The Natural History of Prenatally Diagnosed Conjoined Twins

Journal of Pediatric Surgery. Mar, 2002  |  Pubmed ID: 11877639

Accurate prenatal diagnosis of complex anatomic connections and associated anomalies has only been possible recently with the use of ultrasonography, echocardiography, and fetal magnetic resonance imaging (MRI). To assess the impact of improved antenatal diagnosis in the management and outcome of conjoined twins, the authors reviewed their experience with 14 cases.

Human Mesenchymal Stem Cells: Insights from a Surrogate in Vivo Assay System

Cells, Tissues, Organs. 2002  |  Pubmed ID: 12021494

Mesenchymal stem cells (MSC) are multipotent cells that have been isolated from the bone marrow of multiple species that can be induced to differentiate into at least bone, cartilage, and adipose tissue in vitro. Using a model of in utero cellular transplantation in which human MSC are transplanted into fetal lambs, we have shown that MSC can engraft in multiple tissues and persist for over one year. Furthermore, these cells can differentiate into cardiac and skeletal myocytes, bone marrow stromal cells, adipocytes, thymic epithelial cells, and chondrocytes. These observations lend support to the potential utility of MSC for cellular and/or gene therapy in the treatment of a variety of congenital or acquired diseases such as osteogenesis imperfecta, muscular dystrophy, lysosomal storage diseases, and for enhancement of bone marrow transplantation.

Engraftment of Bone Marrow and Fetal Liver Cells After in Utero Transplantation in MDX Mice

Journal of Pediatric Surgery. Jul, 2002  |  Pubmed ID: 12077771

In utero hematopoietic stem cell transplantation (IUHSCTx) has been experimentally or clinically effective only in circumstances in which there is a survival advantage for donor cells. A survival advantage exists for normal muscle cells in muscular dystrophy. Because hematopoietic and mesenchymal stem cells may have the capacity to differentiate into muscle cells, the authors hypothesized that in utero bone marrow (BM) or fetal liver (FL) stem cell transplantation may be used to treat muscular dystrophy.

The Ex-utero Intrapartum Treatment

Current Opinion in Pediatrics. Aug, 2002  |  Pubmed ID: 12130912

Advances in prenatal diagnosis, combined with a better understanding of the natural history of prenatally diagnosed anomalies, are providing increasing opportunities to consider fetal intervention in selected cases of life-threatening malformations. Accurate prenatal diagnosis can now accurately identify fetal pathophysiology that poses an immediate threat to the life of the newborn infant on separation from the placental circulation. In this circumstance, the ex-utero intrapartum treatment (EXIT) procedure, which maintains intrapartum uteroplacental support, can be life saving. The most common indications for the EXIT procedure are fetal lesions causing extrinsic or intrinsic airway obstruction. However, fetuses with other anomalies that may compromise neonatal resuscitation can also benefit from this approach. The EXIT procedure differs significantly from a cesarean delivery, and caution must be taken to avoid maternal morbidity. As with all endeavors involving maternal-fetal intervention, a team approach is crucial to ensure accurate diagnosis and optimal perinatal management.

Efficient Transduction of Liver and Muscle After in Utero Injection of Lentiviral Vectors with Different Pseudotypes

Molecular Therapy : the Journal of the American Society of Gene Therapy. Sep, 2002  |  Pubmed ID: 12231171

In this study we investigate the efficacy of lentiviral vectors of different pseudotypes for gene transfer to tissues of the preimmune fetus. BALB/c fetuses at 14-15 days' gestation received lentiviral vectors carrying the transgene lacZ under the control of the human cytomegalovirus (CMV) promoter by intramuscular (i.m.) or intrahepatic (i.h.) injection. We pseudotyped the lentiviral vectors with vesicular stomatitis virus (VSV-G), with Mokola virus, or with Ebola virus envelope glycoproteins. We harvested the pups at time points between 5 days and 9 months following injection and performed a detailed histologic assessment. The efficiency and distribution of transduction after in utero administration was highly dependent upon the route of administration and the pseudotype of vector used. Biodistribution studies showed widespread distribution of vector sequences in multiple tissues, albeit at very low levels, and transduced cells were found in significant numbers only in liver, heart, and muscle. Overall, VSV-G was the most efficient in transducing hepatocytes, whereas Mokola and Ebola were more efficient in transducing myocytes. Transduction of cardiomyocytes was observed after both i.m. and i.h. injection of all three vectors. Our findings of long-term transduction of skeletal myocytes and cardiomyocytes after in utero administration suggest a novel strategy for the treatment of congenital muscular dystrophies.

