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'.

Boosting Antitumour Immunity through Targeted Delivery of Interferon-α.

Immune checkpoint inhibitors (ICIs) have revolutionised cancer immunotherapy but their success is wholly dependent on amplifying an existing immune response directed against the tumour. A recent study by Tsuchiya et al. suggests how the properties of induced pluripotent stem cells (iPSCs) may be exploited for the targeted delivery of interferon-α (IFNα) to elicit an appropriate response.

Induced pluripotent stem cells reprogrammed from primary dendritic cells provide an abundant source of immunostimulatory dendritic cells for use in immunotherapy.

Cell types differentiated from induced pluripotent stem cells (iPSCs) are frequently arrested in their development program, more closely resembling a fetal rather than an adult phenotype, potentially limiting their utility for downstream clinical applications. The fetal phenotype of iPSC-derived dendritic cells (ipDCs) is evidenced by their low expression of MHC class II and costimulatory molecules, impaired secretion of IL-12, and poor responsiveness to conventional maturation stimuli, undermining their use for applications such as immune-oncology. Given that iPSCs display an epigenetic memory of the cell type from which they were originally derived, we investigated the feasibility of reprogramming adult DCs to pluripotency to determine the impact on the phenotype and function of ipDCs differentiated from them.

Directed Differentiation of Human Induced Pluripotent Stem Cells into Dendritic Cells Displaying Tolerogenic Properties and Resembling the CD141 Subset.

The advent of induced pluripotent stem cells (iPSCs) has begun to revolutionize cell therapy by providing a convenient source of rare cell types not normally available from patients in sufficient numbers for therapeutic purposes. In particular, the development of protocols for the differentiation of populations of leukocytes as diverse as naïve T cells, macrophages, and natural killer cells provides opportunities for their scale-up and quality control prior to administration. One population of leukocytes whose therapeutic potential has yet to be explored is the subset of conventional dendritic cells (DCs) defined by their surface expression of CD141.

Harnessing the properties of dendritic cells in the pursuit of immunological tolerance.

The acquisition of self-perpetuating, immunological tolerance specific for graft alloantigens has long been described as the "holy grail" of clinical transplantation. By removing the need for life-long immunosuppression following engraftment, the adverse consequences of immunosuppressive regimens, including chronic infections and malignancy, may be avoided. Furthermore, autoimmune diseases and allergy are, by definition, driven by aberrant immunological responses to ordinarily innocuous antigens.

Beneath the sword of Damocles: regenerative medicine and the shadow of immunogenicity.

Few topics in regenerative medicine have inspired such impassioned debate as the immunogenicity of cell types and tissues differentiated from pluripotent stem cells. While early predictions suggested that tissues derived from allogeneic sources may evade immune surveillance altogether, the pendulum has since swung to the opposite extreme, with reports that the ectopic expression of a few developmental antigens may prompt rejection, even of tissues differentiated from autologous cell lines. Here we review the evidence on which these contradictory claims are based in order to reach an objective assessment of the likely magnitude of the immunological challenges ahead.

Dendritic cells and pluripotency: unlikely allies in the pursuit of immunotherapy.

As the fulcrum on which the balance between the opposing forces of tolerance and immunity has been shown to pivot, dendritic cells (DC) hold significant promise for immune intervention in a variety of disease states. Here we discuss how the directed differentiation of human pluripotent stem cells may address many of the current obstacles to the use of monocyte-derived DC in immunotherapy, providing a novel source of previously inaccessible DC subsets and opportunities for their scale-up, quality control and genetic modification. Indeed, given that it is the immunological legacy DC leave behind that is of therapeutic value, rather than their persistence per se, we propose that immunotherapy should serve as an early target for the clinical application of pluripotent stem cells.

Ultrafiltration with size-exclusion liquid chromatography for high yield isolation of extracellular vesicles preserving intact biophysical and functional properties.

