Unaffected Donors Research Articles

Gene Therapy for Fanconi Anemia in Seattle: Clinical Experience and Next Steps

One hallmark of the rare, monogenic disorder called Fanconi anemia (FA) is an accelerated decline in hematopoietic stem cells (HSCs) leading to bone marrow (BM) failure. Long-term treatment requires successful bone marrow transplant (BMT) from an unaffected donor. However, BMT success is limited if the donor is not a matched sibling and ~70% of FA patients lack such donors. Gene therapy could be an alternative, correcting the genetic defect in the patient’s own HSCs, and negating the need for a BMT donor. Based on lessons learned in previous FA gene therapy studies, we developed an optimized protocol for lentivirus (LV)-mediated FANCA gene transfer into HSCs from FA-A patients. This phase I clinical trial incorporates vector recommendations from the International FA Gene Therapy Working Group. Two patients have been treated on this trial to date (National Clinical Trials Registry ID: NCT01331018). This protocol harvests BM to collect unmanipulated HSC and does not include conditioning prior to cell infusion. Patient 1 is a 22-year old male with confirmed FA-A resulting from a splice variant in exon 22 of the FANCA gene (c. 1827-1 G>A). Baseline ANC averaged 0.5-1.0 K/mcL and baseline platelet counts averaged 40 K/mcL. A total of 3.2 x 107 CD34+ cells were present in 1.1L of BM, but only 9.4 x 106 total CD34+ cells were successfully isolated by magnetic bead separation, due to low level CD34 expression. LV transduction at 10 infectious units (IU)/cell resulted in a vector copy number (VCN) of 0.33 per cell and 18.4% of colony-forming cells transduced. Patient 2 is a 10-year old male with confirmed FA-A resulting from gross deletion of exons 6-31 of the FANCA gene. Baseline ANC and platelets declined over a 4.5-year interval prior to gene therapy and were 0.67 K/mcL and 82 K/mcL, respectively, in the 6 months prior to treatment. A total of 400mL of BM was collected, containing a total of 30.6 x 106 CD34+ cells. To avoid excessive CD34+ cell loss, the CD34+ cell magnetic bead purification step was omitted and the entire red blood cell depleted BM product was subjected to LV transduction at 10 IU/cell. We observed a VCN of 1.83 per cell and 43% of colony-forming cells transduced, suggesting more efficient transduction of the mixed cell population. Both patients tolerated the harvest and infusion procedures but displayed low and declining levels of transduced cells in peripheral blood after infusion. For future subjects, use of pre-infusion conditioning may be required to achieve long-term engraftment in vivo. Interestingly, both patients have maintained stable blood cell counts since gene therapy. These data demonstrate that LV gene therapy in FA patients is safe and suggest that avoidance of direct CD34 selection is advantageous for transduction and gene transfer. However, one complicating factor is the volume of concentrated LV vector required to transduce the non-purified cell product infused in Patient 2. To address these barriers, we developed a modified clinical protocol which utilizes depletion of mature cell lineages including CD3+, CD14+, CD16+ and CD19+ cells. Using healthy donor bone marrow we demonstrate that this protocol efficiently depletes >85% of cells expressing each lineage marker, reducing the volume of LV vector required for gene transfer by 60-70%. Most importantly, we demonstrate that this protocol preserves >90% of CD34+ cells present in the starting bone marrow product, and that these cells are efficiently transduced and capable of engrafting in a xenotransplant model. This protocol is currently being implemented for subjects in the ongoing phase I trial. DisclosuresAdair:Rocket Pharmaceuticals: Consultancy, Equity Ownership. Kiem:Rocket Pharmaceuticals: Consultancy, Equity Ownership, Research Funding.

