Immunological reconstitution of sex-linked lymphopenic immunological deficiency

Gene Therapy Strategies for RAG1 Deficiency: Challenges and Breakthroughs

Mutations in the recombination activating genes (RAG) cause various forms of immune deficiency. Hematopoietic stem cell transplant (HSCT) is the only cure for patients with severe manifestations of RAG deficiency; however, outcomes are suboptimal with mismatched donors. Gene therapy aims to correct autologous hematopoietic stem and progenitor cells (HSPC) and is emerging as an alternative to allogeneic HSCT. Gene therapy based on viral gene addition exploits viral vectors to add a correct copy of a mutated gene into the genome of HSPCs. Only recently, after a prolonged phase of development, viral gene addition has been approved for clinical testing in RAG1-SCID patients. In the meantime, a new technology, CRISPR/Cas9, has made its debut to compete with viral gene addition. Gene editing based on CRISPR/Cas9 allows to perform targeted genomic integrations of a correct copy of a mutated gene, circumventing the risk of virus-mediated insertional mutagenesis. In this review, we present the biology of the RAG genes, the challenges faced during the development of viral gene addition for RAG1-SCID, and the current status of gene therapy for RAG1 deficiency. In particular, we highlight the latest advances and challenges in CRISPR/Cas9 gene editing and their potential for the future of gene therapy.

[Advances in gene therapy for inborn errors of immunity]

Inborn errors of immunity (IEI) are a diverse group of disorders caused by defects in immune system structure or function, involving both innate and adaptive immunity. The 2022 update of the IEI classification includes 485 distinct disorders, categorized into ten major disease groups. With the rapid development of molecular biology, the specific pathogenesis of many IEI has been revealed, making gene therapy possible in preclinical and clinical research of this type of disease. This article reviews the advancements in gene therapy for IEI, aiming to increase awareness and understanding of these disorders.

Advancements in Hematopoietic Stem Cell Gene Therapy: A Journey of Progress for Viral Transduction

Hematopoietic stem cell (HSC) transduction has undergone remarkable advancements in recent years, revolutionizing the landscape of gene therapy specifically for inherited hematologic disorders. The evolution of viral vector-based transduction technologies, including retroviral and lentiviral vectors, has significantly enhanced the efficiency and specificity of gene delivery to HSCs. Additionally, the emergence of small molecules acting as transduction enhancers has addressed critical barriers in HSC transduction, unlocking new possibilities for therapeutic intervention. Furthermore, the advent of gene editing technologies, notably CRISPR-Cas9, has empowered precise genome modification in HSCs, paving the way for targeted gene correction. These striking progresses have led to the clinical approval of medicinal products based on engineered HSCs with impressive therapeutic benefits for patients. This review provides a comprehensive overview of the collective progress in HSC transduction via viral vectors for gene therapy with a specific focus on transduction enhancers, highlighting the latest key developments, challenges, and future directions towards personalized and curative treatments.

Survival After Hematopoietic Stem Cell Transplantation in Severe Combined Immunodeficiency (SCID): A Worldwide Review of the Prognostic Variables

This study aims to perform an extensive review of the literature that evaluates various factors that affect the survival rates of patients with severe combined immunodeficiency (SCID) after hematopoietic stem cell transplantation (HSCT) in developed and developing countries. An extensive search of the literature was made in four different databases (PubMed, Embase, Scopus, and Web of Science). The search was carried out in December 2022 and updated in July 2023, and the terms such as "hematopoietic stem cell transplantation," "bone marrow transplant," "mortality," "opportunistic infections," and "survival" associated with "severe combined immunodeficiency" were sought based on the MeSH terms. The language of the articles was "English," and only articles published from 2000 onwards were selected. Twenty-three articles fulfilled the inclusion criteria for review and data extraction. The data collected corroborates that early HSCT, but above all, HSCT in patients without active infections, is related to better overall survival. The universal implementation of newborn screening for SCID will be a fundamental pillar for enabling most transplants to be carried out in this "ideal scenario" at an early age and free from infection. HSCT with an HLA-identical sibling donor is also associated with better survival rates, but this is the least common scenario. For this reason, transplantation with matched unrelated donors (MUD) and mismatched related donors (mMRD/Haploidentical) appear as alternatives. The results obtained with MUD are improving and show survival rates similar to those of MSD, as well as they do not require manipulation of the graft with expensive technologies. However, they still have high rates of complications after HSCT. Transplants with mMRD/Haplo are performed just in a few large centers because of the high costs of the technology to perform CD3/CD19 depletion and TCRαβ/CD19 depletion or CD34 + selection techniques in vitro. The new possibility of in vivo T cell depletion using post-transplant cyclophosphamide could also be a viable alternative for performing mMRD transplants in centers that do not have this technology, especially in developing countries.

Metabolic instruction of the graft-versus-leukemia immunity

Allogeneic hematopoietic cell transplantation (allo-HCT) is frequently performed to cure hematological malignancies, such as acute myeloid leukemia (AML), through the graft-versus-leukemia (GVL) effect. In this immunological process, donor immune cells eliminate residual cancer cells in the patient and exert tumor control through immunosurveillance. However, GVL failure and subsequent leukemia relapse are frequent and associated with a dismal prognosis. A better understanding of the mechanisms underlying AML immune evasion is essential for developing novel therapeutic strategies to boost the GVL effect. Cellular metabolism has emerged as an essential regulator of survival and cell fate for both cancer and immune cells. Leukemia and T cells utilize specific metabolic programs, including the orchestrated use of glucose, amino acids, and fatty acids, to support their growth and function. Besides regulating cell-intrinsic processes, metabolism shapes the extracellular environment and plays an important role in cell-cell communication. This review focuses on recent advances in the understanding of how metabolism might affect the anti-leukemia immune response. First, we provide a general overview of the mechanisms of immune escape after allo-HCT and an introduction to leukemia and T cell metabolism. Further, we discuss how leukemia and myeloid cell metabolism contribute to an altered microenvironment that impairs T cell function. Next, we review the literature linking metabolic processes in AML cells with their inhibitory checkpoint ligand expression. Finally, we focus on recent findings concerning the role of systemic metabolism in sustained GVL efficacy. While the majority of evidence in the field still stems from basic and preclinical studies, we discuss translational findings and propose further avenues for bridging the gap between bench and bedside.

Advances in gene therapy for inborn errors of immunity

PURPOSE OF REVIEW

Provide an overview of the landmark accomplishments and state of the art of gene therapy for inborn errors of immunity (IEI).

