Long-range inhibition synchronizes and updates prefrontal task activity

Changes in patterns of activity within the medial prefrontal cortex enable rodents, non-human primates and humans to update their behaviour to adapt to changes in the environment-for example, during cognitive tasks^1-5. Parvalbumin-expressing inhibitory neurons in the medial prefrontal cortex are important for learning new strategies during a rule-shift task^6-8, but the circuit interactions that switch prefrontal network dynamics from maintaining to updating task-related patterns of activity remain unknown. Here we describe a mechanism that links parvalbumin-expressing neurons, a new callosal inhibitory connection, and changes in task representations. Whereas nonspecifically inhibiting all callosal projections does not prevent mice from learning rule shifts or disrupt the evolution of activity patterns, selectively inhibiting only callosal projections of parvalbumin-expressing neurons impairs rule-shift learning, desynchronizes the gamma-frequency activity that is necessary for learning⁸ and suppresses the reorganization of prefrontal activity patterns that normally accompanies rule-shift learning. This dissociation reveals how callosal parvalbumin-expressing projections switch the operating mode of prefrontal circuits from maintenance to updating by transmitting gamma synchrony and gating the ability of other callosal inputs to maintain previously established neural representations. Thus, callosal projections originating from parvalbumin-expressing neurons represent a key circuit locus for understanding and correcting the deficits in behavioural flexibility and gamma synchrony that have been implicated in schizophrenia and related conditions^9,10.

Study protocol: a multicentre, open-label, parallel-group, phase 2, randomised controlled trial of autologous macrophage therapy for liver cirrhosis (MATCH)

INTRODUCTION

Liver cirrhosis is a growing global healthcare challenge. Cirrhosis is characterised by severe liver fibrosis, organ dysfunction and complications related to portal hypertension. There are no licensed antifibrotic or proregenerative medicines and liver transplantation is a scarce resource. Hepatic macrophages can promote both liver fibrogenesis and fibrosis regression. The safety and feasibility of peripheral infusion of ex vivo matured autologous monocyte-derived macrophages in patients with compensated cirrhosis has been demonstrated.

METHODS AND ANALYSIS

The efficacy of autologous macrophage therapy, compared with standard medical care, will be investigated in a cohort of adult patients with compensated cirrhosis in a multicentre, open-label, parallel-group, phase 2, randomised controlled trial. The primary outcome is the change in Model for End-Stage Liver Disease score at 90 days. The trial will provide the first high-quality examination of the efficacy of autologous macrophage therapy in improving liver function, non-invasive fibrosis markers and other clinical outcomes in patients with compensated cirrhosis.

ETHICS AND DISSEMINATION

The trial will be conducted according to the ethical principles of the Declaration of Helsinki 2013 and has been approved by Scotland A Research Ethics Committee (reference 15/SS/0121), National Health Service Lothian Research and Development department and the Medicine and Health Care Regulatory Agency-UK. Final results will be presented in peer-reviewed journals and at relevant conferences.

TRIAL REGISTRATION NUMBERS

ISRCTN10368050 and EudraCT; reference 2015-000963-15.

Cytometric analysis of T cell phenotype using cytokine profiling for improved manufacturing of an EBV-specific T cell therapy

Adoptive immunotherapy using Epstein–Barr Virus (EBV)‐specific T cells is a potentially curative treatment for patients with EBV‐related malignancies where other clinical options have proved ineffective. We describe improved good manufacturing practice (GMP)‐compliant culture and analysis processes for conventional lymphoblastoid cell line (LCL)‐driven EBV‐specific T cell manufacture, and describe an improved phenotyping approach for analysing T cell products. We optimized the current LCL‐mediated clinical manufacture of EBV‐specific T cells to establish an improved process using xenoprotein‐free GMP‐compliant reagents throughout, and compared resulting products with our previous banked T cell clinical therapy. We assessed effects of changes to LCL:T cell ratio in T cell expansion, and developed a robust flow cytometric marker panel covering T cell memory, activation, differentiation and intracellular cytokine release to characterize T cells more effectively. These data were analysed using a t‐stochastic neighbour embedding (t‐SNE) algorithm. The optimized GMP‐compliant process resulted in reduced cell processing time and improved retention and expansion of central memory T cells. Multi‐parameter flow cytometry determined the optimal protocol for LCL stimulation and expansion of T cells and demonstrated that cytokine profiling using interleukin (IL)‐2, tumour necrosis factor (TNF)‐α and interferon (IFN)‐γ was able to determine the differentiation status of T cells throughout culture and in the final product. We show that fully GMP‐compliant closed‐process culture of LCL‐mediated EBV‐specific T cells is feasible, and profiling of T cells through cytokine expression gives improved characterization of start material, in‐process culture conditions and final product. Visualization of the complex multi‐parameter flow cytometric data can be simplified using t‐SNE analysis.

Enhancing WNT Signaling Restores Cortical Neuronal Spine Maturation and Synaptogenesis in Tbr1 Mutants

Tbr1 is a high-confidence autism spectrum disorder (ASD) gene encoding a transcription factor with distinct pre- and postnatal functions. Postnatally, Tbr1 conditional knockout (CKO) mutants and constitutive heterozygotes have immature dendritic spines and reduced synaptic density. Tbr1 regulates expression of several genes that underlie synaptic defects, including a kinesin (Kif1a) and a WNT-signaling ligand (Wnt7b). Furthermore, Tbr1 mutant corticothalamic neurons have reduced thalamic axonal arborization. LiCl and a GSK3β inhibitor, two WNT-signaling agonists, robustly rescue the dendritic spines and the synaptic and axonal defects, suggesting that this could have relevance for therapeutic approaches in some forms of ASD.

Fazel Darbandi et al. demonstrate that TBR1 directly regulates transcriptional circuits in cortical layers 5 and 6, which promote dendritic spine and synaptic density. Enhancing WNT signaling rescues dendritic spine maturation and synaptogenesis defects in Tbr1 mutants. These results provide insights into mechanisms that underlie ASD pathophysiology.

