Endocrine profiles after triggering of final oocyte maturation with GnRH agonist after cotreatment with the GnRH antagonist ganirelix during ovarian hyperstimulation for in vitro fertilization

In a randomized multicenter study, the efficacies of two different GnRH agonists were compared with that of hCG for triggering final stages of oocyte maturation after ovarian hyperstimulation for in vitro fertilization. Ovarian stimulation was conducted by recombinant FSH (Puregon), and the GnRH antagonist ganirelix (Orgalutran) was coadministered for the prevention of a premature LH rise. Luteal support was provided by daily progestin administration. Frequent blood sampling was performed at midcycle in the first 47 eligible subjects included in the current study, who were randomized for a single dose of 0.2 mg triptorelin (n = 17), 0.5 mg leuprorelin (n = 15), or 10,000 IU hCG (n = 15). Serum concentrations of LH, FSH, E2, and progesterone (P) were assessed at variable intervals. LH peaked at 4 h after both triptorelin and leuprorelin administration, with median LH levels of 130 and 107 IU/liter (P < 0.001), respectively. LH levels returned to baseline after 24 h. Subjects receiving hCG showed peak levels of 240 IU/liter hCG 24 h after administration. A rise in FSH to 19 IU/liter (P < 0.001) was noted in both GnRH agonist groups 8 h after injection. Within 24 h the areas under the curve for LH and FSH were significantly higher (P < 0.001) in both GnRH agonist groups compared with that for hCG. E2 and P levels were similar for all groups up to the day of oocyte retrieval. Luteal phase areas under the curve for P and E2 were significantly elevated (P < 0.001) in the hCG group. The mean (+/-SD) numbers of oocytes retrieved were 9.8 +/- 5.4, 8.7 +/- 4.5, and 8.3 +/- 3.3; the percentages of metaphase II oocytes were 72%, 85%, and 86%; and fertilization rates were 61%, 62%, and 56% in the triptorelin, leuprorelin, and hCG group, respectively (P = NS for all three comparisons). These findings support the effective induction of final oocyte maturation in both GnRH agonist groups. In summary, after treatment with the GnRH antagonist ganirelix for the prevention of premature LH surges, triggering of final stages of oocyte maturation can be induced effectively by a single bolus injection of GnRH agonist, as demonstrated by the induced endogenous LH and FSH surge and the quality and fertilization rate of recovered oocytes. Moreover, corpus luteum formation is induced by GnRH agonists with luteal phase steroid levels closer to the physiological range compared with hCG. This more physiological approach for inducing oocyte maturation may represent a successful and safer alternative for in vitro fertilization patients undergoing ovarian hyperstimulation

Identification of Five Developmental Processes during Chondrogenic Differentiation of Embryonic Stem Cells

Chondrogenesis is the complex process that leads to the establishment of cartilage and bone formation. Due to their ability to differentiate in vitro and mimic development, embryonic stem cells (ESCs) show great potential for investigating developmental processes. In this study, we used chondrogenic differentiation of ESCs as a model to analyze morphogenetic events during chondrogenesis.ESCs were differentiated into the chondrocyte lineage, forming small cartilaginous aggregates in suspension. Differentiated ESCs showed that chondrogenesis was typically characterized by five overlapping stages. During the first stage, cell condensation and aggregate formation was observed. The second stage was characterized by differentiation into chondrocytes and fibril scaffold formation within spherical aggregates. Deposition of cartilaginous extracellular matrix and cartilage formation were hallmarks of the third stage. Apoptosis of chondrocytes, hypertrophy and/or degradation of cartilage occurred during the fourth stage. Finally, during the fifth stage, bone replacement with membranous calcified tissues took place.We demonstrate that ESCs show the chondrogenic differentiation pathway from the pluripotent stem cell to terminal skeletogenesis through these five stages in vitro. During each stage, morphological changes acquired in preceding stages played an important role in further development as a scaffold or template in subsequent stages. The study of chondrogenesis via ESC differentiation may be informative to our further understanding of skeletal growth and regeneration

Human embryonic stem cells from aneuploid blastocysts identified by pre-implantation genetic screening

Human embryonic stem cells are derived from the inner cell mass of pre-implantation embryos. The cells have unlimited proliferation potential and capacity to differentiate into the cells of the three germ layers. Human embryonic stem cells are used to study human embryogenesis and disease modeling and may in the future serve as cells for cell therapy and drug screening. Human embryonic stem cells are usually isolated from surplus normal frozen embryos and were suggested to be isolated from diseased embryos detected by pre-implantation genetic diagnosis. Here we report the isolation of 12 human embryonic stem cell lines and their thorough characterization. The lines were derived from embryos detected to have aneuploidy by pre-implantation genetic screening. Karyotype analysis of these cell lines showed that they are euploid, having 46 chromosomes. Our interpretation is that the euploid cells originated from mosaic embryos, and in vitro selection favored the euploid cells. The undifferentiated cells exhibited long-term proliferation and expressed markers typical for embryonic stem cells such as OCT4, NANOG, and TRA-1-60. The cells manifested pluripotent differentiation both in vivo and in vitro. To further characterize the different lines, we have analyzed their ethnic origin and the family relatedness among them. The above results led us to conclude that the aneuploid mosaic embryos that are destined to be discarded can serve as source for normal euploid human embryonic stem cell lines. These lines represent various ethnic groups; more lines are needed to represent all populations

