Longitudinal neurocognitive effects of nonmyeloablative hematopoietic stem cell transplant among older adolescents and adults with sickle cell disease: A description and comparison with sibling donors

Sickle cell disease (SCD) is associated with increased risk of neurocognitive deficits. However, whether functioning changes following nonmyeloablative hematopoietic stem cell transplant (HSCT) remains unclear. This study aimed to examine changes in neuropsychological functioning pre- to post-transplant among patients with SCD and compare patients and siblings. Adults with SCD (n = 47; Mage = 31.8 ± 8.9) and their sibling stem cell donors (n = 22; Mage = 30.5± 9.2) enrolled on a nonmyeloablative HCST protocol completed cognitive and patient-reported outcome assessments at baseline and 12 months post-transplant. Path analyses were used to assess associations between pre-transplant variables and sibling/patient group status and post-transplant function. Mean patient cognitive scores were average at both timepoints. Patient processing speed and somatic complaints improved from baseline to follow-up. Baseline performance predicted follow-up performance across cognitive variables; patient/sibling status predicted follow-up performance on some processing speed measures. Results suggest that patients with SCD demonstrate slower processing speed than siblings. Processing speed increased pre- to post-HSCT among patients and siblings, and on some measures patients demonstrated greater improvement. Thus, HSCT may improve processing speed in patients, although further confirmation is needed. Findings provide promising evidence that neurocognitive functioning remains stable without detrimental effects from pre- to 12-months post nonmyeloablative HSCT in individuals with SCD.

Abstract TP178: Cerebral Infarction after Hematopoietic Stem Cell Transplantation (HSCT) in Adult Patients with Sickle Cell Disease

Introduction: Symptomatic and silent cerebral infarcts (SCIs) are common in children and adults with sickle cell disease (SCD). SCIs are associated with cognitive performance and risk of future symptomatic stroke. The incidence of overt stroke and SCI post HSCT is low in children, but there is limited information in adults. We sought to determine the impact of HSCT on the rate of new symptomatic and silent cerebral infarcts in adults with SCD.

Methods: The study population included patients with SCD (HbSS, HbSC, and HbS/beta-thalassemia) that were enrolled in NIH studies (14-H-0077, 09-H-0225) and underwent HSCT from 2004-19 and received pre- and post-transplant MRI studies. MRI FLAIR, T1, and T2 images were reviewed by two independent readers and scored for presence of prior ischemic stroke and silent cerebral infarct (≥ 3mm on T2 or FLAIR images in 2 imaging planes). Changes in SCIs and ischemic strokes were compared before and after transplantation.

Results: Eighty-four patients were included in the study, mean age 32.3 yrs. (range 10-65 yrs.) and 57% male. Median follow-up period was 3.3 yrs. (range: 6 months -17 yrs.) for a total of 412 patient-years. Overall, 60% had evidence of SCI and or prior ischemic stroke at transplant; 54% (45/84) with SCI and 23% with imaging evidence of a prior stroke. During the follow-up period, 13% (11/84) patients developed new ischemic injury, two patients developed a new stroke and nine patients developed new SCIs. The post-HSCT incidence rate of new stroke was 0.49 events/100 patient-years, and SCIs was 2.2 events/100 patient-years. Patients who progressed compared to those who did not were older at transplant (36.1 yrs. vs. 31.2 yrs.; p=0.09), had a prior history of stroke (27% vs. 22%, p=0.71), had a prior history of SCI (64% vs. 52%, p=0.47), and a prior history of stenotic vasculopathy (18% vs. 14%, p= 0.65).

Conclusions: The incidence of new ischemic events after HSCT for SCD in adults is low. Our rates are comparable to incidence rates reported in children with SCD after HSCT. While rates of progression were higher in patients with prior stroke, SCI, and vasculopathy, we did not find a significant difference between groups.

Acute Myeloid Leukemia Case after Gene Therapy for Sickle Cell Disease

Gene therapy with LentiGlobin for sickle cell disease (bb1111, lovotibeglogene autotemcel) consists of autologous transplantation of a patient's hematopoietic stem cells transduced with the BB305 lentiviral vector that encodes the β^A-T87Q-globin gene. Acute myeloid leukemia developed in a woman approximately 5.5 years after she had received LentiGlobin for sickle cell disease as part of the initial cohort (Group A) of the HGB-206 study. An analysis of peripheral-blood samples revealed that blast cells contained a BB305 lentiviral vector insertion site. The results of an investigation of causality indicated that the leukemia was unlikely to be related to vector insertion, given the location of the insertion site, the very low transgene expression in blast cells, and the lack of an effect on expression of surrounding genes. Several somatic mutations predisposing to acute myeloid leukemia were present after diagnosis, which suggests that patients with sickle cell disease are at increased risk for hematologic malignant conditions after transplantation, most likely because of a combination of risks associated with underlying sickle cell disease, transplantation procedure, and inadequate disease control after treatment. (Funded by Bluebird Bio.).

Alemtuzumab clearance, lymphocyte count, and T-cell chimerism after hematopoietic stem cell transplant in sickle cell disease

STUDY OBJECTIVE

Alemtuzumab is a monoclonal antibody that targets the cell surface antigen CD52 on lymphocytes. Although it is used for the treatment of hematologic malignancies, such as chronic lymphocytic leukemia, and incorporated into many hematopoietic stem cell transplant (HSCT) conditioning regimens, few studies have evaluated the pharmacology of alemtuzumab in adult patients with sickle cell disease (SCD). We therefore examined the pharmacokinetics (PK) and pharmacodynamics (PD) of alemtuzumab in adults with SCD who received a matched related donor HSCT to determine if the clearance of alemtuzumab affects transplant outcomes.

DESIGN

PK and PD analysis of patient data from a single-center clinical trial.

SETTING

Clinical research center.

PATIENTS

Twenty-two adult patients with SCD who received one of two nonmyeloablative allogeneic HSCT regimens: alemtuzumab and total body irradiation (Alem-TBI) or pentostatin, cyclophosphamide, alemtuzumab, and total body irradiation (Pento-Cy-Alem-TBI).

