Heterogeneity of Stem Cells in Human Amniotic Fluid

Heterogeneity of Stem Cells in Human Amniotic Fluid

Amniotic fluid contains a mixture of cells with capacity to differentiate into all germ layers. These cells are present in large numbers in midtrimester samples obtained for cytogenetic diagnosis, and have been identified by stem cell surface markers and transcription factors. We studied cultured samples from patients who had both direct cultures and matched cultures obtained 2 weeks later from the cytogenetics laboratory as well as patients with cytogenetics material only. Samples were cryogenically frozen, thawed, expanded in culture with excellent viability. There was considerable individual variation unrelated to gestational age or telomere length. Phenotype for embryonic markers was assessed by flow cytometry and by quantitative polymerase chain reaction. The most consistently present stem cell markers in substantial amounts were CD90, SSEA-4, & TRA-1-60. Cells with CD90, SSEA-4 & TRA-1-60 double and triple labeled also could be identified and subcultured, confirming the heterogeneity of the amniotic fluid stem cell population.