Defects in insulin secretion and reduction in β-cell mass are associated with type 2 diabetes in humans, and understanding the basis for these dysfunctions may reveal strategies for diabetes therapy. In this study, we show that pancreas-specific knockout of growth factor receptor–binding protein 10 (Grb10), which is highly expressed in pancreas and islets, leads to elevated insulin/IGF-1 signaling in islets, enhanced β-cell mass and insulin content, and increased insulin secretion in mice. Pancreas-specific disruption of Grb10 expression also improved glucose tolerance in mice fed with a high-fat diet and protected mice from streptozotocin-induced β-cell apoptosis and body weight loss. Our study has identified Grb10 as an important regulator of β-cell proliferation and demonstrated that reducing the expression level of Grb10 could provide a novel means to increase β-cell mass and reduce β-cell apoptosis. This is critical for effective therapeutic treatment of both type 1 and 2 diabetes.

BACKGROUND Hemophilia B, an X-linked disorder, is ideally suited for gene therapy. We investigated the use of a new gene therapy in patients with the disorder. METHODS We infused a single dose of a serotype-8-pseudotyped, self-complementary adenovirus-associated virus (AAV) vector expressing a codon-optimized human factor IX (FIX) transgene (scAAV2/8-LP1-hFIXco) in a peripheral vein in six patients with severe hemophilia B (FIX activity, <1% of normal values). Study participants were enrolled sequentially in one of three cohorts (given a high, intermediate, or low dose of vector), with two participants in each group. Vector was administered without immunosuppressive therapy, and participants were followed for 6 to 16 months. RESULTS AAV-mediated expression of FIX at 2 to 11% of normal levels was observed in all participants. Four of the six discontinued FIX prophylaxis and remained free of spontaneous hemorrhage; in the other two, the interval between prophylactic injections was increased. Of the two participants who received the high dose of vector, one had a transient, asymptomatic elevation of serum aminotransferase levels, which was associated with the detection of AAV8-capsid-specific T cells in the peripheral blood; the other had a slight increase in liver-enzyme levels, the cause of which was less clear. Each of these two participants received a short course of glucocorticoid therapy, which rapidly normalized aminotransferase levels and maintained FIX levels in the range of 3 to 11% of normal values. CONCLUSIONS Peripheral-vein infusion of scAAV2/8-LP1-hFIXco resulted in FIX transgene expression at levels sufficient to improve the bleeding phenotype, with few side effects. Although immune-mediated clearance of AAV-transduced hepatocytes remains a concern, this process may be controlled with a short course of glucocorticoids without loss of transgene expression. (Funded by the Medical Research Council and others; ClinicalTrials.gov number, NCT00979238.).

6525 Background: Transplantation of CD34+ stem cells from a haploidentical family member plus a cord blood (UCB) unit is a promising approach for patients (pts) who lack HLA donors that facilitates early engraftment while preserving long-term cord blood reconstitution. Methods: We prospectively investigated this approach in combination with reduced intensity conditioning consisting of fludarabine, melphalan and ATG in 39 patients with high-risk hematological malignancies from January 29, 2007 to November 12, 2010. Median age was 48 yrs (20-69); 24 (62%) had active disease at transplant. 12 pts belonged to ethnic minorities. Results: The median haploidentical donor CD34+ dose was 3.08 x 106/kg (1.0-11); CD3+ cells were 0.8 x 104/kg (0.03-2.4). Median UCB nucleated cell dose was 1.55 x 107/kg (range, 0.86-5.23); CD34+ cells were 0.06 x 106/kg (0.02-0.75). 37 (95%) pts had neutrophil recovery with a median time to ANC >500/mL of 11 days (9-43). 27 (69%) pts became platelet transfusion independent at median time of 19.5 days (10-132). In the majority of pts, early haploidentical engraftment was replaced by durable engraftment of UCB by 100 days. However, 5 pts had persistent haploidentical only chimerism, while 4 pts had delayed engraftment with only UCB. Acute GVHD grade II-IV occurred in 10 pts (26%) with only 2 Grade III GVHD (5%). Day 100 mortality rate was 21%. With a median follow up for survivors of 298 days (89-1133), 19 pts (49%) are currently alive. 8 pts died from disease relapse, 4 from infection, and 3 from graft failure. For the entire cohort 1 yr OS was 47% and PFS 38%. For pts in CR at SCT 1 yr PFS was 63% and OS 70%. For pts with active disease at SCT 1 yr OS and PFS were 37%. Conclusions: Combined haploidentical donor and UCB transplantation in the large majority of patients results in rapid neutrophil engraftment due to the haplo-identical progenitor cells. Durable engraftment is provided by the UCB graft with a low rate of GVHD and excellent long term disease control, even in patients with active disease at transplant.