MEASUREMENTS AND MAIN RESULTS

Alemtuzumab serum concentrations, absolute lymphocyte counts, T-cell (CD3), and myeloid (CD14/15) chimerism were collected at distinct time points and analyzed. A semi-mechanistic PK population model was built to understand inter-individual differences in pharmacology. Alemtuzumab was detectable up to 28 days post-HSCT. The mean alemtuzumab level 7 days after transplant for patients on Alem-TBI was 818 ng/ml, significantly lower than the mean level of 1502 ng/ml for patients on Pento-Cy-Alem-TBI (p < 0.001), but this difference decreased as time progressed. The clearance of alemtuzumab was linear, and the half-life was longer in the Pento-Cy-Alem-TBI group (average half-life = 61.1 h) compared to the Alem-TBI group (average half-life = 44.1 h) (p < 0.001). The CD3 chimerism at 2 and 4 months after transplant positively correlated with alemtuzumab levels collected on day 14 after transplant (R²  = 0.40 and p = 0.004 at 2 months, R²  = 0.36 and p = 0.005 at 4 months), but this significance was lost by 6 months after HSCT. No correlation was seen between alemtuzumab levels and CD14/15 chimerism.

CONCLUSION

Between 2 and 4 months after transplant, higher alemtuzumab levels measured 14 days after transplant correlated with patients having better engraftment, suggesting more lymphodepletion may be needed to reduce graft failure in these two non-myeloablative matched related donor HSCT regimens.

Development of β-globin gene correction in human hematopoietic stem cells as a potential durable treatment for sickle cell disease

Sickle cell disease (SCD) is the most common serious monogenic disease with 300,000 births annually worldwide. SCD is an autosomal recessive disease resulting from a single point mutation in codon six of the β-globin gene (HBB). Ex vivo β-globin gene correction in autologous patient-derived hematopoietic stem and progenitor cells (HSPCs) may potentially provide a curative treatment for SCD. We previously developed a CRISPR-Cas9 gene targeting strategy that uses high-fidelity Cas9 precomplexed with chemically modified guide RNAs to induce recombinant adeno-associated virus serotype 6 (rAAV6)-mediated HBB gene correction of the SCD-causing mutation in HSPCs. Here, we demonstrate the preclinical feasibility, efficacy, and toxicology of HBB gene correction in plerixafor-mobilized CD34⁺ cells from healthy and SCD patient donors (gcHBB-SCD). We achieved up to 60% HBB allelic correction in clinical-scale gcHBB-SCD manufacturing. After transplant into immunodeficient NSG mice, 20% gene correction was achieved with multilineage engraftment. The long-term safety, tumorigenicity, and toxicology study demonstrated no evidence of abnormal hematopoiesis, genotoxicity, or tumorigenicity from the engrafted gcHBB-SCD drug product. Together, these preclinical data support the safety, efficacy, and reproducibility of this gene correction strategy for initiation of a phase 1/2 clinical trial in patients with SCD.

Sleep disturbance in adults with sickle cell disease: relationships with executive and psychological functioning

Sleep disturbance is common among children with sickle cell disease (SCD) and is related to neurocognitive difficulties. However, research on sleep disturbances and related variables among adults with SCD is extremely limited. The present study examined the relationship between sleep, executive functioning, and emotional functioning among 62 adults (29 females; M age = 32 years, SD = 7.79) with SCD preparing to undergo a stem cell transplant. Participants were administered a neurocognitive evaluation that included objective and subjective measures of executive functioning, and they completed PROMIS self-report measures of anxiety, depression, and pain intensity. Results showed that about 17% of participants endorsed clinically significant sleep disruptions, while 16.1% and 8% endorsed clinically significant symptoms of anxiety and depression, respectively. Sleep disturbance in these adults was not significantly correlated with objective or subjective measures of executive functioning. Moreover, anxiety, but not depression, was a significant mediator between self-reported sleep difficulties and both objective and subjective measures of executive functioning while controlling for pain intensity. Future research on sleep interventions will be essential for ameliorating the effects of sleep disturbance on executive functioning and anxiety among adults with SCD.

Curative options for sickle cell disease: haploidentical stem cell transplantation or gene therapy?

Haematopoietic stem cell transplantation (HSCT) is curative in sickle cell disease (SCD); however, the lack of available matched donors makes this therapy out of reach for the majority of patients with SCD. Alternative donor sources such as haploidentical HSCT expand the donor pool to nearly all patients with SCD, with recent data showing high overall survival, limited toxicities, and effective reduction in acute and chronic graft-versus-host disease (GVHD). Simultaneously, multiple gene therapy strategies are entering clinical trials with preliminary data showing their success, theoretically offering all patients yet another curative strategy without the morbidity and mortality of GVHD. As improvements are made for alternative donors in the allogeneic setting and as data emerge from gene therapy trials, the optimal curative strategy for any individual patient with SCD will be determined by many critical factors including efficacy, transplant morbidity and mortality, safety, patient disease status and preference, cost and applicability. Haploidentical may be the preferred choice now based mostly on availability of data; however, gene therapy is closing the gap and may ultimately prove to be the better option. Progress in both strategies, however, makes cure more attainable for the individual with SCD.

Neurocognitive functioning in symptomatic adults with sickle cell disease: A description and comparison with unaffected siblings

Children and adults with sickle cell disease (SCD) are at risk for neuropsychological deficits; however, the neurocognitive functioning of adults with SCD and related comorbidities has not been widely reported in the literature. We examined specific cognitive domains in symptomatic adults with SCD and compared them with their unaffected siblings. We also examined relationships between cognitive scores, patient-reported outcomes (PROs), and medical/laboratory values. Thirty patient-sibling pairs (M patient age = 32.5 years, M sibling age = 32.1 years) completed evaluations as part of a medical clinical trial (NCT00061568). All patient and sibling neurocognitive test scores were within normal limits. Patients scored significantly lower (M = 91.0 ± 11.3) than their siblings (M = 100.6 ± 12.3; t = -3.5, p < .01) on the Wechsler Processing Speed Index. They also indicated more problems than siblings on an executive functioning questionnaire, although these differences were nonsignificant after accounting for depressive symptoms. Higher fetal hemoglobin and lower creatinine correlated with better scores on particular cognitive and PRO measures. In summary, our sample of adults with symptomatic SCD demonstrated worse processing speed and experience more executive challenges than their siblings, despite treatment with hydroxyurea. These relative weakness likely relate to disease processes but the specific physiological mechanism is unclear.

