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

Umbilical Cord Blood Hematopoietic Cells: From Biology to Hematopoietic Transplants and Cellular Therapies

Umbilical cord blood (UCB) is a rich source of hematopoietic stem and progenitor cells that are biologically superior to their adult counterparts. UCB cells can be stored for several years without compromising their numbers or function. Today, public and private UCB banks have been established in several countries around the world. After 35 years since the first UCB transplant (UCBT), more than 50,000 UCBTs have been performed worldwide. In pediatric patients, UCBT is comparable to or superior to bone marrow transplantation. In adult patients, UCB can be an alternative source of hematopoietic cells when an HLA-matched unrelated adult donor is not available and when a transplant is urgently needed. Delayed engraftment (due to reduced absolute numbers of hematopoietic cells) and higher costs have led many medical institutions not to consider UCB as a first-line cell source for hematopoietic transplants. As a result, the use of UCB as a source of hematopoietic stem and progenitor cells for transplantation has declined over the past decade. Several approaches are being investigated to make UCBTs more efficient, including improving the homing capabilities of primitive UCB cells and increasing the number of hematopoietic cells to be infused. Several of these approaches have already been applied in the clinic with promising results. UCB also contains immune effector cells, including monocytes and various lymphocyte subsets, which, together with stem and progenitor cells, are excellent candidates for the development of cellular therapies for hematological and non-hematological diseases.

iPS cell therapy 2.0: Preparing for next-generation regenerative medicine

This year marks the tenth anniversary of the world's first transplantation of tissue generated from induced pluripotent stem cells (iPSCs). There is now a growing number of clinical trials worldwide examining the efficacy and safety of autologous and allogeneic iPSC-derived products for treating various pathologic conditions. As we patiently wait for the results from these and future clinical trials, it is imperative to strategize for the next generation of iPSC-based therapies. This review examines the lessons learned from the development of another advanced cell therapy, chimeric antigen receptor (CAR) T cells, and the possibility of incorporating various new bioengineering technologies in development, from RNA engineering to tissue fabrication, to apply iPSCs not only as a means to achieve personalized medicine but also as designer medical applications.

Regenerative treatment of ophthalmic diseases with stem cells: Principles, progress, and challenges

Background

Degenerate eye disorders, such as glaucoma, cataracts and age-related macular degeneration (AMD), are prevalent causes of blindness and visual impairment worldwide. Other eye disorders, including limbal stem cell deficiency (LSCD), dry eye diseases (DED), and retinitis pigmentosa (RP), result in symptoms such as ocular discomfort and impaired visual function, significantly impacting quality of life. Traditional therapies are limited, primarily focus on delaying disease progression, while emerging stem cell therapy directly targets ocular tissues, aiming to restore ocular function by reconstructing ocular tissue.

Main text

The utilization of stem cells for the treatment of diverse degenerative ocular diseases is becoming increasingly significant, owing to the regenerative and malleable properties of stem cells and their functional cells. Currently, stem cell therapy for ophthalmopathy involves various cell types, such as embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs), mesenchymal stem cells (MSCs), and retinal progenitor cells (RPCs). In the current article, we will review the current progress regarding the utilization of stem cells for the regeneration of ocular tissue covering key eye tissues from the cornea to the retina. These therapies aim to address the loss of functional cells, restore damaged ocular tissue and or in a paracrine-mediated manner. We also provide an overview of the ocular disorders that stem cell therapy is targeting, as well as the difficulties and opportunities in this field.

Conclusions

Stem cells can not only promote tissue regeneration but also release exosomes to mitigate inflammation and provide neuroprotection, making stem cell therapy emerge as a promising approach for treating a wide range of eye disorders through multiple mechanisms.

Induced pluripotent stem cells (iPSCs): molecular mechanisms of induction and applications

The induced pluripotent stem cell (iPSC) technology has transformed in vitro research and holds great promise to advance regenerative medicine. iPSCs have the capacity for an almost unlimited expansion, are amenable to genetic engineering, and can be differentiated into most somatic cell types. iPSCs have been widely applied to model human development and diseases, perform drug screening, and develop cell therapies. In this review, we outline key developments in the iPSC field and highlight the immense versatility of the iPSC technology for in vitro modeling and therapeutic applications. We begin by discussing the pivotal discoveries that revealed the potential of a somatic cell nucleus for reprogramming and led to successful generation of iPSCs. We consider the molecular mechanisms and dynamics of somatic cell reprogramming as well as the numerous methods available to induce pluripotency. Subsequently, we discuss various iPSC-based cellular models, from mono-cultures of a single cell type to complex three-dimensional organoids, and how these models can be applied to elucidate the mechanisms of human development and diseases. We use examples of neurological disorders, coronavirus disease 2019 (COVID-19), and cancer to highlight the diversity of disease-specific phenotypes that can be modeled using iPSC-derived cells. We also consider how iPSC-derived cellular models can be used in high-throughput drug screening and drug toxicity studies. Finally, we discuss the process of developing autologous and allogeneic iPSC-based cell therapies and their potential to alleviate human diseases.

Innovations in bio-engineering and cell-based approaches to address immunological challenges in islet transplantation

Human allogeneic pancreatic islet transplantation is a life-changing treatment for patients with severe Type 1 Diabetes (T1D) who suffer from hypoglycemia unawareness and high risk of severe hypoglycemia. However, intensive immunosuppression is required to prevent immune rejection of the graft, that may in turn lead to undesirable side effects such as toxicity to the islet cells, kidney toxicity, occurrence of opportunistic infections, and malignancies. The shortage of cadaveric human islet donors further limits islet transplantation as a treatment option for widespread adoption. Alternatively, porcine islets have been considered as another source of insulin-secreting cells for transplantation in T1D patients, though xeno-transplants raise concerns over the risk of endogenous retrovirus transmission and immunological incompatibility. As a result, technological advancements have been made to protect transplanted islets from immune rejection and inflammation, ideally in the absence of chronic immunosuppression, to improve the outcomes and accessibility of allogeneic islet cell replacement therapies. These include the use of microencapsulation or macroencapsulation devices designed to provide an immunoprotective environment using a cell-impermeable layer, preventing immune cell attack of the transplanted cells. Other up and coming advancements are based on the use of stem cells as the starting source material for generating islet cells 'on-demand'. These starting stem cell sources include human induced pluripotent stem cells (hiPSCs) that have been genetically engineered to avoid the host immune response, curated HLA-selected donor hiPSCs that can be matched with recipients within a given population, and multipotent stem cells with natural immune privilege properties. These strategies are developed to provide an immune-evasive cell resource for allogeneic cell therapy. This review will summarize the immunological challenges facing islet transplantation and highlight recent bio-engineering and cell-based approaches aimed at avoiding immune rejection, to improve the accessibility of islet cell therapy and enhance treatment outcomes. Better understanding of the different approaches and their limitations can guide future research endeavors towards developing more comprehensive and targeted strategies for creating a more tolerogenic microenvironment, and improve the effectiveness and sustainability of islet transplantation to benefit more patients.

Beneath the radar: immune-evasive cell sources for stroke therapy

Stem cell therapy is an emerging treatment paradigm for stroke patients with remaining neurological deficits. While allogeneic cell transplants overcome the manufacturing constraints of autologous grafts, they can be rejected by the recipient's immune system, which identifies foreign cells through the human leukocyte antigen (HLA) system. The heterogeneity of HLA molecules in the human population would require a very high number of cell lines, which may still be inadequate for patients with rare genetic HLAs. Here, we outline key progress in genetic HLA engineering in pluripotent stem and derived cells to evade the host's immune system, reducing the number of allogeneic cell lines required, and examine safety measures explored in both preclinical studies and upcoming clinical trials.

