Les hépatocytes foetaux, vecteurs potentiels de thérapie cellulaire des maladies hépatiques. Transplantation chez l'adulte et in utero

L'utilisation d'hépatocytes foetaux pourrait permettre de surmonter les difficultés rencontrées avec les hépatocytes adultes dans les programmes de thérapie cellulaire hépatique. La transplantation prénatale vise à optimiser la prise de greffe, tout en proposant une alternative à l'IMG en cas de diagnostic prénatal. Nous avons isolés, transduits et congelés des hépatocytes foetaux de primatenon humain (Macaque cynomolgus) Après allo-transplantation in utero à 2/3 de gestation, les cellules sont retrouvées à court terme. Nous avons isolé, caractérisé, transduits et congelés des hépatocytes humains foetaux (HHF) précoces (10-13 SA). Après transplantation dans le foie de souris athymiques, les HHF s'intègrent à long terme (12 sem), prolifèrent (chimérisme jusqu'à 7-10%)....PARIS5-BU-Necker : Fermée (751152101) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Dilatation mitrale percutanée en cours de grossesse

PARIS7-Xavier Bichat (751182101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Hepatocyte transplantation: studies in preclinical models.

International audienceTransplantation of allogeneic or genetically modified autologous hepatocytes may be an alternative to whole-liver transplantation for the treatment of hereditary metabolic liver diseases. Human hepatocytes have already been transplanted in patients, demonstrating the safety and feasibility of both approaches. Although a few cases of allogeneic transplantation have resulted in long-term engraftment and function, only a partial and transient correction of the disease was achieved. This may partly result from a lack of proliferation of transplanted cells. In rodents, transplanted hepatocytes do not proliferate in adult quiescent livers and repopulate recipient livers only when they display a proliferative advantage over resident hepatocytes. Most of these models are not transposable to humans, however. Our aim is to develop preclinical approaches to hepatocyte transplantation in nonhuman primates. We have defined a strategy that increases the engraftment efficiency of transplanted hepatocytes by inducing their proliferation together with that of resident hepatocytes. We have also immortalized simian fetal hepatic progenitor cells and shown that these cells do not proliferate in situ after transplantation into the livers of immunodeficient mice. By contrast early human hepatoblasts repopulate mouse livers more efficiently. However, if we consider the number of cells to be transplanted (one to several billion), the means of expanding and differentiating stem or progenitor cells other than hepatocytes will have to be determined prior to envisaging treating patients

: New Development in Stem Cell Research

Circulating Endothelial Progenitor Cells: Relevant in Physiopathology, A Promise for Clinical applications, Turning Embryonic and Fetal Stem Cells into red cells : Erythropoiesis as a Model for the challenges of Tissue Engineering, Endothelial Progenitor Cells Potential for Vasculogenesis and Cardiomyogenesis, Primate Liver Progenitor Cells, Tracing Clonal Lineages of Stem Cells in vivo, Agent-Dependent Effects of parp-a Deficiency on DNA Damage Responses and Genomic Stability in Mouse ES Cells, Tissue Engineering Using Adipose-Derived Stem Cells Harvested from GFP Transgenic Animals, Prostate Stem Cell

Termination of pregnancy following prenatal diagnosis in France: how severe are the foetal anomalies?

International audienceOBJECTIVE: To determine how severe were the conditions leading to termination of pregnancy for foetal anomaly (TOPFA) in France. METHODS: Detailed indications for TOPFA were extracted from medical charts. RESULTS: Of 2465 completed records, indications were: chromosomal anomalies n = 963 (39.1%), malformations of a single organ without chromosomal or genetic aetiologies n = 898 (36.4%), multiple malformations without chromosomal or genetic aetiologies n = 238 (9.7%), obstetrical complications n = 161 (6.5%), non-chromosomal genetic diseases n = 158 (6.4%), foetal infections n = 21 (0.9%), unexplained severe oligohydramnios n = 20 (0.8%), foetal exposure to teratogenic agents n = 6. Overall, 33.3% of anomalies were lethal (e.g. anencephaly), 25.2% were expected to result in isolated mental retardation (e.g. Down) and 35.1% in substantial handicap (e.g. myelomeningocele). In 6.4% of cases, the anomaly was either of late onset (e.g. Huntington's disease) or with uncertain prognosis (e.g. agenesis of corpus callosum) or severity was debatable (e.g. single limb agenesis, sickle cell disease). CONCLUSIONS: Although there is no indisputable definition of which anomalies are 'severe', 93.6% of the decisions to terminate the pregnancy were made by women and professionals in reaction to anomalies which clearly were lethal or would lead to substantial physical and/or mental disabilities

