Healthy bone marrow may be important in fertility

A study in mice suggests that bone marrow-derived stem cells may play a role in establishing pregnancy. The research showed that the stem cells can travel through blood circulation to the uterus, making it more receptive for a new embryo. Specifically, the authors showed that these cells concentrate in the lining of the uterus where the embryo is about to implant. There, they become specialised uterine cells or decidual cells, which are critical for maintaining the embryo. 'We have always known that two kind of things were necessary for pregnancy: you must have ovaries to make eggs, and you must also have a uterus to receive the embryo,' said senior author, Dr Hugh Taylor at Yale University in New Haven, Connecticut. 'But knowing that bone marrow has a significant role is a paradigm shift.' Previous studies had shown that small numbers of bone-marrow stem cells contribute to the renewal of the lining of the non-pregnant uterus, but it remained unknown whether they play a part in pregnancy.

This study is the first to show a physiological role for bone-marrow stem cells in pregnancy. This work was possible due to a methodological breakthrough. Dr Taylor and his team at Yale were able to develop a mild chemotherapy for their mouse model that 'wiped out' the bone marrow of these mice without affecting their eggs, and therefore their fertility. Then they fertilised these mice before and after healthy bone-marrow transplantation to investigate whether the bone-marrow stem cells contributed to the establishment of pregnancy.