HLA-based banking of induced pluripotent stem cells in Saudi Arabia

BACKGROUND

Human iPSCs' derivation and use in clinical studies are transforming medicine. Yet, there is a high cost and long waiting time associated with autologous iPS-based cellular therapy, and the genetic engineering of hypo-immunogenic iPS cell lines is hampered with numerous hurdles. Therefore, it is increasingly interesting to create cell stocks based on HLA haplotype distribution in a given population. This study aimed to assess the potential of HLA-based iPS banking for the Saudi population.

METHODS

In this study, we interrogated the HLA database of the Saudi Stem Cell Donor Registry (SSCDR), containing high-resolution HLA genotype data from 64,315 registered Saudi donors at the time of analysis. This database was considered to be a representative sample of the Saudi population. The most frequent HLA haplotypes in the Saudi population were determined, and an in-house developed iterative algorithm was used to identify their HLA matching percentages in the SSCDR database and cumulative coverage. Subsequently, to develop a clinically relevant protocol for iPSCs generation, and to illustrate the applicability of the concept of HLA-based banking for cell therapy purposes, the first HLA-based iPS cell line in Saudi Arabia was generated. Clinically relevant methods were employed to generate the two iPS clones from a homozygous donor for the most prevalent HLA haplotype in the Saudi population. The generated lines were then assessed for pluripotency markers, and their ability to differentiate into all three germ layers, beating cardiomyocytes, and neural progenitors was examined. Additionally, the genetic stability of the HLA-iPS cell lines was verified by comparing the mutational burden in the clones and the original blood sample, using whole-genome sequencing. The standards set by the American College of Medical Genetics and Genomics (ACMG) were used to determine the clinical significance of identified variants.

RESULTS

The analysis revealed that the establishment of only 13 iPSC lines would match 30% of the Saudi population, 39 lines would attain 50% coverage, and 596 lines would be necessary for over 90% coverage. The proof-of-concept HLA-iPSCs, which cover 6.1% of the Saudi population, successfully demonstrated pluripotency and the ability to differentiate into various cell types including beating cardiomyocytes and neuronal progenitors. The comprehensive genetic analysis corroborated that all identified variants in the derived iPSCs were inherently present in the original donor sample and were classified as benign according to the standards set by the ACMG.

CONCLUSIONS

Our study sets a road map for introducing iPS-based cell therapy in the Kingdom of Saudi Arabia. It underscores the pragmatic approach of HLA-based iPSC banking which circumvents the limitations of autologous iPS-based cellular therapies. The successful generation and validation of iPSC lines based on the most prevalent HLA haplotype in the Saudi population signify a promising step toward broadening the accessibility and applicability of stem cell therapies and regenerative medicine in Saudi Arabia.

Generation of a bank of clinical-grade, HLA-homozygous iPSC lines with high coverage of the Spanish population

BACKGROUND

Induced pluripotent stem cell (iPSC)-derived cell therapies are an interesting new area in the field of regenerative medicine. One of the approaches to decrease the costs of iPSC-derived therapies is the use of allogenic homozygous human leukocyte antigen (HLA)-matched donors to generate iPSC lines and to build a clinical-grade iPSC bank covering a high percentage of the Spanish population.

METHODS

The Spanish Stem Cell Transplantation Registry was screened for cord blood units (CBUs) homozygous for the most common HLA-A, HLA-B and HLA-DRB1 haplotypes. Seven donors were selected with haplotypes covering 21.37% of the haplotypes of the Spanish population. CD34-positive hematopoietic progenitors were isolated from the mononuclear cell fraction of frozen cord blood units from each donor by density gradient centrifugation and further by immune magnetic labeling and separation using purification columns. Purified CD34 + cells were reprogrammed to iPSCs by transduction with the CTS CytoTune-iPS 2.1 Sendai Reprogramming Kit.

RESULTS

The iPSCs generated from the 7 donors were expanded, characterized, banked and registered. Master cell banks (MCBs) and working cell banks (WCBs) from the iPSCs of each donor were produced under GMP conditions in qualified clean rooms.

CONCLUSIONS

Here, we present the first clinical-grade, iPSC haplobank in Spain made from CD34 + cells from seven cord blood units homozygous for the most common HLA-A, HLA-B and HLA-DRB1 haplotypes within the Spanish population. We describe their generation by transduction with Sendai viral vectors and their GMP-compliant expansion and banking. These haplolines will constitute starting materials for advanced therapy medicinal product development (ATMP).

Challenges of CRISPR/Cas-Based Cell Therapy for Type 1 Diabetes: How Not to Engineer a "Trojan Horse"

Type 1 diabetes mellitus (T1D) is an autoimmune disease caused by the destruction of insulin-producing β-cells in the pancreas by cytotoxic T-cells. To date, there are no drugs that can prevent the development of T1D. Insulin replacement therapy is the standard care for patients with T1D. This treatment is life-saving, but is expensive, can lead to acute and long-term complications, and results in reduced overall life expectancy. This has stimulated the research and development of alternative treatments for T1D. In this review, we consider potential therapies for T1D using cellular regenerative medicine approaches with a focus on CRISPR/Cas-engineered cellular products. However, CRISPR/Cas as a genome editing tool has several drawbacks that should be considered for safe and efficient cell engineering. In addition, cellular engineering approaches themselves pose a hidden threat. The purpose of this review is to critically discuss novel strategies for the treatment of T1D using genome editing technology. A well-designed approach to β-cell derivation using CRISPR/Cas-based genome editing technology will significantly reduce the risk of incorrectly engineered cell products that could behave as a "Trojan horse".

Creating an HLA-homozygous iPS cell bank for the Brazilian population: Challenges and opportunities

Identifying human leukocyte antigen (HLA) haplotype-homozygous donors for the generation of induced pluripotent stem (iPS) cell lines permits the construction of biobanks immunologically compatible with significant numbers of individuals for use in therapy. However, two questions must be addressed to create such a bank: how many cell lines are necessary to match most of the recipient population and how many people should be tested to find these donors? In Japan and the UK, 50 and 100 distinct HLA-A, -B, and -DRB1 triple-homozygous haplotypes would cover 90% of those populations, respectively. Using data from the Brazilian National Registry of Bone Marrow Donors (REDOME), encompassing 4,017,239 individuals, we identified 1,906 distinct triple-homozygous HLA haplotypes. In Brazil, 559 triple-homozygous cell lines cover 95% of the population, and 3.8 million people would have to be screened. Finally, we show the contribution of the 30 most frequent triple-homozygous HLA haplotypes in Brazil to populations of different countries.

Factors Affecting Stem Cell-Based Regenerative Approaches in Retinal Degeneration

Inherited and age-associated vision loss is often associated with degeneration of the cells of the retina, the light-sensitive layer at the back of the eye. The mammalian retina, being a postmitotic neural tissue, does not have the capacity to repair itself through endogenous regeneration. There has been considerable excitement for the development of cell replacement approaches since the isolation and development of culture methods for human pluripotent stem cells, as well as the generation of induced pluripotent stem cells. This has now been combined with novel three-dimensional organoid culture systems that closely mimic human retinal development in vitro. In this review, we cover the current state of the field, with emphasis on the cell delivery challenges, role of the recipient immunological microenvironment, and challenges related to connectivity between transplanted cells and host circuitry both locally and centrally to the different areas of the brain.

Potency assays and biomarkers for cell-based advanced therapy medicinal products

Advanced Therapy Medicinal Products (ATMPs) based on somatic cells expanded in vitro, with or without genetic modification, is a rapidly growing area of drug development, even more so following the marketing approval of several such products. ATMPs are produced according to Good Manufacturing Practice (GMP) in authorized laboratories. Potency assays are a fundamental aspect of the quality control of the end cell products and ideally could become useful biomarkers of efficacy in vivo. Here we summarize the state of the art with regard to potency assays used for the assessment of the quality of the major ATMPs used clinic settings. We also review the data available on biomarkers that may substitute more complex functional potency tests and predict the efficacy in vivo of these cell-based drugs.

