In utero fetal hematopoietic stem cell transplantation.

The fetus is the preferred candidate for transplantation for a number of reasons. First, the fetal period is the earliest time at which an identified disorder can potentially be treated. If a fetus is identified with a treatable disorder in utero, and if that disorder can affect fetal development, then treatment during fetal life is potentially beneficial. A second advantage of in utero fetal HSC transplantation is the immunotolerance of the fetus, making it both a favorable donor and a favorable recipient. Finding a histocompatible donor and minimizing GVH disease are major concerns in bone marrow HSC transplantation. Fetal immuno-tolerance may eliminate the need for the former and significantly reduce the incidence and severity of the latter. The first hematologic disorders for fetal HSC transplantation may be sickle cell disease and the thalassemias, as recent technologic developments allow diagnosis in the first trimester. However, the potential targets for in utero fetal HSC transplantation are numerous and include a variety of genetic disorders of lymphocyte, platelet, leukocyte, red cell, and enzyme function. Disadvantages of in utero fetal HSC transplantation exist. First, it is necessary to have identified the fetus as being at risk for a genetic disorder, before the prenatal diagnosis can be made. This happens in one of two ways--either a previous pregnancy resulted in an affected fetus, or the parents of the fetus have been identified as being carriers of the genetic disorder.(ABSTRACT TRUNCATED AT 250 WORDS)