Hematopoietic Stem Cell Gene-Addition/Editing Therapy in Sickle Cell Disease

Genetic Modifiers of Hemoglobin Expression from a Clinical Perspective in Hemoglobinopathy Patients with Beta Thalassemia and Sickle Cell Disease

Hemoglobinopathies, namely β-thalassemia and sickle cell disease (SCD), are hereditary diseases, characterized by molecular genetic aberrations in the beta chains of hemoglobin. These defects affect the normal production of hemoglobin with severe anemia due to less or no amount of beta globins in patients with β-thalassemia (quantitative disorder), while SCD is a serious disease in which a mutated form of hemoglobin distorts the red blood cells into a crescent shape at low oxygen levels (qualitative disorder). Despite the revolutionary progress in recent years with the approval of gene therapy and gene editing for specific patients, there is an unmet need for highlighting the mechanisms influencing hemoglobin production and for the development of novel drugs and targeted therapies. The identification of the transcription factors and other genetic modifiers of hemoglobin expression is of utmost importance for discovering novel therapeutic approaches for patients with hemoglobinopathies. The aim of this review is to describe these complex molecular mechanisms and pathways affecting hemoglobin expression and to highlight the relevant investigational approaches or pharmaceutical interventions focusing on restoring the hemoglobin normal function by linking the molecular background of the disease with the clinical perspective. All the associated drugs increasing the hemoglobin expression in patients with hemoglobinopathies, along with gene therapy and gene editing, are also discussed.

Interventions to reduce the risk of side-effects of cancer treatments in childhood

INTRODUCTION

Childhood cancers as a group affect around 1 in 500 children but each individual diagnosis is a rare disease. While research largely focuses on improving cure rates, the management of side effects of treatment are high priority for clinicians, families and children and young people.

AREAS COVERED

The prevention and efficient management of infectious complications, oral mucositis, nausea and vomiting and graft-vs-host disease illustrated with examples of implementation research, translation of engineering to care, advances in statistical methodologies, and traditional bench-to-patient development. The reviews draw from existing systematic reviews and well conducted clinical practice guidelines.

EXPERT OPINION

The four areas are driven from patient and family priorities. Some of the problems outlined are ready for proven interventions, others require us to develop new technologies. Advancement needs us to make the best use of new methods of applied health research and clinical trial methodologies. Some of the greatest challenges may be those we're not fully aware of, as new therapies move from their use in adult oncological practice into children. This will need us to continue our collaborative, multi-professional, multi-disciplinary and eclectic approach.

Gene Therapy: A Revolutionary Step in Treating Thalassemia

Beta thalassemia is an inherited blood disorder that results in inefficient erythropoiesis due to genetic mutation that leads to the reduction or absence of the hemoglobin beta-globulin protein. Approximately 8.5% of UAE residents suffer from β-thalassemia, a significant health and financial problem. The treatment options available for β-Thalassemia major are limited and associated with a wide range of complications. β-thalassemia gene therapy is emerging as a potential novel treatment option that eliminates the complications caused by the current long-term treatment modalities and the associated economic burden. This paper reviews the scientific literature related to emerging gene therapy for β-Thalassemia by analyzing all the articles published from January 2010 to December 2023 in the English language on Databases like PubMed, Scopus, ProQuest, and CINAHL. The use of gene therapy has demonstrated promising outcomes for a permanent cure of β-Thalassemia. To conclude, gene therapy is an innovative solution. It demonstrates a promising future, but does come with its own setbacks and is something that must be tackled in order to revolutionize it in the medical world. FDA-approved ZYNTEGLO is a potentially one-time curative treatment for β-Thalassemia. Although cutting-edge, its use is limited because of the high cost-a price of USD 2.8 million per patient.

