Long-term cryopreserved amniocytes retain proliferative capacity and differentiate to ectodermal and mesodermal derivatives in vitro.

Putative stem cells have recently been isolated from several extra-embryonic tissues, including Wharton's Jelly and umbilical cord blood. Relevant studies have focused on primary cultures established from freshly isolated tissues. In this report, we examine the plasticity of 472 cells, a cryopreserved human amniocyte cell line originally isolated in 1974. Under conditions conducive for proliferation, the amniocytes displayed fibroblast-like morphologies and expressed Oct4 and Rex1, genes associated with pluripotency. Perhaps indicative of inherent plasticity, 472 cells simultaneously expressed ectodermal beta-III-tubulin and mesodermal fibronectin. When cultured under conditions that promote neural differentiation, the cells adopted neuronal morphologies and expressed neuronal genes, including Gap-43, NF-M, tau, and synaptophysin. Exposure to culture conditions that encourage osteogenic differentiation resulted in increased expression of alkaline phosphatase (ALP) and the deposition of mineralized matrix, established markers of bone cell differentiation. In sum, this population of human amniocytes appears to be multipotent, capable of in vitro differentiation to ectodermal and mesodermal cell types. Retention of this plasticity through decades of cryopreservation suggests that amniocytes might be candidates for future cell-based therapies.