Induced pluripotent stem cells in companion animals: how can we move the field forward?

Following a one medicine approach, the development of regenerative therapies for human patients leads to innovative treatments for animals, while pre-clinical studies on animals provide knowledge to advance human medicine. Among many different biological products under investigation, stem cells are among the most prominent. Mesenchymal stromal cells (MSCs) are extensively investigated, but they present challenges such as senescence and limited differentiation ability. Embryonic stem cells (ESCs) are pluripotent cells with a virtually unlimited capacity for self-renewal and differentiation, but the use of embryos carries ethical concerns. Induced pluripotent stem cells (iPSCs) can overcome all of these limitations, as they closely resemble ESCs but are derived from adult cells by reprogramming in the laboratory using pluripotency-associated transcription factors. iPSCs hold great potential for applications in therapy, disease modeling, drug screening, and even species preservation strategies. However, iPSC technology is less developed in veterinary species compared to human. This review attempts to address the specific challenges associated with generating and applying iPSCs from companion animals. Firstly, we discuss strategies for the preparation of iPSCs in veterinary species and secondly, we address the potential for different applications of iPSCs in companion animals. Our aim is to provide an overview on the state of the art of iPSCs in companion animals, focusing on equine, canine, and feline species, as well as to identify which aspects need further optimization and, where possible, to provide guidance on future advancements. Following a "step-by-step" approach, we cover the generation of iPSCs in companion animals from the selection of somatic cells and the reprogramming strategies, to the expansion and characterization of iPSCs. Subsequently, we revise the current applications of iPSCs in companion animals, identify the main hurdles, and propose future paths to move the field forward. Transferring the knowledge gained from human iPSCs can increase our understanding in the biology of pluripotent cells in animals, but it is critical to further investigate the differences among species to develop specific approaches for animal iPSCs. This is key for significantly advancing iPSC application in veterinary medicine, which at the same time will also allow gaining pre-clinical knowledge transferable to human medicine.

A clinical-grade HLA haplobank of human induced pluripotent stem cells matching approximately 40% of the Japanese population

BACKGROUND

Human induced pluripotent stem cells (iPSCs) are expected to be useful for regenerative medicine for many diseases. Many researchers have focused on and enabled the generation of differentiated cells or tissue-like structures, including organoids, which help to ameliorate target diseases. To promote such cell therapies, we established a clinically applicable iPSC haplobank matching as many people as possible in Japan.

METHODS

Through cooperation with several organizations, we recruited donors whose human leukocyte antigens (HLAs) involved in immunorejection were homozygous. The peripheral or umbilical cord blood collected from the donors was used for iPSC production by electroporation of episomal vectors. These iPSC lines were then subjected to testing, including genome analyses and sterility, to maximize safety.

FINDINGS

We constructed a clinical-grade haplobank of 27 iPSC lines from 7 donors according to good manufacturing practice regulations. However, reasons to avoid using iPSC lines include the presence of residual episomal vectors or genetic mutations in cancer-related genes.

CONCLUSIONS

This haplobank provides HLA-matched iPSC lines for approximately 40% of the Japanese population. Since the haplobank's release in 2015, these iPSC lines have been used in more than 10 clinical trials. The establishment of this haplobank is an important step toward the clinical application of iPSCs in cell therapies.

FUNDING

This study was supported by a research center network for the realization of regenerative medicine of the Japan Agency for Medical Research and Development (AMED) under grant number JP20bm0104001h0108.

Umbilical cord blood: an undervalued and underutilized resource in allogeneic hematopoietic stem cell transplant and novel cell therapy applications

PURPOSE OF REVIEW

The purpose of this review is to primarily discuss the unwarranted decline in the use of umbilical cord blood (UCB) as a source of donor hematopoietic stem cells (HSC) for hematopoietic cell transplantation (HCT) and the resulting important implications in addressing healthcare inequities, and secondly to highlight the incredible potential of UCB and related birthing tissues for the development of a broad range of therapies to treat human disease including but not limited to oncology, neurologic, cardiac, orthopedic and immunologic conditions.

RECENT FINDINGS

When current best practices are followed, unrelated donor umbilical cord blood transplant (CBT) can provide superior quality of life-related survival compared to other allogeneic HSC donor sources (sibling, matched or mismatched unrelated, and haploidentical) through decreased risks of relapse and chronic graft vs. host disease. Current best practices include improved UCB donor selection criteria with consideration of higher resolution human leukocyte antigen (HLA) typing and CD34+ cell dose, availability of newer myeloablative but reduced toxicity conditioning regimens, and rigorous supportive care in the early posttransplant period with monitoring for known complications, especially related to viral and other infections that may require intervention. Emerging best practice may include the use of ex vivo expanded single-unit CBT rather than double-unit CBT (dCBT) or 'haplo-cord' transplant, and the incorporation of posttransplant cyclophosphamide as with haploidentical transplant and/or incorporation of novel posttransplant therapies to reduce the risk of relapse, such as NK cell adoptive transfer. Novel, non-HCT uses of UCB and birthing tissue include the production of UCB-derived immune effector cell therapies such as unmodified NK cells, chimeric antigen receptor-natural killer cells and immune T-cell populations, the isolation of mesenchymal stem cells for immune modulatory treatments and derivation of induced pluripotent stem cells haplobanks for regenerative medicine development and population studies to facilitate exploration of drug development through functional genomics.

SUMMARY

The potential of allogeneic UCB for HCT and novel cell-based therapies is undervalued and underutilized. The inventory of high-quality UCB units available from public cord blood banks (CBB) should be expanding rather than contracting in order to address ongoing healthcare inequities and to maintain a valuable source of cellular starting material for cell and gene therapies and regenerative medicine approaches. The expertise in Good Manufacturing Practice-grade manufacturing provided by CBB should be supported to effectively partner with groups developing UCB for novel cell-based therapies.

Blood donor biobank and HLA imputation as a resource for HLA homozygous cells for therapeutic and research use

Background

Allogeneic therapeutic cells may be rejected if they express HLA alleles not found in the recipient. As finding cell donors with a full HLA match to a recipient requires vast donor pools, the use of HLA homozygous cells has been suggested as an alternative. HLA homozygous cells should be well tolerated by those who carry at least one copy of donor HLA alleles. HLA-A-B homozygotes could be valuable for HLA-matched thrombocyte products. We evaluated the feasibility of blood donor biobank and HLA imputation for the identification of potential cell donors homozygous for HLA alleles.

Methods

We imputed HLA-A, -B, -C, -DRB1, -DQA1, -DQB1 and -DPB1 alleles from genotypes of 20,737 Finnish blood donors in the Blood Service Biobank. We confirmed homozygosity by sequencing HLA alleles in 30 samples and by examining 36,161 MHC-located polymorphic DNA markers.

Results

Three hundred and seventeen individuals (1.5%), representing 41 different haplotypes, were found to be homozygous for HLA-A, -B, -C, -DRB1, -DQA1 and -DQB1 alleles. Ten most frequent haplotypes homozygous for HLA-A to -DQB1 were HLA-compatible with 49.5%, and three most frequent homozygotes to 30.4% of the Finnish population. Ten most frequent HLA-A-B homozygotes were compatible with 75.3%, and three most frequent haplotypes to 42.6% of the Finnish population. HLA homozygotes had a low level of heterozygosity in MHC-located DNA markers, in particular in HLA haplotypes enriched in Finland.

Conclusions

The present study shows that HLA imputation in a blood donor biobank of reasonable size can be used to identify HLA homozygous blood donors suitable for cell therapy, HLA-typed thrombocytes and research. The homozygotes were HLA-compatible with a large fraction of the Finnish population. Regular blood donors reported to have positive attitude to research donation appear a good option for these purposes. Differences in population frequencies of HLA haplotypes emphasize the need for population-specific collections of HLA homozygous samples.