Rapamycin Corrects T Regulatory Cell Depletion and Improves Embryo Implantation and Live Birth Rates in a Murine Model

There are few treatments for patients with recurrent pregnancy loss (RPL) or recurrent implantation failure (RIF). Women with RPL and unexplained infertility have lower T regulatory cell (T_reg) expression when compared to fertile controls. A murine model has been developed with depletion of regulatory T cells (DEREG) after administration of diphtheria toxin (DT), resulting in smaller litter sizes, secondary to embryo implantation failure. Numerous murine studies have shown that adoptive transfer of CD4⁺CD25⁺FoxP3⁺ T_regs from donors improves litter sizes in DEREG mice with depleted T_regs. Our hypothesis is that DEREG mice treated with a single dose of DT will deplete T_regs and subsequently decrease litter sizes and that treatment with rapamycin (sirolimus; Pfizer) during the time of embryo implantation will increase T_regs and restore litter sizes nearly back to normal levels. Syngeneic mating of DEREG mice after depletion of T_regs resulted in smaller litter sizes and this defect was reversed when these DEREG mice were treated with rapamycin at the time of embryo implantation. The importance of T_regs at the time of embryo implantation has been well established and immunotherapy treatments, such as rapamycin (mammalian target of rapamycin inhibitor), may prove to be an effective treatment for patients with RPL, RIF, or unexplained infertility with low T_reg.

Stem cell transplantation in sickle cell disease: therapeutic potential and challenges faced

INTRODUCTION

Sickle cell disease (SCD) is the most common inherited hemoglobinopathy worldwide, and is a life-limiting disease with limited therapeutic options to reduce disease severity. Despite being a monogenic disorder, the clinical phenotypes of SCD are variable, with few reliable predictors of disease severity easily identifying patients where the benefits of curative therapy outweigh the risks. Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative option, though significant advances in gene therapy raise the promise for additional curative methods. Areas covered: Allogeneic transplantation in SCD has evolved and improved over the last two decades, now offering a standard of care curative option using a human leukocyte antigen (HLA)-matched sibling donor. Many of the seminal transplantation studies are reviewed here, demonstrating how initial failures and successes have influenced and led to current HSCT strategies. Such strategies aim to overcome setbacks and limitations, and focus on conditioning regimens, immune suppression methods, the use alternative donor sources, and gene therapy approaches. Expert commentary: SCD is a curable disease. Each dedicated effort to refine transplantation methods, expand the donor pool, and bring gene therapy models to fruition will make enormous impacts reducing disease burden and improving outcomes and quality of life for patients with SCD.

Relationship between Mixed Donor-Recipient Chimerism and Disease Recurrence after Hematopoietic Cell Transplantation for Sickle Cell Disease

Mixed donor chimerism after hematopoietic cell transplantation for sickle cell disease (SCD) can result in resolution of disease symptoms, but symptoms recur when donor chimerism is critically low. The relationship between chimerism, hemoglobin S (HbS) level, and symptomatic disease was correlated retrospectively in 95 patients who had chimerism reports available at day 100 and at 1 and 2 years after transplantation. Recurrent disease was defined as recurrence of vaso-occlusive crises, acute chest syndrome, stroke, and/or HbS levels > 50%. Thirty-five patients maintained full donor chimerism (myeloid or whole blood) through 2 years. Donor chimerism was less than 10% (defined as graft failure) in 13 patients during this period. Mixed chimerism was reported in the remaining 47 patients (range, 10% to 94%). The lowest documented donor chimerism without symptomatic disease was 26%. Of 12 surviving patients with recurrent disease, 2 had recurrence of symptoms before documented graft failure (donor chimerism of 11% and 17%, respectively). Three patients underwent second transplantation for graft failure. None received donor leukocyte infusion to maintain mixed chimerism or prevent graft failure. We conclude stable donor chimerism greater than 25% is associated with resolution of SCD-related symptoms, and HbS levels in transplant recipients should be interpreted in context of the sickle trait status of the donors.

β-Globin-Expressing Definitive Erythroid Progenitor Cells Generated from Embryonic and Induced Pluripotent Stem Cell-Derived Sacs

Human embryonic stem (ES) cells and induced pluripotent stem (iPS) cells represent a potential alternative source for red blood cell transfusion. However, when using traditional methods with embryoid bodies, ES cell-derived erythroid cells predominantly express embryonic type ɛ-globin, with lesser fetal type γ-globin and very little adult type β-globin. Furthermore, no β-globin expression is detected in iPS cell-derived erythroid cells. ES cell-derived sacs (ES sacs) have been recently used to generate functional platelets. Due to its unique structure, we hypothesized that ES sacs serve as hemangioblast-like progenitors capable to generate definitive erythroid cells that express β-globin. With our ES sac-derived erythroid differentiation protocol, we obtained ∼120 erythroid cells per single ES cell. Both primitive (ɛ-globin expressing) and definitive (γ- and β-globin expressing) erythroid cells were generated from not only ES cells but also iPS cells. Primitive erythropoiesis is gradually switched to definitive erythropoiesis during prolonged ES sac maturation, concurrent with the emergence of hematopoietic progenitor cells. Primitive and definitive erythroid progenitor cells were selected on the basis of glycophorin A or CD34 expression from cells within the ES sacs before erythroid differentiation. This selection and differentiation strategy represents an important step toward the development of in vitro erythroid cell production systems from pluripotent stem cells. Further optimization to improve expansion should be required for clinical application. Stem Cells 2016;34:1541-1552.

Dynamics of oligodendrocyte generation and myelination in the human brain

The myelination of axons by oligodendrocytes has been suggested to be modulated by experience, which could mediate neural plasticity by optimizing the performance of the circuitry. We have assessed the dynamics of oligodendrocyte generation and myelination in the human brain. The number of oligodendrocytes in the corpus callosum is established in childhood and remains stable after that. Analysis of the integration of nuclear bomb test-derived (14)C revealed that myelin is exchanged at a high rate, whereas the oligodendrocyte population in white matter is remarkably stable in humans, with an annual exchange of 1/300 oligodendrocytes. We conclude that oligodendrocyte turnover contributes minimally to myelin modulation in human white matter and that this instead may be carried out by mature oligodendrocytes, which may facilitate rapid neural plasticity.

