Stem cells are cells that have not yet differentiated into particular types of cell; they are capable of giving rise to indefinitely more cells of the same type. As your body incurs damage throughout your life, it sends these cells to the damaged parts to begin repair. Unfortunately, as you undergo senescence, or biological aging, your stem cell production diminishes, so you take longer to heal and have less potential for rejuvenation. The question in recent years has become whether we can make use of stem cells to delay this process.
The proposed solution is to harvest and freeze your stem cells in your youth, so that they can be used to rejuvenate you in old age. We speak to Steven Holder, co-founder of Acorn Cryotech, a company which provides cellular cryotherapy.
How will stored stem cells help clients who undergo gene therapy and organ regeneration?
Organ regeneration is a promising field that may soon allow scientists to 3D-print new organs or grow them from individual cells on organ-like scaffolds. However, in order for those organs to be completely immune-compatible, the cells used to grow them will need to come from the patient they will be used on. While aged patients will have the greatest need, their old stem cells will be of the lowest quality. Younger stem cells will provide more robust cellular inputs and even produce younger versions of the organs they’re being used to replace. Gene therapy is the direct manipulation of a person’s genome in order to correct or augment DNA code. While the technology is still in its infancy, the ability to modify a person’s genetics – or epigenetics – will allow researchers to fix genomic mistakes that have accumulated throughout the cells of a person’s body over time. Having young cells cryopreserved may allow future scientists to look back at the way our cells were once genetically compromised, and use that information as a template for gene therapy, to help correct aging in our old cells.
What is the difference between stem cells harvested from an umbilical cord and stem cells harvested from other areas of the body when a person is older?
Umbilical cord stem cells are multipotent, which means they have a limited potential to become other cell types. Specifically, they are hematopoietic, which means they can only be directly differentiated into blood cell lines for treatment of blood- related disorders. Stem cells harvested from urine are also multipotent, but specifically mesenchymal, which means they can only directly differentiate into bone, cartilage, muscle and fat cells. There are cell populations in the bulb of plucked hair that have been shown to be pluripotent stem cells, which means they have the capacity to directly differentiate into any other cell type of the body. While umbilical cord stem cells are younger than mature stem cells collected from adults, aging itself is an exponential process. The quality of the cells of young adults is not drastically different from that of newborns.
Do all stem cells have an equal capacity to develop into body parts – or are they more likely to turn into tissue, bone and fat?
Umbilical stem cells have a limited capacity to be directly differentiated into anything other than blood cells, and possibly bone and fat. That being said, umbilical cord cells have been successfully de-differentiated into induced pluripotent stem cells (iPSCs). As iPSCs, they have the same theoretical potential to be differentiated into any type of cell in the body as do pluripotent stem cells. The same logic applies to stem cells collected from urine – multipotent populations capable of direct differentiation into a limited number of other cell types can be de-differentiated into iPSCs, then differentiated into any other type of cell.
What does the freezing process entail?
At the molecular level, one of the greatest dangers for cell survival is the formation of ice crystals during the freezing process that can rupture cellular membranes. In order to circumvent the problem, cells are cooled very slowly and are frozen in a solution containing chemical protectants such as DMSO that limit ice crystal formation. Once frozen, cells are moved into -196° Celsius liquid nitrogen; at this temperature, biological activity is almost completely halted and cells retain their existing characteristics.
How certain is it that the stem cells will remain young and still function when defrosted?
Nothing can be said to be certain, especially when we look out onto such a long-term horizon. That being said, we can take cues from decades of experiments scientists have conducted on cellular cryopreservation to inform our level of confidence. One especially promising experiment showed that sperm cells frozen for 40 years were successfully used for in vitro fertilization that produced healthy twins. Stem cells have similarly been frozen, thawed and shown to retain their ability to differentiate into multiple cell types.
That frozen cells will remain young is a matter of chemistry – at colder temperatures, chemical reactions and cellular events occur much more slowly, bringing the aging process to a standstill.
Is there a particular subset of people who should be placing this option at the forefront of their medical choices, such as those with a family history of genetic disorders?
Young adults with a family history of age-related disease have a higher probability of benefiting from our service, especially if there is currently research that has made progress on those specific ailments. Cryotherapy may be the way of the future. However, those who choose to cryopreserve their young cells should not rely on future technology to save them from poor lifestyle choices.
Combining healthy choices with young cell cryopreservation is the best way to improve one’s odds of a longer healthy life.