APP Processing in Human Pluripotent Stem Cell-Derived Neurons Is Resistant to NSAID-Based γ-Secretase Modulation

SummaryIncreasing evidence suggests that elevated Aβ42 fractions in the brain cause Alzheimer’s disease (AD). Although γ-secretase modulators (GSMs), including a set of nonsteroidal anti-inflammatory drugs (NSAIDs), were found to lower Aβ42 in various model systems, NSAID-based GSMs proved to be surprisingly inefficient in human clinical trials. Reasoning that the nonhuman and nonneuronal cells typically used in pharmaceutical compound validation might not adequately reflect the drug responses of human neurons, we used human pluripotent stem cell-derived neurons from AD patients and unaffected donors to explore the efficacy of NSAID-based γ-secretase modulation. We found that pharmaceutically relevant concentrations of these GSMs that are clearly efficacious in conventional nonneuronal cell models fail to elicit any effect on Aβ42/Aß40 ratios in human neurons. Our work reveals resistance of human neurons to NSAID-based γ-secretase modulation, highlighting the need to validate compound efficacy directly in the human cell type affected by the respective disease.

S38 TGF-Beta1 Negatively Regulates BMP4 Signalling in Human Pulmonary Artery Smooth Muscle Cells Via A Smad3-Dependent Mechanism

IntroductionBMP4 signals via the Smad pathway to induce the expression of the ID dominant-negative basic helix-loop-helix transcription factors (ID1–4) that regulate cell differentiation. We have shown that ID induction is...

Whole-Exome Capture and Sequencing Identifies HEATR2 Mutation as a Cause of Primary Ciliary Dyskinesia

Motile cilia are essential components of the mucociliary escalator and are central to respiratory-tract host defenses. Abnormalities in these evolutionarily conserved organelles cause primary ciliary dyskinesia (PCD). Despite recent strides characterizing the ciliome and sensory ciliopathies through exploration of the phenotype-genotype associations in model organisms, the genetic bases of most cases of PCD remain elusive. We identified nine related subjects with PCD from geographically dispersed Amish communities and performed exome sequencing of two affected individuals and their unaffected parents. A single autosomal-recessive nonsynonymous missense mutation was identified in HEATR2, an uncharacterized gene that belongs to a family not previously associated with ciliary assembly or function. Airway epithelial cells isolated from PCD-affected individuals had markedly reduced HEATR2 levels, absent dynein arms, and loss of ciliary beating. MicroRNA-mediated silencing of the orthologous gene in Chlamydomonas reinhardtii resulted in absent outer dynein arms, reduced flagellar beat frequency, and decreased cell velocity. These findings were recapitulated by small hairpin RNA-mediated knockdown of HEATR2 in airway epithelial cells from unaffected donors. Moreover, immunohistochemistry studies in human airway epithelial cells showed that HEATR2 was localized to the cytoplasm and not in cilia, which suggests a role in either dynein arm transport or assembly. The identification of HEATR2 contributes to the growing number of genes associated with PCD identified in both individuals and model organisms and shows that exome sequencing in family studies facilitates the discovery of novel disease-causing gene mutations.

A unique library of myogenic cells from facioscapulohumeral muscular dystrophy subjects and unaffected relatives: family, disease and cell function

To explore possible mechanisms of pathology in facioscapulohumeral muscular dystrophy (FSHD), we generated a novel library of myogenic cells composed of paired cultures derived from FSHD subjects and unaffected first-degree relatives. We prepared cells from biopsies of both biceps and deltoid muscles obtained from each of 10 FSHD and 9 unaffected donors. We used this new collection to determine how family background and disease affected patterns of growth and differentiation, expression of a panel of candidate, and muscle-specific genes, and responses to exogenous stressors. We found that FSHD and unaffected cells had, on average, indistinguishable patterns of differentiation, gene expression, and dose-response curves to staurosporine, paraquat, hydrogen peroxide, and glutathione depletion. Differentiated FSHD and unaffected cultures were both more sensitive to glutathione depletion than proliferating cultures, but showed similar responses to paraquat, staurosporine, and peroxide. For stress responses, the sample size was sufficient to detect a 10% change in effect at the observed variability with a power of >99%. In contrast, for each of these properties, we found significant differences among cells from different cohorts, and these differences were independent of disease status, gender, or muscle biopsied. Thus, though none of the properties we examined could be used to reliably distinguish between FSHD and unaffected cells, family of origin was an important contributor to gene-expression patterns and stressor responses in cultures of both FSHD and unaffected myogenic cells.