Neurogenesis in the striatum of the adult human brain

In most mammals, neurons are added throughout life in the hippocampus and olfactory bulb. One area where neuroblasts that give rise to adult-born neurons are generated is the lateral ventricle wall of the brain. We show, using histological and carbon-14 dating approaches, that in adult humans new neurons integrate in the striatum, which is adjacent to this neurogenic niche. The neuronal turnover in the striatum appears restricted to interneurons, and postnatally generated striatal neurons are preferentially depleted in patients with Huntington's disease. Our findings demonstrate a unique pattern of neurogenesis in the adult human brain.

Addition of rapamycin to anti-CD3 antibody improves long-term glycaemia control in diabetic NOD mice

Aims/Hypothesis

Non-Fc-binding Anti CD3 antibody has proven successful in reverting diabetes in the non-obese diabetes mouse model of type 1 diabetes and limited efficacy has been observed in human clinical trials. We hypothesized that addition of rapamycin, an mTOR inhibitor capable of inducing operational tolerance in allogeneic bone marrow transplantation, would result in improved diabetes reversal rates and overall glycemia.

Methods

Seventy hyperglycemic non-obese diabetic mice were randomized to either a single injection of anti CD3 alone or a single injection of anti CD3 followed by 14 days of intra-peritoneal rapamycin. Mice were monitored for hyperglycemia and metabolic control.

Results

Mice treated with the combination of anti CD3 and rapamycin had similar rates of diabetes reversal compared to anti CD3 alone (25/35 vs. 22/35). Mice treated with anti CD3 plus rapamycin had a significant improvement in glycemia control as exhibited by lower blood glucose levels in response to an intra-peritoneal glucose challenge; average peak blood glucose levels 30 min post intra-peritoneal injection of 2 gr/kg glucose were 6.9 mmol/L in the anti CD3 plus rapamycin group vs. 10 mmo/L in the anti CD3 alone (P<0.05).

Conclusions/Interpretation

The addition of rapamycin to anti CD3 results in significant improvement in glycaemia control in diabetic NOD mice.

Nonmyeloablative conditioning employing busulfan and sirolimus permits donor-dominant stable chimerism in a murine model of haploidentical allogeneic stem cell transplantation (P2192)

Allogeneic stem cell transplant (SCT) is a potentially curative option for many hematologic diseases, yet donor availability remains a challenge, and haploidentical SCT is associated with a higher risk of rejection. We successfully translated a model based on total-body irradiation (TBI) with to humans; however, TBI involves toxicities and risk of malignant side-effects, and we hypothesize that busulfan may be a superior alternative in some settings. G-CSF-mobilized F1/J (C57BL/6-BALB/c hybrid) splenocytes were injected into C57BL/6 hosts who had received 10-30mg/kg IP busulfan the previous day. All recipients received 31 days of 3mg/kg IP sirolimus beginning the day before transplant. No GvHD was observed and counts recovered by week 8 in all groups. Mice conditioned with 30mg/kg busulfan displayed remarkably high donor chimerism (&gt;90%), which was significantly higher than 300cGy TBI-conditioned control mice (64-86%) across all timepoints. Mice receiving 30mg/kg or 20mg/kg busulfan maintained stable chimerism for over 18 months. Mice conditioned with 10mg/kg busulfan showed only transient chimerism through 4 weeks. Proliferation of CD4+ cells in response to donor increases with decreasing busulfan, and mice receiving 30mg/kg responded more strongly than mice receiving TBI. A memory effect was observed in mice that received 10mg/kg busulfan and lost their grafts. Notably, a slightly higher incidence of host-derived Tregs in mice was also observed after graft rejection.

Characterization of lymphocytes emerging early after nonmyeloablative conditioning and hematopoietic stem cell transplant supported with sirolimus (P2186)

Hematopoietic stem cell transplant is a curative option for patients with severe congenital anemias such as Sickle Cell Disease. Due to the higher transplant-related mortality associated with myeloablative conditioning and the reversal of the SCD phenotype achieved with as low as 11% stable donor chimerism, we developed a successful non-myeloablative regimen for patients with matched-sibling donors consisting of pre-transplant alemtuzumab, 300cGy TBI, and post-transplant sirolimus. However, mechanisms that promote tolerance in these patients remain unclear. We hypothesized that lymphocytes emerging early post-transplant would display a toleragenic phenotype. Samples were thawed from time points near day 60 or day 100 post-transplant. 17-parameter flow cytometry was performed, revealing dramatically high proportion of Tregs (6.3%-32.8%) and T-helper-17 (Th17) (8.2-21.2%) cells, elevated markers of proliferation, activation, and B cell maturity in engrafting patients. Using multiplex cytokine immunoassay, 67 analytes were measured, revealing high expression of IL-17A in the engrafting patients, MCP-1 in the rejecting patients, but little difference in Treg/Th1/Th2-associated cytokines. These unexpected observations have provided insight into reconstitution following nonmyeloablative conditioning and sirolimus-based immunosupporession and suggest targets for further investigation into both the long-term, stable mixed chimerism and the lack of GvHD observed in our patients.

A pilot study evaluating the safety and CD34+ cell mobilizing activity of escalating doses of plerixafor in healthy volunteers

This study evaluated the safety and CD34+ cell mobilizing activity of escalating doses of plerixafor in healthy volunteers. Three cohorts of six subjects received two different doses of plerixafor separated by at least 2 weeks to allow for adequate pharmacodynamic wash-out. The following dosing cohorts were evaluated: 0·24 and 0·32 mg/kg (Cohort 1); 0·32 and 0·40 mg/kg (Cohort 2); and 0·40 and 0·48 mg/kg (Cohort 3). Circulating CD34+ cells were measured 0, 2, 4, 6, 8, 10, 12, 14, 18 and 24 h after each dose. Blood colony-forming units were measured at baseline and 6 h after each dose. Common adverse events were diarrhoea, injection site erythema, perioral numbness, sinus tachycardia, headache, nausea, abdominal distention and injection site pain. No dose limiting toxicities occurred. When higher doses of plerixafor were administered, there was a trend towards higher peak CD34+ counts and CD34+ area under the curves, although these differences did not achieve statistical significance, perhaps due to intra-subject variability. Together, these data show that the higher doses of plerixafor evaluated in this study are reasonably safe and suggest that a larger study should be performed to definitively answer whether increased numbers of CD34+ cell are mobilized with higher doses of plerixafor.

