Probing Stemness and Neural Commitment in Human Amniotic Fluid Cells

Abstract

Recently, human amniotic fluid (AF) cells have attracted a great deal of attention as an alternative cell source for transplantation and tissue engineering. AF contains a variety of cell types derived from fetal tissues, of which a small percentage is believed to represent stem cell sub-population(s). In contrast to human embryonic stem (ES) cells, AF cells are not subject to extensive legal or ethical considerations; nor are they limited by lineage commitment characteristic of adult stem cells. However, to become therapeutically valuable, better protocols for the isolation of AF stem cell sub-populations need to be developed. This study was designed to examine the molecular components involved in self-renewal, neural commitment and differentiation of AF cells obtained at different gestational ages. Our results showed that, although morphologically heterogeneous, AF cells derived from early gestational periods ubiquitously expressed KERATIN 8 (K8), suggesting that the majority of these cells may have an epithelial origin. In addition, AF cells expressed various components of NOTCH signaling (ligands, receptors and target genes), a pathway involved in stem cell maintenance, determination and differentiation. A sub-population of K8 positive cells (<10%) co-expressed NESTIN, a marker detected in the neuroepithelium, neural stem cells and neural progenitors. Throughout the gestational periods, a much smaller AF cell sub-population (<1%) expressed pluripotency markers, OCT4a, NANOG and SOX2, from which SOX2 positive AF cells could be isolated through single cell cloning. The SOX2 expressing AF clones showed the capacity to give rise to a neuron-like phenotype in culture, expressing neuronal markers such as MAP2, NFL and NSE. Taken together, our findings demonstrated the presence of fetal cells with stem cell characteristics in the amniotic fluid, highlighting the need for further research on their biology and clinical applications.

Amniotic Fluid-Derived Stem Cells for Cardiovascular Tissue Engineering Applications

“…27,29,30 AFSC are being explored for use in tissue engineering applications for a variety of tissue types. This review focuses on cardiovascular cell types and tissue engineering, which are addressed further below, but AFSC are also being investigated for osteogenic, 13,31,32 renal, 33,34 myogenic, 35 epithelial, 36,37 and neuronal 14,[38][39][40][41][42][43][44][45] differentiation and tissue engineering. An area of contention that remains with AFSC is whether sorting for c-kit expression is necessary or appropriate.…”

“…18 Oct4, Sox2, and Nanog, transcription factors necessary for maintaining pluirpotency in ESCs, also displayed mixed results across different studies of AFSC. 16,17,20,23,24,[29][30][31]35,37,[39][40][41]46,[48][49][50][51][52]54 In Vitro Cardiac Myocyte Differentiation of AFSC AFSC have been investigated for cardiac tissue engineering. 55 AFSC applications to in vitro cardiac tissue engineering are summarized in this section and Table 3.…”

Novel RBPJ Transcripts Identified in Human Amniotic Fluid Cells

“…Many studies have demonstrated that the RBPJ-mediated NOTCH signaling pathway is indispensable for cells at various stages of development. Hence, we developed a protocol to better characterize the molecular profile of RBPJ expression in human amniotic fluid (AF) cells, a source of fetal cells with stem cell characteristics [18,19], and embryonal carcinoma (EC) NT2 cells, which have many shared features with human embryonic stem (ES) cells [20,21]. Since NT2 cells are known as a well-established cellular model of neuronal and glial differentiation [22][23][24], we also used this model system to compare RBPJ expression in undifferentiated cells and terminally differentiated neurons and astrocytes.…”

Neurogenic differentiation of amniotic fluid stem cells

“…So far, neurogenic differentiation of AFS cells has been demonstrated in mouse, pig, and human (Mareschi et al 2009;Phermthai et al 2010;Jezierski et al 2010;Zheng et al 2010). It has been suggested that the efficiency of neurogenic differentiation depends on extracellular growth factors (Orciani et al 2008(Orciani et al , 2011.…”