RECENT FINDINGS

Three decades after the first clinical application of gene therapy for IEI, there is one market authorized product available, while for several others efficacy has been demonstrated or is currently being tested in ongoing clinical trials. Gene editing approaches using programmable nucleases are being explored preclinically and could be beneficial for genes requiring tightly regulated expression, gain-of-function mutations and dominant-negative mutations.

SUMMARY

Gene therapy by modifying autologous hematopoietic stem cells (HSCs) offers an attractive alternative to allogeneic hematopoietic stem cell transplantation (HSCT), the current standard of care to treat severe IEI. This approach does not require availability of a suitable allogeneic donor and eliminates the risk of graft versus host disease (GvHD). Gene therapy can be attempted by using a viral vector to add a copy of the therapeutic gene (viral gene addition) or by using programmable nucleases (gene editing) to precisely correct mutations, disrupt a gene or introduce an entire copy of a gene at a specific locus. However, gene therapy comes with its own challenges such as safety, therapeutic effectiveness and access. For viral gene addition, a major safety concern is vector-related insertional mutagenesis, although this has been greatly reduced with the introduction of safer vectors. For gene editing, the risk of off-site mutagenesis is a main driver behind the ongoing search for modified nucleases. For both approaches, HSCs have to be manipulated ex vivo, and doing this efficiently without losing stemness remains a challenge, especially for gene editing.

Successes and challenges in clinical gene therapy

Despite the ups and downs in the field over three decades, the science of gene therapy has continued to advance and provide enduring treatments for increasing number of diseases. There are active clinical trials approaching a variety of inherited and acquired disorders of different organ systems. Approaches include ex vivo modification of hematologic stem cells (HSC), T lymphocytes and other immune cells, as well as in vivo delivery of genes or gene editing reagents to the relevant target cells by either local or systemic administration. In this article, we highlight success and ongoing challenges in three areas of high activity in gene therapy: inherited blood cell diseases by targeting hematopoietic stem cells, malignant disorders using immune effector cells genetically modified with chimeric antigen receptors, and ophthalmologic, neurologic, and coagulation disorders using in vivo administration of adeno-associated virus (AAV) vectors. In recent years, there have been true cures for many of these diseases, with sustained clinical benefit that exceed those from other medical approaches. Each of these treatments faces ongoing challenges, namely their high one-time costs and the complexity of manufacturing the therapeutic agents, which are biological viruses and cell products, at pharmacologic standards of quality and consistency. New models of reimbursement are needed to make these innovative treatments widely available to patients in need.

Haematopoietic Stem Cell Transplantation for Chronic Granulomatous Disease

Chronic granulomatous disease (CGD) is an inborn error of immunity due to defects in the transport or function of subunits of nicotinamide adenine dinucleotide phosphate oxidase, the enzyme that generates the phagocyte respiratory burst responsible for intracellular killing of engulfed micro-organisms. Patients present with infectious or inflammatory complications. Common bacterial pathogens include Staphylococcus aureus and Burkholderia cepacia complex. Fungal pathogens include Aspergillus species, particularly Aspergillus fumigatus. Inflammatory complications most commonly manifest as inflammatory bowel disease or lung disease. Granulomata are the distinguishing histological feature. Haematopoietic stem cell transplantation (HSCT) was first considered for CGD in the early 1970's. Since then, refinements in transplant technique, donor selection, conditioning regimens, and graft engineering have widened the option of HSCT to most patients with CGD. This review charts the progress made in HSCT for CGD.

Small volume bone marrow aspirates with high progenitor cell concentrations maximize cell therapy dose manufacture and substantially reduce donor hemoglobin loss

BACKGROUND

Bone marrow (BM) transplantation is a life-saving therapy for hematological diseases, and the BM harbors also highly useful (progenitor) cell types for novel cell therapies manufacture. Yet, the BM collection technique is not standardized.

METHODS

Benchmarking our collection efficiency to BM collections worldwide (N = 1248), we noted a great variability of total nucleated cell (TNC) yields in BM products (HPC-M) with superior performance of our center, where we have implemented a small volume aspirate policy. Thus, we next prospectively aimed to assess the impact of BM collection technique on HPC-M quality. For each BM collection (N = 20 donors), small volume (3 mL) and large volume (10 mL) BM aspirates were sampled at 3 time points and analyzed for cell composition.

RESULTS

Compared to large volume aspirates, small volume aspirates concentrated more TNCs, immune cells, platelets, hematopoietic stem/progenitor cells, mesenchymal stromal cells (MSCs), and endothelial progenitors. Inversely, the hemoglobin concentration was higher in large volume aspirates indicating more hemoglobin loss. Manufacturing and dosing scenarios showed that small volume aspirates save up to 42% BM volume and 44% hemoglobin for HPC-M donors. Moreover, MSC production efficiency can be increased by more than 150%.

CONCLUSIONS

We propose to consider small volume BM aspiration as standard technique for BM collection.

Current approaches and potential challenges in the delivery of gene editing cargos into hematopoietic stem and progenitor cells

Advancements in gene delivery and editing have expanded the applications of autologous hematopoietic stem and progenitor cells (HSPCs) for the treatment of monogenic and acquired diseases. The gene editing toolbox is growing, and the ability to achieve gene editing with mRNA or protein delivered intracellularly by vehicles, such as electroporation and nanoparticles, has highlighted the potential of gene editing in HSPCs. Ongoing phase I/II clinical trials with gene-edited HSPCs for β-hemoglobinopathies provide hope for treating monogenic diseases. The development of safe and efficient gene editing reagents and their delivery into hard-to-transfect HSPCs have been critical drivers in the rapid translation of HSPC gene editing into clinical studies. This review article summarizes the available payloads and delivery vehicles for gene editing HSPCs and their potential impact on therapeutic applications.

A Tribute to Two Master Teachers of Immunology

A Special Issue dedicated in memory of Prof. Fernando Aiuti is a special tribute to a clinician who led the field of Clinical Immunology in Italy and introduced the entire Italian medical and academic scene to it. [...].

Changing outcomes of stem cell transplantation in primary immunodeficiencies: Results from a tertiary-care charitable trust hospital in Mumbai

Background

Hematopoietic stem cell transplantation in primary immunodeficiency disorders has come a long way since the first transplant in 1968. In India, pediatric stem cell transplantation long-term survival outcomes range from 62.5% to 75%, compared to 90% in high-income countries.

Objective

We present single-center data of primary immunodeficiency transplants with immune-reconstitution evaluation after transplantation from a charitable trust hospital.

