Childbirth after organ transplantation in Hungary

BACKGROUND

The first successfully delivered newborn after organ transplantation was reported in 1963; since then, >14,000 women have delivered after transplantation. Patients with an end-stage organ disease develop fertility disturbances. One year after a successful solid organ transplantation with stable graft function, fertile women can give birth to a child from a medical point of view. Pregnant transplant patients do experience a high risk of graft function worsening, a rejection episode, and opportunistic infections. Furthermore, the medical therapy may influence teratogenicity.

METHODS

Between 1974 and September 1, 2010, 5 Hungarian centers performed 6802 solid organ transplantation and lungs were grafted in Vienna, Austria. The organ distribution was: 5971 kidney, 454 liver, 187 heart, 90 combined pancreas-kidney, 5 combined islet-kidney, and 95 lung transplantation. There were no pregnancies among heart, lung, and pancreas recipients.

RESULTS

In all, 3.9% of the renal and 14.3% of the fertile liver transplanted women gave birth to children. To wit, 23 kidney recipients delivered 27 healthy children (17 boys and 10 girls). In 4 cases, 2 children were born, twice as twins. Among liver recipients, 8 women delivered 8 healthy babies. There was no hepatitis C or B virus-positive patient among the mothers. There was no graft insufficiency, rejection or birth defect. Transplanted mothers often display toxemia or preeclampsia during pregnancy requiring cesarean section. The relatively higher ratio of liver recipients was perhaps due to the rarer occurrence of extrahepatic organ damage, like diabetic nephropathy or cardiomyopathy, and the reversible nature of hepatorenal or hepatopulmonary syndrome.

CONCLUSION

Delivery of a child by a transplanted mother carries an high risk, requiring interdisciplinary cooperation. The quality of life of solid organ recipients can be significantly raised by childbirth under appropriate circumstances.

Nrarp is a novel intracellular component of the Notch signaling pathway

The Lin12/Notch receptors regulate cell fate during embryogenesis by activating the expression of downstream target genes. These receptors signal via their intracellular domain (ICD), which is released from the plasma membrane by proteolytic processing and associates in the nucleus with the CSL family of DNA-binding proteins to form a transcriptional activator. How the CSL/ICD complex activates transcription and how this complex is regulated during development remains poorly understood. Here we describe Nrarp as a new intracellular component of the Notch signaling pathway in Xenopus embryos. Nrarp is a member of the Delta-Notch synexpression group and encodes a small protein containing two ankyrin repeats. Nrarp expression is activated in Xenopus embryos by the CSL-dependent Notch pathway. Conversely, overexpression of Nrarp in embryos blocks Notch signaling and inhibits the activation of Notch target genes by ICD. We show that Nrarp forms a ternary complex with the ICD of XNotch1 and the CSL protein XSu(H) and that in embryos Nrarp promotes the loss of ICD. By down-regulating ICD levels, Nrarp could function as a negative feedback regulator of Notch signaling that attenuates ICD-mediated transcription.

Activation of Xenopus genes required for lateral inhibition and neuronal differentiation during primary neurogenesis

XNGN-1, a member of the neurogenin family of basic helix-loop-helix proteins, plays a critical role in promoting neuronal differentiation in Xenopus embryos. When ectopically expressed, XNGN-1 induces the expression of a set of genes required for neuronal differentiation such as XMyT1 and NeuroD. At the same time, however, XNGN-1 induces the expression of genes that antagonize neuronal differentiation by a process called lateral inhibition. Here, we present evidence that XNGN-1 activates the expression of genes required for differentiation and lateral inhibition by recruiting transcriptional coactivators p300/CBP (CREB-binding protein) or PCAF (p3OO/CBP-associated protein), both of which contain histone acetyltransferase (HAT) activity. Significantly, transcriptional activation of the genes in the lateral inhibitory pathway is less dependent on the HAT activity than is the activation of the genes that mediate differentiation. We propose that this difference enables the genes in the lateral inhibition pathway to be induced prior to the genes that promote differentiation, thus enabling lateral inhibition to establish a negative feedback loop and restrict the number of cells undergoing neuronal differentiation.

The Notch ligand, X-Delta-2, mediates segmentation of the paraxial mesoderm in Xenopus embryos

Segmentation of the vertebrate embryo begins when the paraxial mesoderm is subdivided into somites, through a process that remains poorly understood. To study this process, we have characterized X-Delta-2, which encodes the second Xenopus homolog of Drosophila Delta. Strikingly, X-Delta-2 is expressed within the presomitic mesoderm in a set of stripes that corresponds to prospective somitic boundaries, suggesting that Notch signaling within this region establishes a segmental prepattern prior to somitogenesis. To test this idea, we introduced antimorphic forms of X-Delta-2 and Xenopus Suppressor of Hairless (X-Su(H)) into embryos, and assayed the effects of these antimorphs on somite formation. In embryos expressing these antimorphs, the paraxial mesoderm differentiated normally into somitic tissue, but failed to segment properly. Both antimorphs also disrupted the segmental expression of X-Delta-2 and Hairy2A, a basic helix-loop-helix (bHLH) gene, within the presomitic mesoderm. These observations suggest that X-Delta-2, via X-Notch-1, plays a role in segmentation, by mediating cell-cell interactions that underlie the formation of a segmental prepattern prior to somitogenesis.