Amniotic fluid as a source of multipotent cells for clinical use.

Amniotic fluid cells (AFC) from 2nd trimester amniocentesis have been found to be a source of multipotent stem cells which might overcome the limitations of expansion, histocompatibility, tumorigenesis, and ethical issues associated with using human embryonic cells, umbilical cord, cord blood, bone marrow, and induced pluripotent cells. Previous work by our group and others demonstrated multipotency and the ability to grow well in culture. However, all these studies were done in media containing fetal calf serum. We sought to observe the properties of AFC grown in serum-free media as that would be required for clinical transplantation in humans. Fresh samples were obtained from three patients, and each sample divided into a culture whose cells were not exposed to fetal calf serum, and the other half into a standard culture medium containing fetal calf serum. Doubling time and stem cell marker expression by flow cytometry were assessed. Differentiation to neural, osteoid, and chondrogenic lineages was induced using appropriate media and confirmed by fluorescent microscopy, histology, and immunohistochemistry. There were no statistically significant differences between cells grown serum-free and in standard media in any of these parameters. The data supports the possibility of clinical use of AFC in stem cell transplantation.