Methods

Retrospective data of children transplanted for primary immunodeficiency disorders from March 2019 to March 2022 in a newly established transplant unit were collected. Data of pretransplant infections and comorbidities, surveillance for carbapenem-resistant Enterobacteriaceae, transplant characteristics, donor source, graft-versus-host disease, posttransplant infections, immune reconstitution, overall survival at 1 year, and immunodeficiency-free survival were collated.

Results

Twenty-one patients underwent transplantation for primary immunodeficiency disorders. The median age at transplantation was 3 years and 5 months (range, 7 months to 17 years). Seventy-five percent of the cohort had organ involvement, with lung being the most common organ involved, followed by central nervous system. Fifty-two percent of children had peritransplant infections, with most of them recognized at the pretransplant assessment. Among 20 of 21 children with engraftment, 94% had complete chimerism initially, with 33% developing mixed chimerism over time. The median duration of immunosuppression was 3 months after transplantation, and only 1 child required systemic graft-versus-host disease treatment for more than a year. Immune-reconstitution showed good T-cell recovery at 3 months and naive T-cell production at 6 months. There was no regimen-related or sepsis-related mortality. Overall survival of the cohort was 95% at 1-year follow-up. Immunodeficiency-free survival was 86% after a median follow-up of 20 months.

Conclusions

Immunodeficiency-free and graft-versus-host disease-free survival can be achieved in the majority of children with primary immunodeficiencies using enhanced supportive care and the latest transplantation algorithms.

The Treatment of Primary Immune Deficiencies: Lessons Learned and Future Opportunities

Primary immunodeficiency is a group of disorders associated with susceptibility to infectious agents and the development of various comorbidities. Many primary immunodeficiencies are complicated by immune dysregulation, autoinflammation, or autoimmunity which impacts multiple organ systems. Major advances in the treatment of these disorders have occurred over the last half-century, and deeper molecular understanding of many disorders combined with clinically available genetic testing is allowing for use of precision therapy for several primary immunodeficiencies. Patients with antibody deficiencies who rely on immunoglobulin replacement therapy now have many treatment options with products that are much safer and better tolerated compared to the past. Newborn screening for severe combined immunodeficiency, now implemented throughout the USA and in many countries worldwide, has lowered the age at which many patients are diagnosed with these diseases. Early diagnosis of severe combined immunodeficiency allows infants to proceed to definitive therapy such as stem cell transplantation or gene therapy prior to facing potentially life-threatening infections. While stem cell transplantation continues to carry significant risks, knowledge gained over recent decades is allowing for improved survival with less toxicity and less graft versus host disease.

Measuring the effect of newborn screening on survival after haematopoietic cell transplantation for severe combined immunodeficiency: a 36-year longitudinal study from the Primary Immune Deficiency Treatment Consortium

BACKGROUND

Severe combined immunodeficiency (SCID) is fatal unless durable adaptive immunity is established, most commonly through allogeneic haematopoietic cell transplantation (HCT). The Primary Immune Deficiency Treatment Consortium (PIDTC) explored factors affecting the survival of individuals with SCID over almost four decades, focusing on the effects of population-based newborn screening for SCID that was initiated in 2008 and expanded during 2010-18.

METHODS

We analysed transplantation-related data from children with SCID treated at 34 PIDTC sites in the USA and Canada, using the calendar time intervals 1982-89, 1990-99, 2000-09, and 2010-18. Categorical variables were compared by χ2 test and continuous outcomes by the Kruskal-Wallis test. Overall survival was estimated by the Kaplan-Meier method. A multivariable analysis using Cox proportional hazards regression models examined risk factors for HCT outcomes, including the variables of time interval of HCT, infection status and age at HCT, trigger for diagnosis, SCID type and genotype, race and ethnicity of the patient, non-HLA-matched sibling donor type, graft type, GVHD prophylaxis, and conditioning intensity.

FINDINGS

For 902 children with confirmed SCID, 5-year overall survival remained unchanged at 72%-73% for 28 years until 2010-18, when it increased to 87% (95% CI 82·1-90·6; n=268; p=0·0005). For children identified as having SCID by newborn screening since 2010, 5-year overall survival was 92·5% (95% CI 85·8-96·1), better than that of children identified by clinical illness or family history in the same interval (79·9% [69·5-87·0] and 85·4% [71·8-92·8], respectively [p=0·043]). Multivariable analysis demonstrated that the factors of active infection (hazard ratio [HR] 2·41, 95% CI 1·56-3·72; p<0·0001), age 3·5 months or older at HCT (2·12, 1·38-3·24; p=0·001), Black or African-American race (2·33, 1·56-3·46; p<0·0001), and certain SCID genotypes to be associated with lower overall survival during all time intervals. Moreover, after adjusting for several factors in this multivariable analysis, HCT after 2010 no longer conveyed a survival advantage over earlier time intervals studied (HR 0·73, 95% CI 0·43-1·26; p=0·097). This indicated that younger age and freedom from infections at HCT, both directly driven by newborn screening, were the main drivers for recent improvement in overall survival.

INTERPRETATION

Population-based newborn screening has facilitated the identification of infants with SCID early in life, in turn leading to prompt HCT while avoiding infections. Public health programmes worldwide can benefit from this definitive demonstration of the value of newborn screening for SCID.

FUNDING

National Institute of Allergy and Infectious Diseases, Office of Rare Diseases Research, and National Center for Advancing Translational Sciences.

Gene Therapy for Inborn Errors of Immunity

In the early 1990s, gene therapy (GT) entered the clinical arena as an alternative to hematopoietic stem cell transplantation for forms of inborn errors of immunity (IEIs) that are not medically manageable because of their severity. In principle, the use of gene-corrected autologous hematopoietic stem cells presents several advantages over hematopoietic stem cell transplantation, including making donor searches unnecessary and avoiding the risks for graft-versus-host disease. In the past 30 years or more of clinical experience, the field has witnessed multiple examples of successful applications of GT to a number of IEIs, as well as some serious drawbacks, which have highlighted the potential genotoxicity of integrating viral vectors and stimulated important progress in the development of safer gene transfer tools. The advent of gene editing technologies promises to expand the spectrum of IEIs amenable to GT to conditions caused by mutated genes that require the precise regulation of expression or by dominant-negative variants. Here, we review the main concepts of GT as it applies to IEIs and the clinical results obtained to date. We also describe the challenges faced by this branch of medicine, which operates in the unprofitable sector of human rare diseases.

Late-onset enteric virus infection associated with hepatitis (EVAH) in transplanted SCID patients

BACKGROUND

Allogenic hematopoietic stem cell transplantation (HSCT) and gene therapy (GT) are potentially curative treatments for severe combined immunodeficiency (SCID). Late-onset posttreatment manifestations (such as persistent hepatitis) are not uncommon.

