Artificial Gametes: Will Sperm and Eggs Become Obsolete Someday?
By Andrew Dorfmann, MS ELD(ABB)
A recent article in the journal Reproductive BioMedicine Online Vol 16:4 2008 (Development of Artificial Gametes, by Dr. Zsolt Peter Nagy) explores the fascinating though controversial topic of artificial gametes. Using artificial gametes, we may someday be able to overcome certain untreatable forms of infertility using non-germ cells derived from the infertile patients themselves.
While all normal cells can replicate themselves, the germ cells; sperm and oocytes (eggs), are capable of replicating an entire organism. Germ cells are able to do this by a mechanism known as meiosis, a specialized form of cell division in which the genetic material is reduced by half in each gamete in preparation for fertilization and embryo formation. In this manner, male and female germ cells can come together, combine the two single sets of genetic material and form a new and unique individual. Though scientists have been studying these processes in plants, animals and humans for many years, there is still much that is unknown about the molecular and biochemical details of this special form of cell division in sperm and oocytes.
The article by Dr Nagy presents two strategies in which one could potentially create artificial gametes. One idea is to use somatic cells (i.e.- any cell type in the body other than germ cells) and trick them into going through a meiosis-like cell division that results in cells containing one half of the genetic material that was present in the original cells. This “reduction division” process is called “somatic cell haploidization” that results in cells that contain the same amount of genetic material as there is in germ cells and half the genetic material present in somatic cells. There have been some modest success in this area, but to date, there are too many problems in the accuracy of the reduction division. The cells that result from haploidization have errors in ploidy -- (the number of chromosomes), and also problems with epi-genetic effects -- a kind of conditioning effect of the germ cell environment or other effects external to the genome that impact the way the genes are expressed.
The other artificial gamete strategy is to direct the differentiation of stem cells (either embryonic or adult in origin) in a manner to create new germ cells. At the present time while various strategies are being attempted, this is only an experimental procedure being used in animal models, though certainly a very appealing one. So far, these artificial gametes also seem to have the same problems of ploidy and epi-genetic errors. Using embryonic stem cells is more likely to be fruitful for this type of strategy, but there is of course great controversy surrounding these cell lines. Adult stem cells may be suitable, but since they are further down the path of differentiation, it will be harder to direct their development back to functional germ cells.
So, at least for the present and the foreseeable future, we will still need to capture and culture sperm cells and oocytes in the IVF laboratory to treat infertility. But the future holds much promise in this exciting area of biomedicine.
A recent article in the journal Reproductive BioMedicine Online Vol 16:4 2008 (Development of Artificial Gametes, by Dr. Zsolt Peter Nagy) explores the fascinating though controversial topic of artificial gametes. Using artificial gametes, we may someday be able to overcome certain untreatable forms of infertility using non-germ cells derived from the infertile patients themselves.
While all normal cells can replicate themselves, the germ cells; sperm and oocytes (eggs), are capable of replicating an entire organism. Germ cells are able to do this by a mechanism known as meiosis, a specialized form of cell division in which the genetic material is reduced by half in each gamete in preparation for fertilization and embryo formation. In this manner, male and female germ cells can come together, combine the two single sets of genetic material and form a new and unique individual. Though scientists have been studying these processes in plants, animals and humans for many years, there is still much that is unknown about the molecular and biochemical details of this special form of cell division in sperm and oocytes.
The article by Dr Nagy presents two strategies in which one could potentially create artificial gametes. One idea is to use somatic cells (i.e.- any cell type in the body other than germ cells) and trick them into going through a meiosis-like cell division that results in cells containing one half of the genetic material that was present in the original cells. This “reduction division” process is called “somatic cell haploidization” that results in cells that contain the same amount of genetic material as there is in germ cells and half the genetic material present in somatic cells. There have been some modest success in this area, but to date, there are too many problems in the accuracy of the reduction division. The cells that result from haploidization have errors in ploidy -- (the number of chromosomes), and also problems with epi-genetic effects -- a kind of conditioning effect of the germ cell environment or other effects external to the genome that impact the way the genes are expressed.
The other artificial gamete strategy is to direct the differentiation of stem cells (either embryonic or adult in origin) in a manner to create new germ cells. At the present time while various strategies are being attempted, this is only an experimental procedure being used in animal models, though certainly a very appealing one. So far, these artificial gametes also seem to have the same problems of ploidy and epi-genetic errors. Using embryonic stem cells is more likely to be fruitful for this type of strategy, but there is of course great controversy surrounding these cell lines. Adult stem cells may be suitable, but since they are further down the path of differentiation, it will be harder to direct their development back to functional germ cells.
So, at least for the present and the foreseeable future, we will still need to capture and culture sperm cells and oocytes in the IVF laboratory to treat infertility. But the future holds much promise in this exciting area of biomedicine.
posted by Kathleen, Contributing Editor at
1:55 PM
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