Physical Passaging of Embryoid Bodies Generated from Human Pluripotent Stem Cells

Spherical three-dimensional cell aggregates called embryoid bodies (EBs), have been widely used in in vitro differentiation protocols for human pluripotent stem cells including human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs). Recent studies highlight the new devices and techniques for hEB formation and expansion, but are not involved in the passaging or subculture process. Here, we provide evidence that a simple periodic passaging markedly improved hEB culture condition and thus allowed the size-controlled, mass production of human embryoid bodies (hEBs) derived from both hESCs and hiPSCs. hEBs maintained in prolonged suspension culture without passaging (>2 weeks) showed a progressive decrease in the cell growth and proliferation and increase in the apoptosis compared to 7-day-old hEBs. However, when serially passaged in suspension, hEB cell populations were significantly increased in number while maintaining the normal rates of cell proliferation and apoptosis and the differentiation potential. Uniform-sized hEBs produced by manual passaging using a 1∶4 split ratio have been successfully maintained for over 20 continuous passages. The passaging culture method of hEBs, which is simple, readily expandable, and reproducible, could be a powerful tool for improving a robust and scalable in vitro differentiation system of human pluripotent stem cells

Extracellular Matrix Aggregates from Differentiating Embryoid Bodies as a Scaffold to Support ESC Proliferation and Differentiation

Embryonic stem cells (ESCs) have emerged as potential cell sources for tissue engineering and regeneration owing to its virtually unlimited replicative capacity and the potential to differentiate into a variety of cell types. Current differentiation strategies primarily involve various growth factor/inducer/repressor concoctions with less emphasis on the substrate. Developing biomaterials to promote stem cell proliferation and differentiation could aid in the realization of this goal. Extracellular matrix (ECM) components are important physiological regulators, and can provide cues to direct ESC expansion and differentiation. ECM undergoes constant remodeling with surrounding cells to accommodate specific developmental event. In this study, using ESC derived aggregates called embryoid bodies (EB) as a model, we characterized the biological nature of ECM in EB after exposure to different treatments: spontaneously differentiated and retinoic acid treated (denoted as SPT and RA, respectively). Next, we extracted this treatment-specific ECM by detergent decellularization methods (Triton X-100, DOC and SDS are compared). The resulting EB ECM scaffolds were seeded with undifferentiated ESCs using a novel cell seeding strategy, and the behavior of ESCs was studied. Our results showed that the optimized protocol efficiently removes cells while retaining crucial ECM and biochemical components. Decellularized ECM from SPT EB gave rise to a more favorable microenvironment for promoting ESC attachment, proliferation, and early differentiation, compared to native EB and decellularized ECM from RA EB. These findings suggest that various treatment conditions allow the formulation of unique ESC-ECM derived scaffolds to enhance ESC bioactivities, including proliferation and differentiation for tissue regeneration applications. © 2013 Goh et al

Evolutionary Emergence of microRNAs in Human Embryonic Stem Cells

Human embryonic stem (hES) cells have unique abilities to divide indefinitely without differentiating and potential to differentiate into more than 200 cell types. These properties make hES cells an ideal model system for understanding early human development and for regenerative medicine. Molecular mechanisms including cellular signaling and transcriptional regulation play important roles in hES cell differentiation. However, very little information is available on posttranscriptional regulation of hES cell pluripotency, self-renewal, and early decisions about cell fate. microRNAs (miRNAs), 22-nt long non-coding small RNAs found in plants and animals, regulate gene expression by targeting mRNAs for cleavage or translation repression. In hES cells we found that 276 miRNAs were expressed; of these, a set of 30 miRNAs had significantly changed expression during differentiation. Using a representative example, miR-302b, we show that miRNAs in human ES cells assemble into a bona fide RISC that contains Ago2 and can specifically cleave perfectly matched target RNA. Our results demonstrate that human ES cell differentiation is accompanied by changes in the expression of a unique set of miRNAs, providing a glimpse of a new molecular circuitry that may regulate early development in humans. Chromosomes 19 and X contained 98 and 40 miRNA genes, respectively, indicating that majority of miRNA genes in hES cells were expressed from these two chromosomes. Strikingly, distribution analysis of miRNA gene loci across six species including dog, rat, mouse, rhesus, chimpanzee, and human showed that miRNA genes encoded in chromosome 19 were drastically increased in chimpanzees and humans while miRNA gene loci on other chrosmomes were decreased as compared with dog, rat, and mouse. Comparative genomic studies showed 99% conservation of chromosome 19 miRNA genes between chimpanzees and humans. Together, these findings reveal the evolutionary emergence, ∼5 million years ago, of miRNAs involved in regulating early human development. One could imagine that this burst of miRNA gene clusters at specific chromosomes was part of an evolutionary event during species divergence