Human umbilical cord perivascular cells improve human pancreatic islet transplant function by increasing vascularization

Islet transplantation is an efficacious therapy for type 1 diabetes; however, islets from multiple donor pancreata are required, and a gradual attrition in transplant function is seen. Here, we manufactured human umbilical cord perivascular mesenchymal stromal cells (HUCPVCs) to Good Manufacturing Practice (GMP) standards. HUCPVCs showed a stable phenotype while undergoing rapid ex vivo expansion at passage 2 (p2) to passage 4 (p4) and produced proregenerative factors, strongly suppressing T cell responses in the resting state and in response to inflammation. Transplanting an islet equivalent (IEQ):HUCPVC ratio of 1:30 under the kidney capsule in diabetic NSG mice demonstrated the fastest return to normoglycemia by 3 days after transplant: Superior glycemic control was seen at both early (2.7 weeks) and later stages (7, 12, and 16 weeks) versus ratios of 1:0, 1:10, and 1:50, respectively. Syngeneic islet transplantation in immunocompetent mice using the clinically relevant hepatic portal route with a marginal islet mass showed that mice transplanted with an IEQ:HUCPVC ratio of 1:150 had superior glycemic control versus ratios of 1:0, 1:90, and 1:210 up to 6 weeks after transplant. Immunodeficient mice transplanted with human islets (IEQ:HUCPVC ratio of 1:150) exhibited better glycemic control for 7 weeks after transplant versus islet transplant alone, and islets transplanted via the hepatic portal vein in an allogeneic mouse model using a curative islet mass demonstrated delayed rejection of islets when cotransplanted with HUCPVCs (IEQ:HUCPVC ratio of 1:150). The immunosuppressive and proregenerative properties of HUCPVCs demonstrated long-term positive effects on graft function in vivo, indicating that they may improve long-term human islet allotransplantation outcomes.

Rapid GMP-Compliant Expansion of SARS-CoV-2-Specific T Cells From Convalescent Donors for Use as an Allogeneic Cell Therapy for COVID-19

COVID-19 disease caused by the SARS-CoV-2 virus is characterized by dysregulation of effector T cells and accumulation of exhausted T cells. T cell responses to viruses can be corrected by adoptive cellular therapy using donor-derived virus-specific T cells. One approach is the establishment of banks of HLA-typed virus-specific T cells for rapid deployment to patients. Here we show that SARS-CoV-2–exposed blood donations contain CD4 and CD8 memory T cells which recognize SARS-CoV-2 spike, nucleocapsid and membrane antigens. Peptides of these antigens can be used to isolate virus-specific T cells in a GMP-compliant process. The isolated T cells can be rapidly expanded using GMP-compliant reagents for use as an allogeneic therapy. Memory and effector phenotypes are present in the selected virus-specific T cells, but our method rapidly expands the desirable central memory phenotype. A manufacturing yield ranging from 10¹⁰ to 10¹¹ T cells can be obtained within 21 days culture. Thus, multiple therapeutic doses of virus-specific T cells can be rapidly generated from convalescent donors for potential treatment of COVID-19 patients.

Haplobanking induced pluripotent stem cells for clinical use

The development of induced pluripotent stem cells (iPSCs) by Shinya Yamanaka and colleagues in 2006 has led to a potential new paradigm in cellular therapeutics, including the possibility of producing patient-specific, disease-specific and immune matched allogeneic cell therapies. One can envisage two routes to immunologically compatible iPSC therapies: using genetic modification to generate a 'universal donor' with reduced expression of Human Leukocyte Antigens (HLA) and other immunological targets or developing a haplobank containing iPSC lines specifically selected to provide HLA matched products to large portions of the population. HLA matched lines can be stored in a designated physical or virtual global bank termed a 'haplobank'. The process of 'iPSC haplobanking' refers to the banking of iPSC cell lines, selected to be homozygous for different HLA haplotypes, from which therapeutic products can be derived and matched immunologically to patient populations. By matching iPSC and derived products to a patient's HLA class I and II molecules, one would hope to significantly reduce the risk of immune rejection and the use of immunosuppressive medication. Immunosuppressive drugs are used in several conditions (including autoimmune disease and in transplantation procedures) to reduce rejection of infused cells, or transplanted tissue and organs, due to major and minor histocompatibility differences between donor and recipient. Such regimens can lead to immune compromise and pathological consequences such as opportunistic infections or malignancies due to decreased cancer immune surveillance. In this article, we will discuss what is practically involved if one is developing and executing an iPSC haplobanking strategy.

The Global Alliance for iPSC Therapies (GAiT)

The Global Alliance for iPSC Therapies (GAiT) is a new initiative to support the implementation and clinical application of therapies derived from pluripotent stem cells to the benefit of patients globally. GAiT's mission is to serve as a central, international resource for those organisations developing therapies from clinical-grade induced pluripotent stem cells, and to support the expansion of this nascent field. With the support of its international partners, GAiT already has an early position on manufacturing, regulatory and quality standards. This article details GAiT's development, its mission and structure, as well as how, and by whom, it is funded. The article ends with brief overview of current and upcoming activities.

Pancreas-derived mesenchymal stromal cells share immune response-modulating and angiogenic potential with bone marrow mesenchymal stromal cells and can be grown to therapeutic scale under Good Manufacturing Practice conditions

BACKGROUND AIMS

Mesenchymal stromal cells (MSCs) isolated from various tissues are under investigation as cellular therapeutics in a wide range of diseases. It is appreciated that the basic biological functions of MSCs vary depending on tissue source. However, in-depth comparative analyses between MSCs isolated from different tissue sources under Good Manufacturing Practice (GMP) conditions are lacking. Human clinical-grade low-purity islet (LPI) fractions are generated as a byproduct of islet isolation for transplantation. MSC isolates were derived from LPI fractions with the aim of performing a systematic, standardized comparative analysis of these cells with clinically relevant bone marrow-derived MSCs (BM MSCs).

METHODS

MSC isolates were derived from LPI fractions and expanded in platelet lysate-supplemented medium or in commercially available xenogeneic-free medium. Doubling rate, phenotype, differentiation potential, gene expression, protein production and immunomodulatory capacity of LPIs were compared with those of BM MSCs.

