NEW YORK (Reuters Health) - Developing human embryos can accept blastomere transplants and integrate them into their architecture, according to a report in the April issue of Fertility & Sterility. The finding offers proof-of-principle that single gene diseases might be treatable at the embryo stage of life.
Experimental studies indicate that the repair of single gene defects may not have to be complete in order to effect a cure, the authors explain, suggesting that single gene defects might be treatable through the transplantation of normal blastomeres that contain the missing or defective gene.
Dr. Norbert Gleicher from Center for Human Reproduction, Chicago, Illinois and Dr. Ya Xu Tang from the Foundation for Reproductive Medicine, Chicago, Illinois tested this concept using a human blastomere transplantation model involving 44 cryopreserved embryos that were specifically donated to research.
The researchers transplanted male (XY) blastomeres into female (XX) day 3 embryos and tracked the XY cells through the blastocyst stage (days 5-6) and into the hatching period (day 6).
Representative slides demonstrated considerable integration of the Y chromosome throughout the inner cell mass and the trophectoderm of day 5 blastocyst stage recipient embryos and throughout day 6 completely hatched recipient embryos.
Twelve normally developing embryos showed an even and well-distributed staining pattern for the Y chromosome, the authors note, whereas the remaining 9 abnormally developing or arrested embryos showed uneven, spotty, and diminished staining patterns.
“The fact that transplanted blastomeres demonstrate an apparently normal distribution of daughter cells throughout inner cell mass and trophectoderm suggests that these transplanted blastomeres are, indeed, integrated into the early development of recipient embryos,” the investigators write.
“What remains to be demonstrated is that this integration is normal and would result in the birth of an anatomically, genetically, and functionally normal child.”
While the usefulness of the technique remains to be seen “the here-presented study strongly suggests that such transplantations are technically feasible,” Drs. Gleicher and Tang conclude.
“Before blastomere transplantation in humans can, therefore, be further considered,” the researchers add, “it would appear essential to establish appropriate animal models to investigate potential adverse consequences.”
Source: Fertil Steril 2004;81:977-981. [ Google search on this article ]
MeSH Headings:Genetic Techniques: Investigative Techniques: Gene Transfer: Analytical, Diagnostic and Therapeutic Techniques and EquipmentCopyright © 2002 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Reuters and the Reuters sphere logo are registered trademarks and trademarks of the Reuters group of companies around the world.
