Contribution of human amniotic fluid stem cells to renal tissue formation depends on mTOR

Neurogenic differentiation of amniotic fluid stem cells

In 2003, human amniotic fluid has been shown to contain stem cells expressing Oct-4, a marker for pluripotency. This finding initiated a rapidly growing and very promising new stem cell research field. Since then, amniotic fluid stem (AFS) cells have been demonstrated to harbour the potential to differentiate into any of the three germ layers and to form three-dimensional aggregates, so-called embryoid bodies, known as the principal step in the differentiation of pluripotent stem cells. Marker selection and minimal dilution approaches allow the establishment of monoclonal AFS cell lineages with high proliferation potential. AFS cells have a lower risk for tumour development and do not raise the ethical issues of embryonic stem cells. Compared to induced pluripotent stem cells, AFS cells do not need exogenic treatment to induce pluripotency, are chromosomal stable and do not harbour the epigenetic memory and accumulated somatic mutations of specific differentiated source cells. Compared to adult stem cells, AFS can be grown in larger quantities and show higher differentiation potential. Accordingly, in the recent past, AFS became increasingly accepted as an optimal tool for basic research and probably also for specific cell-based therapies. Here, we review the current knowledge on the neurogenic differentiation potential of AFS cells.

An improved kidney dissociation and reaggregation culture system results in nephrons arranged organotypically around a single collecting duct system

Methods for constructing engineered "tissues" from simple suspensions of cells are valuable for investigations into basic developmental biology and for tissue engineering. We recently published a method for producing embryonic renal tissues from suspensions of embryonic mouse renal cells. This method reproduced the anatomies and differentiation states of nephrons and stroma very well; it had the limitation, however, that what would, in normal development, be a single, highly branched collecting duct tree leading to a ureter developed, in the engineered system, as a multitude of very small collecting duct trees. These were isolated from each other and therefore would not be effective for draining urine to a common exit, were the tissue to be supplied with blood and physiologically active. Here, we report an improvement on the original method; it results in the formation of nephrons arranged around one single collecting duct tree as would happen in a normal kidney.