Allogeneic cellular and autologous stem cell therapy for sickle cell disease: 'whom, when and how'

On-Chip Neural Induction Boosts Neural Stem Cell Commitment: Toward a Pipeline for iPSC-Based Therapies

The clinical translation of induced pluripotent stem cells (iPSCs) holds great potential for personalized therapeutics. However, one of the main obstacles is that the current workflow to generate iPSCs is expensive, time-consuming, and requires standardization. A simplified and cost-effective microfluidic approach is presented for reprogramming fibroblasts into iPSCs and their subsequent differentiation into neural stem cells (NSCs). This method exploits microphysiological technology, providing a 100-fold reduction in reagents for reprogramming and a ninefold reduction in number of input cells. The iPSCs generated from microfluidic reprogramming of fibroblasts show upregulation of pluripotency markers and downregulation of fibroblast markers, on par with those reprogrammed in standard well-conditions. The NSCs differentiated in microfluidic chips show upregulation of neuroectodermal markers (ZIC1, PAX6, SOX1), highlighting their propensity for nervous system development. Cells obtained on conventional well plates and microfluidic chips are compared for reprogramming and neural induction by bulk RNA sequencing. Pathway enrichment analysis of NSCs from chip showed neural stem cell development enrichment and boosted commitment to neural stem cell lineage in initial phases of neural induction, attributed to a confined environment in a microfluidic chip. This method provides a cost-effective pipeline to reprogram and differentiate iPSCs for therapeutics compliant with current good manufacturing practices.

The implementation of automated red blood cell exchange (erythrocytapheresis) as a treatment modality in sickle cell disease patients: Single center experience

BACKGROUND

Improvements of health infrastructure, preventive care and clinical management is important to reduce the morbidity and mortality of sickle cell disease (SCD).

OBJECTIVE

This prospective, investigator-initiated non-randomized open-label intervention, single centre study describes the implementation of the automated erythrocytapheresis in low-middle income country as a treatment modality for SCD patients to improve the standard of care and highlights its benefits and challenges.

METHODOLOGY

Eligible patients with SCD who had overt stroke, abnormal/conditional transcranial doppler (TCD), or other indications were subjected to regular automated erythrocytapheresis program.

RESULTS

From 18th Dec 2017 till 17th Dec 2022, 21 subjects were enrolled; seventeen (80.9 %) were Egyptian and four (19.1 %) were non-Egyptian (three Sudanese and one Nigerian). Totalling 133 sessions had been performed mainly in working hours with fluctuating frequency per month. All sessions maintained isovolumic status and were performed using central venous access. The target HbS concentration was set from the start; the mean final FCR % fraction was 51, most of the session (n = 78, 58.7 %) were able to achieve target FCR. The majority of session pass smoothly with no adverse event (n = 81, 60.9 %), except for certain challenges as shortage of the required blood (n = 38), hypotension (n = 2), hypocalcaemia (n = 2).

CONCLUSION

Automated erythrocytapheresis is safe and effective modality for management of patients with sickle cell disease.

Donor chimerism and immune reconstitution following haploidentical transplantation in sickle cell disease

Introduction

We previously reported the initial results of a phase II multicenter transplant trial using haploidentical parental donors for children and aolescents with high-risk sickle cell disease achieving excellent survival with exceptionally low rates of graft-versus-host disease and resolution of sickle cell disease symptoms. To investigate human leukocyte antigen (HLA) sensitization, graft characteristics, donor chimerism, and immune reconstitution in these recipients.

Methods

CD34 cells were enriched using the CliniMACS^® system with a target dose of 10 x 10⁶ CD34⁺ cells/kg with a peripheral blood mononuclear cell (PBMNC) addback dose of 2x10⁵ CD3/kg in the final product. Pre-transplant HLA antibodies were characterized. Donor chimerism was monitored 1-24 months post-transplant. Comprehensive assessment of immune reconstitution included lymphocyte subsets, plasma cytokines, complement levels, anti-viral T-cell responses, activation markers, and cytokine production. Infections were monitored.

Results

HLA antibodies were detected in 7 of 11 (64%) evaluable patients but rarely were against donor antigens. Myeloid engraftment was rapid (100%) at a median of 9 days. At 30 days, donor chimerism was 93-99% and natural killer cell levels were restored. By 60 days, CD19 B cells were normal. CD8 and CD4 T-cells levels were normal by 279 and 365 days, respectively. Activated CD4 and CD8 T-cells were elevated at 100-365 days post-transplant while naïve cells remained below baseline. Tregs were elevated at 100-270 days post-transplant, returning to baseline levels at one year. At one year, C3 and C4 levels were above baseline and CH50 levels were near baseline. At one year, cytokine levels were not significantly different from baseline.