Culture of Mouse Embryonic Stem Cells with Serum but without Exogenous Growth Factors Is Sufficient to Generate Functional Hepatocyte-Like Cells

Mouse embryonic stem cells (mESC) have been used to study lineage specification in vitro, including towards a hepatocyte-like fate, and such investigations guided lineage differentiation protocols for human (h)ESC. We recently described a four-step protocol to induce hepatocyte-like cells from hESC which also induced hepatocyte-like cell differentiation of mouse induced pluripotent stem cells. As ESC also spontaneously generate hepatocyte-like cells, we here tested whether the growth factors and serum used in this protocol are required to commit mESC and hESC to hepatocyte-like cells. Culture of mESC from two different mouse strains in the absence of serum and growth factors did not induce primitive streak/definitive endoderm genes but induced default differentiation to neuroectoderm on day 6. Although Activin-A and Wnt3 induced primitive streak/definitive endoderm transcripts most robustly in mESC, simple addition of serum also induced these transcripts. Expression of hepatoblast genes occurred earlier when growth factors were used for mESC differentiation. However, further maturation towards functional hepatocyte-like cells was similar in mESC progeny from cultures with serum, irrespective of the addition of growth factors, and irrespective of the mouse strain. This is in contrast to hESC, where growth factors are required for specification towards functional hepatocyte-like cells. Culture of mESC with serum but without growth factors did not induce preferential differentiation towards primitive endoderm or neuroectoderm. Thus, although induction of primitive streak/definitive endoderm specific genes and proteins is more robust when mESC are exposed to a combination of serum and exogenous growth factors, ultimate generation of hepatocyte-like cells from mESC occurs equally well in the presence or absence of exogenous growth factors. The latter is in contrast to what we observed for hESC. These results suggest that differences exist between lineage specific differentiation potential of mESC and hESC, requiring optimization of different protocols for ESC from either species

Studying Early Lethality of 45,XO (Turner's Syndrome) Embryos Using Human Embryonic Stem Cells

Turner's syndrome (caused by monosomy of chromosome X) is one of the most common chromosomal abnormalities in females. Although 3% of all pregnancies start with XO embryos, 99% of these pregnancies terminate spontaneously during the first trimester. The common genetic explanation for the early lethality of monosomy X embryos, as well as the phenotype of surviving individuals is haploinsufficiency of pseudoautosomal genes on the X chromosome. Another possible mechanism is null expression of imprinted genes on the X chromosome due to the loss of the expressed allele. In contrast to humans, XO mice are viable, and fertile. Thus, neither cells from patients nor mouse models can be used in order to study the cause of early lethality in XO embryos. Human embryonic stem cells (HESCs) can differentiate in culture into cells from the three embryonic germ layers as well as into extraembryonic cells. These cells have been shown to have great value in modeling human developmental genetic disorders. In order to study the reasons for the early lethality of 45,XO embryos we have isolated HESCs that have spontaneously lost one of their sex chromosomes. To examine the possibility that imprinted genes on the X chromosome play a role in the phenotype of XO embryos, we have identified genes that were no longer expressed in the mutant cells. None of these genes showed a monoallelic expression in XX cells, implying that imprinting is not playing a major role in the phenotype of XO embryos. To suggest an explanation for the embryonic lethality caused by monosomy X, we have differentiated the XO HESCs in vitro an in vivo. DNA microarray analysis of the differentiated cells enabled us to compare the expression of tissue specific genes in XO and XX cells. The tissue that showed the most significant differences between the clones was the placenta. Many placental genes are expressed at much higher levels in XX cells in compare to XO cells. Thus, we suggest that abnormal placental differentiation as a result of haploinsufficiency of X-linked pseudoautosomal genes causes the early lethality in XO human embryos

Prepatterning in the Stem Cell Compartment

The mechanism by which an apparently uniform population of cells can generate a heterogeneous population of differentiated derivatives is a fundamental aspect of pluripotent and multipotent stem cell behaviour. One possibility is that the environment and the differentiation cues to which the cells are exposed are not uniform. An alternative, but not mutually exclusive possibility is that the observed heterogeneity arises from the stem cells themselves through the existence of different interconvertible substates that pre-exist before the cells commit to differentiate. We have tested this hypothesis in the case of apparently homogeneous pluripotent human embryonal carcinoma (EC) stem cells, which do not follow a uniform pattern of differentiation when exposed to retinoic acid. Instead, they produce differentiated progeny that include both neuronal and non-neural phenotypes. Our results suggest that pluripotent NTERA2 stem cells oscillate between functionally distinct substates that are primed to select distinct lineages when differentiation is induced