OBJECTIVE

We sought to characterize the prevalence and pathophysiology of persistent hepatitis in transplanted SCID patients (SCIDH+) and to evaluate risk factors and treatments.

METHODS

We used various techniques (including pathology assessments, metagenomics, single-cell transcriptomics, and cytometry by time of flight) to perform an in-depth study of different tissues from patients in the SCIDH+ group and corresponding asymptomatic similarly transplanted SCID patients without hepatitis (SCIDH-).

RESULTS

Eleven patients developed persistent hepatitis (median of 6 years after HSCT or GT). This condition was associated with the chronic detection of enteric viruses (human Aichi virus, norovirus, and sapovirus) in liver and/or stools, which were not found in stools from the SCIDH- group (n = 12). Multiomics analysis identified an expansion of effector memory CD8+ T cells with high type I and II interferon signatures. Hepatitis was associated with absence of myeloablation during conditioning, split chimerism, and defective B-cell function, representing 25% of the 44 patients with SCID having these characteristics. Partially myeloablative retransplantation or GT of patients with this condition (which we have named as "enteric virus infection associated with hepatitis") led to the reconstitution of T- and B-cell immunity and remission of hepatitis in 5 patients, concomitantly with viral clearance.

CONCLUSIONS

Enteric virus infection associated with hepatitis is related to chronic enteric viral infection and immune dysregulation and is an important risk for transplanted SCID patients with defective B-cell function.

Personalized hematopoietic stem cell transplantation for inborn errors of immunity

Patients with inborn errors of immunity (IEI) have been transplanted for more than 50 years. Many long-term survivors have ongoing medical issues showing the need for further improvements in how hematopoietic stem cell transplantation (HSCT) is performed if patients in the future are to have a normal quality of life. Precise genetic diagnosis enables early treatment before recurrent infection, autoimmunity and organ impairment occur. Newborn screening for severe combined immunodeficiency (SCID) is established in many countries. For newly described disorders the decision to transplant is not straight-forward. Specific biologic therapies are effective for some diseases and can be used as a bridge to HSCT to improve outcome. Developments in reduced toxicity conditioning and methods of T-cell depletion for mismatched donors have made transplant an option for all eligible patients. Further refinements in conditioning plus precise graft composition and additional cellular therapy are emerging as techniques to personalize the approach to HSCT for each patient.

The research on the treatment of primary immunodeficiency diseases by hematopoietic stem cell transplantation: A bibliometric analysis from 2013 to 2022

Hematopoietic stem cell transplantation (HSCT) is curative in patients with primary immunodeficiency syndrome. The safety and efficacy of HSCT as a therapeutic option for primary immunodeficiency diseases (PID) have been studied by many research groups. The purpose of our study was to perform a bibliometric analysis of research on HSCT for the treatment of PID, to assess research trends in this field, and note future research priorities. The Web of Science Core Collection (WOSCC) was used to identify relevant publications. VOSviewer and CiteSpace software were used to analyze bibliometric parameters, such as yearly records, authors, grouped authors, countries, institutions, categories and keywords. There are 602 relevant records for the last decade (2013-2022). The top 5 productive authors and high-quality paper journals are listed. Reference co-citations analysis demonstrated recent research trends were "inborn errors of immunity," "gene editing," and "enteropathy." Research on HSCT for the treatment of PID has increased rapidly in the last decade, and bibliometrics are valuable for researchers to obtain an overview of hot categories, academic collaborations and trends in this study field.

Early Is the Key for Treatment of Severe Combined Immunodeficiency

This Pillars of Immunology article is a commentary on “Hematopoietic stem cell transplantation for severe combined immunodeficiency in the neonatal period leads to superior thymic output and improved survival,” a pivotal article written by L. A. Myers, D. D. Patel, J. M. Puck, and R. H. Buckley, and published in Blood, in 2002. https://pubmed.ncbi.nlm.nih.gov/11806989/.

Transplant for non-malignant disorders: an International Society for Cell & Gene Therapy Stem Cell Engineering Committee report on the role of alternative donors, stem cell sources and graft engineering

Hematopoietic stem cell transplantation (HSCT) is curative for many non-malignant disorders. As HSCT and supportive care technologies improve, this life-saving treatment may be offered to more and more patients. With the development of new preparative regimens, expanded alternative donor availability, and graft manipulation techniques, there are many options when choosing the best regimen for patients. Herein the authors review transplant considerations, transplant goals, conditioning regimens, donor choice, and graft manipulation strategies for patients with non-malignant disorders undergoing HSCT.

Advances and Challenges of the Decade: The Ever-Changing Clinical and Genetic Landscape of Immunodeficiency

In the past 10 years, we have witnessed major advances in clinical immunology. Newborn screening for severe combined immunodeficiency has become universal in the United States and screening programs are being extended to severe combined immunodeficiency and other inborn errors of immunity globally. Early genetic testing is becoming the norm for many of our patients and allows for informed selection of targeted therapies including biologics repurposed from other specialties. During the COVID-19 pandemic, our understanding of essential immune responses expanded and the discovery of immune gene defects continued. Immunoglobulin products, the backbone of protection for antibody deficiency syndromes, came into use to minimize side effects. New polyclonal and monoclonal antibody products emerged with increasing options to manage respiratory viral agents such as SARS-CoV-2 and respiratory syncytial virus. Against these advances, we still face major challenges. Atypical is becoming typical as phenotypes of distinct genetic disease overlap whereas the clinical spectrum of the same genetic defect widens. Therefore, clinical judgment needs to be paired with repeated deep immune phenotyping and upfront genetic testing, as technologies rapidly evolve, and clinical disease often progresses with age. Managing patients with organ damage resulting from immune dysregulation poses a special major clinical challenge and management often lacks standardization, from autoimmune cytopenias, granulomatous interstitial lung disease, enteropathy, and liver disease to endocrine, rheumatologic, and neurologic complications. Clinical, translational, and basic science networks will continue to advance the field; however, cross-talk and education with practicing allergists/immunologists are essential to keep up with the ever-changing clinical and genetic landscape of inborn errors of immunity.

A great disturbance in the force: IL-2 receptor defects disrupt immune homeostasis

PURPOSE OF REVIEW

The current review highlights how inborn errors of immunity (IEI) due to IL-2 receptor (IL-2R) subunit defects may result in children presenting with a wide variety of infectious and inflammatory presentations beyond typical X-linked severe combined immune deficiency (X-SCID) associated with IL-2Rγ.