Long-term Transgene Expression in Cardiac and Skeletal Muscle Following Fetal Administration of Adenoviral or Adeno-associated Viral Vectors in Mice

The Journal of Gene Medicine. Nov, 2003  |  Pubmed ID: 14601131

In utero gene transfer may provide advantages for the correction of congenital genetic disorders. In the present study we compare the ability of adenovirus (AdCMVLacZ), and two serotypes of adeno-associated virus (AAVCMVLacZ serotypes 2 and 2/5), to target cardiac and skeletal muscle after prenatal systemic or intramuscular injection in mice and assess the immune response to the vectors.

Transduction of Satellite Cells After Prenatal Intramuscular Administration of Lentiviral Vectors

The Journal of Gene Medicine. Jan, 2005  |  Pubmed ID: 15515139

We have previously reported long-term expression of lacZ in myocytes after in utero intramuscular injection of Mokola and Ebola pseudotyped lentiviral vectors. In further experiments, we have noted that these vectors also transduce small cells at the periphery of the muscle fibers that have the morphology of satellite cells, or muscle stem cells. In this study we performed experiments to further define the morphology and function of these cells.

Impact of Continuous Intraoperative Monitoring on Outcomes in Open Fetal Surgery

Fetal Diagnosis and Therapy. Jul-Aug, 2005  |  Pubmed ID: 15980648

There are shifts in fetal hemodynamics during open fetal surgery that were not appreciated until the use of intraoperative fetal echocardiography. We have developed an intraoperative monitoring strategy to continuously assess fetal hemodynamics. We hypothesized that this approach would enhance intraoperative management and survival.

Persistent Expression of HF.IX After Tolerance Induction by in Utero or Neonatal Administration of AAV-1-F.IX in Hemophilia B Mice

Molecular Therapy : the Journal of the American Society of Gene Therapy. Sep, 2007  |  Pubmed ID: 17565352

The major complication associated with protein replacement therapy currently used in the treatment of hemophilia B (HB) is the development of antibodies to the infused human Factor IX (hF.IX). We hypothesized that vector-mediated expression of hF.IX, either at a prenatal stage or early in life may lead to tolerance to hF.IX and long-term transgene expression. Fetal, neonatal, and adult F.IX-deficient mice were injected with AAV-1-hF.IX, and the hF.IX levels as well as antibodies to hF.IX in the circulation were assayed. In utero injection followed by postnatal re-administration of adeno-associated virus 1 (AAV-1) vector achieved persistent expression of hF.IX in all animals, with no cellular or humoral immune response to F.IX. Similar results were seen after initial injection in neonatal mice followed by re-administration, whereas all mice injected at the adult stage developed antibodies to hF.IX. In contrast, after administration of AAV-2-hF.IX in the neonatal period, antibodies to hF.IX were formed in all the injected animals. We conclude that in utero or neonatal-stage injection of AAV-1-hF.IX can lead to long-term expression and absence of immune response. The differences in immune response between the AAV-1 and AAV-2 groups suggests that tolerance may be related to differences in bio-distribution, timing of expression, and/or the initial levels of hF.IX expression. This supports the concept of a narrow "window of opportunity" for tolerance induction.

