[Human embryonic stem cells: from the human embryo transgressed to the regenerative medicine of tomorrow]

Human embryonic stem cells (hESC) are derived from the inner cell mass (ICM) of the human blastocyst at day 5 or 6 of the early embryo development. These cells display two cardinal features: they are able to differentiate into cell types from many if not all human tissue (pluripotency) and they proliferate strongly and indefinitely without senescence in vitro. Therefore, hESC are a source of choice for stem cells for regenerative medicine and are a reference model to study the biology of pluripotency. Since 2004, the French law (loi de Bioéthique) authorizes hESC research under certain conditions.

Gene expression profile of human endometrial receptivity: comparison between natural and stimulated cycles for the same patients

BACKGROUND

The adjunction of exogenous hormones for controlled ovarian stimulation (COS) may alter endometrial receptiveness. In order to identify the genes misregulated under COS, we compared the endometrium gene expression profiles, from the same patients, in a natural cycle and in a subsequent COS cycle.

METHODS

For the same normal-responder patients (n = 21), endometrial biopsies (n = 84) were collected during the pre-receptive (LH + 2) and receptive stages (LH + 7) of a natural cycle and, subsequently, on oocyte retrieval day (hCG + 2) and on transfer day (hCG + 5) of a stimulated cycle. Samples were analyzed using DNA microarrays. Gene expression profiles and biological pathways involved in endometrial receptivity were analyzed.

RESULTS

Although endometrium transition profiles from pre-receptive to receptive phases are similar between patients, COS regimens alter endometrial receptivity in comparison with natural cycle. Under COS conditions, two endometrial profiles were identified and were associated either with a moderately altered receptivity profile for the majority of the patients or a strongly altered profile for a sub-category of patients. The receptive endometrium transcription profile under COS was defective for biological functions such as TGFbeta signaling, leukocyte transendothelial migration and the cell cycle.

CONCLUSIONS

Gonadotrophin treatments in COS cycles led to disruptions of the transcriptional activation of genes involved in normal endometrial receptivity. We propose that when the receptiveness of the endometrium is seriously compromised by the COS protocol, fresh embryo replacement should be cancelled, the embryo frozen and thawed embryo replacement should be performed under natural cycles.

[Streptococcus pneumoniae neonatal infection]

One case of early onset invasive pneumococcal disease in the newborn, acquired from the maternal vagina, is reported. Streptococcus pneumoniae has been estimated to be rarely responsible for neonatal sepsis (1-8%) together with maternal infection. Clinical features are similar to other neonatal infections, but outcome is particularly severe (mortality: 50%, neurological sequelae: 13%). Newborn are most often infected from the maternal vagina that has been colonized with S. pneumoniae, despite the rarity of vaginal carriage of S. pneumoniae (yield in genital swabs from 0.03 to 0.75%). Severe outcome should lead to presumptive treatment (amoxicillin +/- vancomycin) of babies colonized with pneumococcus or born to colonized mother, even if asymptomatic, and, when necessary, of the mother. The rarity of the genital carriage, together with the difficulty to isolate S. pneumoniae from vaginal swabs makes unrealistic to systematically search for this organism. However, given the high ratio infection: colonization, greater significance should be attached to the discovery of vaginal colonization with pneumococcus in the pregnant or in the newborn in order to improve treatment and outcome.