Retinoids and spermatogenesis: lessons from mutant mice lacking the plasma retinol binding protein.

Using Rbp4-null mice as models, we have established for the first time the kinetics of the spermatogenetic alterations during vitamin A deficiency (VAD). Our data demonstrate that the VAD-induced testicular degeneration arises through the normal maturation of germ cells in a context of spermatogonia differentiation arrest. They indicate that retinoic acid (RA) appears dispensable for the transition of premeiotic to meiotic spermatocytes, meiosis, and spermiogenesis. They confirm that RA plays critical roles in controlling spermatogonia differentiation, spermatid adhesion to Sertoli cells, and spermiation, and suggest that the VAD-induced arrest of spermatogonia differentiation results from simultaneous blocks in RA-dependent events mediated by RA receptor gamma (RARgamma) in spermatogonia and by RARalpha in Sertoli cells. They also provide evidence that expression of major RA-metabolizing enzymes is increased in mouse Sertoli cells upon VAD and that vitamin A-deficient A spermatogonia differ from their RA-sufficient counterparts by the expression of the Stra8 gene.     

Preimplantation genetic diagnosis of monogenic diseases

Preimplantation genetic diagnosis (PGD) is an alternative to prenatal diagnosis allowing the detection of genetic diseases on IVF embryos before their transfer into the uterus and before the pregnancy. The aim of this procedure is to obtain unaffected or carrier embryos in order to avoid the burden of termination of pregnancy after prenatal diagnosis for couples at risk of transmitting particularly severe genetic disorders to their offspring. For monogenic diseases, PGD is most often based on single blastomere amplification by polymerase chain reaction (PCR). More than a decade after the first births, the possibilities of diagnosis for monogenic diseases have considerably increased. As for molecular biology and conventional diagnosis, the technologies and strategies for PGD are continually improved, with for instance introduction of fluorescent PCR or multiplex amplification. In this review, we describe several approaches for PGD of monogenic diseases, followed by an overview of the French practice, particularly in our lab.     

Trisomy 7 mosaicism, maternal uniparental heterodisomy 7 and Hirschsprung's disease in a child with Silver-Russell syndrome

Prenatal trisomy 7 is usually a cell culture artifact in amniocytes with normal diploid karyotype at birth and normal fetal outcome. In the same way, true prenatal trisomy 7 mosaicism usually results in a normal child except when trisomic cells persist after birth or when trisomy rescue leads to maternal uniparental disomy, which is responsible for 5.5-7% of patients with Silver-Russell syndrome (SRS). We report here on the unusual association of SRS and Hirschsprung's disease (HSCR) in a patient with maternal uniparental heterodisomy 7 and trisomy 7 mosaicism in intestine and skin fibroblasts. HSCR may be fortuitous given its frequency, multifactorial inheritance and genetic heterogeneity. However, the presence of the trisomy 7 mosaicism in intestine as well as in skin fibroblasts suggests that SRS and HSCR might possibly be related. Such an association might result from either an increased dosage of a nonimprinted gene due to trisomy 7 mosaicism in skin fibroblasts (leading to SRS) and in intestine (leading to HSCR), or from an overexpression, through genomic imprinting, of maternally expressed imprinted allele(s) in skin fibroblasts and intestine or from a combination of trisomy 7 mosaicism and genomic imprinting. This report suggests that the SRS phenotype observed in maternal uniparental disomy 7 (mUPD(7)) patients might also result from an undetected low level of trisomy 7 mosaicism. In order to validate this hypothesis, we propose to perform a conventional and molecular cytogenetic analysis in different tissues every time mUPD7 is displayed.     

ESHRE PGD Consortium data collection VI: cycles from January to December 2003 with pregnancy follow-up to October 2004

The sixth report of the ESHRE PGD Consortium is presented, relating to cycles collected for the calendar year 2003 and follow-up of the pregnancies and babies born up to October 2004. Since the beginning of the data collections, there has been a steady rise in the number of cycles, pregnancies and babies reported. For this report, 50 centres participated, reporting on 2984 cycles, 501 pregnancies and 373 babies born. Five hundred and twenty-nine cycles were reported for chromosomal abnormalities, 516 cycles were reported for monogenic diseases, 137 cycles were reported for sexing for X-linked diseases, 1722 cycles were reported for preimplantation genetic screening (PGS) and 80 cycles were reported for social sexing. Data VI is compared to the cumulative data for data collections I-V.     

