A girl who underwent a bone marrow transplant using healthy cells from her baby brother--conceived artificially after his embryo was genetically screened and selected specifically to save his sister--was recovering well, doctors said on Wednesday.

Three weeks after Molly Nash, 6, underwent a bone marrow transplant using stem cells from the umbilical cord of her baby brother, Adam, her blood counts have steadily increased, indicating marrow recovery, University of Minnesota blood specialist John Wagner told a news conference.

"The tests over the last few days...show that there is donor cell engraftment and that the cellularity of the bone marrow is phenomenal," he added. "What we know for sure is that for the first time in years, Molly is making neutrophils (a white blood cell that fights bacteria) and platelets."

The girl needed a transplant to treat a life-threatening blood disease. To find the proper stem cells, doctors at the Reproductive Genetics Institute in Chicago first formed several embryos with eggs and sperm from the girl's parents.

Then using genetic screening techniques, they checked the embryos for disease and picked one with a tissue type that matched the couple's ailing daughter and would provide her with an immune system to fight her disease.

That embryo was implanted and the boy was born to the mother. The family lives in Englewood, Colorado. Stem cells were taken from Adam's umbilical cord.

Doctors involved said it marked the first time an embryo diagnosis before implantation had been used for this purpose. Culling embryos has been used before for other purposes, such as selecting one that will develop into a healthy baby.

The university said the girl will probably be discharged within a week but will have to monitored for two months.

(From Reuters)