Whereas TH1-type immunity to trophoblast is associated with URA and may play a role in reproductive failure, TH2-type immunity may be a natural response to trophoblast contributing to successful pregnancy.

The metanephric kidney is a mesodermal organ that develops as a result of reciprocal interactions between the ureteric bud and the blastema. The generation of embryonic stem (ES) cell-derived progenitors offers potential for regenerative therapies but is often limited by development of tumor formation. Because brachyury (T) denotes mesoderm specification, a mouse ES cell line with green fluorescence protein (GFP) knocked into the functional T locus as well as lacZ in the ROSA26 locus (LacZ/T/GFP) was used in cell selection and lineage tracing. In the absence of leukemia inhibitory factor, mouse ES cells give rise to embryoid bodies that can differentiate into mesoderm. Culture conditions were optimized (4 d, 10 ng/ml Activin-A) to generate maximal numbers of renal progenitor populations identified by expression of the specific combination of renal markers cadherin-11, WT-1, Pax-2, and Wnt-4. LacZ/T/GFP؉ cells were further enriched by FACS selection. Five days after injection of LacZ/T/GFP؉ cells into embryonic kidney explants in organ culture, ␤-galactosidase immunohistochemistry showed incorporation into blastemal cells of the nephrogenic zone. After a single injection into developing live newborn mouse kidneys, co-localization studies showed that the LacZ/T/GFP؉ cells were stably integrated into proximal tubules with normal morphology and normal polarization of alkaline phosphatase and aquaporin-1 for 7 mo, without teratoma formation. It is concluded that defined differentiation of ES cells into embryoid bodies with Activin-A and selection for T expression provides a means to isolate and purify renal proximal tubular progenitor cells with the potential for safe use in regenerative therapies.

Recently, cultured human adult skin cells were reprogrammed to induced pluripotent stem (iPS) cells, which have characteristics similar to human embryonic stem (hES) cells. Patient-derived iPS cells offer genetic and immunologic advantages for cell and tissue replacement or engineering. The efficiency of generating human iPS cells has been very low; therefore an easily and efficiently reprogrammed cell type is highly desired. Here, we demonstrate that terminally differentiated human amniotic fluid (AF) skin cells provide an accessible source for efficiently generating abundant-induced pluripotent stem (AF-iPS) cells. By induction of pluripotency with the transcription factor quartet (OCT3/4, SOX2, KLF4, and c-MYC) the terminally differentiated, cultured AF skin cells formed iPS colonies approximately twice as fast and yielded nearly a two-hundred percent increase in number, compared to cultured adult skin cells. AF-iPS cells were identical to hES cells for morphological and growth characteristics, antigenic stem cell markers, stem cell gene expression, telomerase activity, in vitro and in vivo differentiation into the three germ layers and for their capacity to form embryoid bodies (EBs) and teratomas. Our findings provide a biological interesting conclusion that these fetal AF cells are more rapidly, easily, and efficiently reprogrammed to pluripotency than neonatal and adult cells. AF-iPS cells may have a "young," more embryonic like epigenetic background, which may facilitate and accelerate pluripotency. The ability to efficiently and rapidly reprogram terminally differentiated AF skin cells and generate induced pluripotent stem cells provides an abundant iPS cell source for various basic studies and a potential for future patient-specific personalized therapies.

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A dichotomous T-helper 1 (Th1) versus T-helper 2 (Th2) cytokine response to trophoblast has been proposed to mediate reproductive failure and success, respectively. Progesterone has immunosuppressive properties. In this study, peripheral blood mononuclear cells from women with and without unexplained recurrent pregnancy loss who had and did not have evidence of embryotoxic, Th1 immunity to trophoblast were cultured with progesterone (10(-5) mol/l) or interleukin (IL)-10 (1500 pg/ml) to determine whether these agents were capable of inhibiting embryotoxic, Th1 immunity to trophoblast. The effects of progesterone on Th2 cytokines and transforming growth factor (TGF)-beta secretion were also assessed. Progesterone was found to specifically block Th1 immunity to trophoblast, as was IL-10. Progesterone also appeared to upregulate TGF-beta secretion in response to trophoblast but had no effect on Th2 cytokine secretion. Our data suggest that assaying Th1 cytokines in supernatants of peripheral blood mononuclear cells cultured with a protein extract from trophoblast may identify individuals more likely to benefit from potentially immunosuppressive doses of progesterone. An appropriately designed clinical trial is needed to determine whether therapies modifying Th1 cytokine secretion in response to trophoblast are useful in the clinical management of recurrent pregnancy loss in women producing these cytokines in response to reproductive antigen stimulation.