Continuous and differential improvement in worldwide access to hematopoietic cell transplantation: activity has doubled in a decade with a notable increase in unrelated and non-identical related donors

Promoting access to and excellence in hematopoietic cell transplantation (HCT) by collecting and disseminating data on global HCT activities is one of the principal activities of the Worldwide Network for Blood and Marrow Transplantation, a non-governmental organization in working relations with the World Health Organization. HCT activities are recorded annually by member societies, national registries and individual centers including indication, donor type (allogeneic/autologous), donor match and stem cell source (bone marrow/peripheral blood stem cells/cord blood). In 2018, 1,768 HCT teams in 89 countries (6 World Health Organization regions) reported 93,105 (48,680 autologous and 44,425 allogeneic) HCT. Major indications were plasma cell disorders and lymphoma for autologous, and acute leukemias and MDS/MPN for allogeneic HCT. HCT numbers increased from 48,709 in 2007. Notable increases were seen for autoimmune diseases in autologous and hemoglobinopathies in allogeneic HCT. The number of allogeneic HCT more than doubled with significant changes in donor match. While HCT from HLA-identical siblings has seen only limited growth, HCT from non-identical related donors showed significant increase worldwide. Strongest correlation between economic growth indicator of gross national income/capita and HCT activity/10 million population was observed for autologous HCT (correlation coefficient [r]=0.79). HCT from unrelated donors showed strong correlation (r=0.68), but only moderate correlation was detected from related donors (r=0.48 for HLA-identical sibling; r=0.45 for other). The use of HCT doubled in about a decade worldwide at different speed and with significant changes regarding donor match as a sign of improved access to HCT worldwide. Although narrowing, significant gaps remain between developing and non-developing countries.

Gene therapies on the horizon for sickle cell disease: a clinician's perspective

INTRODUCTION

Sickle cell disease (SCD) is a monogenic disorder that exerts several detrimental health effects on those affected, ultimately resulting in significant morbidity and early mortality. There are millions of individuals globally impacted by this disease. Research in gene therapy has been growing significantly over the past decade, now with two FDA approved products, aiming to find another cure for this complex disease.

AREAS COVERED

This perspective article aims to provide a clinician's insight into the current landscape of gene therapies, exploring the novel approaches, clinical advances, and potential impact on the management and prognosis of SCD. A comprehensive literature search encompassing databases such as PubMed, Web of Science and Google Scholar was employed. The search covered literature published from 1980 to 2024, focusing on SCD and curative therapy.

EXPERT OPINION

After careful evaluation of the risks and benefits associated with the use of gene therapy for affected patients, the need for a cure outweighs the risks associated with treatment in most cases of SCD. With advances in current technologies, gene therapies can increase access to cures for patients with SCD.

Peptide-enabled ribonucleoprotein delivery for CRISPR engineering (PERC) in primary human immune cells and hematopoietic stem cells

Peptide-enabled ribonucleoprotein delivery for CRISPR engineering (PERC) is a new approach for ex vivo genome editing of primary human cells. PERC uses a single amphiphilic peptide reagent to mediate intracellular delivery of the same pre-formed CRISPR ribonucleoprotein enzymes that are broadly used in research and therapeutics, resulting in high-efficiency editing of stimulated immune cells and cultured hematopoietic stem and progenitor cells (HSPCs). PERC facilitates nuclease-mediated gene knockout, precise transgene knock-in, and base editing. PERC involves mixing the CRISPR ribonucleoprotein enzyme with peptide and then incubating the formulation with cultured cells. For efficient transgene knock-in, adeno-associated virus (AAV) bearing homology-directed repair template DNA may be included. In contrast to electroporation, PERC is appealing as it requires no dedicated hardware and has less impact on cell phenotype and viability. Due to the gentle nature of PERC, delivery can be performed multiple times without substantial impact to cell health or phenotype. Here we report methods for improved PERC-mediated editing of T cells as well as novel methods for PERC-mediated editing of HSPCs, including knockout and precise knock-in. Editing efficiencies can surpass 90% using either Cas9 or Cas12a in primary T cells or HSPCs. Because PERC calls for only three readily available reagents - protein, RNA, and peptide - and does not require dedicated hardware for any step, PERC demands no special expertise and is exceptionally straightforward to adopt. The inherent compatibility of PERC with established cell engineering pipelines makes this approach appealing for rapid deployment in research and clinical settings.