Unlabelled: Extracellular vesicles (EVs) are natural nanoparticles that mediate intercellular transfer of RNA and proteins and are of great medical interest; serving as novel biomarkers and potential therapeutic agents. However, there is little consensus on the most appropriate method to isolate high-yield and high-purity EVs from various biological fluids. Here, we describe a systematic comparison between two protocols for EV purification: ultrafiltration with subsequent liquid chromatography (UF-LC) and differential ultracentrifugation (UC).

A highly optimized protocol for reprogramming cancer cells to pluripotency using nonviral plasmid vectors.

In spite of considerable interest in the field, reprogramming induced pluripotent stem cells (iPSCs) directly from cancer cells has encountered considerable challenges, including the extremely low reprogramming efficiency and instability of cancer-derived iPSCs (C-iPSCs). In this study, we aimed to identify the main obstacles that limit cancer cell reprogramming. Through a detailed multidimensional kinetic optimization, a highly optimized protocol is established for reprogramming C-iPSCs using nonviral plasmid vectors.

Induced pluripotent stem cells: challenges and opportunities for cancer immunotherapy.

Despite recent advances in cancer treatment over the past 30 years, therapeutic options remain limited and do not always offer a cure for malignancy. Given that tumor-associated antigens (TAA) are, by definition, self-proteins, the need to productively engage autoreactive T cells remains at the heart of strategies for cancer immunotherapy. These have traditionally focused on the administration of autologous monocyte-derived dendritic cells (moDC) pulsed with TAA, or the ex vivo expansion and adoptive transfer of tumor-infiltrating lymphocytes (TIL) as a source of TAA-specific cytotoxic T cells (CTL).

Immune privilege of stem cells.

Immune privilege provides protection to vital tissues or cells of the body when foreign antigens are introduced into these sites. The modern concept of relative immune privilege applies to a variety of tissues and anatomical structures, including the hair follicles and mucosal surfaces. Even sites of chronic inflammation and developing tumors may acquire immune privilege by recruiting immunoregulatory effector cells.

Interaction of Salmonella typhimurium with dendritic cells derived from pluripotent embryonic stem cells.

Using an in vitro differentiation protocol we isolated cells with the properties of dendritic cells (DCs) from immunologically refractive pluripotent murine embryonic stem cells (ESCs). These ES-derived dendritic cells (ESDCs) expressed cytokines and were able to present antigen to a T cell line. Infection of ESDCs with Salmonella Typhimurium stimulated the expression of immune cell markers and thousands of murine genes, many associated with the immune response.

Cross presentation of antigen by dendritic cells: mechanisms and implications for immunotherapy.

Dendritic cells (DCs) possess the specialized potential to present exogenously derived antigen to cytotoxic T lymphocytes to elicit an immune response. This process, termed cross presentation, is crucial in the generation of immune response to viruses, tumors and in autoimmune disease. The ability of DCs to cross-present exogenous antigen to cytotoxic T lymphocytes makes them an attractive target for exploitation in immunotherapy.

Rapamycin conditioning of dendritic cells differentiated from human ES cells promotes a tolerogenic phenotype.

While human embryonic stem cells (hESCs) may one day facilitate the treatment of degenerative diseases requiring cell replacement therapy, the success of regenerative medicine is predicated on overcoming the rejection of replacement tissues. Given the role played by dendritic cells (DCs) in the establishment of immunological tolerance, we have proposed that DC, rendered tolerogenic during their differentiation from hESC, might predispose recipients to accept replacement tissues. As a first step towards this goal, we demonstrate that DC differentiated from H1 hESCs (H1-DCs) are particularly responsive to the immunosuppressive agent rapamycin compared to monocyte-derived DC (moDC).

Optimization of protocols for derivation of mouse embryonic stem cell lines from refractory strains, including the non obese diabetic mouse.

The derivation of pluripotent embryonic stem cells (ESCs) from a variety of genetic backgrounds remains a desirable objective in the generation of mice functionally deficient in genes of interest and the modeling of human disease. Nevertheless, disparity in the ease with which different strains of mice yield ESC lines has long been acknowledged. Indeed, the generation of bona fide ESCs from the non obese diabetic (NOD) mouse, a well-characterized model of human type I diabetes, has historically proved especially difficult to achieve.