Identification and Re-consent of Existing Cord Blood Donors for Creation of Induced Pluripotent Stem Cell Lines for Potential Clinical Applications

We aim to create a bank of clinical grade cord blood-derived induced pluripotent stem cell lines in order to facilitate clinical research leading to the development of new cellular therapies. Here we present a clear pathway toward the creation of such a resource, within a strong quality framework, and with the appropriate regulatory, government and ethics approvals, along with a dynamic follow-up and re-consent process of cord blood donors from the public BMDI Cord Blood Bank. Interrogation of the cord blood bank inventory and next generation sequencing was used to identify and confirm 18 donors with suitable HLA homozygous haplotypes. Regulatory challenges that may affect global acceptance of the cell lines, along with the quality standards required to operate as part of a global network, are being met by working in collaboration with bodies such as the International Stem Cell Banking Initiative (ISCBI) and the Global Alliance for iPSC Therapies (GAiT). Ethics approval was granted by an Institutional Human Research Ethics Committee, and government approval has been obtained to use banked cord blood for this purpose. New issues of whole-genome sequencing and the relevant donor safeguards and protections were considered with input from clinical genetics services, including the rights and information flow to donors, and commercialization aspects. The success of these processes has confirmed feasibility and utility of using banked cord blood to produce clinical-grade iPSC lines for potential cellular therapies.

Public Cord Blood Banks as a source of starting material for clinical grade HLA-homozygous induced pluripotent stem cells

BACKGROUND

The increasing number of clinical trials for induced pluripotent stem cell (iPSC)-derived cell therapy products makes the production on clinical grade iPSC more and more relevant and necessary. Cord blood banks are an ideal source of young, HLA-typed and virus screened starting material to produce HLA-homozygous iPSC lines for wide immune-compatibility allogenic cell therapy approaches. The production of such clinical grade iPSC lines (haplolines) involves particular attention to all steps since donor informed consent, cell procurement and a GMP-compliant cell isolation process.

METHODS

Homozygous cord blood units were identified and quality verified before recontacting donors for informed consent. CD34+ cells were purified from the mononuclear fraction isolated in a cell processor, by magnetic microbeads labelling and separation columns.

RESULTS

We obtained a median recovery of 20.0% of the collected pre-freezing CD34+, with a final product median viability of 99.1% and median purity of 83.5% of the post-thawed purified CD34+ population.

CONCLUSIONS

Here we describe our own experience, from unit selection and donor reconsenting, in generating a CD34+ cell product as a starting material to produce HLA-homozygous iPSC following a cost-effective and clinical grade-compliant procedure. These CD34+ cells are the basis for the Spanish bank of haplolines envisioned to serve as a source of cell products for clinical research and therapy.

Generation of universal natural killer cells from a cryopreserved cord blood mononuclear cell-derived induced pluripotent stem cell library

Natural killer (NK) cells play a key role in innate immunity and are regarded as a promising candidate for cellular immunotherapy. Natural killer cells may be generated from different sources, including induced pluripotent stem cells (iPSCs); these stem cells produce an abundant amount of NK cells to meet the needs of a wide range of clinical applications. Autologous iPSCs are expensive and labor-intensive to prepare, while allogeneic iPSCs require human leukocyte antigen (HLA) matched cells to avoid the risk of immune rejection. In the current study, we prepared HLA-matched iPSCs using HLA common haplotype homozygous (HLAh) donors from cryopreserved human cord blood (CB) sourced from the Tianjin Cord Blood Public Bank. This approach was designed to generate a CB-derived iPSC library from HLAh donors and use it to produce off-the-shelf NK cells. Starting with readily available cryopreserved CB mononuclear cells (cryoCBMCs), we produced cryoCBMC-derived iPSCs (cryoCB-iPSCs). These cryoCB-iPSCs were induced to generate embryoid bodies (EBs) using an improved 3D suspension culture method, and induced NK (iNK) cells were differentiated from EBs. iNK cells expressed specific surface markers of NK cells, exhibited cytotoxicity comparable with NK cells generated from CB (CB-NK) and peripheral blood (PB-NK), and expressed lower levels of KIRs and HLA-DR compared to CB-NK and PB-NK. Taken together, we have shown that an iPSC library can be established from HLAh cryoCBMCs, and cryoCB-iPSCs can be used to generate a large number of 'universal' NK cells for future clinical applications.

Utility of iPSC-Derived Cells for Disease Modeling, Drug Development, and Cell Therapy

The advent of induced pluripotent stem cells (iPSCs) has advanced our understanding of the molecular mechanisms of human disease, drug discovery, and regenerative medicine. As such, the use of iPSCs in drug development and validation has shown a sharp increase in the past 15 years. Furthermore, many labs have been successful in reproducing many disease phenotypes, often difficult or impossible to capture, in commonly used cell lines or animal models. However, there still remain limitations such as the variability between iPSC lines as well as their maturity. Here, we aim to discuss the strategies in generating iPSC-derived cardiomyocytes and neurons for use in disease modeling, drug development and their use in cell therapy.

Cellular interplay between cardiomyocytes and non-myocytes in diabetic cardiomyopathy

Patients with Type 2 diabetes mellitus (T2DM) frequently exhibit a distinctive cardiac phenotype known as diabetic cardiomyopathy. Cardiac complications associated with T2DM include cardiac inflammation, hypertrophy, fibrosis and diastolic dysfunction in the early stages of the disease, which can progress to systolic dysfunction and heart failure. Effective therapeutic options for diabetic cardiomyopathy are limited and often have conflicting results. The lack of effective treatments for diabetic cardiomyopathy is due in part, to our poor understanding of the disease development and progression, as well as a lack of robust and valid preclinical human models that can accurately recapitulate the pathophysiology of the human heart. In addition to cardiomyocytes, the heart contains a heterogeneous population of non-myocytes including fibroblasts, vascular cells, autonomic neurons and immune cells. These cardiac non-myocytes play important roles in cardiac homeostasis and disease, yet the effect of hyperglycaemia and hyperlipidaemia on these cell types are often overlooked in preclinical models of diabetic cardiomyopathy. The advent of human induced pluripotent stem cells provides a new paradigm in which to model diabetic cardiomyopathy as they can be differentiated into all cell types in the human heart. This review will discuss the roles of cardiac non-myocytes and their dynamic intercellular interactions in the pathogenesis of diabetic cardiomyopathy. We will also discuss the use of sodium-glucose cotransporter 2 inhibitors as a therapy for diabetic cardiomyopathy and their known impacts on non-myocytes. These developments will no doubt facilitate the discovery of novel treatment targets for preventing the onset and progression of diabetic cardiomyopathy.

The Promoting Equity in Stem Cell Genomics Survey

Aim: This study aimed to determine knowledge and attitudes toward induced pluripotent stem cell technology and biobanking. Methods: A survey instrument was developed to determine individuals' knowledge of and attitudes toward these technologies. Results: Results from 276 ethnically diverse participants who took the online survey demonstrated significant associations (p ≤ 0. 05) in knowledge by ethnicity and race regarding properties of stem cells, different types of stem cells and previous sample donation behavior. Significantly more Whites 39% (n = 53) compared with Blacks or African-Americans 19.2% (n = 14) had previous knowledge of induced pluripotent stem cells (χ² = 8.544; p = 0.003) Conclusion: Overall, White race was associated with greater knowledge about stem cells and biobanks and greater willingness to donate samples for future research.