RECENT FINDINGS

Newborn screening has made diagnosis of typical SCID presenting with severe infections less common. Instead, infants are typically diagnosed in the first days of life when they appear healthy. Although earlier diagnosis has improved clinical outcomes for X-SCID, atypical SCID or other IEI not detected on newborn screening may present with more limited infectious presentations and/or profound immune dysregulation. Early management to prevent/control infections and reduce inflammatory complications is important for optimal outcomes of definitive therapies. Hematopoietic stem cell transplant (HSCT) is curative for IL-2Rα, IL-2Rβ, and IL-2Rγ defects, but gene therapy may yield comparable results for X-SCID.

SUMMARY

Defects in IL-2R subunits present with infectious and inflammatory phenotypes that should raise clinician's concern for IEI. Immunophenotyping may support the suspicion for diagnosis, but ultimately genetic studies will confirm the diagnosis and enable family counseling. Management of infectious and inflammatory complications will determine the success of gene therapy or HSCT.

Impact of DNA evidence in criminal justice system: Indian legislative perspectives

Background

The scientific and technological advances along with the changing socio-economical standards of society have posed new challenges to the criminal justice system. With the changes in society and technology, there is also an increase in crime rate. Forensics provides the scientific proofs beyond the shadow of reasonable doubt and thus significantly contributes in criminal as well as civil investigations and legal matters.

Main body of the abstract

Discovery of DNA has opened new avenues and the advancement of DNA technology and its introduction into the court of law has provided extensive aid in the resolution of civil and criminal disputes. In India, the DNA technology was first introduced in a paternity dispute in 1989. However, the need for legislation and guidelines to support grounds for the use of DNA profiling for forensic purposes in India has been recognized for some time now. In July 2019, the DNA Technology (Use and Application) Bill 2019 was introduced in the Indian parliament.

Short conclusion

Herein, this article is focused on the current aspects of DNA based evidence in the Indian Criminal Justice system along with the associated issues, highlighting the need for specific DNA based legislation.

Population pharmacokinetics and initial dose optimization of tacrolimus in children with severe combined immunodeficiency undergoing hematopoietic stem cell transplantation

The present study aimed to explore the population pharmacokinetics and initial dose optimization of tacrolimus in children with severe combined immunodeficiency (SCID) undergoing hematopoietic stem cell transplantation (HSCT). Children with SCID undergoing HSCT treated with tacrolimus were enrolled for analysis. Population pharmacokinetics of tacrolimus was built up by a nonlinear mixed-effects model (NONMEM), and initial dose optimization of tacrolimus was simulated with the Monte Carlo method in children weighing <20 kg at different doses. A total of 18 children with SCID undergoing HSCT were included for analysis, with 130 tacrolimus concentrations. Body weight was included as a covariable in the final model. Tacrolimus CL/F was 0.36–0.26 L/h/kg from body weights of 5–20 kg. Meanwhile, we simulated the tacrolimus concentrations using different body weights (5–20 kg) and different dose regimens (0.1–0.8 mg/kg/day). Finally, the initial dose regimen of 0.6 mg/kg/day tacrolimus was recommended for children with SCID undergoing HSCT whose body weights were 5–20 kg. It was the first time to establish tacrolimus population pharmacokinetics in children with SCID undergoing HSCT; in addition, the initial dose optimization of tacrolimus was recommended.

Conditioning regimens for inborn errors of immunity: current perspectives and future strategies

Inborn errors of immunity (IEI) are caused by germline genetic mutations, resulting in defects of innate or acquired immunity. Hematopoietic cell transplantation (HCT) is indicated for curative therapy especially in patients with IEI who develop fatal opportunistic infections or severe manifestations of immune dysregulation. The first successful HCT for severe combined immunodeficiency (SCID) was reported in 1968. Since then, the indications for HCT have expanded from SCID to various non-SCID IEI. In general, HCT for IEI differs from that for other hematological malignancies in that the goal is not to eradicate certain immune cells but to achieve immune reconstitution. European Society for Blood and Marrow Transplantation/European Society for Immunodeficiencies guidelines recommend reduced-intensity conditioning to avoid treatment-related toxicity, and the optimal conditioning regimen should be considered for each IEI. We review conditioning regimens for some representative IEI disorders in Japanese and worldwide cohort studies, and future strategies for treating IEI.

100 plus years of stem cell research-20 years of ISSCR

The International Society for Stem Cell Research (ISSCR) celebrates its 20th anniversary in 2022. This review looks back at some of the key developments in stem cell research as well as the evolution of the ISSCR as part of that field. Important discoveries from stem cell research are described, and how the improved understanding of basic stem cell biology translates into new clinical therapies and insights into disease mechanisms is discussed. Finally, the birth and growth of ISSCR into a leading stem cell society and a respected voice for ethics, advocacy, education and policy in stem cell research are described.

T and NK Cells in IL2RG-Deficient Patient 50 Years After Hematopoietic Stem Cell Transplantation

The first successful European hematopoietic stem cell transplantation (HSCT) was performed in 1968 as treatment in a newborn with IL2RG deficiency using an HLA-identical sibling donor. Because of declining naive T and natural killer (NK) cells, and persistent human papilloma virus (HPV)-induced warts, the patient received a peripheral stem cell boost at the age of 37 years. NK and T cells were assessed before and up to 14 years after the boost by flow cytometry. The boost induced renewed reconstitution of functional NK cells that were 14 years later enriched for CD56dimCD27+ NK cells. T-cell phenotype and T-cell receptor (TCR) repertoire were simultaneously analyzed by including TCR Vβ antibodies in the cytometry panel. Naive T-cell numbers with a diverse TCR Vβ repertoire were increased by the boost. Before and after the boost, clonal expansions with a homogeneous TIGIT and PD-1 phenotype were identified in the CD27− and/or CD28− memory population in the patient, but not in the donor. TRB sequencing was applied on sorted T-cell subsets from blood and on T cells from skin biopsies. Abundant circulating CD8 memory clonotypes with a chronic virus-associated CD57+KLRG1+CX3CR1+ phenotype were also present in warts, but not in healthy skin of the patient, suggesting a link with HPV. In conclusion, we demonstrate in this IL2RG-deficient patient functional NK cells, a diverse and lasting naive T-cell compartment, supported by a stem cell boost, and an oligoclonal memory compartment half a century after HSCT.