Abstract 3685: A strategy to identify therapeutic candidates for chronic lymphocytic leukemia from a library of FDA approved drugs

Abstract Chronic lymphocytic leukemia (CLL) is an adult lymphoid malignancy with a variable clinical course. There is considerable interest in the identification of new treatments, as most current approaches are not curative. While most patients respond to initial chemotherapy, relapsed disease is often resistant to the drugs commonly used in CLL and are left without limited therapeutic options. In this study, we used a luminescent cell viability assay based on ATP levels (CellTiter-Glo, Promega) to find compounds that were potent and efficacious in killing CLL cells. We employed an in-house process of quantitative high throughput screening (qHTS) to assess 8-9 concentrations of each member of a 2,816 compound library (including FDA-approved drugs and those known to be bio-active from commercial suppliers). Using qHTS we generated potency values on each compound in lymphocytes donated from each of six individuals with CLL and five unaffected individuals. We found 102 compounds efficacious against cells from all six individuals with CLL (“consensus” drugs) with seven of these showing no efficacy on lymphocytes from a majority of unaffected donors, suggesting some degree of specificity for the leukemic cells. Furthermore, to determine if we could save time and cost we screened the same library using CLL cells pooled from these individuals. We found that over 90% of the 102 drugs identified as efficacious on cells from individuals were also efficacious in the pooled experiment. Importantly, a near perfect correlation was observed in potency values between the single and pooled studies. The results of this “pooling” approach suggests it is rationale to apply pooling and qHTS when screening CLL cells against much larger collections (>300,000 unapproved compounds) where novel compounds could be identified as starting points for drug discovery and development. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3685.

Donor Dominance Cures CHILD Nevus

Background: Congenital hemidysplasia with ichthyosiform nevus and limb defects (MIM 308050, CHILD) syndrome is an X-linked dominant, male-lethal, multisystem birth defect. Patients suffer from an inflammatory nevus that covers large areas, predominantly of one side of the body, with a sharp midline demarcation. Treatment of CHILD nevus is notoriously difficult. Objective: The aim of this study was to develop a novel surgical approach for this disorder. Methods: In 2 patients, the CHILD nevus was dermabraded, and the area was covered with split skin grafts obtained from a contralateral unaffected donor region. In a third patient, papillomatous, strawberry-like lesions on fingers and toes were excised, and the defects were covered with full-thickness grafts obtained from the unaffected left, gluteal area. Results: Highly satisfying functional and cosmetic results were documented during a follow-up period ranging from 3 to 8 years. Conclusion: The favorable outcome, superior to that obtained by simple dermabrasion or extensive plastic surgery, can best be explained by the donor dominance of the grafted skin samples that carried, in all or most cells, the mutant X chromosome in an inactivated form.

The Iron Carrier Transferrin Is Upregulated in Retinas from Patients with Age-Related Macular Degeneration

Iron can cause oxidative stress, and elevated iron levels have been associated with several neurodegenerative diseases including age-related macular degeneration (AMD). Transferrin, an iron transport protein, is expressed at high levels in the retina. The purpose of this study was to assess transferrin involvement in AMD by determining the expression profile of transferrin in retinas with AMD compared with retinas without evidence of disease. Postmortem retinas were obtained from AMD and non-AMD eyes. Expression of transferrin was assessed in a microarray dataset from 33 retinas of unaffected donors and 12 retinas of patients with AMD (six with neovascular AMD and six with non-neovascular AMD). Quantitative real-time RT-PCR (QPCR) was used to confirm the microarray results. Transferrin protein expression was assessed by semiquantitative Western blot analysis and immunohistochemistry. In comparison to unaffected retinas, mean transferrin mRNA levels, as measured by microarray analysis were elevated 3.5- and 2.1-fold in non-neovascular and neovascular AMD retinas, respectively. Semiquantitative Western blot analysis demonstrated a 2.1-fold increase in transferrin protein in AMD eyes. Immunohistochemistry showed more intense and widespread transferrin label in AMD maculas, particularly in large drusen, Müller cells, and photoreceptors. These data demonstrate that transferrin expression is increased in the retinas of patients with AMD relative to those of healthy control patients of comparable age. Along with previous studies that have demonstrated elevated iron levels in AMD retinas, early onset drusen formation in a patient with retinal iron overload resulting from aceruloplasminemia, and retinal degeneration with some features of macular degeneration in the iron-overloaded retinas of ceruloplasmin/hephestin knockout mice, the present study suggests that altered iron homeostasis is associated with AMD.