RESULTS

MSCs can be readily derived in vitro from non-transplanted fractions resulting from islet cell processing (i.e., LPI MSCs). LPI MSCs grow stably in serum-free or platelet lysate-supplemented media and demonstrate in vitro self-renewal, as measured by colony-forming unit assay. LPI MSCs express patterns of chemokines and pro-regenerative factors similar to those of BM MSCs and, importantly, are equally able to attract immune cells in vitro and in vivo and suppress T-cell proliferation in vitro. Additionally, LPI MSCs can be expanded to therapeutically relevant doses at low passage under GMP conditions.

CONCLUSIONS

LPI MSCs represent an alternative source of GMP MSCs with functions comparable to BM MSCs.

Safety profile of autologous macrophage therapy for liver cirrhosis

Therapies to reduce liver fibrosis and stimulate organ regeneration are urgently needed. We conducted a first-in-human, phase 1 dose-escalation trial of autologous macrophage therapy in nine adults with cirrhosis and a Model for End-Stage Liver Disease (MELD) score of 10-16 (ISRCTN 10368050). Groups of three participants received a single peripheral infusion of 10⁷, 10⁸ or up to 10⁹ cells. Leukapheresis and macrophage infusion were well tolerated with no transfusion reactions, dose-limiting toxicities or macrophage activation syndrome. All participants were alive and transplant-free at one year, with only one clinical event recorded, the occurrence of minimal ascites. The primary outcomes of safety and feasibility were met. This study informs and provides a rationale for efficacy studies in cirrhosis and other fibrotic diseases.

A Report from a Workshop of the International Stem Cell Banking Initiative, Held in Collaboration of Global Alliance for iPSC Therapies and the Harvard Stem Cell Institute, Boston, 2017

This report summarizes the recent activity of the International Stem Cell Banking Initiative held at Harvard Stem Cell Institute, Boston, MA, USA, on June 18, 2017. In this meeting, we aimed to find consensus on ongoing issues of quality control (QC), safety, and efficacy of human pluripotent stem cell banks and their derivative cell therapy products for the global harmonization. In particular, assays for the QC testing such as pluripotency assays test and general QC testing criteria were intensively discussed. Moreover, the recent activities of global stem cell banking centers and the regulatory bodies were briefly summarized to provide an overview on global developments and issues. stem cells2019;37:1130–1135

Microcircuit Mechanisms through which Mediodorsal Thalamic Input to Anterior Cingulate Cortex Exacerbates Pain-Related Aversion

Hyperexcitability of the anterior cingulate cortex (ACC) is thought to drive aversion associated with chronic neuropathic pain. Here, we studied the contribution of input from the mediodorsal thalamus (MD) to ACC, using sciatic nerve injury and chemotherapy-induced mouse models of neuropathic pain. Activating MD inputs elicited pain-related aversion in both models. Unexpectedly, excitatory responses of layer V ACC neurons to MD inputs were significantly weaker in pain models compared to controls. This caused the ratio between excitation and feedforward inhibition elicited by MD input to shift toward inhibition, specifically for subcortically projecting (SC) layer V neurons. Furthermore, direct inhibition of SC neurons reproduced the pain-related aversion elicited by activating MD inputs. Finally, both the ability to elicit pain-related aversion and the decrease in excitation were specific to MD inputs; activating basolateral amygdala inputs produced opposite effects. Thus, chronic pain-related aversion may reflect activity changes in specific pathways, rather than generalized ACC hyperactivity.

Allogeneic Ex Vivo Expanded Corneal Epithelial Stem Cell Transplantation: A Randomized Controlled Clinical Trial

Limbal stem cell deficiency (LSCD) is a disease resulting from the loss or dysfunction of epithelial stem cells, which seriously impairs sight. Autologous limbal stem cell transplantation is effective in unilateral or partial bilateral disease but not applicable in total bilateral disease. An allogeneic source of transplantable cells for use in total bilateral disease can be obtained from culture of donated cadaveric corneal tissue. We performed a controlled multicenter study to examine the feasibility, safety, and efficacy of allogeneic corneal epithelial stem cells in the treatment of bilateral LSCD. Patients were randomized to receive corneal epithelial stem cells cultured on amniotic membrane (AM): investigational medicinal product (IMP) or control AM only. Patients received systemic immunosuppression. Primary endpoints were safety and visual acuity, secondary endpoint was change in composite ocular surface score (OSS). Sixteen patients were treated and 13 patients completed all assessments. Safety was demonstrated and 9/13 patients had improved visual acuity scores at the end of the trial, with no significant differences between IMP and control groups. Patients in the IMP arm demonstrated significant, sustained improvement in OSS, whereas those in the control arm did not. Serum cytokine levels were measured during and after the period of immune suppression and we identified strongly elevated levels of CXCL8 in the serum of patients with aniridia, which persisted throughout the trial. This first randomized control trial of allogeneic corneal epithelial stem cells in severe bilateral LSCD demonstrates the feasibility and safety of this approach. stem cells translational medicine2019;8:323–331

Repurposing the Cord Blood Bank for Haplobanking of HLA-Homozygous iPSCs and Their Usefulness to Multiple Populations

Although autologous induced pluripotent stem cells (iPSCs) can potentially be useful for treating patients without immune rejection, in reality it will be extremely expensive and labor-intensive to make iPSCs to realize personalized medicine. An alternative approach is to make use of human leukocyte antigen (HLA) haplotype homozygous donors to provide HLA matched iPSC products to significant numbers of patients. To establish a haplobank of iPSCs, we repurposed the cord blood bank by screening ∼4,200 high resolution HLA typed cord blood samples, and selected those homozygous for the 10 most frequent HLA-A,-B,-DRB1 haplotypes in the Korean population. Following the generation of 10 iPSC lines, we conducted a comprehensive characterization, including morphology, expression of pluripotent markers and cell surface antigens, three-germ layer formation, vector clearance, mycoplasma/microbiological/viral contamination, endotoxin, and short tandem repeat (STR) assays. Various genomic analyses using microarray and comparative genomic hybridization (aCGH)-based single nucleotide polymorphism (SNP) and copy number variation (CNV) were also conducted. These 10 HLA-homozygous iPSC lines match 41.07% of the Korean population. Comparative analysis of HLA population data shows that they are also of use in other Asian populations, such as Japan, with some limited utility in ethnically diverse populations, such as the UK. Taken together, the generation of the 10 most frequent Korean HLA-homozygous iPSC lines serves as a useful pointer for the development of optimal methods for iPSC generation and quality control and indicates the benefits and limitations of collaborative HLA driven selection of donors for future stocking of worldwide iPSC haplobanks. Stem Cells 2018;36:1552-1566.

