In utero hematopoietic cell transplantation: what are the important questions?

The treatment of congenital hematologic disorders before birth by in utero hematopoietic stem cell transplantation remains a challenging goal. Although success has been achieved in X-linked severe combined immunodeficiency, the approach has failed in all other disorders attempted thus far. In this review, we examine relevant experimental data from the perspective of an analysis of why failure has occurred. We will also attempt to pose the important questions that will need to be answered prior to further clinical attempts to treat most target disorders by this approach.