Abstract Abstract 3378 Poster Board III-266 Introduction: Haploidentical-cord blood transplantation is a promising approach for patients (pts) who lack HLA donors and may improve rates of early engraftment while allowing long term cord blood reconstitution with low rates of GVHD. We enrolled 29 pts (17 AML/MDS, 4 ALL, 3 CML, 4 NHL/HL, 1 severe aplastic anemia) lacking HLA identical donors. The median age was 40 years (range, 4-67), and median weight was 75 kg (range, 14-125). Twenty-two (76%) pts had active disease at time of transplant; 6 had prior autologous transplants. 14 pts were Caucasian; 15 were other race or ethnicity. The haploidentical donor was the mother in 4; father in 3; child in 10; sibling in 10; and half-sibling in 2 cases. The median haploidentical CD34+ dose was 2.51 × 106/kg (range, 1.25-10.95); CD3+ cells were 1.0 × 104/kg (range, 0.3-3.7). Single unrelated CB units were matched by low resolution at HLA-A and B and high-resolution at DRB1, and matched 6/6 in 2 pts; 5/6 in 18 pts; 4/6 in 9 pts. Median cord total nucleated cells equaled 1.93 × 107/kg (range, 1.07-9.36); CD34+ cells were 0.08 × 106/kg (range, 0.03-0.75). The conditioning regimen for 18 pts was fludarabine (Flu) (30 mg/m2 on d-7 through -3), melphalan (Mel) (70 mg/m2 on d -3 and -2), and Thymoglobulin (rATG) (1.5 mg/kg on d-7, -5, -3, -1). Eleven pts received Flu, thiotepa (5 mg/kg on d -7 and -6), total-body irradiation (TBI) (12 Gy lateral opposed fields in 2 Gy fractions BID on d-3 through -1), and rATG. GVHD prophylaxis consisted of tacrolimus (Tac) + methylprednisolone or Tac + mycophenolate. Engraftment: Two pts died early (sepsis, CVA). Three other pts failed to engraft with either haploidentical or CB and died of infection on d36, 43, and 63. One of these had anti-donor HLA antibodies. 24 pts engrafted with a median time to ANC >500/mL of 10 days (range, 9-31) and median time to sustained platelets >20,000/mL of 20 days (range, 15-63). In the majority of pts, early haploidentical engraftment was replaced by durable engraftment of CB by 100 days. However, 3 pts had persistent hematopoiesis associated with only the haploidentical donor, while a fourth pt engrafted with only CB on day 31. Late graft failure and death from sepsis occurred in one of the patients with haploidentical engraftment. In unfractionated peripheral blood or bone marrow cells, median haploidentical chimerism was 95% (range, 0-100) on d14; 76% (range, 0-95) on d30; 6% (range, 0-87) on d100. Median unfractionated cord chimerism was <5% (range, 0-100) on d14; 20% (range, 0-100) on d30; 85% (range, 0-100) on d100. In the CD3+ compartment, median haploidentical chimerism was 95% (range, 0-100) on d14; 86% (range, 0-95) on d30; 6% (range, 0-79) on d100. Median CD3+ cord chimerism was 5% (range, 0-100) on d14; 26% (range, 0-100) on d30; 90% (range, 1-100) on d100. Toxicities and outcome: Other fatal toxicities included VOD (1), EBV-associated PTLD (1), ARDS (1), cardiac arrest (1), intractable seizures (1). Two patients developed TTP and later died of complications related to sepsis. Five pts relapsed of whom 4 have died. Acute GVHD (aGVHD) grade II occurred in 3 pts, one of whom developed the only case of chronic GVHD after failing to continue prograf. No aGVHD grade III-IV was seen. Twelve pts are currently alive; 11 are without disease. The median follow up for survivors is 186 days (range, 16-642). Estimated one year survival is 26% (95%CI, 6-46), and PFS is 19% (1-36). Conclusions: Combined haploidentical and CB transplantation results in early haploidentical engraftment followed by durable CB predominance in a majority of pts. The median times to neutrophil engraftment are considerably shorter - and the range narrower - than with other methods of cord blood transplantation. Early haploidentical engraftment failed in four patients; cord blood engraftment also failed in three of these pts and in three others. Rates of acute and particularly of chronic GVHD are low. Durable remissions can be achieved even in high risk pts regardless of age or remission status at the time of transplant. Disclosures: Rich: Genzyme: Research Funding. Odenike:Genzyme: Honoraria, Membership on an entity's Board of Directors or advisory committees. van Besien:Genzyme: Research Funding.