Allotransplantation in utero et immortalisation d’hépatocytes fœtaux de primates

Nous développons des approches précliniques chez le primate comme modèle de thérapie cellulaire pour le traitement de maladies métaboliques hépatiques. Chez le fœtus, les tissus, dont le foie, sont en expansion, ce qui devrait faciliter la prise de greffe des hépatocytes, et le système immunitaire devient pleinement mature seulement après la naissance. Nous avons défini les conditions d’isolement d’hépatocytes fœtaux de macaques à la fin du 2ème trimestre de gestation (90-100 jours), ainsi que les conditions de culture, de cryopreservation et de transduction rétrovirale. Nous avons également évalué deux voies d’administration différentes des hépatocytes : la veine ombilicale, qui s’est révélée délétère pour les fœtus, et l’injection intraparenchymateuse qui a été parfaitement tolérée par les animaux. Cette dernière a permis de mettre en évidence la présence d’hépatocytes allogéniques, c’est-à-dire un microchimérisme 9 jours après transplantation. Nous avons également immortalisé des hépatocytes simiens fœtaux en utilisant un vecteur retroviral exprimant grand T de SV40 flanqué de sites lox P. Une lignée cellulaire est maintenant établie depuis 2 ans : elle n’est pas tumorigène après injection sous-cutanée à des souris nude et expriment des marqueurs caractéristiques d’hépatoblastes bipotents, précurseurs des hépatocytes et des cellules des voies biliaires. Après transplantation orthotopique via la veine porte chez des souris nude, ces cellules exprimaient l’albumine jusqu’au moment du sacrifice des animaux (17 jours). Les prochaines étapes seront la mise au point des conditions de transplantation d’hépatocytes transduits primaires et/ou immortalisés chez des fœtus plus jeunes (60 jours de gestation) et chez le macaque nouveau-né

Paradoxic activation of the renin-angiotensin system in twin-twin transfusion syndrome: An explanation for cardiovascular disturbances in the recipient

Despite advances in treatment, twin-to-twin transfusion syndrome (TTTS) still carries a high risk for perinatal mortality and morbidity. Simple blood transfer from the donor to the recipient twin cannot explain all of the features of this disease, in particular the recipient's hypertensive cardiomyopathy. We report a case in which TTTS resulted in preterm delivery with early neonatal death of both twins, allowing assessment of the renin angiotensin system (RAS) status of each fetus, both by cord blood renin and aldosterone assay and by renal immunohistochemistry. The donor had severe oliguria/oligohydramnios, whereas the recipient, in addition to severe polyuria/polyhydramnios, had cardiomyopathy, atrioventricular regurgitation, and ascites. Although immunohistochemistry demonstrated that renal secretion of renin was up-regulated in the donor and down-regulated in the recipient, cord blood levels of renin and aldosterone were similar, with high renin levels in both twins. This observation supports the hypothesis that despite renal RAS down-regulation, the recipient is exposed to RAS effectors elaborated in the donor and transferred via placental shunts. This may contribute to cardiomyopathy and hypertension in the recipient, which cannot be accounted for by hypervolemia alone. We thus hypothesized that in TTTS, the recipient's hypertensive cardiomyopathy could be due to a mechanism similar to the classical model of hypertension referred to as "2 kidneys-1 clip." Thus the hypovolemic donor twin, comparable to the clipped kidney, produces vasoactive hormones that compromise the recipient, comparable to the normal kidney, causing hypertension and cardiomyopathy

Fertility and pregnancy outcomes following conservative treatment for placenta accreta.: Fertility after placenta accreta

International audienceBACKGROUND: The aim of this study was to estimate the fertility and pregnancy outcomes after successful conservative treatment for placenta accreta. METHODS: This retrospective national multicenter study included women with a history of conservative management for placenta accreta in French university hospitals from 1993 through 2007. Success of conservative treatment was defined by uterine preservation. Data were retrieved from medical files and telephone interviews. RESULTS: Follow-up data were available for 96 (73.3%) of the 131 women included in the study. There were eight women who had severe intrauterine synechiae and were amenorrheic. Of the 27 women who wanted more children, 3 women were attempting to become pregnant (mean duration: 11.7 months, range: 7-14 months), and 24 (88.9% [95% confidence interval (CI), 70.8-97.6%]) women had had 34 pregnancies (21 third-trimester deliveries, 1 ectopic pregnancy, 2 elective abortions and 10 miscarriages) with a mean time to conception of 17.3 months (range, 2-48 months). All 21 deliveries had resulted in healthy babies born after 34 weeks of gestation. Placenta accreta recurred in 6 of 21 cases [28.6% (95% CI, 11.3-52.2%)] and was associated with placenta previa in 4 cases. Post-partum hemorrhage occurred in four [19.0% (95% CI, 5.4-41.9%)] cases, related to placenta accreta in three and to uterine atony in one. CONCLUSIONS: Successful conservative treatment for placenta accreta does not appear to compromise the patients' subsequent fertility or obstetrical outcome. Nevertheless, patients should be advised of the high risk that placenta accreta may recur during future pregnancies