Discussion

These results suggest that haploidentical transplantation with CD34-enriched cells and peripheral blood mononuclear cell addback results in rapid engraftment, sustained donor chimerism and broad-based immune reconstitution.

Parent and Guardian Knowledge of Hematopoietic Cell Transplantation as a Treatment Option for Sickle Cell Disease

Beginning early in childhood, patients with sickle cell disease (SCD) are at risk of life-threatening and debilitating health events. Despite the high morbidity and mortality of this disease, hematopoietic cell transplantation (HCT), a curative treatment for SCD, remains underutilized. In the literature there is a paucity of data concerning medical decision maker (MDM) awareness of HCT as a treatment option for SCD. The objective of this study was to estimate the proportion of parents/guardians of children with SCD who are aware of HCT as a treatment option, and to identify the demographic factors associated with knowledge of this therapy's curative potential. Between November 2015 and December 2016, 327 parents/guardians were surveyed across 4 clinical sites in 3 Midwestern US cities. Although 82% of parents/guardians had heard of HCT in the past and 78% were aware of the therapy's curative potential, nearly half indicated that they did not know whether HCT could specifically cure their child of the disease. Respondents who had discussed HCT with their child's physician had 5 times higher odds of being aware of HCT's curative potential than those who had not. These findings suggest that additional efforts to enhance MDM knowledge of HCT as well as shared decision making in the use of this therapy, is warranted.

The past, present and future management of sickle cell retinopathy within an African context

Sickle cell retinopathy is a potentially blinding condition that affects young people in the working age group. This review looks at the past, present and future management of sickle cell retinopathy within an African context. After Sickle cell disease was first reported in 1910, some reports from Africa were pivotal in describing the retinal changes associated with the disease. It soon became obvious that there was a varied clinical picture and clinical course. Several landmark studies were carried out in Jamaica to help elucidate the complexities of the disease and outline appropriate clinical management. In most of the developed world, the clinical management of sickle cell disease has improved with concurrent improvement in outcomes. Currently resource constraints in most Sub-Saharan African countries where there is a high burden of disease means that the management of sickle cell retinopathy is fraught with numerous challenges. Future large scale trials in Africa shall hopefully help to better elucidate the mechanisms behind proliferative sickle retinopathy and help in the development of new and improved therapeutic pathways. The use of technology can help immensely in the screening of patients with sickle cell to detect early proliferative changes and if necessary treat accordingly.

Smoothing the crescent curve: sickle cell disease

Sickle cell disease (SCD) is an inherited disorder secondary to a point mutation at the sixth position of the beta chain of human hemoglobin that results in the replacement of valine for glutamic acid. This recessive genetic abnormality precipitates the polymerization of the deoxygenated form of hemoglobin S that induces a major distortion of red blood cells (sickle red blood cells), which decreases sickle red blood cell deformability, leading to chronic hemolysis and vasoocclusion. These processes can result in severe complications, including chronic pain, end organ dysfunction, stroke, and early mortality. The only proven curative therapy for patients with SCD is myeloablative conditioning and allogeneic stem cell transplantation from HLA-matched sibling donors. In this review, we discuss the most recent advances in allogeneic stem cell transplantation in SCD, including more novel approaches such as reduced toxicity conditioning and the use of alternative allogeneic donors (matched unrelated donors, umbilical cord blood transplantation, haploidentical donors) and autologous gene correction stem cell strategies. Prospects are bright for new stem cell approaches for patients with SCD that will enable curative stem and genetic correction therapies for a greater number of patients suffering from this chronic and debilitating condition.

Hematopoietic stem cell transplantation for sickle cell disease: state of the science

Sickle cell disease (SCD) is an inherited disorder secondary to a point mutation at the sixth position of the beta chain of human hemoglobin resulting in the replacement of valine for glutamic acid. This recessive genetic abnormality precipitates the polymerization of the deoxygenated form of hemoglobin S inducing a major distortion of red blood cells (S-RBC), which decreases S-RBC deformability leading to chronic hemolysis and vaso-occlusion. These processes can result in severe complications including chronic pain, end-organ dysfunction, stroke, and early mortality. The only proven curative therapy for patients with SCD is myeloablative conditioning and allogeneic stem cell transplantation from HLA-matched sibling donors. In this review, we discuss the most recent advances in allogeneic stem cell transplantation in patients with SCD including more novel approaches such as reduced toxicity conditioning and the use of alternative allogeneic donors, including matched unrelated donors (MUDs), unrelated cord blood donors (UCBT), and familial haploidentical (FHI) donors. The results to date are very encouraging regarding allogeneic stem cell transplantation for patients with SCD including high survival rates and enabling a greater number of patients suffering from this chronic and debilitating condition to receive curative allogeneic stem cell therapies. However, we still have several areas to investigate and barriers to overcome to successfully cure the majority of patients with severe SCD through allogeneic stem cell therapies.