Although allogeneic hematopoietic progenitor cell transplantation (HPCT) can be curative for sickle cell anemia (SCA), most patients lack an HLA matched sibling donor or matched unrelated donor. A 2002 multidisciplinary conference held at St. Jude Children’s Research Hospital reached consensus that pilot studies using parental donors were reasonable and ethical. Subsequently, eight children with a history of clinically overt stroke were transplanted on two sequential pilot studies. Peripheral blood progenitor cells were obtained from parents with sickle cell trait. Conditioning was i.v. busulfan (targeted to Css 900 ng/ml) q 6 hours x 4 days, fludarabine 150–200 mg/m2, and OKT3/methylprednisolone and infusion of CD34+ HPCT for 3 patients. Five patients received i.v. busulfan (targeted to Css 900 ng/ml) x 4 days, cyclophosphamide 200 mg/kg, thiotepa 10 mg/kg, OKT3/methylprednisolone, and infusion of both CD34+ cells and CD3+ cells with a fixed T-cell addback of 1.0–1.5 x 105 CD3+ cells/kg. Six children received pre-transplant immunosuppression with hydroxyurea and azathioprine. The median follow-up of eight patients is 1.4 years (range 2 months–4 years). Five of eight had durable donor engraftment,4 of whom are alive and free of SCA post-HPCT. Rejection occurred in 4 patients and was successfully reversed with additional CD34+ cells in one of three patients. GVHD occurred in patients receiving a fixed T-cell addback or DLI: two patients had grade II acute graft-versus-host disease (aGVHD), one grade III aGVHD, and three patients developed chronic GVHD, including a fatal case of bronchiolitis obliterans organizing pneumonia (BOOP) and fungal sepsis. One engrafted patient developed medulloblastoma 2 years post-HPCT and is in remission after treatment. Further investigation revealed that this child inherited a novel germline p53 mutation. In this preliminary experience, haploidentical HPCT for children with SCA and stroke was associated with significant graft rejection and chronic GVHD. The addition of pre-transplant hydroxyurea and azathioprine, increased intensity of conditioning, and the use of T-cell addback to the graft did not improve engraftment in the second cohort. While offering the possibility of cure, haploidentical HPCT for SCA as performed in this experience is associated with significant toxicity and should only be pursued in the context of a rigorously designed and controlled prospective clinical trial.