Cardiomyogenesis in the adult human heart

RATIONALE

The ability of the human heart to regenerate large quantities of myocytes remains controversial, and the extent of myocyte renewal claimed by different laboratories varies from none to nearly 20% per year.

OBJECTIVE

To address this issue, we examined the percentage of myocytes, endothelial cells, and fibroblasts labeled by iododeoxyuridine in postmortem samples obtained from cancer patients who received the thymidine analog for therapeutic purposes. Additionally, the potential contribution of DNA repair, polyploidy, and cell fusion to the measurement of myocyte regeneration was determined.

METHODS AND RESULTS

The fraction of myocytes labeled by iododeoxyuridine ranged from 2.5% to 46%, and similar values were found in fibroblasts and endothelial cells. An average 22%, 20%, and 13% new myocytes, fibroblasts, and endothelial cells were generated per year, suggesting that the lifespan of these cells was approximately 4.5, 5, and 8 years, respectively. The newly formed cardiac cells showed a fully differentiated adult phenotype and did not express the senescence-associated protein p16(INK4a). Moreover, measurements by confocal microscopy and flow cytometry documented that the human heart is composed predominantly of myocytes with 2n diploid DNA content and that tetraploid and octaploid nuclei constitute only a small fraction of the parenchymal cell pool. Importantly, DNA repair, ploidy formation, and cell fusion were not implicated in the assessment of myocyte regeneration.

CONCLUSIONS

Our findings indicate that the human heart has a significant growth reserve and replaces its myocyte and nonmyocyte compartment several times during the course of life.

Glutaredoxin 5 deficiency causes sideroblastic anemia by specifically impairing heme biosynthesis and depleting cytosolic iron in human erythroblasts

Glutaredoxin 5 (GLRX5) deficiency has previously been identified as a cause of anemia in a zebrafish model and of sideroblastic anemia in a human patient. Here we report that GLRX5 is essential for iron-sulfur cluster biosynthesis and the maintenance of normal mitochondrial and cytosolic iron homeostasis in human cells. GLRX5, a mitochondrial protein that is highly expressed in erythroid cells, can homodimerize and assemble [2Fe-2S] in vitro. In GLRX5-deficient cells, [Fe-S] cluster biosynthesis was impaired, the iron-responsive element-binding (IRE-binding) activity of iron regulatory protein 1 (IRP1) was activated, and increased IRP2 levels, indicative of relative cytosolic iron depletion, were observed together with mitochondrial iron overload. Rescue of patient fibroblasts with the WT GLRX5 gene by transfection or viral transduction reversed a slow growth phenotype, reversed the mitochondrial iron overload, and increased aconitase activity. Decreased aminolevulinate delta, synthase 2 (ALAS2) levels attributable to IRP-mediated translational repression were observed in erythroid cells in which GLRX5 expression had been downregulated using siRNA along with marked reduction in ferrochelatase levels and increased ferroportin expression. Erythroblasts express both IRP-repressible ALAS2 and non-IRP-repressible ferroportin 1b. The unique combination of IRP targets likely accounts for the tissue-specific phenotype of human GLRX5 deficiency.

Over a thousand ambulatory hernia repairs in a primary care setting

INTRODUCTION

This paper outlines the development and feasibility of a dedicated ambulatory primary care hernia service and examines the outcomes achieved during the period 1 March 2005 to 31 December 2008.

PATIENTS AND METHODS

A prospective analysis of 1164 patients who underwent abdominal wall hernia repair at Probus Surgical Centre during the study period. The operations were carried out by two GPs with a special interest (GPwSI) and one retired surgeon. The techniques used were a Lichtenstein mesh repair or modified Shouldice repair for inguinal hernias and a primary sutured repair for ventral hernias. All procedures were performed as day-cases under local anaesthesia without sedation. All patients were reviewed routinely at 6 weeks. The primary outcomes of the study were recurrence and patient satisfaction levels, and complications such as infection, haematoma and chronic pain.

RESULTS

No patient required conversion to general anaesthesia. There were three (0.3%) recurrences. Complication rates were low and similar to those obtained in other specialist hernia units. More than 90% of patients were satisfied with the service and would recommend it to a friend.

CONCLUSIONS

Routine elective abdominal wall hernia repairs can be performed in a primary care setting, safely and with excellent outcomes.

Cerebrovascular disease associated with sickle cell pulmonary hypertension

In patients with sickle cell disease, anemia is a recognized risk factor for stroke, death, and the development of pulmonary hypertension. We have proposed that hemolytic anemia results in endothelial dysfunction and vascular instability and can ultimately lead to a proliferative vasculopathy leading to pulmonary hypertension. Consistent with this mechanism of disease, we now report a case series of six patients with obliterative central nervous system vasculopathy who also have pulmonary hypertension and high hemolytic rate. These patients, identified in the course of a prospective screening study for pulmonary hypertension, presented with neurological symptoms prompting neuroimaging studies. Compared to 164 other patients of similar age in the screened population, those with newly diagnosed or clinically active cerebrovascular disease have significantly lower hemoglobin levels and higher levels of lactate dehydrogenase. A review of the literature suggests that many clinical, epidemiological, and physiological features of the arteriopathy of pulmonary hypertension closely overlap with those of stroke in sickle cell disease, both known to involve proliferative vascular intimal and smooth muscle hypertrophy and thrombosis. These cases suggest that cerebrovascular disease and pulmonary hypertension in sickle cell disease share common mechanisms, in particular, reduced nitric oxide bioactivity associated with particularly high-grade hemolysis. Clinicians should suspect occult cerebrovascular disease in sickle cell patients with pulmonary hypertension.