New frontiers in pediatric Allo-SCT

The inaugural meeting of 'New Frontiers in Pediatric Allogeneic Stem Cell Transplantation' organized by the Pediatric Blood and Transplant Consortium (PBMTC) was held at the American Society of Pediatric Hematology and Oncology Annual Meeting. This meeting provided an international platform for physicians and investigators active in the research and utilization of pediatric Allo-SCT in children and adolescents with malignant and non-malignant disease (NMD), to share information and develop future collaborative strategies. The primary objectives of the conference included: (1) to present advances in Allo-SCT in pediatric ALL and novel pre and post-transplant immunotherapy; (2) to highlight new strategies in alternative allogeneic stem cell donor sources for children and adolescents with non-malignant hematological disorders; (3) to discuss timing of immune reconstitution after Allo-SCT and methods of facilitating more rapid recovery of immunity; (4) to identify strategies of utilizing Allo-SCT in pediatric myeloproliferative disorders; (5) to develop diagnostic and therapeutic approaches to hematological complications post pediatric Allo-SCT; (6) to enhance the understanding of new novel cellular therapeutic approaches to pediatric malignant and non-malignant hematological disorders; and (7) to discuss optimizing drug therapy in pediatric recipients of Allo-SCT. This paper will provide a brief overview of the conference.

Reduced toxicity, myeloablative conditioning with BU, fludarabine, alemtuzumab and SCT from sibling donors in children with sickle cell disease

BU and CY (BU/CY; 200 mg/kg) before HLA-matched sibling allo-SCT in children with sickle cell disease (SCD) is associated with ~85% EFS but is limited by the acute and late effects of BU/CY myeloablative conditioning. Alternatives include reduced toxicity but more immunosuppressive conditioning. We investigated in a prospective single institutional study, the safety and efficacy of a reduced-toxicity conditioning (RTC) regimen of BU 12.8-16 mg/kg, fludarabine 180 mg/m(2), alemtuzumab 54 mg/m(2) (BFA) before HLA-matched sibling donor transplantation in pediatric recipients with symptomatic SCD. Eighteen patients, median age 8.9 years (2.3-20.2), M/F 15/3, 15 sibling BM and 3 sibling cord blood (CB) were transplanted. Mean whole blood and erythroid donor chimerism was 91% and 88%, at days +100 and +365, respectively. Probability of grade II-IV acute GVHD was 17%. Two-year EFS and OS were both 100%. Neurological, pulmonary and cardiovascular function were stable or improved at 2 years. BFA RTC and HLA-matched sibling BM and CB allo-SCT in pediatric recipients result in excellent EFS, long-term donor chimerism, low incidence of GVHD and stable/improved organ function.

Umbilical cord blood: an evolving stem cell source for sickle cell disease transplants

Allogeneic hematopoietic stem cell transplantation has proven benefit in controlling sickle cell disease-related vasculopathy and organ damage. Myeloablative matched sibling donor cord transplants have excellent outcomes in sickle cell disease. Unrelated donor transplant options are often deferred because of a lack of suitable human leukocyte antigen-matched donors, a problem especially relevant to minority populations. Umbilical cord blood transplantation allows for more mismatching from the graft-versus-host disease perspective and the donor pool is expandable with effort and education. Drawbacks such as increased rates of graft rejection, a fixed cell dose, delayed immune reconstitution, and transplant-related mortality have deterred unrelated cord transplant efforts. However, the transplant community continues to make enormous strides in this transplant realm in areas of immunogenetics, stem cell expansion, conditioning regimens, and supportive care. This has allowed the development of new studies that are currently ongoing, exploring ways to make cord blood transplantation successful and safer. The goal is to make unrelated donor cord blood transplantation for sickle cell disease merit early consideration in patients who stand to benefit from this approach.

Stem cell and genetic therapies for the fetus

The prenatal diagnosis and management of congenital disease has made significant progress over the previous decade. Currently, fetal therapy (including open surgery and fetoscopic intervention) provides therapeutic options for a range of congenital anomalies; however, it is restricted to the treatment of fetal pathophysiology. Improvements in prenatal screening and the early diagnosis of genetic disease allow for preemptive treatment of anticipated postnatal disease by stem cell or genetic therapy. While currently awaiting clinical application, in utero stem cell therapy has made significant advances in overcoming the engraftment and immunologic barriers in both murine and pre-clinical large animal models. Likewise, proof in principle for fetal gene therapy has been demonstrated in rodent and large animal systems as a method to prevent the onset of inherited genetic disease; however, safety and ethical risks still need to be addressed prior to human application. In this review, we examine the current status and future direction of stem cell and genetic therapy for the fetus.