Graves’ disease following unrelated umbilical cord blood transplantation in pediatric patients

Graves’ disease (GD) is the most prevalent autoimmune disease in the United States with a peak incidence in the fifth to sixth decades of life and a female to male predominance of ∼10:1. In recipients of allogeneic bone marrow and peripheral blood stem cell transplants, GD recurs in previously affected recipients, occurs in unaffected recipients by adoptive transfer of autoimmune thyroiditis from an affected donor, and occurs less frequently in unaffected recipients transplanted with unaffected donors.

Decreased Thickness and Integrity of the Macular Elastic Layer of Bruch's Membrane Correspond to the Distribution of Lesions Associated with Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a leading cause of blindness in the elderly. In its severest form, choroidal neovessels breach the macular Bruch's membrane, an extracellular matrix compartment comprised of elastin and collagen laminae, and grow into the retina. We sought to determine whether structural properties of the elastic lamina (EL) correspond to the region of the macula that is predilected toward degeneration in AMD. Morphometric assessment of the macular and extramacular regions of 121 human donor eyes, with and without AMD, revealed a statistically significant difference in both the integrity (P < 0.0001) and thickness (P < 0.0001) of the EL between the macular and extramacular regions in donors of all ages. The EL was three to six times thinner and two to five times less abundant in the macula than in the periphery. The integrity of the macular EL was significantly lower in donors with early-stage AMD (P = 0.028), active choroidal neovascularization (P = 0.020), and disciform scars (P = 0.003), as compared to unaffected, age-matched controls. EL thickness was significantly lower only in individuals with disciform scars (P = 0.008). The largest gaps in macular EL integrity were significantly larger in all categories of AMD (each P < 0.0001), as compared to controls. EL integrity, thickness, and gap length in donors with geographic atrophy did not differ from those of controls. These structural properties of the macular EL correspond spatially to the distribution of macular lesions associated with AMD and may help to explain why the macula is more susceptible to degenerative events that occur in this disease.

Successful umbilical cord blood transplantation for Fanconi anemia using preimplantation genetic diagnosis for HLA‐matched donor

Fanconi anemia is a rare autosomal recessive disease characterized by bone marrow failure, developmental anomalies, and a high incidence of myelodysplasia and acute myeloid leukemia. Stem cell transplantation is the only curative treatment. In the absence of matched- sibling donor, an alternative mismatched family or matched unrelated donor can be used, but the results are inferior to the matched-sibling transplant and carry a high risk of morbidity and mortality. Preimplantation genetic diagnosis (PGD) has been increasingly used in recent years for mutation analysis for many genetic disorders and results in the birth of healthy children, saving the need for the termination of pregnancy of an affected embryo. The use of PGD for combined analysis of mutation and HLA-matching was reported for the first time in 2001. This enables the birth of an unaffected child who can serve as a donor for an affected sibling in need for stem cell transplantation. We report successful cord blood transplantation for a Fanconi anemia patient from his HLA-matched sibling, born after PGD that included mutation analysis for Fanconi anemia and HLA typing. PGD can provide an unaffected donor for a sibling affected by genetic disease in the absence of a compatible related donor.

A cellular model for Friedreich Ataxia reveals small-molecule glutathione peroxidase mimetics as novel treatment strategy.