SUPT4H1-edited stem cell therapy rescues neuronal dysfunction in a mouse model for Huntington's disease

Huntington’s disease (HD) is a severe inherited neurological disorder caused by a CAG repeat expansion in the huntingtin gene (HTT), leading to the accumulation of mutant huntingtin with polyglutamine repeats. Despite its severity, there is no cure for this debilitating disease. HTT lowering strategies, including antisense oligonucleotides (ASO) showed promising results very recently. Attempts to develop stem cell-based therapeutics have shown efficacy in preclinical HD models. Using an HD patient’s autologous cells, which have genetic defects, may hamper therapeutic efficacy due to mutant HTT. Pretreating these cells to reduce mutant HTT expression and transcription may improve the transplanted cells’ therapeutic efficacy. To investigate this, we targeted the SUPT4H1 gene that selectively supports the transcription of long trinucleotide repeats. Transplanting SUPT4H1-edited HD-induced pluripotent stem cell-derived neural precursor cells (iPSC-NPCs) into the YAC128 HD transgenic mouse model improved motor function compared to unedited HD iPSC-NPCs. Immunohistochemical analysis revealed reduced mutant HTT expression without compensating wild-type HTT expression. Further, SUPT4H1 editing increased neuronal and decreased reactive astrocyte differentiation in HD iPSC-NPCs compared to the unedited HD iPSC-NPCs. This suggests that ex vivo editing of SUPT4H1 can reduce mutant HTT expression and provide a therapeutic gene editing strategy for autologous stem cell transplantation in HD.

Stem Cell Transplantation Therapy and Neurological Disorders: Current Status and Future Perspectives

Neurodegenerative diseases are a global health issue with inadequate therapeutic options and an inability to restore the damaged nervous system. With advances in technology, health scientists continue to identify new approaches to the treatment of neurodegenerative diseases. Lost or injured neurons and glial cells can lead to the development of several neurological diseases, including Parkinson's disease, stroke, and multiple sclerosis. In recent years, neurons and glial cells have successfully been generated from stem cells in the laboratory utilizing cell culture technologies, fueling efforts to develop stem cell-based transplantation therapies for human patients. When a stem cell divides, each new cell has the potential to either remain a stem cell or differentiate into a germ cell with specialized characteristics, such as muscle cells, red blood cells, or brain cells. Although several obstacles remain before stem cells can be used for clinical applications, including some potential disadvantages that must be overcome, this cellular development represents a potential pathway through which patients may eventually achieve the ability to live more normal lives. In this review, we summarize the stem cell-based therapies that have been explored for various neurological disorders, discuss the potential advantages and drawbacks of these therapies, and examine future directions for this field.

The Rise of Induced Pluripotent Stem Cell Approach to Hair Restoration

SUMMARY

The advent of pluripotent stem cells following the discovery of Shinya Yamanaka (2012 Nobel prize in Medicine) brought about a regenerative medicine approach to virtually every human condition including hair loss. It is now possible to reprogram somatic cells (eg, blood or skin cells) from a person experiencing hair loss to generate autologous induced pluripotent stem cells (iPSCs), which could be amplified and cryopreserved. Subsequently, these iPSCs could be differentiated into various cell types such as dermal papilla cells, epithelial cells, melanocytes, and other cell types constituting functional hair follicle. Transplantation of human iPSC-derived folliculogenic cells into the nude mice has successfully generated xenografts with hair outgrowth. Because iPSCs provide a virtually unlimited source of folliculogenic cells for de novo formation of hair follicles, this approach has major advantages over current surgical hair restoration procedures, which merely redistribute existing hair follicles from one part of the sculp to another. Combined with robotics and automation of the transplantation process, this novel regenerative medicine approach is well poised to make hair restoration a routine procedure affordable for everybody who can benefit from it.

Somatic Reprogramming-Above and Beyond Pluripotency

Pluripotent stem cells, having long been considered the fountain of youth, have caught the attention of many researchers from diverse backgrounds due to their capacity for unlimited self-renewal and potential to differentiate into all cell types. Over the past 15 years, the advanced development of induced pluripotent stem cells (iPSCs) has displayed an unparalleled potential for regenerative medicine, cell-based therapies, modeling human diseases in culture, and drug discovery. The transcription factor quartet (Oct4, Sox2, Klf4, and c-Myc) reprograms highly differentiated somatic cells back to a pluripotent state recapitulated embryonic stem cells (ESCs) in different aspects, including gene expression profile, epigenetic signature, and functional pluripotency. With the prior fruitful studies in SCNT and cell fusion experiments, iPSC finds its place and implicates that the differentiated somatic epigenome retains plasticity for re-gaining the pluripotency and further stretchability to reach a totipotency-like state. These achievements have revolutionized the concept and created a new avenue in biomedical sciences for clinical applications. With the advent of 15 years’ progress-making after iPSC discovery, this review is focused on how the current concept is established by revisiting those essential landmark studies and summarizing its current biomedical applications status to facilitate the new era entry of regenerative therapy.

Human Neural Stem Cells for Cell-Based Medicinal Products

Neural stem cells represent an attractive tool for the development of regenerative therapies and are being tested in clinical trials for several neurological disorders. Human neural stem cells can be isolated from the central nervous system or can be derived in vitro from pluripotent stem cells. Embryonic sources are ethically controversial and other sources are less well characterized and/or inefficient. Recently, isolation of NSC from the cerebrospinal fluid of patients with spina bifida and with intracerebroventricular hemorrhage has been reported. Direct reprogramming may become another alternative if genetic and phenotypic stability of the reprogrammed cells is ensured. Here, we discuss the advantages and disadvantages of available sources of neural stem cells for the production of cell-based therapies for clinical applications. We review available safety and efficacy clinical data and discuss scalability and quality control considerations for manufacturing clinical grade cell products for successful clinical application.

Umbilical Cord Blood Units Cryopreserved in the Public Cord Blood Bank: A Breakthrough in iPSC Haplobanking?

The use of induced pluripotent stem cells (iPSCs) is an emerging therapeutic option for precision medicine. Cord blood (CB) cells with lower immunogenicity, fewer genomic changes, and persistent epigenetic memory might be ideal candidates for iPSC production. Based on the human leukocyte antigen (HLA) distribution of cord blood units (CBUs) in the public CB bank, we estimated the coverage of the Korean population with HLA-homozygous iPSCs to repurpose cryopreserved CBUs. We analyzed a total of 27,904 Korean CBUs donated to the public CB bank. Low-to-intermediate resolution typing was performed for HLA-A, -B, and -DRB1 alleles, and individuals possessing homozygous HLA haplotypes were identified by direct counting. Moreover, the matching probabilities for zero-mismatch transplantation were calculated for 27,904 CBUs and 50,000,000 potential Korean patients. Among the preserved CBUs, 15 HLA-A, 40 HLA-B, and 13 HLA-DRB1 alleles as well as 48 homozygous HLA-A-B-DRB1 haplotypes were identified at serological equivalents (2 digits). The 48 identified homozygous haplotypes cumulatively matched 78.18% of the 27,904 Korean CB donors as zero HLA-mismatch iPSC sources. Among the combinations of 1,699 haplotypes with frequencies greater than 0.001%, assuming a population of 50 million, those 48 haplotypes can provide a match for 78.37% of potential Korean recipients. A practicable number of HLA-A, -B, and -DRB1 homozygous iPSC lines derived from CBUs may be an efficient option in allogeneic iPSC therapy because this type of haplobanking may provide cell lines with optimal HLA matching for up to three-quarters of the Korean population.

Human iPSC-derived neural precursor cells differentiate into multiple cell types to delay disease progression following transplantation into YAC128 Huntington's disease mouse model

OBJECTIVES

To investigate whether human HLA-homozygous induced pluripotent stem cell (iPSC)-derived neural precursor cells (iPSC-NPCs) can provide functional benefits in Huntington's disease (HD), we transplanted them into the YAC128 transgenic HD mouse model.