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BACKGROUND:Therapy-related myelodysplastic syndrome (t-MDS) and acute myeloid leukemia (t-AML) carry a poor prognosis. We analyzed the results of allogeneic HSCT in 38 children to determine which factors, if any, affected outcome.PROCEDURE:The effects of demographic, donor, and disease-related factors were analyzed to determine their effects on overall and disease-free survival (OS, DFS), relapse, and non-relapse mortality (NRM).RESULTS:OS and DFS for t-AML and t-MDS were similar. Three-year OS and EFS were the same (15.4 +/- 5.8%) and the 3-year NRM was 59.6 +/- 8.4%. The 1-year cumulative risk of grade III-IV acute graft-versus-host disease (GVHD) and relapse were 23.7 +/- 7.0% and 18.7 +/- 6.5%, respectively. The percentage of pre-transplant bone marrow (BM) blasts was positively associated with relapse (P = 0.05), while the percentage of BM blasts at diagnosis of therapy-related disease tended to associate with NRM (P = 0.07). Alternative donor and matched sibling donor grafts had similar outcomes. NRM was higher among patients who did not develop acute GVHD as compared to those with grade 1-2 acute GVHD (69.2 +/- 14.2% vs. +/- 12.7%, respectively), while NRM was 100% in patients with grade III-IV acute GVHD (P = 0.007).CONCLUSIONS:The percentage of BM blasts is associated with relapse in these disorders. High rates of NRM negatively impact the outcome of allogeneic HSCT for children with t-AML and t-MDS. Future studies should focus on reducing NRM.

Genome-wide chemical mutagenesis screens have been successfully performed in zebrafish to identify genes involved in erythropoiesis. We have now executed a large-scale screen for genes involved in red cell production in mice by using N-ethyl-N-nitrosurea mutagenesis. Five thousand G1 mice were screened by automated haematological analysis at 7 weeks of age for abnormalities of their red cell indices that lay more than 3 standard deviations outside the normal population average. Mice with co-incident abnormalities in white cell or platelet counts were excluded. Six mutant lines were identified with microcytosis (RBC1-6) that was heritable with subsequent backcrossing. Three of these lines (RBC 1, 4, 5) were found by gene mapping and candidate gene sequence analysis to harbour different mutations in the transferrin receptor gene (TfR) that led to embryonic lethality in their homozygous state. These mutations were clustered in the sequence encoding the domain involved in receptor homodimerisation, providing, for the first time, in vivo functional correlations of the previous structural analyses. The RBC3 line was also mapped to the interval containing the TfR gene, although no mutations were present in the TfR coding region or splice donor/acceptor sites in this line, raising the possibility of a regulatory sequence mutation, which we are investigating. The RBC2 line was mapped to chromosome 8, and found to contain a splice acceptor mutation in the ankyrin gene. This mutation results in a 22 bp deletion with a resultant frame shift in the regulatory domain. Mice homozygous for this mutation are born jaundiced with massive splenomegaly and a blood film consistent with severe spherocytosis, and die within 6 weeks of progressive anemia. As such, this line represents a new mouse model of severe hereditary spherocytosis. The final line, RBC6 displays a profound hypochromic, microcytic anemia in the homozygous state at birth, with apparent normality of all other organ systems. The mutation has been mapped to a chromosomal interval containing only a few genes, none of which have been previously linked to red cell production or differentiation, and therefore represents a novel erythropoietic gene/allele.

Binding of the stage selector protein (SSP) to the stage selector element (SSE) in the human gamma-globin promoter contributes to the preferential expression of the gamma-gene in fetal erythroid cells. The SSP contains the transcription factor CP2 and an erythroid-specific partner, NF-E4. The NF-E4 gene encodes a 22-kDa polypeptide employing a non-AUG initiation codon. Antisera specific to NF-E4 detects this species and an additional 14 kDa protein, which initiates from an internal methionine. Enforced expression of p14 NF-E4 in the K562 fetal/erythroid cell line, and in primary erythroid cord blood progenitors, results in repression of gamma-gene expression. Biochemical studies reveal that p14 NF-E4 interacts with CP2, resulting in diminished association of CP2 with the SSE in chromatin immunoprecipitation assays. p45 NF-E2 recruitment to the gamma-promoter is also lost, resulting in a reduction in RNA polymerase II and TBP binding and a fall in promoter transcriptional activity. This effect is specific, as enforced expression of a mutant form of p14 NF-E4, which fails to interact with CP2, also fails to repress gamma-gene expression in K562 cells. These findings provide one potential mechanism that could contribute to the autonomous silencing of the human gamma-genes in adult erythroid cells.

