How about going to sleep and after waking up, finding out that you have been fast-forwarded a hundred years! What if I tell you that your body can be hibernated and you will be awakened later…alive! Well, preservation of the human body has not just been confined within Egyptian mummies. After the death of Rosalia Lombardo – an Italian girl who died at the age of two due to pneumonia, her father was so devastated that he decided to preserve her body which can be seen in the Catacombs of Palermo. In today’s world, the preservation of organs and tissues has made organ transplantation possible. Over the years, science has developed so fast that now we are already preserving live cells, organelles and tissues in very low temperature by a technique called cryopreservation [1]. The principle behind cryopreservation is simple: freezing and storing the biological material at or close to -196 °C in liquid nitrogen so that a dehydrating environment is created for the preservation of cells that will slow down the biological process [2]. It is almost like freezing food to save it from decomposition and then bringing it back to normal temperature before consumption. Agonizingly, it is not as simple as it has just sound. None of our cells has any genetic intrinsic capability to withstand such an increased extracellular stimulus and as a result, cell differentiation capacity is reduced [3]. In addition to that, a major component of our cells is water and freezing of water will cause irreversible expansion and formation of ice crystal, fracture damage and freezing injury that subsequently leads to the inactivation of cells [4]. That is why scientists use cryoprotectant – chemical compounds that prevent cell damage during freezing. Glycerol, Propylene Glycol, Dimethyl Sulfoxide (DMSO) are some of the most commonly known cryoprotectants or anti-freezing agents that are used by a method called vitrification. In this method, cryoprotectants work by substituting water in the cells. Hence, upon cooling, instead of producing crystallization of ice, the end product becomes solid, clumpy and molecularly similar to glass. Absence of cryoprotectant will cause the damage of cells at low temperatures and loss of their stiffness while changing from solid to liquid [5]. Several factors of cryoprotectants like pH, concentration, and osmotic pressure, need to be maintained properly to avoid cryoinjuries. The toxicity of cryoprotectants also needs to be considered as some of them (like ethylene glycol) can be metabolized to toxic elements while others might also penetrate the cells due to their high lipophilicity and cause destabilization [6]. Cryogenetics – a prominent Norwegian company is well known for preserving marine species, whereas some other companies are also involved in plant cryopreservation for the conservation of genetic resources [7]. Since 1996, the cryopreservation technique is being used in oocytes, semen and sperm preservation in sperm banks without showing any side effects during and after childbirth [8]. Moreover, the use of such low temperature, that is the cryogenic temperature is already mainstream in healthcare. Cryotherapy is used in an effort to relieve muscle pain, sprains and swelling after soft tissue damage or surgery [9]. Now, tell me: who does not want to cheat death? You, me- I think, everyone! Probably that is why currently 300 individuals and 30 pets have been cryopreserved in Alcor, a Michigan-based cryonics company in an attempt to determine if this technique can lead us to immortality [10]. Perhaps we won’t live long enough to see the results, but don’t we want to make ourselves forever young and be called as the mummies of 21st century? I bet we all do!
References:
(1) Karnieli, O. Bioreactors and Downstream Processing for Stem Cell Manufacturing. In Stem Cell Manufacturing; Elsevier Inc., 2016; pp 141–160. https://doi.org/10.1016/B978-0-444-63265-4.00006-6.
(2) Pegg, D. E. Principles of Cryopreservation. Methods in molecular biology (Clifton, N.J.). 2007, pp 39–57. https://doi.org/10.1007/978-1-59745-362-2_3.
(3) Naaldijk, Y.; Staude, M.; Fedorova, V.; Stolzing, A. Effect of Different Freezing Rates during Cryopreservation of Rat Mesenchymal Stem Cells Using Combinations of Hydroxyethyl Starch and Dimethylsulfoxide. BMC Biotechnol. 2012, 12 (1), 1–10. https://doi.org/10.1186/1472-6750-12-49.
(4) Vajta, G.; Kuwayama, M.; Vanderzwalmen, P.; Kuwayama, M.; Vanderzwalmen, P. Disadvantages and Benefits of Vitrification. 2007, 49–60. https://doi.org/10.3109/9780203090022-8.
(5) Bhattacharya, S. Cryopretectants and Their Usage in Cryopreservation Process. In Cryopreservation Biotechnology in Biomedical and Biological Sciences; IntechOpen, 2018. https://doi.org/10.5772/intechopen.80477.
(6) Bhattacharya, M. S. A Review on Cryoprotectant and Its Modern Implication in Cryonics. Asian J. Pharm. 2016, 10 (3).
(7) Cryogenetics • Cryopreservation and fertilisation https://www.cryogenetics.com/cryopreservation-and-fertilisation/ (accessed Apr 3, 2020).
(8) Swenson, C.; Swärd, L.; Karlsson, J. Cryotherapy in Sports Medicine. Scand. J. Med. Sci. Sports 2007, 6 (4), 193–200. https://doi.org/10.1111/j.1600-0838.1996.tb00090.x.
(9) Pegg, D. E. - Principles of Cryopreservation. 2009, 34–46. https://doi.org/10.3109/9780203092873-6.
(10) 50 years ago, the world’s first cryonically preserved human started his long, disturbing journey to immortality — Quartz https://qz.com/883524/fifty-years-frozen-the-worlds-first-cryonically-preserved-humans-disturbing-journey-to-immortality/ (accessed Apr 3, 2020).