Living with the threat of losing a child: Parents' experiences of the transplantation process with a severely ill child who received stem cells from a sibling

PURPOSE

When a child needs a hematopoietic stem cell transplant, the seriousness of the child's illness is highlighted. The purpose of this study was to explore parents' experiences of the transplantation process when two children in the family are involved, one severely ill child as the recipient and the other as the donor.

METHODS

In this qualitative study, interviews were conducted with 18 parents of 13 healthy minor donors after successful stem cell transplants. Qualitative content analysis was used to explore parents' experiences.

FINDINGS

The parents described they were living with the threat of losing a child. They lived with an uncertain future as they were confronted with life-changing information. Whether the ill child would survive or not could not be predicted; thus, parents had to endure unpredictability, and to cope with this they chose to focus on positives. Finally, the parents managed family life in the midst of chaos, felt an inadequacy and a perception that the family became a fragmented although close team during hospital stays. They expressed a need for both tangible and emotional support.

CONCLUSIONS

When a child needs a stem cell transplant, the parents feel inadequate to their healthy children including the donating child. It is obvious that they experience an uncertain future and struggle to keep the family together amid the chaos.

PRACTICE IMPLICATIONS

Considering these results, psychosocial support should be mandatory for parents in connection with pediatric HSCT, to enable a process where parents can prepare for the outcome, whether successful or not.

Role of gene therapy in sickle cell disease

BACKGROUND

Gene therapy is an emerging treatment for sickle cell disease that works by replacing a defective gene with a healthy gene, allowing the body to produce normal red blood cells. This form of treatment has shown promising results in clinical trials, and is a promising alternative to traditional treatments. Gene therapy involves introducing a healthy gene into the body to replace a defective gene. The new gene can be delivered using a viral vector, which is a modified virus that carries the gene. The vector, carrying the healthy gene, is injected into the bloodstream. The healthy gene then enters the patient's cells and begins to produce normal hemoglobin, the protein in red blood cells that carries oxygen throughout the body.

METHODOLOGY

We conducted an all-language literature search on Medline, Cochrane, Embase, and Google Scholar until December 2022. The following search strings and Medical Subject Heading (MeSH) terms were used: "Sickle Cell," "Gene Therapy" and "Stem Cell Transplantation". We explored the literature on Sickle Cell Disease for its epidemiology, etiopathogenesis, the role of various treatment modalities and the risk-benefit ratio of gene therapy over conventional stem cell transplant.

RESULTS

Gene therapy can reduce or eliminate painful episodes, prevent organ damage, and raise the quality of life for those living with the disease. Additionally, gene therapy may reduce the need for blood transfusions and other traditional treatments. Gene therapy has the potential to improve the lives of those living with sickle cell disease, as well as reduce the burden of the disease on society.

End Organ Affection in Sickle Cell Disease

Sickle cell disease is an orphan disease affecting ethnic minorities and characterized by profound systemic manifestations. Although around 100,000 individuals with SCD are living in the US, the exact number of individuals is unknown, and it is considered an orphan disease. This single-gene disorder leads to red blood cell sickling and the deoxygenation of hemoglobin, resulting in hemolysis. SCD is associated with acute complications such as vaso-occlusive crisis, infections, and chronic target organ complications such as pulmonary disease and renal failure. While genetic therapy holds promise to alter the fundamental disease process, the major challenge in the field remains the target end organ damage and ways to mitigate or reverse it. Here, we provide an overview of the clinical manifestations and pathogenesis with a focus on end-organ damage and current therapeutic options, including recent FDA-approved stem cell and gene editing therapies.

Looking ahead: ethical and social challenges of somatic gene therapy for sickle cell disease in Africa