MATERIALS AND METHODS

CHAi001-A, an HLA-homozygous iPSC line (A*33:03-B*44:03-DRB1*13:02), was differentiated into neural precursor cells, and then, they were transplanted into 6 months-old YAC128 mice. Various behavioural and histological analyses were performed for five months after transplantation.

RESULTS

Motor and cognitive functions were significantly improved in transplanted animals. Cells transplanted in the striatum showed multipotential differentiation. Five months after transplantation, the donor cells had differentiated into neurons, oligodendrocytes and astrocytes. Transplantation restored DARPP-32 expression, synaptophysin density, myelin basic protein expression in the corpus callosum and astrocyte function.

CONCLUSION

Altogether, these results strongly suggest that iPSC-NPCs transplantation induces neuroprotection and functional recovery in a mouse model of HD and should be taken forward for clinical trials in HD patients.

Human Leukocyte Antigen Class I Pseudo-Homozygous Mesenchymal Stem Cells Derived from Human Induced Pluripotent Stem Cells

Mesenchymal stem cells (MSC) are an important type of cell that are highly recognized for their safety and efficacy as a cell therapy agent. In order to obtain MSC, primary tissues (adipose tissue, bone marrow, and umbilical cord blood) must be used; however, these tissues, especially umbilical cord blood, are difficult to obtain due to various reasons, such as the low birth rate trend. In addition, to maximize the safety and efficacy of MSC as allogenic cell therapeutic agents, it is desirable to minimize the possibility of an immune rejection reaction after in vivo transplantation. This study tried to establish a novel method for producing induced pluripotent stem cells (iPSC)-derived MSC in which the human leukocyte antigen (HLA)-class I gene is knocked out. To do so, dermal fibroblast originated iPSC generation using Yamanaka 4-factor, HLA class I gene edited iPSC generation using CRISPR/Cas9, and differentiation from iPSC to MSC using MSC culture medium was utilized. Through this, HLA-A, B, and C pseudo-homozygous iPSC-derived MSC (KO iMSC) were produced by monoallelically knocking out the polymorphic HLA-A, B, and C genes, which are the major causes of immune rejection during allogenic cell transplantation. Produced KO iMSC possesses multipotency and it was safe in vivo to be able to be differentiated to cartilage. In addition, it was not attacked by natural killer cells unlike HLA class I null cells. In conclusion, KO iMSC that do not induce immune rejection during allogenic cell transplantation can be produced. In the future, KO iMSC can be successfully utilized as allogenic cell therapeutic agents for many recipients through HLA screening.

Immunologic Rejection of Transplanted Retinal Pigmented Epithelium: Mechanisms and Strategies for Prevention

Replacement of dysfunctional retinal pigmented epithelium (RPE) with grafts derived from stem cells has the potential to improve vision for patients with retinal disorders. In fact, the potential is such that a great number of groups are attempting to realize this therapy through individual strategies with a variety of stem cell products, hosts, immunomodulatory regimen, and techniques to assess the success of their design. Comparing the findings of different investigators is complicated by a number of factors. The immune response varies greatly between xenogeneic and allogeneic transplantation. A unique immunologic environment is created in the subretinal space, the target of RPE grafts. Both functional assessment and imaging techniques used to evaluate transplants are susceptible to erroneous conclusions. Lastly, the pharmacologic regimens used in RPE transplant trials are as numerous and variable as the trials themselves, making it difficult to determine useful results. This review will discuss the causes of these complicating factors, digest the strategies and results from clinical and preclinical studies, and suggest places for improvement in the design of future transplants and investigations.

Generation of hypoimmunogenic T cells from genetically engineered allogeneic human induced pluripotent stem cells

Avoiding the immune rejection of transplanted T cells is central to the success of allogeneic cancer immunotherapies. One solution to protecting T-cell grafts from immune rejection involves the deletion of allogeneic factors and of factors that activate cytotoxic immune cells. Here we report the generation of hypoimmunogenic cancer-antigen-specific T cells derived from induced pluripotent stem cells (iPSCs) lacking β₂-microglobulin, the class-II major histocompatibility complex (MHC) transactivator and the natural killer (NK) cell-ligand poliovirus receptor CD155, and expressing single-chain MHC class-I antigen E. In mouse models of CD20-expressing leukaemia or lymphoma, differentiated T cells expressing a CD20 chimeric antigen receptor largely escaped recognition by NKG2A⁺ and DNAM-1⁺ NK cells and by CD8 and CD4 T cells in the allogeneic recipients while maintaining anti-tumour potency. Hypoimmunogenic iPSC-derived T cells may contribute to the creation of off-the-shelf T cell immunotherapies.

Harnessing pluripotent stem cells as models to decipher human evolution

The study of human evolution, long constrained by a lack of experimental model systems, has been transformed by the emergence of the induced pluripotent stem cell (iPSC) field. iPSCs can be readily established from noninvasive tissue sources, from both humans and other primates; they can be maintained in the laboratory indefinitely, and they can be differentiated into other tissue types. These qualities mean that iPSCs are rapidly becoming established as viable and powerful model systems with which it is possible to address questions in human evolution that were until now logistically and ethically intractable, especially in the quest to understand humans' place among the great apes, and the genetic basis of human uniqueness. In this review, we discuss the key lessons and takeaways of this nascent field; from the types of research, iPSCs make possible to lingering challenges and likely future directions. We provide a comprehensive overview of how the seemingly unlikely combination of iPSCs and explicit evolutionary frameworks is transforming what is possible in our understanding of humanity's past and present.

The wider perspective: cord blood banks and their future prospects

Over the past three decades, cord blood transplantation (CBT) has established its role as an alternative allograft stem cell source. But the future of stored CB units should be to extend their use in updated transplant approaches and develop new CB applications. Thus, CBT will require a coordinated, multicentric, review of transplantation methods and an upgrade and realignment of banking resources and operations. Significant improvements have already been proposed to support the clinical perspective including definition of the cellular threshold for engraftment, development of transplantation methods for adult patients, engraftment acceleration with single cell expansion and homing technologies, personalised protocols to improve efficacy, use of adoptive cell therapy to mitigate delayed immune reconstitution, and further enhancement of the graft-versus-leukaemia effect using advanced therapies. The role of CB banks in improving transplantation results are also critical by optimizing the collection, processing, storage and characterization of CB units, and improving reproducibility, efficiency and cost of banking. But future developments beyond transplantation are needed. This implies the extension from transplantation banks to banks that support cell therapy, regenerative medicine and specialized transfusion medicine. This new "CB banking 2.0" concept will require promotion of international scientific and technical collaborations between bank specialists, clinical investigators and transplant physicians.

Evaluation of the Spanish population coverage of a prospective HLA haplobank of induced pluripotent stem cells

Background

iPSC (induced pluripotent stem cells) banks of iPSC lines with homozygous HLA (human leukocyte antigen) haplotypes (haplobanks) are proposed as an affordable and off-the-shelf approach to allogeneic transplantation of iPSC derived cell therapies. Cord blood banks offer an extensive source of HLA-typed cells suitable for reprogramming to iPSC. Several initiatives worldwide have been undertaken to create national and international iPSC haplobanks that match a significant part of a population.

Methods

To create an iPSC haplobank that serves the Spanish population (IPS-PANIA), we have searched the Spanish Bone Marrow Donor Registry (REDMO) to identify the most frequently estimated haplotypes. From the top ten donors identified, we estimated the population coverage using the criteria of zero mismatches in HLA-A, HLA-B, and HLA-DRB1 with different stringencies: high resolution, low resolution, and beneficial mismatch.

Results

We have calculated that ten cord blood units from homozygous donors stored at the Spanish cord blood banks can provide HLA-A, HLA-B, and HLA-DRB1 matching for 28.23% of the population.