Multifocal oral squamous cell carcinoma post haematopoietic stem cell transplantation: A case report

Oral squamous cell carcinoma is considered a rare complication of post-haematopoietic stem cell transplantation (HSCT). Early detection of these lesions is further complicated by the overlapping clinical appearance and presentation of lesions associated with chronic graft versus host disease (cGVHD). We report a case of oral squamous cell carcinoma in a 33 year-old man who presented with severe intraoral pain on the lower left side of the cheek and jaw 19 months after undergoing HSCT for the treatment of underlying acute lymphoblastic leukaemia. He was previously treated with intravenous cyclophosphamide as a conditioning regimen for HSCT and later developed cGVHD of the liver, eyes, and gut, which resolved with treatment. Intraoral examination revealed two separate lesions. The first lesion presented as a raised oval nodular swelling with a well-circumscribed margin and irregular surface on the left buccal mucosa. A similar, but more extensive, lesion was noted on the left lingual gingiva and was associated with spontaneous bleeding. Biopsy revealed that both lesions were well-differentiated squamous cell carcinomas and were p16 positive. He underwent palliative radiotherapy but succumbed to his disease 3 months after initiation of treatment.

Clinical Development of Regenerative Medicine Targeted for Intervertebral Disc Disease

Low back pain is critical health, social, and economic issue in modern societies. This disease is often associated with intervertebral disc degeneration; however, contemporary treatments are unable to target this underlying pathology to alleviate the pain symptoms. Cell therapy offers a promising novel therapeutic that, in theory, should be able to reduce low back pain through mitigating the degenerative disc environment. With the clinical development of cell therapeutics ongoing, this review aims to summarize reporting on the different clinical trials and assess the different regenerative strategies being undertaken to collectively obtain an impression on the potential safety and effectiveness of cell therapeutics against intervertebral disc-related diseases.

Management of externally manufactured cell therapy products: the Mayo Clinic approach

BACKGROUND

The rise of investigative and commercially available cell therapy products adds a new dynamic to academic medical centers; that is, the management of patient-specific cell products. The scope of cell therapy has rapidly expanded beyond in-house collection and infusion of cell products such as bone marrow and peripheral blood transplant. The complexities and volumes of cell therapies are likely to continue to become more demanding. As patient-specific "living drugs," cell therapy products typically require material collection, product provenance, transportation and maintenance of critical quality attributes, including temperature and expiration dates. These requirements are complicated by variations in product-specific attributes, reporting requirements and interactions with industry not required of typical pharmaceuticals.

METHODS

To manage these requirements, the authors set out to establish a framework within the Immune, Progenitor and Cell Therapeutics Lab, the Current Good Manufacturing Practice facility responsible for cell manufacturing at Mayo Clinic Rochester housed within the Division of Transfusion Medicine. The authors created a work unit (biopharmaceutical unit) dedicated to addressing the specialized procedures required to properly handle these living drugs from collection to delivery and housing the necessary processes to more easily integrate externally manufactured cell therapies into clinical practice.

RESULTS

The result is a clear set of expectations defined for each step of the process, with logical documentation of critical steps that are concise and easy to follow.

CONCLUSIONS

The authors believe this system is scalable for addressing the promised growth of cell therapy products well into the future. Here the authors describe this system and provide a framework that could be used by other centers to manage these important new therapies.

Hematopoietic Cell Transplantation for Inborn Errors of Immunity Other than Severe Combined Immunodeficiency in Japan: Retrospective Analysis for 1985-2016

PURPOSE

Hematopoietic cell transplantation (HCT) is a curative therapy for most patients with inborn errors of immunity (IEI). We conducted a nationwide study on HCT for patients with IEI other than severe combined immunodeficiency (non-SCID) in Japan.

METHODS

Data from the Japanese national database (Transplant Registry Unified Management Program, TRUMP) for 566 patients with non-SCID IEI, who underwent their first HCT between 1985 and 2016, were retrospectively analyzed.

RESULTS

The 10-year overall survival (OS) and event-free survival (EFS) were 74% and 64%, respectively. The 10-year OS for HCT from unrelated bone marrow (URBM), accounting for 39% of HCTs, was comparable to that for HCT from matched sibling donor (MSD), 79% and 81%, respectively. HCT from unrelated cord blood (URCB), accounting for 28% of HCTs, was also common, with a 10-year OS of 69% but less robust engraftment. The intensity of conditioning was not associated with OS or neutrophil recovery; however, myeloablative conditioning was more frequently associated with infection-related death. Patients who received myeloablative irradiation showed poor OS. Multivariate analyses revealed that HCT in 1985-1995 (hazard ratio [HR], 2.0; P = 0.03), URCB (HR, 2.0; P = 0.01), and related donor other than MSD (ORD) (HR, 2.9; P < 0.001) were associated with poor OS, and URCB (HR, 3.6; P < 0.001) and ORD (HR, 2.7; P = 0.02) showed a higher incidence of retransplantation.

CONCLUSIONS

We present the 1985-2016 status of HCT for non-SCID IEI in Japan with sufficient statistical power, highlighting the potential of URBM as an alternative donor and the feasibility of reduced intensity conditioning.

In Utero Gene Therapy for Primary Immunodeficiencies

Primary immunodeficiencies (PIDs) have become a prime target for gene therapy given the morbidity, mortality, and the single gene etiology. Given that outcomes are better the earlier gene therapy is implemented, it is possible that fetal gene therapy may be an important future direction for the treatment of PIDs. In this chapter, the current treatments available for several PIDs will be reviewed, as well as the history and current status of gene therapy for PIDs. The possibility of in utero gene therapy as a possibility will then be discussed.

Hematopoietic cell transplantation in severe combined immunodeficiency: The SCETIDE 2006-2014 European cohort

BACKGROUND

Hematopoietic stem cell transplantation (HSCT) represents a curative treatment for patients with severe combined immunodeficiency (SCID), a group of monogenic immune disorders with an otherwise fatal outcome.

OBJECTIVE

We performed a comprehensive multicenter analysis of genotype-specific HSCT outcome, including detailed analysis of immune reconstitution (IR) and the predictive value for clinical outcome.

METHODS

HSCT outcome was studied in 338 patients with genetically confirmed SCID who underwent transplantation in 2006-2014 and who were registered in the SCETIDE registry. In a representative subgroup of 152 patients, data on IR and long-term clinical outcome were analyzed.

RESULTS

Two-year OS was similar with matched family and unrelated donors and better than mismatched donor HSCT (P < .001). The 2-year event-free survival (EFS) was similar in matched and mismatched unrelated donor and less favorable in mismatched related donor (MMRD) HSCT (P < .001). Genetic subgroups did not differ in 2-year OS (P = .1) and EFS (P = .073). In multivariate analysis, pretransplantation infections and use of MMRDs were associated with less favorable OS and EFS. With a median follow-up of 6.2 years (range, 2.0-11.8 years), 73 of 152 patients in the IR cohort were alive and well without Ig dependency. IL-2 receptor gamma chain/Janus kinase 3/IL-7 receptor-deficient SCID, myeloablative conditioning, matched donor HSCT, and naive CD4 T lymphocytes >0.5 × 10^e3/μL at +1 year were identified as independent predictors of favorable clinical and immunologic outcome.