Quality control guidelines for clinical-grade human induced pluripotent stem cell lines

Use of clinical-grade human induced pluripotent stem cell (iPSC) lines as a starting material for the generation of cellular therapeutics requires demonstration of comparability of lines derived from different individuals and in different facilities. This requires agreement on the critical quality attributes of such lines and the assays that should be used. Working from established recommendations and guidance from the International Stem Cell Banking Initiative for human embryonic stem cell banking, and concentrating on those issues more relevant to iPSCs, a series of consensus workshops has made initial recommendations on the minimum dataset required to consider an iPSC line of clinical grade, which are outlined in this report. Continued evolution of this field will likely lead to revision of these guidelines on a regular basis.

Development, functional characterization and validation of methodology for GMP-compliant manufacture of phagocytic macrophages: A novel cellular therapeutic for liver cirrhosis

Background aims

Autologous macrophage therapy represents a potentially significant therapeutic advance for the treatment of severe progressive liver cirrhosis. Administration of macrophages has been shown to reduce inflammation and drive fibrotic scar breakdown and tissue repair in relevant models. This therapeutic approach is being assessed for safety and feasibility in a first-in-human trial (MAcrophages Therapy for liver CirrHosis [MATCH] trial).

Methods

We outline the development and validation phases of GMP production. This includes use of the CliniMACS Prodigy cell sorting system to isolate CD14⁺ cells; optimizing macrophage culture conditions, assessing cellular identity, product purity, functional capability and determining the stability of the final cell product.

Results

The GMP-compliant macrophage products have a high level of purity and viability, and have a consistent phenotypic profile, expressing high levels of mature macrophage markers 25F9 and CD206 and low levels of CCR2. The macrophages demonstrate effective phagocytic capacity, are constitutively oriented to an anti-inflammatory profile and remain responsive to cytokine and TLR stimulation. The process validation shows that the cell product in excipient is remarkably robust, consistently passing the viability and phenotypic release criteria up to 48 hours after harvest.

Conclusions

This is the first report of validation of a large-scale, fully Good Manufacturing Practice–compliant, autologous macrophage cell therapy product for the potential treatment of cirrhosis. Phenotypic and functional assays confirm that these cells remain functionally viable for up to 48 h, allowing significant flexibility in administration to patients.

Enhancing electron affinity and tuning band gap in donor-acceptor organic semiconductors by benzothiadiazole directed C-H borylation

Electrophilic borylation using BCl3 and benzothiadiazole to direct the C-H functionalisation of an adjacent aromatic unit produces fused boracyclic materials with minimally changed HOMO energy levels but significantly reduced LUMO energy levels. In situ alkylation and arylation at boron using Al(alkyl)3 or Zn(aryl)2 is facile and affords boracycles that possess excellent stability towards protic solvents, including water, and display large bathochromic shifts leading to far red/NIR emission in the solid state with quantum yields of up to 34%. Solution fabricated OLEDs with far red/NIR electroluminescence are reported with EQEs > 0.4%.

A prion reduction filter does not completely remove endogenous prion infectivity from sheep blood

BACKGROUND

Variant Creutzfeldt-Jakob disease (vCJD) is a transmissible spongiform encephalopathy affecting humans, acquired initially through infection with bovine spongiform encephalopathy (BSE). A small number of vCJD cases have been acquired through the transfusion of blood from asymptomatic donors who subsequently developed vCJD. Filter devices that selectively bind the infectious agent associated with prion disease have been developed for removal of infection from blood. This study independently assessed one such filter, the P-CAPT filter, for efficacy in removing infectivity associated with the BSE agent in sheep blood. The sheep BSE model has previously been used to evaluate the distribution of infectivity in clinically relevant blood components. This is the first study to assess the ability of the P-CAPT filter to remove endogenous infectivity associated with blood components prepared from a large animal model.

STUDY DESIGN AND METHODS

Paired units of leukoreduced red blood cells (LR-RBCs) were prepared from donors at the clinical stage of infection and confirmed as having BSE. One cohort of recipients was transfused with LR-RBCs alone, whereas a parallel cohort received LR and P-CAPT-filtered RBCs (LR-RBCs-P-CAPT).

RESULTS

Of 14 recipients, two have been confirmed as having BSE. These sheep had received LR-RBCs and LR-RBCs-P-CAPT from the same donor.

CONCLUSIONS

The results indicate that, after leukoreduction and P-CAPT filtration, there can still be sufficient residual infectivity in sheep RBCs to transmit infection when transfused into a susceptible recipient.

Identifying viable regulatory and innovation pathways for regenerative medicine: a case study of cultured red blood cells

The creation of red blood cells for the blood transfusion markets represents a highly innovative application of regenerative medicine with a medium term (5-10 year) prospect for first clinical studies. This article describes a case study analysis of a project to derive red blood cells from human embryonic stem cells, including the systemic challenges arising from (i) the selection of appropriate and viable regulatory protocols and (ii) technological constraints related to stem cell manufacture and scale up to clinical Good Manufacturing Practice (GMP) standard. The method used for case study analysis (Analysis of Life Science Innovation Systems (ALSIS)) is also innovative, demonstrating a new approach to social and natural science collaboration to foresight product development pathways. Issues arising along the development pathway include cell manufacture and scale-up challenges, affected by regulatory demands emerging from the innovation ecosystem (preclinical testing and clinical trials). Our discussion reflects on the efforts being made by regulators to adapt the current pharmaceuticals-based regulatory model to an allogeneic regenerative medicine product and the broader lessons from this case study for successful innovation and translation of regenerative medicine therapies, including the role of methodological and regulatory innovation in future development in the field.