Image of the Month--quiz Case. Gastric Duplication Cyst

Archives of Surgery (Chicago, Ill. : 1960). Oct, 2010  |  Pubmed ID: 20956774

Maternal T Cells Limit Engraftment After in Utero Hematopoietic Cell Transplantation in Mice

The Journal of Clinical Investigation. Feb, 2011  |  Pubmed ID: 21245575

Transplantation of allogeneic stem cells into the early gestational fetus, a treatment termed in utero hematopoietic cell transplantation (IUHCTx), could potentially overcome the limitations of bone marrow transplants, including graft rejection and the chronic immunosuppression required to prevent rejection. However, clinical use of IUHCTx has been hampered by poor engraftment, possibly due to a host immune response against the graft. Since the fetal immune system is relatively immature, we hypothesized that maternal cells trafficking into the fetus may pose the true barrier to effective IUHCTx. Here, we have demonstrated that there is macrochimerism of maternal leukocytes in the blood of unmanipulated mouse fetuses, with substantial increases in T cell trafficking after IUHCTx. To determine the contribution of these maternal lymphocytes to rejection after IUHCTx, we bred T and/or B cell-deficient mothers to wild-type fathers and performed allogeneic IUHCTx into the immunocompetent fetuses. There was a marked improvement in engraftment if the mother lacked T cells but not B cells, indicating that maternal T cells are the main barrier to engraftment. Furthermore, when the graft was matched to the mother, there was no difference in engraftment between syngeneic and allogeneic fetal recipients. Our study suggests that the clinical success of IUHCTx may be improved by transplanting cells matched to the mother.

Pancreatic Mesenchyme Regulates Epithelial Organogenesis Throughout Development

PLoS Biology. Sep, 2011  |  Pubmed ID: 21909240

The developing pancreatic epithelium gives rise to all endocrine and exocrine cells of the mature organ. During organogenesis, the epithelial cells receive essential signals from the overlying mesenchyme. Previous studies, focusing on ex vivo tissue explants or complete knockout mice, have identified an important role for the mesenchyme in regulating the expansion of progenitor cells in the early pancreas epithelium. However, due to the lack of genetic tools directing expression specifically to the mesenchyme, the potential roles of this supporting tissue in vivo, especially in guiding later stages of pancreas organogenesis, have not been elucidated. We employed transgenic tools and fetal surgical techniques to ablate mesenchyme via Cre-mediated mesenchymal expression of Diphtheria Toxin (DT) at the onset of pancreas formation, and at later developmental stages via in utero injection of DT into transgenic mice expressing the Diphtheria Toxin receptor (DTR) in this tissue. Our results demonstrate that mesenchymal cells regulate pancreatic growth and branching at both early and late developmental stages by supporting proliferation of precursors and differentiated cells, respectively. Interestingly, while cell differentiation was not affected, the expansion of both the endocrine and exocrine compartments was equally impaired. To further elucidate signals required for mesenchymal cell function, we eliminated β-catenin signaling and determined that it is a critical pathway in regulating mesenchyme survival and growth. Our study presents the first in vivo evidence that the embryonic mesenchyme provides critical signals to the epithelium throughout pancreas organogenesis. The findings are novel and relevant as they indicate a critical role for the mesenchyme during late expansion of endocrine and exocrine compartments. In addition, our results provide a molecular mechanism for mesenchymal expansion and survival by identifying β-catenin signaling as an essential mediator of this process. These results have implications for developing strategies to expand pancreas progenitors and β-cells for clinical transplantation.

The Maternal Immune Response Inhibits the Success of in Utero Hematopoietic Cell Transplantation

Chimerism (Print). 4, 2011  |  Pubmed ID: 21912720

In utero hematopoietic cell transplantation (IUHCTx) is a promising strategy for the treatment of congenital stem cell disorders. Despite the purported immaturity of the fetal immune system, the clinical success of this strategy has been limited by poor engraftment of transplanted cells. The fetal host immune system is thought to be the major barrier to achieving successful IUHCTx. Since the fetal immune system is immature, however, we hypothesized that the maternal immune response may instead pose the true barrier to IUHCTx. We have demonstrated that maternal T cells traffic into the fetus after allogeneic in utero transplantation and that these lymphocytes play a critical role in limiting engraftment. Furthermore, we have shown that MHC matching the donor cells to the mother improves engraftment in the unmatched fetus. These results help renew interest in using the fetal environment to treat patients with congenital stem cell disorders.