Proteomic signature of myeloproliferation and neutrophilia: analysis of serum and plasma from healthy subjects given granulocyte colony-stimulating factor

OBJECTIVE

Proteomic analysis could improve our understanding of the mechanisms and consequences of myeloproliferation. Healthy subjects treated with granulocyte colony-stimulating factor (G-CSF) were used as a model of myeloproliferation.

METHODS

Levels of 80 soluble factors were measured by enzyme-linked immunosorbent assay before and after 5 days of G-CSF. Both serum and plasma levels were measured to generate a comprehensive profile and determine whether serum or plasma best portrays biological and physiological changes.

RESULTS

Comparison of samples collected prior to G-CSF demonstrated that 44 factors differed between serum and plasma. Concentrations of several growth factors and chemokines were greater in serum than in plasma, while the opposite was true for several interleukins. Following G-CSF serum levels of 14 factors and plasma levels of 15 factors changed. Eleven increased in both serum and plasma, including cell adhesion molecules (vascular cell adhesion molecule-1, E-selectin, and L-selectin), matrix metalloproteases (MMP-1, -8, and -13), cytokine receptors (tumor necrosis factor receptor 1 and 2, and interleukin-2 receptor), the acute phase reactant, serum amyloid A, and a growth factor, hepatocyte growth factor.

CONCLUSION

Some protein levels differ markedly in serum and plasma. Myeloproliferation is associated with changes in the levels of several proteases, adhesion molecules, and cytokines.

Nephrotic syndrome: an under-recognised immune-mediated complication of non-myeloablative allogeneic haematopoietic cell transplantation

Nephrotic syndrome (NS) is an extremely rare complication of myeloablative allogeneic haematopoietic cell transplantation (HCT) that usually occurs in association with chronic graft-versus-host disease (C-GVHD). We observed an unexpectedly high incidence of NS in a cohort of 163 consecutive patients undergoing non-myeloablative HCT from a related human leucocyte antigen-compatible donor. Seven patients developed NS at a median 318 d post-transplant (range 119-1203 d; cumulative incidence 6.1%). The median age at onset of NS was 46 years (range 33-59 years); three of the seven patients had no evidence of C-GVHD while four had accompanying limited C-GVHD. At diagnosis, median proteinuria was 16.5 g/24 h (range 3-24 g/24 h). Renal biopsy was performed in four cases and revealed membranous nephropathy. NS was not always associated with other symptoms of C-GVHD, and in contrast to previous reports, usually did not improve with the re-initiation of aggressive immunosuppression, resulting in progressive renal failure necessitating dialysis in three of seven cases. Membranous nephropathy resulting in NS is a previously unrecognised and clinically significant complication of non-myeloablative HCT.

Intracellular interferon-gamma in circulating and marrow T cells detected by flow cytometry and the response to immunosuppressive therapy in patients with aplastic anemia

Immunosuppressive therapy leads to meaningful hematologic improvement in most patients with aplastic anemia (AA). Failure to respond and a later relapse could be due to deficient numbers of hematopoietic stem cells, inadequate treatment of the immune process, or a nonimmunologic etiology. Interferon-gamma (IFN-gamma) has been implicated in the pathophysiology of hematopoietic failure in AA. On the basis of previous findings showing overexpression of IFN-gamma in bone marrow (BM) and peripheral blood (PB) in this disease, we hypothesized that quantitation of IFN-gamma might be applied to predict and monitor responses to immunosuppressive therapy. We measured expression of IFN-gamma in lymphocytes obtained from 123 AA patients, using intracellular 2-color fluorescent staining and flow cytometry. Of 70 patients with severe AA, 36 (51%) demonstrated increased IFN-gamma in circulating T cells. IFN-gamma was detected in only 4 of 53 patients who had recovered from AA. IFN-gamma was not found in PB lymphocytes of patients with other hematologic diseases and heavy transfusion burdens or in healthy volunteers. Among 62 AA patients who were assessed before first treatment with immunosuppressive drugs, 27 of 28 (96%) with circulating IFN-gamma-containing T cells subsequently responded to therapy; in contrast, only 11 of 34 (32%) patients whose PB lacked IFN-gamma lymphocytes improved to transfusion independence. IFN-gamma-containing lymphocytes declined following treatment in all cases. Of 17 patients assessed during relapse, IFN-gamma was present in T cells prior to the blood count decline in 13, and 12 responded to reinstitution of immunosuppressive drugs. Of 30 BMs tested prior to first treatment, 20, all in responding patients, were positive for IFN-gamma, whereas the negative tests were obtained in 10 nonresponding patients. IFN-gamma is increased in the PB lymphocytes of many patients with AA, and these cells decline with therapy. The presence of intracellular IFN-gamma may predict response to immunosuppressive treatment and also the onset of relapse.

Toward gene therapy for disorders of globin synthesis

Inherited disorders of hemoglobin remain desirable targets for genetically based therapies. That stem cell replacement reverses the phenotype of both thalassemia and sickle cell anemia has been well established through allogeneic bone marrow transplantation studies, yet significant toxicities and finite donor availability limit this approach to a minority of affected individuals. Genetically based strategies that have as their goal addition of a normal copy of the human beta-globin gene along with key regulatory sequences to autologous hematopoietic stem cells represent a viable alternative to allogeneic transplantation, but this approach has been impeded by formidable obstacles over the last decade. Large animal models have become the standard for the development of clinically relevant gene addition strategies, and significant progress in the techniques used to deliver potentially therapeutic genes has been achieved. The clinical application of such strategies may be close at hand, at least for disorders in which modest level, constitutive expression is sufficient to correct the phenotype. For the thalassemias and hemoglobinopathies, complex, regulated, lineage specific expression of the beta-globin gene at relatively high levels will be required. The discovery of the beta-globin locus control region renewed interest in the thalassemias and sickle cell anemia as targets for gene transfer, but difficulties in attaining high-titer vectors along with a tendency toward rearrangement when segments of the locus control region (LCR) were incorporated into retroviral vectors stalled further progress. Recent advances in vector construction have circumvented this problem and others limiting both gene transfer efficiency and regulation of transgene expression, offering new hope for clinical application.