Conclusion

We confirm the feasibility of using banked cord blood units to create an iPSC haplobank that will cover a significant percentage of the Spanish and international population for future advanced therapy replacement strategies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02301-0.

Reprogramming: Emerging Strategies to Rejuvenate Aging Cells and Tissues

Aging is associated with a progressive and functional decline of all tissues and a striking increase in many "age-related diseases". Although aging has long been considered an inevitable process, strategies to delay and potentially even reverse the aging process have recently been developed. Here, we review emerging rejuvenation strategies that are based on reprogramming toward pluripotency. Some of these approaches may eventually lead to medical applications to improve healthspan and longevity.

Cord blood beyond transplantation: can we use the experience to advance all cell therapies?

Unrelated cord blood (CB) units, already manufactured, fully tested and stored, are high-quality products for haematopoietic stem cell transplantation and cell therapies, as well as an optimal starting material for cell expansion, cell engineering or cell re-programming technologies. CB banks have been pioneers in the development and implementation of Current Good Manufacturing Practices for cell-therapy products. Sharing their technological and regulatory experience will help advance all cell therapies, CB-derived or not, particularly as they transition from autologous, individually manufactured products to stored, 'off-the shelf' treatments. Such strategies will allow broader patient access and wide product utilisation.

Pluripotent stem cell-based gene therapy approach: human de novo synthesized chromosomes

A novel approach in gene therapy was introduced 20 years ago since artificial non-integrative chromosome-based vectors containing gene loci size inserts were engineered. To date, different human artificial chromosomes (HAC) were generated with the use of de novo construction or "top-down" engineering approaches. The HAC-based therapeutic approach includes ex vivo gene transferring and correction of pluripotent stem cells (PSCs) or highly proliferative modified stem cells. The current progress in the technology of induced PSCs, integrating with the HAC technology, resulted in a novel platform of stem cell-based tissue replacement therapy for the treatment of genetic disease. Nowadays, the sophisticated and laborious HAC technology has significantly improved and is now closer to clinical studies. In here, we reviewed the achievements in the technology of de novo synthesized HACs for a chromosome transfer for developing gene therapy tissue replacement models of monogenic human diseases.

Enhancing Matured Stem-Cardiac Cell Generation and Transplantation: A Novel Strategy for Heart Failure Therapy

Heart failure (HF) remains one of the major causes of morbidity and mortality worldwide. Recent studies have shown that stem cells (SCs) including bone marrow mesenchymal stem (BMSC), embryonic bodies (EB), embryonic stem (ESC), human induced pluripotent stem (hiPSC)-derived cardiac cells generation, and transplantation treated myocardial infarction (MI) in vivo and in human. However, the immature phenotypes compromise their clinical application requiring immediate intervention to improve stem-derived cardiac cell (S-CCs) maturation. Recently, an unbiased multi-omic analysis involving genomics, transcriptomics, epigenomics, proteomics, and metabolomics identified specific strategies for the generation of matured S-CCs that may enhance patients' recovery processes upon transplantation. However, these strategies still remain undisclosed. Here, we summarize the recently discovered strategies for the matured S-CC generation. In addition, cardiac patch formation and transplantation that accelerated HF recuperation in clinical trials are discussed. A better understanding of this work may lead to efficient generation of matured S-CCs for regenerative medicine. Graphical abstract.

Human Pluripotent Stem Cells-Based Therapies for Neurodegenerative Diseases: Current Status and Challenges

Neurodegenerative diseases are characterized by irreversible cell damage, loss of neuronal cells and limited regeneration potential of the adult nervous system. Pluripotent stem cells are capable of differentiating into the multitude of cell types that compose the central and peripheral nervous systems and so have become the major focus of cell replacement therapies for the treatment of neurological disorders. Human embryonic stem cell (hESC) and human induced pluripotent stem cell (hiPSC)-derived cells have both been extensively studied as cell therapies in a wide range of neurodegenerative disease models in rodents and non-human primates, including Parkinson’s disease, stroke, epilepsy, spinal cord injury, Alzheimer’s disease, multiple sclerosis and pain. In this review, we discuss the latest progress made with stem cell therapies targeting these pathologies. We also evaluate the challenges in clinical application of human pluripotent stem cell (hPSC)-based therapies including risk of oncogenesis and tumor formation, immune rejection and difficulty in regeneration of the heterogeneous cell types composing the central nervous system.

Stem Cell-Based Therapies for Parkinson Disease

Parkinson disease (PD) is a neurological movement disorder resulting primarily from damage to and degeneration of the nigrostriatal dopaminergic pathway. The pathway consists of neural populations in the substantia nigra that project to the striatum of the brain where they release dopamine. Diagnosis of PD is based on the presence of impaired motor features such as asymmetric or unilateral resting tremor, bradykinesia, and rigidity. Nonmotor features including cognitive impairment, sleep disorders, and autonomic dysfunction are also present. No cure for PD has been discovered, and treatment strategies focus on symptomatic management through restoration of dopaminergic activity. However, proposed cell replacement therapies are promising because midbrain dopaminergic neurons have been shown to restore dopaminergic neurotransmission and functionally rescue the dopamine-depleted striatum. In this review, we summarize our current understanding of the molecular pathogenesis of neurodegeneration in PD and discuss the development of new therapeutic strategies that have led to the initiation of exploratory clinical trials. We focus on the applications of stem cells for the treatment of PD and discuss how stem cell research has contributed to an understanding of PD, predicted the efficacy of novel neuroprotective therapeutics, and highlighted what we believe to be the critical areas for future research.

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.

Patient and Disease-Specific Induced Pluripotent Stem Cells for Discovery of Personalized Cardiovascular Drugs and Therapeutics

Human induced pluripotent stem cells (iPSCs) have emerged as an effective platform for regenerative therapy, disease modeling, and drug discovery. iPSCs allow for the production of limitless supply of patient-specific somatic cells that enable advancement in cardiovascular precision medicine. Over the past decade, researchers have developed protocols to differentiate iPSCs to multiple cardiovascular lineages, as well as to enhance the maturity and functionality of these cells. Despite significant advances, drug therapy and discovery for cardiovascular disease have lagged behind other fields such as oncology. We speculate that this paucity of drug discovery is due to a previous lack of efficient, reproducible, and translational model systems. Notably, existing drug discovery and testing platforms rely on animal studies and clinical trials, but investigations in animal models have inherent limitations due to interspecies differences. Moreover, clinical trials are inherently flawed by assuming that all individuals with a disease will respond identically to a therapy, ignoring the genetic and epigenomic variations that define our individuality. With ever-improving differentiation and phenotyping methods, patient-specific iPSC-derived cardiovascular cells allow unprecedented opportunities to discover new drug targets and screen compounds for cardiovascular disease. Imbued with the genetic information of an individual, iPSCs will vastly improve our ability to test drugs efficiently, as well as tailor and titrate drug therapy for each patient.

Intracerebral transplantation of HLA-homozygous human iPSC-derived neural precursors ameliorates the behavioural and pathological deficits in a rodent model of ischaemic stroke

OBJECTIVES

Human-induced pluripotent stem cells (hiPSCs) are a promising cell source for treating ischaemic stroke. Although autologous hiPSCs provide the advantage of avoiding immune rejection, their practical limitations, such as substantial amount of time and costs to generate individual iPSC lines, have hampered their widespread application in clinical settings. In this study, we investigated the therapeutic potential of neural precursor cells derived from human HLA-homozygous induced pluripotent stem cells (hiPSC-NPCs) following intracerebral transplantation into a rodent model of middle cerebral artery occlusion (MCAo).