Somatic gene therapy will be one of the most exciting practices of genetic medicine in Africa and is primed to offer a "new life" for persons living with sickle cell disease (SCD). Recently, successful gene therapy trials for SCD in the USA have sparked a ray of hope within the SCD community in Africa. However, the high cost, estimated to exceed 1.5 million USD, continues to be a major concern for many stakeholders. While affordability is a key global health equity consideration, it is equally important to reflect on other ethical, legal and social issues (ELSIs) that may impact the responsible implementation of gene therapy for SCD in Africa. These include informed consent comprehension, risk of therapeutic misestimation and optimistic bias; priorities for SCD therapy trials; dearth of ethical and regulatory oversight for gene therapy in many African countries; identifying a favourable risk-benefit ratio; criteria for the selection of trial participants; decisional conflict in consent; standards of care; bounded justice; and genetic tourism. Given these ELSIs, we suggest that researchers, pharma, funders, global health agencies, ethics committees, science councils and SCD patient support/advocacy groups should work together to co-develop: (1) patient-centric governance for gene therapy in Africa, (2) public engagement and education materials, and (3) decision making toolkits for trial participants. It is also critical to establish harmonised ethical and regulatory frameworks for gene therapy in Africa, and for global health agencies to accelerate access to basic care for SCD in Africa, while simultaneously strengthening capacity for gene therapy.

In vivo selection of anti-HIV-1 gene-modified human hematopoietic stem/progenitor cells to enhance engraftment and HIV-1 inhibition

Hematopoietic stem/progenitor cell (HSPC)-based anti-HIV-1 gene therapy holds great promise to eradicate HIV-1 or to provide long-term remission through a continuous supply of anti-HIV-1 gene-modified cells without ongoing antiretroviral therapy. However, achieving sufficient engraftment levels of anti-HIV gene-modified HSPC to provide therapeutic efficacy has been a major limitation. Here, we report an in vivo selection strategy for anti-HIV-1 gene-modified HSPC by introducing 6-thioguanine (6TG) chemoresistance through knocking down hypoxanthine-guanine phosphoribosyl transferase (HPRT) expression using RNA interference (RNAi). We developed a lentiviral vector capable of co-expressing short hairpin RNA (shRNA) against HPRT alongside two anti-HIV-1 genes: shRNA targeting HIV-1 co-receptor CCR5 and a membrane-anchored HIV-1 fusion inhibitor, C46, for efficient in vivo selection of anti-HIV-1 gene-modified human HSPC. 6TG-mediated preconditioning and in vivo selection significantly enhanced engraftment of HPRT-knockdown anti-HIV-1 gene-modified cells (>2-fold, p < 0.0001) in humanized bone marrow/liver/thymus (huBLT) mice. Viral load was significantly reduced (>1 log fold, p < 0.001) in 6TG-treated HIV-1-infected huBLT mice compared to 6TG-untreated mice. We demonstrated that 6TG-mediated preconditioning and in vivo selection considerably improved engraftment of HPRT-knockdown anti-HIV-1 gene-modified HSPC and repopulation of anti-HIV-1 gene-modified hematopoietic cells in huBLT mice, allowing for efficient HIV-1 inhibition.

CRISPR-Cas9 Gene Editing: Curing Genetic Diseases by Inherited Epigenetic Modifications

Introduction  CRISPR-Cas9 gene editing, leveraging bacterial defense mechanisms, offers precise DNA modifications, holding promise in curing genetic diseases. This review critically assesses its potential, analyzing evidence on therapeutic applications, challenges, and future prospects. Examining diverse genetic disorders, it evaluates efficacy, safety, and limitations, emphasizing the need for a thorough understanding among medical professionals and researchers. Acknowledging its transformative impact, a systematic review is crucial for informed decision-making, responsible utilization, and guiding future research to unlock CRISPR-Cas9's full potential in realizing the cure for genetic diseases. Methods  A comprehensive literature search across PubMed, Scopus, and the Web of Science identified studies applying CRISPR-Cas9 gene editing for genetic diseases, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Inclusion criteria covered in vitro and in vivo models targeting various genetic diseases with reported outcomes on disease modification or potential cure. Quality assessment revealed a generally moderate to high risk of bias. Heterogeneity prevented quantitative meta-analysis, prompting a narrative synthesis of findings. Discussion  CRISPR-Cas9 enables precise gene editing, correcting disease-causing mutations and offering hope for previously incurable genetic conditions. Leveraging inherited epigenetic modifications, it not only fixes mutations but also restores normal gene function and controls gene expression. The transformative potential of CRISPR-Cas9 holds promise for personalized treatments, improving therapeutic outcomes, but ethical considerations and safety concerns must be rigorously addressed to ensure responsible and safe application, especially in germline editing with potential long-term implications.