Friedreich Ataxia (FRDA), the most prevalent of the inherited ataxias, is a multi-systemic disease with loss of sensory neurons and life-threatening hypertrophic cardiomyopathy as its most severe manifestations. Reduced levels of the mitochondrial protein frataxin lead to cell-damaging oxidative stress and consequently FRDA is considered as a model for more common neurodegenerative disorders in which reactive radicals and oxidative stress are involved. We have developed a cellular assay system that discriminates between fibroblasts from FRDA patients and unaffected donors on the basis of their sensitivity to pharmacological inhibition of de novo synthesis of glutathione. With this assay we observed that supplementation with selenium effectively improved the viability of FRDA fibroblasts, indicating that basal selenium concentrations are not sufficient to allow an adequate increase in the activity of certain detoxification enzymes (such as GPX). Furthermore, we characterized potential drug candidates and found that idebenone, a mitochondrially localized antioxidant that ameliorates cardiomyopathy in FRDA patients, as well as other lipophilic antioxidants protected FRDA cells from cell death. Our results also demonstrate for the first time that small-molecule GPX mimetics have potential as a novel treatment strategy for Friedreich Ataxia and presumably also for other neurodegenerative diseases with mitochondrial impairment.

Monosomy 6 in human cultured fibroblast-like cells after long-term stimulation with acidic fibroblast growth factor (FGF1).

Long-term exposure to fibroblast growth factor type 1 (FGF1) of fibroblast-like cells derived from neurofibromas of patients with neurofibromatosis type 1, from angiofibromas of patients with tuberous sclerosis, and from foreskin of unaffected donors resulted in the outgrowth of monosomy 6 in 7 out of 14 cell lines examined. After their initial detection by cytogenetic analysis, the proportion of cells which had lost one chromosome 6 was monitored by FISH using a-satellite probes specific for chromosome 6 and 7, and by PCR analysis of polymorphic microsatellite markers. Monosomy 6 exceeding baseline levels developed only in cultures exposed to FGF 1, and the emergence of monosomic cells could not be correlated with a given donor's genotype. During serial culture, the proportion of monosomic cells increased to over 90% in 5 of the 7 affected strains. A conspicuous change of cellular morphology from spindle-shaped to more epithelial-type cells was noted in monosomic cultures, even though none of them converted to a permanent cell line during the observation period. We conclude that long-term exposure of human fibroblast-like cell strains to FGF1 results in the emergence of monosomy 6 in 50% of the cultures so treated. A selective advantage for such monosomic cells is the most likely explanation for their steady increase during serial culture.

Ultrastructure of lymphocytes from patients with paracoccidioidomycosis in the lymphocyte transformation test by phytohemagglutinin.

The morphology and ultrastructure of peripheral blood lymphocytes from patients with paracoccidioidomycosis (PCM) and from unaffected individuals (controls) were studied before and after Ficoll-Hypaque separation and at the end of culture, stimulated with phytohemagglutinin. Patient lymphocytes were cultured in medium with autologous plasma (from the patient himself) and with homologous plasma (from an unaffected donor), while donor lymphocytes were cultured in medium with plasma from a patient or with plasma from the donor himself. The Ficoll-Hypaque mixture caused no morphological or ultrastructural changes in the lymphocytes of patients or of unaffected donors. Patient lymphocytes cultured in medium with autologous plasma showed different degrees of cytoplasmic and nuclear alterations, such as organelle dissolution, vacuoles, amorphous masses, deformed nuclei, and absence of nucleoli. Lymphocytes from control individuals cultured in patient plasma also showed ultrastructural alterations, though they were less marked, and a reduced number of 'blasts'. Patient lymphocytes cultured in medium with homologous plasma (from a control individual) showed a morphology similar to that of lymphocytes from control individuals cultured in medium with their own plasma, although with a lower number of 'blasts'. On the basis of the results obtained using that methodology, we draw the following conclusions: separation by Ficoll-Hypaque does not seem to alter the ultrastructure of patient or donor lymphocytes; patients with diffuse PCM and more markedly impaired general condition can exhibit lymphocytes with morphological and ultrastructural alterations capable of affecting their biological systems and functionality.(ABSTRACT TRUNCATED AT 250 WORDS)