The in vitro survival of human monosomies and trisomies as embryonic stem cells.

Chromosomal aneuploidies are responsible for severe human genetic diseases. Aiming at creating models for such disorders, we have generated human embryonic stem cell (hESC) lines from pre-implantation genetic screened (PGS) embryos. The overall analysis of more than 400 aneuploid PGS embryos showed a similar risk of occurrence of monosomy or trisomy for any specific chromosome. However, the generation of hESCs from these embryos revealed a clear bias against monosomies in autosomes. Moreover, only specific trisomies showed a high chance of survival as hESC lines, enabling us to present another categorization of human aneuploidies. Our data suggest that chromosomal haploinsufficiency leads to lethality at very early stages of human development.

Human embryonic stem cells as models for aneuploid chromosomal syndromes.

Syndromes caused by chromosomal aneuploidies are widely recognized genetic disorders in humans and often lead to spontaneous miscarriage. Preimplantation genetic screening is used to detect chromosomal aneuploidies in early embryos. Our aim was to derive aneuploid human embryonic stem cell (hESC) lines that may serve as models for human syndromes caused by aneuploidies. We have established 25 hESC lines from blastocysts diagnosed as aneuploid on day 3 of their in vitro development. The hESC lines exhibited morphology and expressed markers typical of hESCs. They demonstrated long-term proliferation capacity and pluripotent differentiation. Karyotype analysis revealed that two-third of the cell lines carry a normal euploid karyotype, while one-third remained aneuploid throughout the derivation, resulting in eight hESC lines carrying either trisomy 13 (Patau syndrome), 16, 17, 21 (Down syndrome), X (Triple X syndrome), or monosomy X (Turner syndrome). On the basis of the level of single nucleotide polymorphism heterozygosity in the aneuploid chromosomes, we determined whether the aneuploidy originated from meiotic or mitotic chromosomal nondisjunction. Gene expression profiles of the trisomic cell lines suggested that all three chromosomes are actively transcribed. Our analysis allowed us to determine which tissues are most affected by the presence of a third copy of either chromosome 13, 16, 17 or 21 and highlighted the effects of trisomies on embryonic development. The results presented here suggest that aneuploid embryos can serve as an alternative source for either normal euploid or aneuploid hESC lines, which represent an invaluable tool to study developmental aspects of chromosomal abnormalities in humans.

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.

Derivation of euploid human embryonic stem cells from aneuploid embryos.

Human embryonic stem cells (HESCs) are pluripotent cells derived from the inner cell mass of preimplantation embryos. In this study, to isolate new lines of HESCs, we used blastocyst-stage embryos diagnosed as aneuploid in preimplantation genetic screening (PGS). During in vitro fertilization treatments, PGS is widely applied to identify chromosomal aneuploidies, especially in cases of advanced maternal age. Embryos that are detected as carrying aneuploidies are destined to be discarded unless donated for research. From 74 fresh PGS-defined aneuploid embryos, we derived seven HESC lines. Most of the embryos were left to hatch spontaneously through the hole created for blastomere biopsy and further treated by immunosurgery. The seven HESC lines exhibited morphology and markers typical of HESCs and the capacity for long-term proliferation. The derived HESC lines manifested pluripotent differentiation potential both in vivo and in vitro. Surprisingly, karyotype analysis of the HESC lines that were derived from these aneuploid embryos showed that the cell lines carry a normal euploid karyotype. We show that the euploidy was not achieved through chromosome duplication. Alternatively, we suggest that the euploid HESC lines originated from mosaic embryos consisting of aneuploid and euploid cells, and in vitro selection occurred to favor euploid cells. We assume that aneuploid HESC lines could be isolated mostly from embryos that are uniform for the aneuploidy. These results led us to conclude that the aneuploid mosaic embryos that are destined to be discarded can serve as an alternative source for normal euploid HESC lines.

The distribution and development of handedness for manual gestures in captive chimpanzees (Pan troglodytes).

This article describes the distribution and development of handedness for manual gestures in captive chimpanzees. Data on handedness for unimanual gestures were collected in a sample of 227 captive chimpanzees. Handedness for these gestures was compared with handedness for three other measures of hand use: tool use, reaching, and coordinated bimanual actions. Chimpanzees were significantly more right-handed for gestures than for all other measures of hand use. Hand use for simple reaching at 3 to 4 years of age predicted hand use for gestures 10 years later. Use of the right hand for gestures was significantly higher when gestures were accompanied by a vocalization than when they were not. The collective results suggest that left-hemisphere specialization for language may have evolved initially from asymmetries in manual gestures in the common ancestor of chimpanzees and humans, rather than from hand use associated with other, non-communicative motor actions, including tool use and coordinated bimanual actions, as has been previously suggested in the literature.

Chimpanzee (Pan troglodytes) intentional communication is not contingent upon food.

Studies of great apes have revealed that they use manual gestures and other signals to communicate about distal objects. There is also evidence that chimpanzees modify the types of communicative signals they use depending on the attentional state of a human communicative partner. The majority of previous studies have involved chimpanzees requesting food items from a human experimenter. Here, these same communicative behaviors are reported in chimpanzees requesting a tool from a human observer. In this study, captive chimpanzees were found to gesture, vocalize, and display more often when the experimenter had a tool than when she did not. It was also found that chimpanzees responded differentially based on the attentional state of a human experimenter, and when given the wrong tool persisted in their communicative efforts. Implications for the referential and intentional nature of chimpanzee communicative signaling are discussed.

Cryopreservation of human embryos at the morula stage and outcomes after transfer.

OBJECTIVE: To evaluate the survival rate of human morula embryo freezing and the morphological alterations during freezing, during and after thawing, and their applications in embryo selection. DESIGN: Retrospective observational study. SETTING: Private infertility clinic. PATIENT(S): Consecutive patients under age 39 undergoing frozen morula embryo transfers from December 1999 to May 2003. INTERVENTION(S): Embryo freezing was performed at the morula stage. Embryo thaw and post-thaw ETs were conducted on the same day, which is equivalent to a day 4 ET. MAIN OUTCOME MEASURE(S): Morphological alterations during freezing and thawing and after thawing. Post-thaw embryo survival rates, transferable rates, pregnancy rates, and implantation rates. RESULT(S): Morula embryos showed reversed morphological alterations during the freezing process; these alterations were recovered during thawing or shortly after the thawing. Post-thaw survival rates showed no significant difference between any of the morula substages. However, embryos scored as grade 3, which represented good quality, had significantly higher post-thaw survival and transferable rates than grade 2 and 1 embryos. Patients who received at least one grade 3 embryo had significantly higher pregnancy rates, implantation rates, and ongoing/live birth rates than other groups. CONCLUSION(S): An acceptable survival rate can be achieved after cryopreservation of human morula embryos, and morphological alterations that occur during and shortly after an embryo thaw can be a feasible index for determining viable embryos.