CONCLUSION

Recent advances in HSCT in SCID patients have resulted in improved OS and EFS in all genotypes and donor types. To achieve a favorable long-term outcome, treatment strategies should aim for optimal naive CD4 T lymphocyte regeneration.

Historical perspective and a glance into the antibody-based conditioning regimens: A new era in the horizon?

The hematopoietic cell transplantation practice has changed significantly over the years. More than 1500 centers around the globe are offering transplant for different types of diseases. This growth was driven by improving the efficacy and the safety of the procedure and the ability to use alternate donors. These improvements made the procedure feasible in virtually all patients in need for it. With the availability of novel therapies and targeted agents, we may be witnessing a new transplant-era. These agents may help to circumvent some of the remaining limitations of the procedure and open the doors for new indications. Herein, we review historical transplant milestones, the accomplishments that led to the modern transplant practice and we discuss the idea of minimal-intensity conditioning and the possibility to adopt chemotherapy and radiation-free preparative regimens in the near future.

Hematopoietic Cell Transplantation for Severe Combined Immunodeficiency Patients: a Japanese Retrospective Study

Purpose

Hematopoietic cell transplantation (HCT) is a curative therapy for patients with severe combined immunodeficiency (SCID). Here, we conducted a nationwide study to assess the outcome of SCID patients after HCT in Japan.

Methods

A cohort of 181 SCID patients undergoing their first allogeneic HCT in 1974–2016 was studied by using the Japanese national database (Transplant Registry Unified Management Program, TRUMP).

Results

The 10-year overall survival (OS) of the patients who received HCT in 2006–2016 was 67%. Umbilical cord blood (UCB) transplantation was performed in 81 patients (45%). The outcomes of HCT from HLA-matched UCB (n = 21) and matched sibling donors (n = 22) were comparable, including 10-year OS (91% vs. 91%), neutrophil recovery (cumulative incidence at 30 days, 89% vs. 100%), and platelet recovery (cumulative incidence at 60 days, 89% vs. 100%). Multivariate analysis of the patients who received HCT in 2006–2016 demonstrated that the following factors were associated with poor OS: bacterial or fungal infection at HCT (hazard ratio (HR): 3.8, P = 0.006), cytomegalovirus infection prior to HCT (HR: 9.4, P = 0.03), ≥ 4 months of age at HCT (HR: 25.5, P = 0.009), and mismatched UCB (HR: 19.8, P = 0.01).

Conclusion

We showed the potential of HLA-matched UCB as a donor source with higher priority for SCID patients. We also demonstrated that early age at HCT without active infection is critical for a better prognosis, highlighting the importance of newborn screening for SCID.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10875-021-01112-5.

State-of-play for cellular therapies in cardiac repair and regeneration

Cardiovascular disease is the primary cause of death around the world. For almost two decades, cell therapy has been proposed as a solution for heart disease. In this article, we report on the “state‐of‐play” of cellular therapies for cardiac repair and regeneration. We outline the progression of new ideas from the preclinical literature to ongoing clinical trials. Recent data supporting the mechanics and mechanisms of myogenic and paracrine therapies are evaluated in the context of long‐term cardiac engraftment. This discussion informs on promising new approaches to indicate future avenues for the field.

Expectations and experience: Parent and patient perspectives regarding treatment for Severe Combined Immunodeficiency (SCID)

INTRODUCTION

Infants with SCID are treated with hematopoietic cell transplantation (HCT) or gene therapy (GT). Caregiver perceptions of pre-treatment counseling and understanding of durability of HCT/GT are poorly understood.

METHODS

A survey was designed and distributed to families of patients with SCID. Topics in the questionnaire included SCID genotype and treatment, family recollections of pre-treatment counseling and present clinical status.

RESULTS

151 surveys were analyzed. 132 were treated with HCT, 19 with GT. From counseling received, 37% expected HCT/GT would lead to "cure"; 43% expected HCT/GT would last a lifetime. Of 136 living patients, 59% reported overall good health but 65% reported some persistent health challenges.

CONCLUSIONS

For some, interpretation of the word "cure" varied, leading to misunderstanding regarding need for continued medical evaluations and additional therapies. Clear communication regarding the importance of lifelong follow-up, no matter the treatment outcome, will help to optimize good health and quality of life.

A Review of Advances in Hematopoietic Stem Cell Mobilization and the Potential Role of Notch2 Blockade

Hematopoietic stem cell (HSC) transplantation can be a potential cure for hematological malignancies and some nonhematologic diseases. Hematopoietic stem and progenitor cells (HSPCs) collected from peripheral blood after mobilization are the primary source to provide HSC transplantation. In most of the cases, mobilization by the cytokine granulocyte colony-stimulating factor with chemotherapy, and in some settings, with the CXC chemokine receptor type 4 antagonist plerixafor, can achieve high yield of hematopoietic progenitor cells (HPCs). However, adequate mobilization is not always successful in a significant portion of donors. Research is going on to find new agents or strategies to increase HSC mobilization. Here, we briefly review the history of HSC transplantation, current mobilization regimens, some of the novel agents that are under investigation for clinical practice, and our recent findings from animal studies regarding Notch and ligand interaction as potential targets for HSPC mobilization.

Therapy Development by Genome Editing of Hematopoietic Stem Cells

Accessibility of hematopoietic stem cells (HSCs) for the manipulation and repopulation of the blood and immune systems has placed them at the forefront of cell and gene therapy development. Recent advances in genome-editing tools, in particular for clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) and CRISPR/Cas-derived editing systems, have transformed the gene therapy landscape. Their versatility and the ability to edit genomic sequences and facilitate gene disruption, correction or insertion, have broadened the spectrum of potential gene therapy targets and accelerated the development of potential curative therapies for many rare diseases treatable by transplantation or modification of HSCs. Ongoing developments seek to address efficiency and precision of HSC modification, tolerability of treatment and the distribution and affordability of corresponding therapies. Here, we give an overview of recent progress in the field of HSC genome editing as treatment for inherited disorders and summarize the most significant findings from corresponding preclinical and clinical studies. With emphasis on HSC-based therapies, we also discuss technical hurdles that need to be overcome en route to clinical translation of genome editing and indicate advances that may facilitate routine application beyond the most common disorders.