Establishment and operation of a Good Manufacturing Practice-compliant allogeneic Epstein-Barr virus (EBV)-specific cytotoxic cell bank for the treatment of EBV-associated lymphoproliferative disease

Epstein-Barr virus (EBV) is associated with several malignancies, including post-transplant lymphoproliferative disorder (PTLD). Conventional treatments for PTLD are often successful, but risk organ rejection and cause significant side effects. EBV-specific cytotoxic T lymphocytes (CTLs) generated in vitro from peripheral blood lymphocytes provide an alternative treatment modality with few side effects, but autologous CTLs are difficult to use in clinical practice. Here we report the establishment and operation of a bank of EBV-specific CTLs derived from 25 blood donors with human leucocyte antigen (HLA) types found at high frequency in European populations. Since licensure, there have been enquiries about 37 patients, who shared a median of three class I and two class II HLA types with these donors. Cells have been infused into ten patients with lymphoproliferative disease, eight of whom achieved complete remission. Neither patient with refractory disease was matched for HLA class II. Both cases of EBV-associated non-haematopoietic sarcoma receiving cells failed to achieve complete remission. Thirteen patients died before any cells could be issued, emphasizing that the bank should be contacted before patients become pre-terminal. Thus, this third party donor-derived EBV-specific CTL cell bank can supply most patients with appropriately matched cells and most recipients have good outcomes.

Quantal and graded stimulation of B lymphocytes as alternative strategies for regulating adaptive immune responses

Lymphocytes undergo a typical response pattern following stimulation in vivo: they proliferate, differentiate to effector cells, cease dividing and predominantly die, leaving a small proportion of long-lived memory and effector cells. This pattern results from cell-intrinsic processes following activation and the influence of external regulation. Here we apply quantitative methods to study B-cell responses in vitro. Our results reveal that B cells stimulated through two Toll-like receptors (TLRs) require minimal external direction to undergo the basic pattern typical of immunity. Altering the stimulus strength regulates the outcome in a quantal manner by varying the number of cells that participate in the response. In contrast, the T-cell-dependent CD40 activation signal induces a response where division times and differentiation rates vary in relation to stimulus strength. These studies offer insight into how the adaptive antibody response may have evolved from simple autonomous response patterns to the highly regulable state that is now observed in mammals.

UK approach to assessing assays and filters designed to reduce the risk of transfusion-transmitted vCJD

Three cases of vCJD transmission by blood transfusion have been reported in the UK, and a fourth case discovered at post-mortem. Modelling has been conducted to predict the number of cases that may occur in the future through transfusion, based on estimates of prevalence, infectivity and susceptibility, and a number of steps have been taken to reduce the risk of transmission. These include deferral of previously transfused donors, leucocyte depletion of all components, importation of plasma for certain patient groups and for fractionation, and the collection of the majority of platelets from single donors (by apheresis). However, even with these interventions, some future cases are still predicted. The UK-wide Advisory Committee on the Safety of Blood, Tissues and Organs (SaBTO) considers the evidence for clinical and cost-effectiveness of any proposed intervention, such as prion assays and filters, and makes recommendations to the governments of the UK. The development of prion assays is challenging as prions do not generate an immune response, do not have nucleic acid and are present in blood in very low concentrations against a high background of normal prion protein. It is critically important that prion assays show high levels of sensitivity and - especially -specificity for a healthy blood donor population. Assessment is impacted by the very short supply of positive human samples, necessitating the use of animal models. Filters that are capable of removing prions from blood components have been developed and CE marked, but it is again necessary to use animal models to study their efficacy. Guidelines have been produced for the assessment of the quality of red cells filtered through these devices, and a clinical safety study has recently been completed. In conclusion, the evaluation of screening assays and prion filters is challenging, time-consuming and costly, but these evaluations are critical to policy making.

Late outgrowth endothelial cells resemble mature endothelial cells and are not derived from bone marrow

A decade of research has sought to identify circulating endothelial progenitor cells (EPC) in order to harness their potential for cardiovascular regeneration. Endothelial outgrowth cells (EOC) most closely fulfil the criteria for an EPC, but their origin remains obscure. Our aim was to identify the source and precursor of EOC and to assess their regenerative potential compared to mature endothelial cells. EOC are readily isolated from umbilical cord blood (6/6 donors) and peripheral blood mononuclear cells (4/6 donors) but not from bone marrow (0/6) or peripheral blood following mobilization with granulocyte-colony stimulating factor (0/6 donors). Enrichment and depletion of blood mononuclear cells demonstrated that EOC are confined to the CD34(+)CD133(-)CD146(+) cell fraction. EOC derived from blood mononuclear cells are indistinguishable from mature human umbilical vein endothelial cells (HUVEC) by morphology, surface antigen expression, immunohistochemistry, real-time polymerase chain reaction, proliferation, and functional assessments. In a subcutaneous sponge model of angiogenesis, both EOC and HUVEC contribute to de novo blood vessel formation giving rise to a similar number of vessels (7.0 ± 2.7 vs. 6.6 ± 3.7 vessels, respectively, n = 9). Bone marrow-derived outgrowth cells isolated under the same conditions expressed mesenchymal markers rather than endothelial cell markers and did not contribute to blood vessels in vivo. In this article, we confirm that EOC arise from CD34(+)CD133(-)CD146(+) mononuclear cells and are similar, if not identical, to mature endothelial cells. Our findings suggest that EOC do not arise from bone marrow and challenge the concept of a bone marrow-derived circulating precursor for endothelial cells.

Immunity and inflammation in the uterus

Microbes often infect the uterus and particularly the endometrium of animals. Infections are most commonly associated with natural service, pregnancy and the post-partum period, leading to inflammation with the elaboration of cytokines, chemokines and prostaglandins. Clinical diseases such as metritis, endometritis and abortion are important causes of infertility. The adaptive immune response to infection has been characterized previously, so the present review aims to highlight the emerging role for innate immunity in the endometrium. The detection of microbes and the innate immune response depends on the detection of pathogen-associated molecular patterns by pattern recognition receptors. The main families of pattern recognition receptors are Toll-like receptors (TLRs), nucleotide oligomerization domain-like receptors, retinoic acid-inducible gene I-like receptors and C-type lectin receptors. These receptors are most often expressed by hematopoietic cells, but the epithelial and stromal cells of the endometrium also possess functional receptors. For example, endometrial cells express TLR4 for recognition of the lipopolysaccharide endotoxin of Gram-negative bacteria, leading to secretion of IL-6, IL-8 and prostaglandin E(2) . It is likely that the epithelial and stromal cells provide a first line of defence in the endometrium to alert hematopoietic cells to the presence of microbes within the uterus.

