Cryopreservation
There are two main methods used for cryopreservation of cells - slow
freezing and vitrification. In slow freezing, cells are cooled at a controlled
rate, usually 1°C/minute, allowing ice crystals to form outside the cells.
Chemical cryoprotectants like dimethyl sulfoxide (DMSO) or glycerol are added
to prevent excessive dehydration. Vitrification avoids ice crystal formation by
ultrarapid cooling of cells suspended in highly concentrated cryoprotectants.
This glass-like solidification process suspends cells in a very viscous state.
Both methods aim to minimize physical damage from ice formation during freezing
and thawing. Researchers are developing new protocols and cryoprotectants to
improve cell survival post-thaw.
Applications in Reproductive Medicine
Cell
Cryopreservation finds major applications in fertility preservation and
assisted reproductive technologies. Ovarian tissue and embryos can be
cryopreserved for future use by cancer patients undergoing sterilizing
therapies like chemotherapy. This allows them the chance to have
genetically-related children later. Sperm banks freeze donor sperm to be used
in fertility treatments. Embryo banking allows for the long-term storage of in
vitro fertilized embryos from fertility treatments. If implantation fails or
multiple births are not desired, the extra healthy embryos can be frozen for
later thawing and transfer.
Cryopreservation in Stem Cell Research
Stem cells have tremendous potential for regenerative medicine due to their
unique ability to self-renew and differentiate. However, they are very
difficult to propagate and maintain in the laboratory without losing
pluripotency or viability over time. Cryopreservation provides an invaluable
method for long-term storage of stem cells like adult stem cells, embryonic stem
cells and induced pluripotent stem cells. Researchers can preserve valuable
stem cell lines and patient-specific cell sources for future experimental and
potential therapeutic use. This reduces costs and saves time associated with
continuous culturing and sub-culturing. Standardized protocols for freeze-thaw
of different stem cell types continue to be refined.
Biobanking of Cells and Tissues
Biobanks are facilities that collect, process, store and distribute biological
samples and associated clinical data for medical research purposes. Cell and
tissue cryopreservation is a core function of modern biobanks. Disease and
normal human cells can be cryopreserved indefinitely to form rich
biorepositories that serve as an important resource for retrospective and prospective
studies in translational medicine. Genetic/genomic analysis of banked cells has
led to discoveries in cancer biology, immunotherapy development and
pharmacogenomics. Population biobanks also aid in investigations linking
genetic variations to health outcomes and disease susceptibility. Strict
quality standards ensure sample integrity over decades of cryogenic storage.
Cryopreservation Challenges and Future
While cryopreservation has made immense progress, certain challenges remain.
Post-thaw viability varies greatly by cell type, with stem cells often
demonstrating poorer survival versus somatic cells. Development of new natural
and synthetic cryoprotectants is ongoing to achieve higher viability outcomes
with fewer cytotoxic effects. Controlling ice nucleation during freezing and
achieving vitrification consistently poses technical hurdles. Standardization
of protocols for different cell types and across laboratories also requires
attention. Looking ahead, cell cryopreservation will continue supporting
advances in assisted reproduction, regenerative therapies using adult and iPS
stem cells, and personalized medicine based on biobank research. Further gains
in our scientific understanding of low-temperature biology may unlock even more
applications for this critical enabling technology.
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