Tissue engineering from human mesenchymal amniocytes: a prelude to clinical trials

Purpose: The surgical treatment of congenital anomalies using tissues engineered from amniotic fluid-derived mesenchymal cells has been validated experimentally. As a prerequisite for testing the clinical feasibility of this therapeutic concept, this study was aimed to expand human mesenchymal amniocytes in the absence of animal products. Methods: Human mesenchymal cells were isolated from amniotic fluid samples (n = 12) obtained at 20 to 37 weeks' gestation. Their phenotypic profiles and cell proliferation rates were compared during expansion under 2 different media, containing either fetal bovine serum or allogeneic human AB serum. Statistical analyses were by the 2-sided Wilcoxon signed rank test and linear regression (P < .05). Results: Mesenchymal cells could be isolated and expanded at any gestational age. There was a greater than 9-fold logarithmic expansion of mesenchymal cells, with no significant differences in the overall proliferation rates based on serum type (P = .94), or gestational age (P = .14). At any passage, cells expanded for up to 50 days remained positive for markers consistent with a multipotent mesenchymal progenitor lineage, regardless of the medium used. Conclusions: Human mesenchymal amniocytes retain their progenitor phenotype and can be dependably expanded ex vivo in the absence of animal serum. Clinical trials of amniotic fluid-based tissue engineering are feasible within preferred regulatory guidelines.