Novel biopolymers to enhance endothelialisation of intra-vascular devices

Rapid endothelisation is of critical importance in the prevention of adverse remodelling after device implantation. Currently, there is a need for alternative strategies to promote re-endothelialisation for intravascular stents and vascular grafts. Using polymer microarray technology 345 polymers are comprehensively assessed and a matrix is identified that specifically supports both progenitor and mature endothelial cell activity in vitro and in vivo while minimising platelet attachment.

In vivo mononuclear cell tracking using superparamagnetic particles of iron oxide: feasibility and safety in humans

BACKGROUND

Cell therapy is an emerging and exciting novel treatment option for cardiovascular disease that relies on the delivery of functional cells to their target site. Monitoring and tracking cells to ensure tissue delivery and engraftment is a critical step in establishing clinical and therapeutic efficacy. The study aims were (1) to develop a Good Manufacturing Practice-compliant method of labeling competent peripheral blood mononuclear cells with superparamagnetic particles of iron oxide (SPIO), and (2) to evaluate its potential for magnetic resonance cell tracking in humans.

METHODS AND RESULTS

Peripheral blood mononuclear cells 1-5 × 10(9) were labeled with SPIO. SPIO-labeled cells had similar in vitro viability, migratory capacity, and pattern of cytokine release to unlabeled cells. After intramuscular administration, up to 10(8) SPIO-labeled cells were readily identifiable in vivo for at least 7 days using magnetic resonance imaging scanning. Using a phased-dosing study, we demonstrated that systemic delivery of up to 10(9) SPIO-labeled cells in humans is safe, and cells accumulating in the reticuloendothelial system were detectable on clinical magnetic resonance imaging. In a healthy volunteer model, a focus of cutaneous inflammation was induced in the thigh by intradermal injection of tuberculin. Intravenously delivered SPIO-labeled cells tracked to the inflamed skin and were detectable on magnetic resonance imaging. Prussian blue staining of skin biopsies confirmed iron-laden cells in the inflamed skin.

CONCLUSIONS

Human peripheral blood mononuclear cells can be labeled with SPIO without affecting their viability or function. SPIO labeling for magnetic resonance cell tracking is a safe and feasible technique that has major potential for a range of cardiovascular applications including monitoring of cell therapies and tracking of inflammatory cells. Clinical Trial Registration- URL: http://www.clinicaltrials.gov; Unique identifier: NCT00972946, NCT01169935.

Sensitivity to biases of case-control studies on medical procedures, particularly surgery and blood transfusion, and risk of Creutzfeldt-Jakob disease

BACKGROUND

Evidence of risk of Creutzfeldt-Jakob disease (CJD) associated with medical procedures, including surgery and blood transfusion, is limited by susceptibility to bias in epidemiological studies.

METHODS

Sensitivity to bias was explored using a central-birth-cohort model using data from 18 case-control studies obtained after a review of 494 reports on medical procedures and risk of CJD, systematic for the period January 1, 1989 to December 31, 2011.

RESULTS

The validity of the findings in these studies may have been undermined by: recall; control selection; exposure assessment in life-time periods of different duration, out of time-at-risk of effect, or asymmetry in case/control data; and confounding by concomitant blood transfusion at the time of surgery. For sporadic CJD (sCJD), a history of surgery or blood transfusion was associated with risk in some, but not all, recent studies at a ≥10 year lag time, when controls were longitudinally sampled. Space-time aggregation of surgical events was not seen. Surgery at early clinical onset might be overrepresented among cases. Neither surgical history nor blood transfusion unlabelled for donor status, dental treatments or endoscopic examinations were linked to variant CJD (vCJD).

CONCLUSIONS

These results indicate the need for further research. Common challenges within these studies include access to and content of past medical/dental treatment records for diseases with long incubation periods.

Systematic assessment in an animal model of the angiogenic potential of different human cell sources for therapeutic revascularization

INTRODUCTION

Endothelial progenitor cells (EPC) capable of initiating or augmenting vascular growth were recently identified within the small population of CD34-expressing cells that circulate in human peripheral blood and which are considered hematopoietic progenitor cells (HPC). Soon thereafter human HPC began to be used in clinical trials as putative sources of EPC for therapeutic vascular regeneration, especially in myocardial and critical limb ischemias. However, unlike HPC where hematopoietic efficacy is related quantitatively to CD34+ cell numbers implanted, there has been no consensus on how to measure EPC or how to assess cellular graft potency for vascular regeneration. We employed an animal model of spontaneous neovascularization to simultaneously determine whether human cells incorporate into new vessels and to quantify the effect of different putative angiogenic cells on vascularization in terms of number of vessels generated. We systematically compared competence for therapeutic angiogenesis in different sources of human cells with putative angiogenic potential, to begin to provide some rationale for optimising cell procurement for this therapy.

METHODS

Human cells employed were mononuclear cells from normal peripheral blood and HPC-rich cell sources (umbilical cord blood, mobilized peripheral blood, bone marrow), CD34+ enriched or depleted subsets of these, and outgrowth cell populations from these. An established sponge implant angiogenesis model was adapted to determine the effects of different human cells on vascularization of implants in immunodeficient mice. Angiogenesis was quantified by vessel density and species of origin by immunohistochemistry.

RESULTS

CD34+ cells from mobilized peripheral blood or umbilical cord blood HPC were the only cells to promote new vessel growth, but did not incorporate into vessels. Only endothelial outgrowth cells (EOC) incorporated into vessels, but these did not promote vessel growth.

CONCLUSIONS

These studies indicate that, since EPC are very rare, any benefit seen in clinical trials of HPC in therapeutic vascular regeneration is predominantly mediated by indirect proangiogenic effects rather than through direct incorporation of any rare EPC contained within these sources. It should be possible to produce autologous EOC for therapeutic use, and evaluate the effect of EPC distinct from, or in synergy with, the proangiogenic effects of HPC therapies.

