Tippi C. MacKenzie

Memory regulatory T cells reside in human skin.

Regulatory T cells (Tregs), which are characterized by expression of the transcription factor Foxp3, are a dynamic and heterogeneous population of cells that control immune responses and prevent autoimmunity. We recently identified a subset of Tregs in murine skin with properties typical of memory cells and defined this population as memory Tregs (mTregs). Due to the importance of these cells in regulating tissue inflammation in mice, we analyzed this cell population in humans and found that almost all Tregs in normal skin had an activated memory phenotype. Compared with mTregs in peripheral blood, cutaneous mTregs had unique cell surface marker expression and cytokine production. In normal human skin, mTregs preferentially localized to hair follicles and were more abundant in skin with high hair density. Sequence comparison of TCRs from conventional memory T helper cells and mTregs isolated from skin revealed little homology between the two cell populations, suggesting that they recognize different antigens. Under steady-state conditions, mTregs were nonmigratory and relatively unresponsive; however, in inflamed skin from psoriasis patients, mTregs expanded, were highly proliferative, and produced low levels of IL-17. Taken together, these results identify a subset of Tregs that stably resides in human skin and suggest that these cells are qualitatively defective in inflammatory skin disease.

Maternal T cells limit engraftment after in utero hematopoietic cell transplantation in mice

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.

Genetic disruption of the pancreatic mesenchyme reveals that it is critical for the expansion of epithelial progenitors and for the proliferation of insulin-producing beta cells.

Long-term surgical outcomes in congenital diaphragmatic hernia: observations from a single institution

BACKGROUND/PURPOSE Surgical complications are common in survivors of congenital diaphragmatic hernia (CDH), but little is known about long-term incidence patterns and associated predictors. METHODS A cohort of 99 CDH survivors was prospectively followed at a single-institution multidisciplinary clinic. Data were gathered regarding the adverse surgical outcomes of hernia recurrence, chest and spinal deformity, and operative small bowel obstruction (SBO), and then were retrospectively analyzed in relation to perinatal and perioperative markers of disease severity to determine significant predictors. Statistical methods used included univariate and multivariate regression analysis, hazard modeling, and Kaplan-Meier analysis. RESULTS At a median cohort age of 4.7 (range, 0.2-10.6) years, 46% of patients with patch repairs and 10% of those with primary repairs had a hernia recurrence at a median time of 0.9 (range, 0.1-7.3) years after repair. Chest deformity was detected in 47%. Small bowel obstruction and scoliosis occurred in 13%. Recurrence and chest deformity were significantly more common with patch repair, liver herniation, age at neonatal extubation greater than 16 days, oxygen requirement at discharge, and prematurity. The strongest predictor of SBO was patch repair. Multivariate analysis showed that patch repair was independently predictive of recurrence and early chest deformity (odds ratios of 5.0 and 4.8, confidence intervals of 1-24 and 1-21, P < .05). Use of an absorbable patch was associated with the highest risk of surgical complications. CONCLUSIONS For long-term survivors of CDH, specific perinatal and operative variables, particularly patch repair, are associated with subsequent adverse surgical outcomes.

A Fetal Lung Lesion Consisting of Bronchogenic Cyst, Bronchopulmonary Sequestration, and Congenital Cystic Adenomatoid Malformation: The Missing Link?

A fetus was found to have a large left thoracic cyst on routine prenatal ultrasound at 23 weeks of gestation. This lesion caused compression of the normal left lung tissue and contralateral mediastinal shift. At 23 weeks of gestation the cyst was percutaneously aspirated without subsequent reaccumulation of fluid. Serial ultrasounds showed decrease in the size of the cyst. The clinical diagnosis of congenital cystic adenomatoid malformation was made. At birth, the child had no respiratory distress, and a CT scan confirmed the finding of a fluid-filled cyst in the left chest. At the time of resection, a nonaerated extralobar bronchopulmonary sequestration (with a systemic arterial blood supply and separate pleural investment) was found. The dominant cyst had ciliated respiratory epithelium with cartilage, indicative of a bronchogenic cyst, and the remainder of the specimen had the histologic hallmarks of a congenital cystic adenomatoid malformation. The coexistence of three separate anomalies in one lesion suggests a common embryological link for these malformations.

Multilineage differentiation of human MSC after in utero transplantation.

Prenatal transplantation of stem cells is an exciting frontier for the treatment of many congenital diseases. The fetus may be an ideal recipient for stem cells, as it is immunologically immature and has rapidly proliferating cellular compartments that may support the engraftment of transplanted cells. Mesenchymal stem cells (MSC), given their ability to differentiate among multiple lineages, could potentially be used to treat diseases such as osteogenesis imperfecta, muscular dystrophy, and a variety of others that can be diagnosed in utero. We have shown, using a human-sheep in utero xenotransplantation model, that human MSC have the ability to engraft, differentiate into many tissue types, and survive for over 1 year in fetal lamb recipients. This observation warrants further studies of the behavior of MSC following systemic or site-directed transplantation.

The ex-utero intrapartum treatment.

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.

Long-term transgene expression in cardiac and skeletal muscle following fetal administration of adenoviral or adeno-associated viral vectors in mice

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.

Human mesenchymal stem cells: insights from a surrogate in vivo assay system.

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.

Decreased risk of graft failure with maternal liver transplantation in patients with biliary atresia.

The presence of maternal cells in offspring may promote tolerance to noninherited maternal antigens (NIMAs). Children with biliary atresia (BA) have increased maternal cells in their livers, which may impact tolerance. We hypothesized that patients with BA would have improved outcomes when receiving a maternal liver. We reviewed all pediatric liver transplants recorded in the SRTR database from 1996 to 2010 and compared BA and non‐BA recipients of maternal livers with recipients of paternal livers for the incidences of graft failure and retransplantation. Rejection episodes after parental liver transplantation were examined for patients transplanted at our institution. BA patients receiving a maternal graft had lower rates of graft failure compared to those receiving a paternal graft (3.7% vs. 10.5%, p = 0.02) and, consequently, fewer episodes of retransplantation (2.7% vs. 7.5%, p = 0.04). These differences were not seen among non‐BA patients or among BA patients who received female deceased donor grafts. In patients transplanted at our institution, paternal liver transplantation was associated with an increased incidence of refractory rejection compared to maternal liver transplantation only in BA. Our data support the concept that maternal cells in BA recipients promote tolerance to NIMAs and may be important in counseling BA patients who require liver transplantation.