In vivo persistence of retrovirally transduced murine long-term repopulating cells is not limited by expression of foreign gene products in the fully or minimally myeloablated setting

Many nonmalignant hematologic disorders could potentially be treated by genetic correction of as few as 5-10% of target lineage cells. However, immune system clearance of cells expressing gene products perceived as foreign could be limiting. There is evidence that tolerance to foreign proteins can result when myeloablative conditioning is used, but this limits the overall applicability of such techniques. Therefore, we sought to evaluate the engraftment of hematopoietic stem cells carrying a foreign transgene after low-dose irradiation by comparing in vivo survival of murine long-term repopulating cells (LTRC) transduced with either a retroviral vector expressing the bacterial neomycin phosphotransferase gene (neo) or a vector containing neo gene sequences but modified to prevent protein expression (nonexpression). First, marrow cells from congenic donors were transduced with either vector and transplanted into recipients treated with standard dose irradiation of 800 rads. High-level engraftment and gene marking resulted, without differences in the marking levels or pattern of persistence of the cells between cells transduced with either vector. Low-dose irradiation at 100 rads was tested using higher cell doses. Marking levels as high as 10% overall were obtained, again with no differences between mice receiving cells transduced with the neo versus the nonexpression vectors. To investigate a potentially more immunogenic protein, marrow cells were transduced with a vector containing the green fluorescent protein (GFP) gene, and their persistence was studied in recipient mice receiving 100 rads. Stable GFP expression in 5-10% of circulating cells was observed long term. We conclude that even with very low dose conditioning, engraftment by genetically modified LTRC cells at clinically significant levels can be achieved without evidence for clearance of cells known to be expressing immunogenic proteins.

Understanding barriers to preventive health actions for occupational noise-induced hearing loss

A theoretically based formative evaluation was conducted with coal miners in the Appalachian Mountains who were at high risk for noise-induced hearing loss (NIHL). The results of four focus groups indicate that despite high levels of knowledge, strong perceived severity of negative consequences, and strong perceived susceptibility to hearing loss, two main categories of barriers (environmental and individual) keep coal miners from using their hearing protection devices (HPD). Further analysis suggests that the environmental factors, rather than individual variables, more strongly influence decisions against protective actions. Recommendations and practical implications are offered.

Regression of metastatic renal-cell carcinoma after nonmyeloablative allogeneic peripheral-blood stem-cell transplantation

BACKGROUND

Since allogeneic stem-cell transplantation can induce curative graft-versus-leukemia reactions in patients with hematologic cancers, we sought to induce analogous graft-versus-tumor effects in patients with metastatic renal-cell carcinoma by means of nonmyeloablative allogeneic peripheral-blood stem-cell transplantation.

METHODS

Nineteen consecutive patients with refractory metastatic renal-cell carcinoma who had suitable donors received a preparative regimen of cyclophosphamide and fludarabine, followed by an infusion of a peripheral-blood stem-cell allograft from an HLA-identical sibling or a sibling with a mismatch of a single HLA antigen. Cyclosporine, used to prevent graft-versus-host disease, was withdrawn early in patients with mixed T-cell chimerism or disease progression. Patients with no response received up to three infusions of donor lymphocytes.

RESULTS

At the time of the last follow-up, 9 of the 19 patients were alive 287 to 831 days after transplantation (median follow-up, 402 days). Two had died of transplantation-related causes, and eight from progressive disease. In 10 patients (53 percent) metastatic disease regressed; 3 had a complete response, and 7 had a partial response. The patients who had a complete response remained in remission 27, 25, and 16 months after transplantation. Regression of metastases was delayed, occurring a median of 129 days after transplantation, and often followed the withdrawal of cyclosporine and the establishment of complete donor-T-cell chimerism. These results are consistent with a graft-versus-tumor effect.

CONCLUSIONS

Nonmyeloablative allogeneic stem-cell transplantation can induce sustained regression of metastatic renal-cell carcinoma in patients who have had no response to conventional immunotherapy.

A National Institute for Occupational Safety and Health Alert sent to hospitals and the intentions of hospital decision makers to advocate for latex allergy control measures

This study evaluated a National Institute for Occupational Safety and Health (NIOSH), Centers for Disease Control and Prevention, Alert concerning the risk and prevention of latex allergy among health care workers. It has been estimated that 8-12% of health care workers are sensitized to latex. NIOSH Alerts are publications that are intended to educate stakeholders about risks in the workplace; this Alert contained four recommendations for administrative control measures that hospital decision makers could adopt to reduce the risk of latex allergy to employees. The Alert was mailed to a random selection of Directors of Infection Control and Directors of Nursing in hospitals in the US. A random sample of these targeted recipients and a control group were surveyed by telephone (N = 298). Although nearly all of the respondents were concerned about latex allergy (96%), those reporting having seen the Alert were significantly more likely to report an intention to advocate for one or more of the control measures.

Engraftment of gene-marked hematopoietic progenitors in myeloma patients after transplant of autologous long-term marrow cultures

We conducted a phase I hematopoietic stem cell (HSC) gene-marking trial in patients undergoing autologous blood or marrow stem cell transplant for the treatment of multiple myeloma. Between 500 and 1000 ml of bone marrow was harvested from each of 14 myeloma patients and 1 syngeneic donor. A mean of 3.3x10(9) cells per patient were plated in 20 to 50 long-term marrow culture (LTMC) flasks and maintained for 3 weeks. LTMCs were exposed on days 8 and 15 to clinical-grade neo(r)-containing retrovirus supernatant (G1Na). A mean of 8.23x10(8) day-21 LTMC cells containing 5.2x10(4) gene-marked granulocyte-macrophage progenitor cells (CFU-GM) were infused along with an unmanipulated peripheral blood stem cell graft into each patient after myeloablative therapy. Proviral DNA was detected in 71% of 68 tested blood and bone marrow samples and 150 of 2936 (5.1%) CFU-GM derived from patient bone marrow samples after transplant. The proportion of proviral DNA-positive CFU-GM declined from a mean of 9.8% at 3 months to a mean of 2.3% at 24 months postinfusion. Southern blots of 26 marrow and blood samples were negative. Semiquantitative PCR analysis indicated that gene transfer was achieved in 0.01-1% of total bone marrow and blood mononuclear cells (MNCs). Proviral DNA was also observed in EBV-transformed B lymphocytes, in CD34+ -enriched bone marrow cells, and in CFUs derived from the latter progenitors. Gene-modified cells were detected by PCR in peripheral blood and bone marrow for 24 months after infusion of LTMC cells. Sensitivity and specificity of the PCR assays were independently validated in four laboratories. Our data confirm that HSCs may be successfully transduced in stromal based culture systems. The major obstacle to therapeutic application of this approach remains the overall low level of genetically modified cells among the total hematopoietic cell pool in vivo.