Drug modification of LPS-stimulated human monocyte-derived dendritic cells

Many drugs have been reported to convert dendritic cells (DCs) into a tolerogenic phenotype in vitro. However, there is evidence that an additional stimulus, such as lipopolysaccharide (LPS), may also be necessary for tolerogenic function in vivo. Little is known concerning the effects of drug modification on LPS-prestimulated DCs. In this study, monocyte-derived immature DCs were stimulated with LPS first and the influence investigated of six different agents on surface antigen expression, cytokine production and lymphocyte proliferation and cytotoxicity. Mycophenolic acid- and rapamycin-exposed DCs had little effect on surface antigen expression or functional activity towards lymphocytes. In contrast, treatment of immature dendritic cells with aspirin, dexamethasone, 1alpha,25-dihydroxyvitamin D3 (VD3) or butyric acid was associated with diminished expression of CD1a, CD1c, CD40, CD80 and CD83. Dendritic cell modification by aspirin, dexamethasone and VD3 were all associated with decreased production of tumour necrosis factor-alpha (TNFalpha). Furthermore, VD3 treatment was associated with a consistent and significant elevation of IL-6 production. Aspirin-, dexamethasone- VD3- and butyric acid-modified DCs suppressed interferon-gamma production, proliferation and cytotoxicity in co-culture with allogeneic mononuclear cells, but inconsistent results were obtained with different allogeneic combinations. Different drugs show varying effects on DC phenotype. No single agent was consistently effective in suppressing the stimulation of allogeneic mononuclear cells and future work is needed to explore drug combinations.

The management of blood safety in the presence of uncertain risk: a United kingdom perspective

Millions of patients in the UK benefit from the use of both plasma derivatives and blood components that are seen as critical interventions in current medicine. Measures are in place to significantly reduce the risks associated with blood transfusion and plasma derivatives; however, these measures themselves are not risk free. Over the past 20 years, advances in technology and regulation have seen major reductions in the risks associated with transfusion. International blood services, industry, and regulators strive to maintain safety levels through constant monitoring, assessment, and response to changing risk factors. Regulation of screening tests together with the development and introduction of nucleic acid technique tests for hepatitis B virus, hepatitis C virus, and human immunodeficiency virus has improved blood safety. However, other risks, including the changing epidemiology of transfusion-transmitted infections, bacterial contamination of platelets, incorrect blood component transfusion, and variant Creutzfeldt-Jakob disease, require further attention. Risks such as these are often complex, and there is a difficult balance to be struck between donors/recipients' benefit and adequacy of blood supply. The introduction of any new safety measure therefore requires robust, evidence-based evaluation of associated benefit, both clinical and economical. This review presents a UK perspective on how the safety of the blood supply is maintained in the face of uncertain risks.

Highly potent human hematopoietic stem cells first emerge in the intraembryonic aorta-gonad-mesonephros region

Human HSCs appear first in the embryonic dorsal aorta, and only later in the yolk sac, liver, and placenta; a single human AGM region HSC can generate at least 300 daughter HSCs that are retransplantable into secondary recipient mice.

Hematopoietic stem cells (HSCs) emerge during embryogenesis and maintain hematopoiesis in the adult organism. Little is known about the embryonic development of human HSCs. We demonstrate that human HSCs emerge first in the aorta-gonad-mesonephros (AGM) region, specifically in the dorsal aorta, and only later appear in the yolk sac, liver, and placenta. AGM region cells transplanted into immunodeficient mice provide long-term high level multilineage hematopoietic repopulation. Human AGM region HSCs, although present in low numbers, exhibit a very high self-renewal potential. A single HSC derived from the AGM region generates at least 300 daughter HSCs in primary recipients, which disseminate throughout the entire recipient bone marrow and are retransplantable. These findings highlight the vast regenerative potential of the earliest human HSCs and set a new standard for in vitro generation of HSCs from pluripotent stem cells for the purpose of regenerative medicine.

Human embryonic stem cells rapidly take up and then clear exogenous human and animal prions in vitro

Susceptibility to prion infection involves interplay between the prion strain and host genetics, but expression of the host-encoded cellular prion protein is a known prerequisite. Here we consider human embryonic stem cell (hESC) susceptibility by characterizing the genetics and expression of the normal cellular prion protein and by examining their response to acute prion exposure. Seven hESC lines were tested for their prion protein gene codon 129 genotype and this was found to broadly reflect that of the normal population. hESCs expressed prion protein mRNA, but only low levels of prion protein accumulated in self-renewing populations. Following undirected differentiation, up-regulation of prion protein expression occurred in each of the major embryonic lineages. Self-renewing populations of hESCs were challenged with infectious human and animal prions. The exposed cells rapidly and extensively took up this material, but when the infectious source was removed the level and extent of intracellular disease-associated prion protein fell rapidly. In the absence of a sufficiently sensitive test for prions to screen therapeutic cells, and given the continued use of poorly characterized human and animal bioproducts during hESC derivation and cultivation, the finding that hESCs rapidly take up and process abnormal prion protein is provocative and merits further investigation.

Granulocyte colony-stimulating factor (G-CSF) depresses angiogenesis in vivo and in vitro: implications for sourcing cells for vascular regeneration therapy

SUMMARY BACKGROUND

The most common source of hematopoietic progenitor cells (HPCs) for hematopoietic reconstitution comprises granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood stem cells (PBSCs). It has been proposed that endothelial progenitor cells (EPCs) share precursors with HPCs, and that EPC release may accompany HPC mobilization to the circulation following G-CSF administration.

OBJECTIVE

To investigate EPC activity following HPC mobilization, and the direct effects of exogenous G-CSF administration on human umbilical vein endothelial cells (HUVECs) and endothelial outgrowth cells (EOCs), using in vitro and in vivo correlates of angiogenesis.

PATIENTS/METHODS

Heparinized venous blood samples were collected from healthy volunteers and from cord blood at parturition. G-CSF-mobilized samples were collected before administration, at apheresis harvest, and at follow-up. PBSCs were phenotyped by flow cytometry, and cultured in standard colony-forming unit (CFU)-EPC and EOC assays. The effect of exogenous G-CSF was investigated by addition of it to HUVECs and EOCs in standard tubule formation and aortic ring assays, and in an in vivo sponge implantation model.

RESULTS

Our data show that G-CSF mobilization of PBSCs produces a profound, reversible depression of circulating CFU-EPCs. Furthermore, G-CSF administration did not mobilize CD34+CD133- cells, which include precursors of EOCs. No EOCs were cultured from any mobilized PBSCs studied. Exogenous G-CSF inhibited CFU-EPC generation, HUVEC and EOC tubule formation, microvessel outgrowth, and implanted sponge vascularization in mice.