The transformative potential of HSC gene therapy as a genetic medicine

Hematopoietic stem cells (HSCs) are precursor cells that give rise to blood, immune and tissue-resident progeny in humans. Their position at the starting point of hematopoiesis offers a unique therapeutic opportunity to treat certain hematologic diseases by implementing corrective changes that are subsequently directed through to multiple cell lineages. Attempts to exploit HSCs clinically have evolved over recent decades, from initial approaches that focused on transplantation of healthy donor allogeneic HSCs to treat rare inherited monogenic hematologic disorders, to more contemporary genetic modification of autologous HSCs offering the promise of benefits to a wider range of diseases. We are on the cusp of an exciting new era as the transformative potential of HSC gene therapy to offer durable delivery of gene-corrected cells to a range of tissues and organs, including the central nervous system, is beginning to be realized. This article reviews the rationale for targeting HSCs, the approaches that have been used to date for delivering therapeutic genes to these cells, and the latest technological breakthroughs in manufacturing and vector design. The challenges faced by the biotechnology cell and gene therapy sector in the commercialization of HSC gene therapy are also discussed.

Treosulfan-based conditioning for inborn errors of immunity

Inborn errors of immunity (IEI) are inherited disorders that lead to defects in the development and/or function of the immune system. The number of disorders that can be treated by haematopoietic stem-cell transplantation (HSCT) has increased rapidly with the advent of next-generation sequencing. The methods used to transplant children with IEI have improved dramatically over the last 20 years. The introduction of reduced-toxicity conditioning is an important factor in the improved outcome of HSCT. Treosulfan has myeloablative and immunosuppressive properties, enabling engraftment with less toxicity than traditionally used doses of busulfan. It is firmly incorporated into the conditioning guidelines of the Inborn Errors Working Party of the European Society for Blood and Marrow Transplantation. Unlike busulfan, pharmacokinetically guided dosing of treosulfan is not part of routine practice, but data are emerging which indicate that further improvements in outcome may be possible, particularly in infants who have a decreased clearance of treosulfan. It is likely that individualized dosing, not just of treosulfan, but of all agents used in conditioning regimens, will be developed and implemented in the future. This will lead to a reduction in unwanted variability in drug exposure, leading to more predictable and adjustable exposure, and improved outcome of HSCT, with fewer late adverse effects and improved quality of life. Such conditioning regimens can be used as the basis to study the need for additional agents in certain disorders which are difficult to engraft or require high levels of donor chimerism, the dosing of individual cellular components within grafts, and effects of adjuvant cellular or immunotherapy post-transplant. This review documents the establishment of treosulfan worldwide, as a safe and effective agent for conditioning children with IEI prior to HSCT.

Case Report: A Novel IL2RG Frame-Restoring Rescue Mutation Mimics Early T Cell Engraftment Following Haploidentical Hematopoietic Stem Cell Transplantation in a Patient With X-SCID

Mutations of the interleukin 2 receptor γ chain (IL2RG) result in the most common form of severe combined immunodeficiency (SCID), which is characterized by severe and persistent infections starting in early life with an absence of T cells and natural killer cells, normal or elevated B cell counts and hypogammaglobulinemia. SCID is commonly fatal within the first year of life, unless the immune system is reconstituted by hematopoietic stem cell transplantation (HSCT) or gene therapy. We herein describe a male infant with X-linked severe combined immunodeficiency (X-SCID) diagnosed at 5 months of age. Genetic testing revealed a novel C to G missense mutation in exon 1 resulting in a 3' splice site disruption with premature stop codon and aberrant IL2 receptor signaling. Following the diagnosis of X-SCID, the patient subsequently underwent a TCRαβ/CD19-depleted haploidentical HSCT. Post transplantation the patient presented with early CD8⁺ T cell recovery with the majority of T cells (>99%) being non-donor T cells. Genetic analysis of CD4⁺ and CD8⁺ T cells revealed a spontaneous 14 nucleotide insertion at the mutation site resulting in a novel splice site and restoring the reading frame although defective IL2RG function was still demonstrated. In conclusion, our findings describe a spontaneous second-site mutation in IL2RG as a novel cause of somatic mosaicism and early T cell recovery following haploidentical HSCT.

Impact of maternal engrafted cytomegalovirus-specific CD8+ T cells in a patient with severe combined immunodeficiency

Objectives

In patients with severe combined immunodeficiency (SCID), the immune system often fails to eradicate maternal cells that enter the foetus via the placenta, resulting in transplacental maternal engraftment (TME) syndrome. However, the clinical significance of TME has not been comprehensively elucidated.

Methods

Here, we describe a patient with SCID with a novel frameshift IL2RG mutation associated with maternal engrafted CD8⁺ T cells that had been expanded by viral infection. To evaluate the origin of the expanded T cells, we HLA‐typed the myeloid and T cells of the patient and analysed the immunological characteristics of the expanded CD8⁺ T cells using T‐cell receptor (TCR) repertoire and flow cytometry analysis.

Results

In our patient, the maternal engrafted CD8⁺ T cells expanded and exerted in vitro antiviral function against human cytomegalovirus (CMV) infection before and after haematopoietic cell transplantation (HCT). After haploidentical HCT from the maternal donor, maternal engrafted CMV‐specific CD8⁺ T cells were maintained, successfully proliferated and activated against CMV. We found no evidence of acute graft‐versus‐host disease or infectious complications other than recurrent episodes of CMV viraemia, which were well controlled by ganciclovir and, possibly by, the maternal engrafted CMV‐specific CD8⁺ T cells.

Conclusion

Our findings elucidate a possible functional role of TME in controlling CMV infection in patient with SCID and suggest an optimal strategy for donor selection in patients with SCID with TME.

Humanized Mice for the Evaluation of Novel HIV-1 Therapies

With the discovery of antiretroviral therapy, HIV-1 infection has transitioned into a manageable but chronic illness, which requires lifelong treatment. Nevertheless, complete eradication of the virus has still eluded us. This is partly due to the virus’s ability to remain in a dormant state in tissue reservoirs, ‘hidden’ from the host’s immune system. Also, the high mutation rate of HIV-1 results in escape mutations in response to many therapeutics. Regardless, the development of novel cures for HIV-1 continues to move forward with a range of approaches from immunotherapy to gene editing. However, to evaluate in vivo pathogenesis and the efficacy and safety of therapeutic approaches, a suitable animal model is necessary. To this end, the humanized mouse was developed by McCune in 1988 and has continued to be improved on over the past 30 years. Here, we review the variety of humanized mouse models that have been utilized through the years and describe their specific contribution in translating HIV-1 cure strategies to the clinic.