Successful treatment of metastatic renal cell carcinoma with a nonmyeloablative allogeneic peripheral-blood progenitor-cell transplant: evidence for a graft-versus-tumor effect

PURPOSE

A 50-year-old man developed progressive pulmonary metastasis resistant to interferon alfa-2b treatment 7 months after he underwent left nephrectomy for stage III renal cell carcinoma. We performed a nonmyeloablative allogeneic peripheral-blood stem-cell transplant in this patient to exploit a possible graft-versus-tumor effect from allogeneic lymphocytes.

MATERIALS AND METHODS

The conditioning regimen consisted of fludarabine and cyclophosphamide followed by a T-cell replete, granulocyte-colony stimulating-factor-mobilized peripheral-blood stem-cell transplant from his HLA-identical brother. Cyclosporine was administered from days -4 to +45 to prevent graft rejection and acute graft-versus-host disease (GVHD).

RESULTS

Serial polymerase chain reaction analysis of hematopoietic lineage-specific minisatellites initiallyshowed mixed chimerism in CD14(+) and CD15(+) myeloid cells, CD3(+) T cells, and CD34(+) progenitor cells, with rapid conversion to 100% donor T-cell chimerism by day +60 and 100% donor myeloid cells by day +100. Serial computed tomography scans of the chest showed stable disease at day +30, slight regression of pulmonary lesions at day +63, and complete disappearance of all pulmonary metastatic disease by day +110. Mild transient acute GVHD disease of the skin occurred on day +60 and limited chronic GVHD of the skin occurred by day +200.

CONCLUSION

The complete regression of metastatic disease, which has now been maintained for more than 1 year, is compatible with a graft-versus-tumor effect.

Growth inhibition of chronic myelogenous leukemia cells by ODN-1, an aptameric inhibitor of p210bcr-abl tyrosine kinase activity

p210bcr-abl-Related tyrosine kinase activity has been shown to cause chronic myelogenous leukemia (CML), a disease of bone marrow stem cells. Having previously demonstrated that the aptameric oligonucleotide, ODN-1, could inhibit p210bcr-abl kinase activity, the current study sought to determine if ODN-1 could selectively inhibit the growth of CML cells relative to that of normal bone marrow. ODN-1, when introduced by electroporation into peripheral blood mononuclear cells (PBMC) from patients with CML, decreased the number of committed progenitors (CML CFU-GM) by an average of 67%+/-19% (mean+/-SEM, range 28-98%). Treatment of CML PBMC with ODN-1 was also shown to decrease the number of more primitive cobblestone area-forming cells (CAFC) by 35%-87%. In contrast, there was little suppressive effect by the combination of electroporation and ODN-1 on either CFU-GM or CAFC numbers from normal donor bone marrow. These studies suggest that inhibition of p210bcr-abl protein-tyrosine kinase (PTK) activity by ODN-1 is associated with some degree of selective growth inhibition of p210bcr-abl-transformed cells. p210bcr-abl kinase inhibitory agents may be useful for the ex vivo purging of bone marrow or peripheral blood progenitor/stem cells in the setting of autologous transplantation for CML.

T cell-depleted bone marrow transplantation and delayed T cell add-back to control acute GVHD and conserve a graft-versus-leukemia effect

Thirty-eight patients with hematological malignancies, received T cell-depleted marrow transplants (BMT) and cyclosporine to prevent acute graft-versus-host disease (aGVHD), followed by delayed add-back of donor lymphocytes to prevent leukemia relapse. In 26 patients scheduled for donor T cell add-back of 2 x 10(6) cells/kg on day 30 and 5 x 10(7) cells/kg on day 45 (schedule 1), the overall probability of grade > or = II aGVHD developing was 31.5%, with a 15.5% probability of aGVHD occurring after T cell add-back. In 12 patients receiving 10(7) donor T cells/kg on day 30 (schedule 2), the probability of grade > or = II aGVHD was 100%. The incidence of grade III-IV aGVHD was higher in schedule 2 than in schedule 1 (P=0.02). Of 24 evaluable patients, 10 (46%) developed chronic GVHD which was limited in eight and extensive in two. Current disease-free survival for 18 patients at standard risk for relapse (chronic myeloid leukemia (CML) in chronic or accelerated phase, acute myeloid leukemia in remission) vs 20 patients with more advanced leukemia or multiple myeloma were respectively 72% vs 12% (P < 0.01) with a 29% vs 69% probability of relapse (P=0.08). In 12 CML patients surviving more than 3 months, PCR analysis of the BCR/ABL transcript showed that minimal residual disease after T cell add-back was transient except in two patients who developed hematological relapse. Results indicate that the risk of acute GVHD is low following substantial T cell doses, transfused 45 days after transplant, using cyclosporine prophylaxis. Furthermore a graft-versus-leukemia effect was conserved.

Transduction of hematopoietic stem cells in humans and in nonhuman primates

Primitive hematopoietic progenitor and stem cells have been pursued as highly desirable targets for genetic therapy. Retroviral vectors have been used for the majority of preclinical and clinical studies directed at these cells; however, both preclinical and early clinical studies indicate that the gene transfer efficiency of the current generation of vectors using known transduction conditions into primate and human repopulating stem cells is too low to be of clinical utility in most situations. In this presentation I will summarize the status of our completed and ongoing clinical genetic marking trials, and describe our efforts in the laboratory and use of primate transplantation models to improve on these results.