CONCLUSIONS

G-CSF administration depresses both endothelial cell angiogenesis and monocyte proangiogenic activity, and we suggest that any angiogenic benefit observed following implantation of cells mobilized by G-CSF may come only from a paracrine effect from HPCs.

Red blood cells from pluripotent stem cells for use in transfusion

The use of donated red blood cells in transfusion is a well-established cellular therapy. However, problems including insufficient supply, transfusion-transmitted infections and the need for immunological matching hamper even in the best services. These issues may be eliminated by using pluripotent stem cells to generate universal donor group O, Rhesus D-negative red blood cells. Human embryonic stem cells can be maintained and expanded indefinitely and can, therefore, produce the very large cell numbers required for this application. Red blood cell production is also an attractive goal for pluripotent stem cell-derived therapeutics because it is a well-characterized single cell suspension, lacking nucleated cells and with a low expression of HLA molecules. Much progress has been made; however, a number of challenges remain including scale-up, clinical effectiveness and product safety.

Fabrication of planar organic nanotransistors using low temperature thermal nanoimprint lithography for chemical sensor applications

A new fabrication process for the patterning of organic semiconductors at the nanoscale has been developed using low temperature thermal nanoimprint lithography and the details of this process are discussed. Novel planar nanotransistors have been fabricated and characterized from poly(3-hexylthiophene) (P3HT) and we demonstrate the feasibility of using such devices as highly sensitive chemical sensors.

L-ficolin (ficolin-2) insufficiency is associated with combined allergic and infectious respiratory disease in children

We previously reported an association between relative L-ficolin deficiency and recurrent respiratory infections co-existing with allergic disorders in children. To confirm and extend this preliminary finding, we performed a prospective study on children of a similar age (mean 8.9 years) designed to establish whether the principal relationship was with infection or allergy. Serum L-ficolin values in healthy children were normally distributed with a mean value of 3838 ng/ml. L-ficolin concentrations were generally lower in patients with asthma and/or allergic rhinitis with (mean 3413 ng/ml; p=0.02) or without (3512 ng/ml; p<0.07) respiratory infections, but not in patients with respiratory infections without allergic disease (3623 ng/ml; p=0.2). The lower average values in the group comprised of children with respiratory allergy and infections were largely due to a high proportion of very low values: 18.3% had values below 2150 ng/ml compared to only 5.5% of healthy controls (OR=3.9; p=0.01). This relationship was not apparent in the groups characterized by allergy without infection or infections without allergy. An association between mannan-binding lectin (MBL) insufficiency and recurrent respiratory infections was also confirmed. One of the patients was MASP-2 deficient, evidenced both by MASP2 genotyping and by lectin pathway activity measurement. In conclusion, L-ficolin may confer some protection from microorganisms that exacerbate allergic inflammation in the lung and its relative deficiency may contribute to enhanced susceptibility to respiratory infections. MBL insufficiency and MASP-2 deficiency are risk factors for recurrence of infections independently of allergic disease.

Two factors of the lectin pathway of complement, l-ficolin and mannan-binding lectin, and their associations with prematurity, low birthweight and infections in a large cohort of Polish neonates

Ficolins and one collectin, mannan-binding lectin (MBL), are the only factors known to activate the lectin pathway (LP) of complement. There is considerable circumstantial evidence that MBL insufficiency can increase susceptibility to various infections and influence the course of several non-infectious diseases complicated by infections. Much less information is available concerning l-ficolin. We report the results of a prospective study to investigate any association between either MBL deficiency or l-ficolin deficiency with prematurity, low birthweight or perinatal infections in a large cohort of Polish neonates, representing an ethnically homogenous population (n=1832). Cord blood samples were analysed to determine mbl-2 gene variants, MBL concentrations and MBL-MASP-2 complex activities (MBL-dependent lectin pathway activity) as well as l-ficolin levels. Median concentrations of l-ficolin and MBL were 2500 and 1124 ng/ml, respectively, while median LP activity was 272 mU/ml. After genotyping, 60.6% of babies were mbl-2 A/A, 35.4% were A/O and 4% were O/O genotypes. We found relative l-ficolin deficiency to be associated with prematurity, low birthweight and infections. l-Ficolin concentration correlated with gestational age and with birthweight, independently of gestational age. Preterm deliveries (<38 weeks) occurred more frequently among neonates with low LP activity but not with those having low serum MBL levels. Similarly, no association of serum MBL deficiency with low birthweight was found, but there was a correlation between LP activity and birthweight. Genotypes conferring very low serum MBL concentrations were associated with perinatal infections, and high-MBL-conferring genotypes were associated with prematurity. Our findings suggest that l-ficolin participates in host defence during the perinatal period and constitute the first evidence that relative l-ficolin deficiency may contribute to the adverse consequences of prematurity. Some similar trends were found with facets of MBL deficiency, but the observed relationships were weaker and less consistent.

Extremes of L-ficolin concentration in children with recurrent infections are associated with single nucleotide polymorphisms in the FCN2 gene

L-ficolin (also called ficolin-2, P35 or hucolin) is a soluble pattern recognition molecule of suspected importance in anti-microbial immunity. It activates the lectin pathway of complement and acts as an opsonin. l-ficolin, encoded by the FCN2 gene, recognizes microbial polysaccharides and glycoconjugates rich in GlcNAc or GalNAc. We report here data concerning four single nucleotide polymorphisms (SNPs) of the FCN2 gene and their relationship to l-ficolin serum concentrations. There are two pairs of SNPs in linkage disequilibrium: ss32469536 (located in promoter) with rs7851696 (in exon 8) and ss32469537 (promoter) with ss32469544 (exon 8). We selected groups possessing low or high serum l-ficolin concentrations (or= 4.5 microg/ml, respectively) from Polish children suffering from recurrent respiratory infections (n = 146). Low l-ficolin levels were associated with variant alleles for ss32469536 and rs7851696 and normal alleles for ss32469537 and ss32469544. Conversely, high l-ficolin levels were associated with variant alleles of ss32469537 and ss32469544. FCN2 genotyping should be a valuable additional tool for disease association studies.