Human embryo research in France

The French law on bioethics, voted upon in July 1994, is going to be revised. This is the occasion for France to reconsider its position concerning research on human embryos, which is currently prohibited in France, as it is in Germany, Switzerland and Austria. However, such research is authorised in other European countries such as the UK, Spain, Belgium, Italy and The Netherlands. The establishment of human embryonic stem (ES) cells has reopened the debate in France because of their potential in human therapy. Indeed, ES cells, derived from early embryos (5-6 days old), preserve in vitro a pluripotent character, and they could provide an infinite source of different tissues that could be used in replacement therapy. This consists of ES cells differentiated in vitro into the desired tissues or cell types and grafted into the patient. The use of human ES cells in replacement therapy raises the major problem of graft rejection. One of the proposed solutions would be to carry out a 'therapeutic cloning' and to derive ES cells from the embryos obtained in this way. We do consider that, for the moment, the interest of the cloning study lies mainly in the understanding of the mechanisms responsible for reprogramming the nuclei. This research can be performed first on animal models. France is now thinking to allow human embryo research. We present here the French law proposed on human embryo research. French government is proposing to allow research exclusively on frozen supernumerary embryos, which no longer have any parental or adoption potential. Creation of human embryos for research purposes will still be prohibited. However, allowance of studies on human cloning in order to realise therapeutic cloning is mentioned in the proposal. We think that allowing research in humans on therapeutic cloning is premature and contradicts the prohibition of the creation of human embryos for research.     

Red blood cell generation from human induced pluripotent stem cells: perspectives for transfusion medicine

Background

Ex vivo manufacture of red blood cells from stem cells is a potential means to ensure an adequate and safe supply of blood cell products. Advances in somatic cell reprogramming of human induced pluripotent stem cells have opened the door to generating specific cells for cell therapy. Human induced pluripotent stem cells represent a potentially unlimited source of stem cells for erythroid generation for transfusion medicine.

Design and Methods

We characterized the erythroid differentiation and maturation of human induced pluripotent stem cell lines obtained from human fetal (IMR90) and adult fibroblasts (FD-136) compared to those of a human embryonic stem cell line (H1). Our protocol comprises two steps: (i) differentiation of human induced pluripotent stem cells by formation of embryoid bodies with indispensable conditioning in the presence of cytokines and human plasma to obtain early erythroid commitment, and (ii) differentiation/maturation to the stage of cultured red blood cells in the presence of cytokines. The protocol dispenses with major constraints such as an obligatory passage through a hematopoietic progenitor, co-culture on a cellular stroma and use of proteins of animal origin.

Results

We report for the first time the complete differentiation of human induced pluripotent stem cells into definitive erythrocytes capable of maturation up to enucleated red blood cells containing fetal hemoglobin in a functional tetrameric form.

Conclusions

Red blood cells generated from human induced pluripotent stem cells pave the way for future development of allogeneic transfusion products. This could be done by banking a very limited number of red cell phenotype combinations enabling the safe transfusion of a great number of immunized patients.     

Twin birth after preimplantation diagnosis for cystic fibrosis]

OBJECTIVE: Cystic fibrosis is a common autosomal recessive disease most often caused by a deletion (delta F508) in the CFTR gene. It is the most common indication for preimplantaion genetic diagnosis which allows genetic analysis of embryos obtained after in vitro fertilization and transfer of unaffected embryos into the patient's uterus. PATIENTS AND METHODS: We report the first preimplantation genetic diagnosis performed in Strasbourg for a couple at risk of having a child affected by severe cystic fibrosis due to a homozygous delta F508 mutation. Three days after fertilisation, embryos obtained after intra-cytoplasmic testiculare sperm injection were biopsied and analysed. PCR amplification of the genomic fragment containing the delta F508 locus allowed detection of the delta F508 mutation and transfer only of the unaffected embryos. RESULTS: Three embryos were transferred after this preimplantation genetic diagnosis. A twin pregnancy was obtained and the babies born from this cycle are both exempt from the mutation. CONCLUSIONS: Preimplantation genetic diagnosis for the cystic fibrosis delta F508 mutation is now available in our centre. In this report, we could resolve both the problem of infertility and the risk of transmission of a severe form of cystic fibrosis. Preimplantation genetic diagnosis is also available for other mutations involved in cystic fibrosis and also for other genetic diseases.     

Buprenorphine and pregnancy. Analysis of 24 cases]

BACKGROUND: Maintenance therapy of drug-addict mothers with medical and psychosocial support may reduce complications (prematurity, growth retardation, fetal distress and fetal death). Methadone has been widely used during pregnancy with beneficial effects. Buprenorphine (BUP) is used more and more and shows the same beneficial effects. PATIENTS AND METHOD: Twenty-four pregnant women received BUP and their infants were enrolled in the study. Thirteen retrospective (GI) and 11 prospective (GII) cases were studied. In the GII, the women were treated and followed up in an interdisciplinary manner. RESULTS: Complications in GII were less frequent than in GI: 9 vs 30% of prematurity, 9 vs 46% of fetal growth retardation and 0 vs 23% of acute fetal distress. However, the frequency of withdrawal syndrome was the same in both groups, 63 vs 69%, though improvements came more rapidly in GII. CONCLUSION: This study shows that the use of BUP during pregnancy, combined with medical and psychosocial support, may reduce addiction complications. This support has to be maintained after the birth.