MATERIALS AND METHODS

We differentiated a GMP-grade HLA-homozygous hiPSC line (CMC-hiPSC-004) into neural precursor cells for transplantation into rats at the subacute stage of ischaemic stroke (ie at 7 days after the induction of MCAo). To investigate functional recovery, the transplanted animals were subjected to five behavioural tests, namely the rotarod, stepping, mNSS, staircase and apomorphine-induced rotation tests, for up to 12 weeks, followed by histological analyses.

RESULTS

We observed that the hiPSC-NPC transplantation produced significant behavioural improvements. At 12 weeks post-transplantation, a high proportion of transplanted cells survived and had differentiated into MAP2⁺ mature neurons, GABAergic neurons and DARPP32⁺ medium spiny neurons. The transplanted cells formed neuronal connections with striatal neurons in the host brain. In addition, hiPSC-NPC transplantation gave rise to enhanced endogenous repair processes, including decreases of post-stroke neuroinflammation and glial scar formation and an increase of proliferating endogenous neural stem cells in the subventricular zone as well as the perilesional capillary networks.

CONCLUSIONS

These results strongly suggest that HLA-homozygous hiPSC-NPCs may be useful for treating ischaemic stroke patients.

GMP-grade CD34+ selection from HLA-homozygous licensed cord blood units and short-term expansion under European ATMP regulations

BACKGROUND

Based on a synergistic consortium, the cord blood (CB) bank Düsseldorf was responsible for the selection of HLA-homozygous (HLA-h) donors, contacting/re-consenting the mothers, Good Manufacturing Practice (GMP)-grade CD34⁺ enrichment, followed by short-term expansion of CD34⁺ cells and qualification of the resulting CD34⁺ population as advanced therapy medicinal product (ATMP)-starting material. Among 20 639 licensed Düsseldorf cord blood units (CBUs), 139 potential HLA-h donors were identified with the most frequent 10 German haplotypes. 100% of the donors were contacted, and for 47·5%, consent was obtained. HLA-A, -B, -C, -DR, -DQ and -DP were determined by sequencing.

METHODS

Thawing/washing of the CBUs was performed in the presence of Volulyte/HSA with Sepax^® , CD34⁺ selection by automated CliniMACS^® -system (Miltenyi), expansion with qualified GMP-grade cytokines and media in the GMP facility.

RESULTS

Here, we specify minimal criteria (≥5 x 10⁵ viable CD34⁺ -count, ≥80% CD34⁺ -purity and ≥70% viability) and confirm that n = 10 CB units (max storage time 16 years) could be qualified for an ATMP starting material. The mean fold change expansion of isolated CD34⁺ cells at Day 3/4 (d3/4) was 3·38 ± 3·02 with a mean purity of 86·90 ± 10·38% and a high viability of 96·07 ± 4·72%.

CONCLUSION

As of March 2019, approval was obtained by the Bezirksregierung Düsseldorf for the GMP-compliant production. The production of HLA-homozygous expanded CD34⁺ cells from cryopreserved CB under European ATMP regulations presented here describes the successful clinical translation and implementation of a qualified manufacturing process. This approach considers the main obstacle of rejection of transplanted cells (due to the immunological HLA barrier) by preselection of HLA-homozygous transplants.

Usefulness of the Hematopoietic Stem Cell Donor Pool as a Source of HLA-Homozygous Induced Pluripotent Stem Cells for Haplobanking: Combined Analysis of the Cord Blood Inventory and Bone Marrow Donor Registry

Induced pluripotent stem cells (iPSCs) have opened up unprecedented opportunities for novel therapeutic options for precision medicine. Hematopoietic stem cell (HSC) donor pools with previously determined HLA types may be ideal sources for iPSC production. Based on the HLA distribution of cryopreserved cord blood units (CBUs) and registered bone marrow (BM) donors, we estimated how much of the Korean population could be covered by HLA-homozygous iPSCs. We analyzed a total of 143,866 Korean HSC donors (27,904 CBUs and 115,962 BM donors). Each donor sample was typed for the HLA-A, -B, and -DRB1 alleles at low to intermediate resolution by DNA-based molecular techniques: PCR sequence-specific oligonucleotide (PCR-SSOP), PCR with sequence-specific primers (PCR-SSP) and PCR with sequence-based typing (PCR-SBT). We also identified individuals possessing homozygous HLA haplotypes by direct counting. The matching probabilities for zero-mismatch transplantation were calculated for 143,866 Koreans and 50 million potential Korean patients. Among the HSC donor pool, 17 HLA-A alleles, 41 HLA-B alleles, and 13 HLA-DRB1 alleles, as well as 128 homozygous HLA-A-B-DRB1 haplotypes, were identified at serologic equivalents, and those haplotypes cumulatively matched 93.20% of the 143,866 Korean donors as zero HLA-mismatch iPSC sources. Among the combinations of 2,056 haplotypes with frequencies ≥ 0.001% in a population of 50 million, those 128 homozygous haplotypes can provide 93.65% coverage for potential Korean recipients. Haplobanking of a reasonable number of HLA-A, -B, and -DRB1 homozygous iPSC lines derived from CBUs and cells of registered BM donors may be an efficient option for allogenic iPSC therapy.

Development of genetic quality tests for good manufacturing practice-compliant induced pluripotent stem cells and their derivatives

Although human induced pluripotent stem cell (hiPSC) lines are karyotypically normal, they retain the potential for mutation in the genome. Accordingly, intensive and relevant quality controls for clinical-grade hiPSCs remain imperative. As a conceptual approach, we performed RNA-seq-based broad-range genetic quality tests on GMP-compliant human leucocyte antigen (HLA)-homozygous hiPSCs and their derivatives under postdistribution conditions to investigate whether sequencing data could provide a basis for future quality control. We found differences in the degree of single-nucleotide polymorphism (SNP) occurring in cells cultured at three collaborating institutes. However, the cells cultured at each centre showed similar trends, in which more SNPs occurred in late-passage hiPSCs than in early-passage hiPSCs after differentiation. In eSNP karyotyping analysis, none of the predicted copy number variations (CNVs) were identified, which confirmed the results of SNP chip-based CNV analysis. HLA genotyping analysis revealed that each cell line was homozygous for HLA-A, HLA-B, and DRB1 and heterozygous for HLA-DPB type. Gene expression profiling showed a similar differentiation ability of early- and late-passage hiPSCs into cardiomyocyte-like, hepatic-like, and neuronal cell types. However, time-course analysis identified five clusters showing different patterns of gene expression, which were mainly related to the immune response. In conclusion, RNA-seq analysis appears to offer an informative genetic quality testing approach for such cell types and allows the early screening of candidate hiPSC seed stocks for clinical use by facilitating safety and potential risk evaluation.

What will Become of the Taxpayer Investment in Public Cord Blood Stem Cell Banking?

Cord Blood (CB) is a unique and readily available source of hematopoietic stem cells for transplantation. CB also contains other types of stem cells, including endothelial stem cells and mesenchymal stem cells, that may prove useful in non-traditional clinical uses. Genetic and molecular analyses have demonstrated that CB stem cells lie somewhere between mature stem cells like those found in Bone Marrow (BM), and fetal stem cells. After 25 years of clinical experience, CB is now used in the same fashion as BM for all typical malignant and genetic diseases treated by bone marrow transplant. Due to the establishment of CB banks in the US and abroad, more than 35,000 CB transplants have been performed over the past 25 years. An average of 700-800 CB transplants are performed annually. In addition, CB is now used more frequently for regenerative medicine and tissue engineering applications. At first glance, it seems that everything could not be better with the public cord blood banks and the use of their samples in the clinic. However, a recent report by the Rand Corp. reviewed the US national cord blood stem cell banking program and detailed many ongoing problems. However, some details were omitted from the report that would shed some light on the causes of many of the problems. This paper will summarize the status of the public cord blood stem cell banking program in the US, detail the problems associated with the program that could jeopardize its existence and suggest possible solutions to resolve these issues.