Sickle Cell Disease: From Genetics to Curative Approaches

Sickle cell disease (SCD) is a monogenic blood disease caused by a point mutation in the gene coding for β-globin. The abnormal hemoglobin [sickle hemoglobin (HbS)] polymerizes under low-oxygen conditions and causes red blood cells to sickle. The clinical presentation varies from very severe (with acute pain, chronic pain, and early mortality) to normal (few complications and a normal life span). The variability of SCD might be due (in part) to various genetic modulators. First, we review the main genetic factors, polymorphisms, and modifier genes that influence the expression of globin or otherwise modulate the severity of SCD. Considering SCD as a complex, multifactorial disorder is important for the development of appropriate pharmacological and genetic treatments. Second, we review the characteristics, advantages, and disadvantages of the latest advances in gene therapy for SCD, from lentiviral-vector-based approaches to gene-editing strategies.

Treatment of sickle cell disease - options and perspective

Sickle Cell Disease (SCD) is one of the most inherited hematologic diseases affecting humans. Clinically, there is a progressive multiorgan failure and increased mortality in severe cases. The highest prevalence is in West Africa, India, the Mediterranean region, and Middle East countries. Hydroxyurea was the primary drug available for SCD and remains first-line therapy for patients with SCD. Three additional drug therapies, L-glutamine, Voxelotor, and Crizanlizumab, have been approved as adjunctive agents. However, none of these treatments are curative. Effective cell-based therapies are available, such as red blood cell (RBC) exchange and the only curative therapy is hematopoietic stem cell transplantation (HSCT). Gene-editing now shows promise in treating SCD and the β-thalassemias. Recent clinical trials have proven that this therapeutic strategy is effective, however costly. Despite the availability of safe and effective drug treatments, questions focusing on the overall value of these drugs exist in light of rising healthcare costs including hospitalizations and medical interventions. Herein, we report a cost-effective evaluation that can guide future efforts in making decisions towards HSCT as cell therapy treatment in SCD patients.

Stem Cell-Based Therapeutic Approaches in Genetic Diseases

Stem cells, which can self-renew and differentiate into different cell types, have become the keystone of regenerative medicine due to these properties. With the achievement of superior clinical results in the therapeutic approaches of different diseases, the applications of these cells in the treatment of genetic diseases have also come to the fore. Foremost, conventional approaches of stem cells to genetic diseases are the first approaches in this manner, and they have brought safety issues due to immune reactions caused by allogeneic transplantation. To eliminate these safety issues and phenotypic abnormalities caused by genetic defects, firstly, basic genetic engineering practices such as vectors or RNA modulators were combined with stem cell-based therapeutic approaches. However, due to challenges such as immune reactions and inability to target cells effectively in these applications, advanced molecular methods have been adopted in ZFN, TALEN, and CRISPR/Cas genome editing nucleases, which allow modular designs in stem cell-based genetic diseases' therapeutic approaches. Current studies in genetic diseases are in the direction of creating permanent treatment regimens by genomic manipulation of stem cells with differentiation potential through genome editing tools. In this chapter, the stem cell-based therapeutic approaches of various vital genetic diseases were addressed wide range from conventional applications to genome editing tools.

Site-specific genome editing in treatment of inherited diseases: possibility, progress, and perspectives

Advancements in genome editing enable permanent changes of DNA sequences in a site-specific manner, providing promising approaches for treating human genetic disorders caused by gene mutations. Recently, genome editing has been applied and achieved significant progress in treating inherited genetic disorders that remain incurable by conventional therapy. Here, we present a review of various programmable genome editing systems with their principles, advantages, and limitations. We introduce their recent applications for treating inherited diseases in the clinic, including sickle cell disease (SCD), β-thalassemia, Leber congenital amaurosis (LCA), heterozygous familial hypercholesterolemia (HeFH), etc. We also discuss the paradigm of ex vivo and in vivo editing and highlight the promise of somatic editing and the challenge of germline editing. Finally, we propose future directions in delivery, cutting, and repairing to improve the scope of clinical applications.