Differentiation of dendritic cells from human embryonic stem cells.

Improving our understanding of the interactions between human dendritic cells (DCs) and T cells may contribute to the development of therapeutic strategies for a variety of immune-mediated disorders. The possibility of using DCs themselves as tools to manipulate immune responses opens even greater therapeutic avenues. Current methods of generating human DCs are both inadequate and susceptible to high levels of variability between individuals.

Pharmacological manipulation of dendritic cells in the pursuit of transplantation tolerance.

Purpose Of Review: Although long-term immune suppression remains the intervention of choice for the treatment of allograft rejection, transplantation tolerance would achieve graft survival with fewer inherent risks. Although the use of dendritic cells for the induction of tolerance might confer antigen specificity, factors determining the balance between tolerogenicity and immunogenicity remain uncertain, as does the stability of the functional phenotype. Here, we review recent studies suggesting that pharmacological agents may profoundly influence this delicate balance and outline the insights they provide into parameters that contribute to the tolerogenic state.

Human induced pluripotent stem cells are capable of B-cell lymphopoiesis.

Induced pluripotent stem (iPS) cells offer a unique potential for understanding the molecular basis of disease and development. Here we have generated several human iPS cell lines, and we describe their pluripotent phenotype and ability to differentiate into erythroid cells, monocytes, and endothelial cells. More significantly, however, when these iPS cells were differentiated under conditions that promote lympho-hematopoiesis from human embryonic stem cells, we observed the formation of pre-B cells.

The challenge of immunogenicity in the quest for induced pluripotency.

Few advances have been so widely acclaimed in biology as the seminal demonstration that adult somatic cells can be induced to acquire the phenotype and differentiation potential of embryonic stem cells. The capacity to produce patient-specific stem cells that are truly pluripotent has raised prospects for the treatment of many degenerative diseases through replacement of the affected cell types. In the race to the clinic, however, questions surrounding the potential immunogenicity of such cells have been largely overlooked.

A role for regulatory T cells in acceptance of ESC-derived tissues transplanted across an major histocompatibility complex barrier.

We have previously reported that ESC-derived tissues are subject to some level of immune privilege, which might facilitate induction of immune tolerance. Herein, we further demonstrate that fully allogeneic ESC-derived tissues are accepted with a regimen of coreceptor blockade even in recipients known to be relatively resistant to such a tolerizing protocol. Moreover, ESC-derived tissues could be spontaneously accepted across a class I major histocompatibility complex disparity.

Approaches for immunological tolerance induction to stem cell-derived cell replacement therapies.

The shortage of donors for organ transplantation and also to treat degenerative diseases has led to the development of the new field of regenerative medicine. One aim of this field, in addition to in vivo induction of endogenous tissue regeneration, is to utilize stem cells as a supplementary source of cells to repair or replace tissues or organs that have ceased to function owing to ageing or autoimmunity. Embryonic stem cells hold promise in this respect because of their developmental capacity to generate all tissues within the body.

Tolerogenicity is not an absolute property of a dendritic cell.

Pharmacological modulation is known to temper the immune capacity of DC, enhancing the notion that modulated Ag-bearing DC might be used therapeutically to induce tolerance. We have investigated phenotypic features shared by such DC, and queried their potential to tolerize in different settings. Immature, IL-10, TGF-beta and 1alpha,25-dihydroxyvitamin D(3)-modulated BMDC all induced tolerance to male skin in female TCR transgenic A1.

Generation of immunogenic dendritic cells from human embryonic stem cells without serum and feeder cells.

Aim: Dendritic cell (DC)-based vaccines have a potential utility for use in the treatment of malignancy. Human embryonic stem cells (hESCs) may provide a more cost-effective and reliable source of DCs for immunotherapy purposes, providing on-demand access for patients.

Method: We developed a protocol to generate DCs from hESCs in vitro in the absence of serum and feeder cells.