Transfer of tissue cells to the fetus

Several diseases of the fetus can be diagnosed prenatally. Some of them are due to insufficient production of a specific substance. It was therefore thought that, with the aid of fetoscopy, it might be possible to supply such an affected fetus with cells capable of producing the deficient substance. To ascertain whether tissue cells injected into the feto-placental circulation can pass through the microcapillaries of the placenta as early as in the second trimester, 125I-labelled cells of fetal liver were injected into an umbilical vessel ex utero after therapeutic abortion by hysterotomy. The distribution pattern of the radioactivity indicated that donor cells passed through the microcapillaries of the placenta and reached the target, i.e., the liver. In each experiment, the activity in the liver was higher than that in other organs studied. The activity in the brain and in the lungs was low. Transfer of tissue cells from a normal fetus to the circulation of an affected fetus in utero thus seems feasible. Permanent colonization of such cells would be facilitated by the fact that the donor as well as the recipient are fetuses of the second trimester and thus immunologically immature.