The Drosophila cuticle is essential for maintaining the surface barrier defenses of the fly. Integral to cuticle resilience is the transcription factor grainy head, which regulates production of the enzyme required for covalent cross-linking of the cuticular structural components. We report that formation and maintenance of the epidermal barrier in mice are dependent on a mammalian homolog of grainy head, Grainy head-like 3. Mice lacking this factor display defective skin barrier function and deficient wound repair, accompanied by reduced expression of transglutaminase 1, the key enzyme involved in cross-linking the structural components of the superficial epidermis. These findings suggest that the functional mechanisms involving protein cross-linking that maintain the epidermal barrier and induce tissue repair are conserved across 700 million years of evolution.

Prospective magnetic resonance imaging (MRI), magnetic resonance angiography (MRA), neuropsychological testing and neurological examinations were performed to determine the long-term effect of successful haematopoietic stem cell transplantation on the neurological status of nine children with sickle cell disease. A scoring system for severity of brain parenchymal and vascular lesions was developed and applied. Neurological examinations and neuropsychometric tests were stable, but MRI and MRA studies were not. Transient changes occurred early in two patients. Persistent changes occurred in five. Parenchymal lesions occurred in zero of two patients without prior lacunae or infarcts and in all seven with prior lacunae or infarcts (P = 0.0278).

Hematopoietic stem cell transplantation has been shown to be curative for approximately 83% of symptomatic children with sickle cell disease who have undergone the procedure. Despite these encouraging results, only 15% of children with symptoms that might merit consideration for transplantation have an available, unaffected HLA-matched sibling donor, severely limiting this therapeutic option. To address this problem, we developed a protocol for children with SCD and stroke using reduced-intensity conditioning and CD34-selected peripheral blood stem cells from haploidentical parental donors. We now report our preliminary experience using this approach in three children with SCD and stroke. After a chemotherapy-only conditioning regimen of fludarabine 150–200 mg/m2, thiotepa 10 mg/kg, i.v. busulfan targeted to a steady state concentration of 900 ng/ml, and OKT3, patients received an average of 27.2 x 106 CD34+cells/kg and 1.1 x 104 CD3+ cells/kg. Two patients required additional immunosuppression with methylprednisolone and OKT3 followed by a CD34 boost after graft rejection. One of these two had durable long-term engraftment, while one had a second rejection. Two of three patients have durable donor engraftment 20 and 24 months after transplantation, respectively. Donor T-cell chimerism evolved from predominantly host-derived to donor-derived over a number of months. One patient developed grade I acute GVHD and none developed chronic GVHD. Two engrafted patients have had no further SCD events. Both have recovery of immune function with normal CD4+ T-cell counts and normal thymic function. This preliminary experience demonstrates the feasibility of using mismatched parental donors for children with sickle cell disease. Future studies will focus on achieving reliable donor engraftment through additional graft manipulation strategies.

Morphogen-dependent epidermal-specific transacting factors have not been defined in vertebrates. We demonstrate that a member of the grainyhead transcription factor family, Grainyhead-like 1 (XGrhl1) is essential for ectodermal ontogeny in Xenopus laevis. Expression of this factor is restricted to epidermal cells. Moreover, XGrhl1 is regulated by the BMP4 signaling cascade. Disruption of XGrhl1 activity in vivo results in a severe defect in terminal epidermal differentiation, with inhibition of XK81A1 epidermal keratin gene expression, a key target of BMP4 signaling. Furthermore, transcription of the XK81A1 gene is modulated directly by binding of XGRHL1 to a promoter-localized binding motif that is essential for high-level expression. These results establish a novel developmental role for XGrhl1 as a crucial tissue-specific regulator of vertebrate epidermal differentiation.