"There was considerable doubt that uniparental stem cells would work since the lack a balanced set of chromosomes from both parents would interfere with the natural outcomes of genomic imprinting," McLaughlin said. "It turns out that genomic imprinting may be more a concern for developing stages and not so much a factor in the routine function of adult tissue, which was the ultimate goal for deriving these stem cells."
To study uniparental stem cells and the possible effects of genomic imprinting, McLaughlin's team created an experiment in which they would attempt to reconstitute the hematopoietic, or blood-producing, stem cells that were destroyed in mice exposed to radiation. The Penn researchers first created gynogenetic (egg-based) and androgenetic (sperm-based) embryonic stem cells and then injected those into blastocysts, a pre-embryonic clump of cells from a fertilized egg. The researchers could then harvest fetal liver cell precursors for transplant. Ultimately, the scientists found that uniparental cells, regardless of parent of origin, were able to functionally replenish the entire blood-producing system of adult mice.
The scientists were able to maintain animals for more than 12 months with entirely uniparental blood and were able to rescue other irradiated mice with bone marrow transplants from these animals. It is clear proof, according to McLaughlin, that uniparental cells could produce hematopoietic stem cells. In addition, McLaughlin's group found no evidence of disease linked to the transplanted cells.
In another finding critical for any clinical approach using embryonic stem cells, the researchers were a
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Source:University of Pennsylvania