A Review of Acute and Long-Term Neurological Complications Following Haematopoietic Stem Cell Transplant for Paediatric Acute Lymphoblastic Leukaemia

Glutamic acid decarboxylase antibody-spectrum disorders and type 1 diabetes mellitus in a patient following allogenic hematopoietic cell transplantation with review of literature

Glutamic acid decarboxylase (GAD) is an enzyme that catalyzes the conversion of glutamic acid into γ-aminobutyric acid (GABA), the primary inhibitory neurotransmitter in the central nervous system (CNS). GAD is widely expressed in the CNS and pancreatic β-cells. GABA produced by GAD plays a role in regulating insulin secretion in pancreatic islets. Anti-GAD antibody is an established marker of type 1 diabetes mellitus (T1DM) and is also associated with stiff-person syndrome (SPS) and several other neurological disorders, including ataxia, cognitive impairment, limbic encephalitis, and epilepsy, collectively referred to as GAD antibody-spectrum disorders (GAD-SD). We report the case of a 17-year-old male patient who developed GAD-SD and T1DM after allogeneic hematopoietic cell transplantation (HCT). He presented with memory disorders, including feelings of déjà vu, accompanied by vomiting and headaches, and exhibited abnormal brain magnetic resonance imaging and electroencephalogram results. In addition to elevated fasting plasma glucose and glycated hemoglobin levels, markedly elevated anti-GAD antibody levels were detected in the serum and cerebrospinal fluid. Based on these findings, the patient was diagnosed with GAD-SD and T1DM and treated with methylprednisolone, followed by multiple daily insulin injections. We also reviewed previously reported cases of GAD-SD following HCT and multiple positive islet-related antibodies.

Myeloid-derived β-hexosaminidase is essential for neuronal health and lysosome function: implications for Sandhoff disease

Lysosomal storage disorders (LSDs) are a large disease class involving lysosomal dysfunction, often resulting in neurodegeneration. Sandhoff disease (SD) is an LSD caused by a deficiency in the β subunit of the β-hexosaminidase enzyme (Hexb). Although Hexb expression in the brain is specific to microglia, SD primarily affects neurons. To understand how a microglial gene is involved in maintaining neuronal homeostasis, we demonstrated that β-hexosaminidase is secreted by microglia and integrated into the neuronal lysosomal compartment. To assess therapeutic relevance, we treated SD mice with bone marrow transplant and colony stimulating factor 1 receptor inhibition, which broadly replaced Hexb -/- microglia with Hexb-sufficient cells. This intervention reversed apoptotic gene signatures, improved behavior, restored enzymatic activity and Hexb expression, ameliorated substrate accumulation, and normalized neuronal lysosomal phenotypes. These results underscore the critical role of myeloid-derived β-hexosaminidase in neuronal lysosomal function and establish microglial replacement as a potential LSD therapy.

Conclusive demonstration of iatrogenic Alzheimer's disease transmission in a model of stem cell transplantation

The risk of iatrogenic disease is often underestimated as a concern in contemporary medical procedures, encompassing tissue and organ transplantation, stem cell therapies, blood transfusions, and the administration of blood-derived products. In this context, despite the prevailing belief that Alzheimer's disease (AD) manifests primarily in familial and sporadic forms, our investigation reveals an unexpected transplantable variant of AD in a preclinical context, potentially indicating iatrogenic transmission in AD patients. Through adoptive transplantation of donor bone marrow stem cells carrying a mutant human amyloid precursor protein (APP) transgene into either APP-deficient knockout or normal recipient animals, we observed rapid development of AD pathological hallmarks. These pathological features were significantly accelerated and emerged within 6-9 months post transplantation and included compromised blood-brain barrier integrity, heightened cerebral vascular neoangiogenesis, elevated brain-associated β-amyloid levels, and cognitive impairment. Furthermore, our findings underscore the contribution of β-amyloid burden originating outside of the central nervous system to AD pathogenesis within the brain. We conclude that stem cell transplantation from donors harboring a pathogenic mutant allele can effectively transfer central nervous system diseases to healthy recipients, mirroring the pathogenesis observed in the donor. Consequently, our observations advocate for genomic sequencing of donor specimens prior to tissue, organ, or stem cell transplantation therapies, as well as blood transfusions and blood-derived product administration, to mitigate the risk of iatrogenic diseases.

Long-term toxicities after allogeneic hematopoietic stem cell transplantation with or without total body irradiation: a population-based study in Korea

PURPOSE

To compare long-term toxicity incidences, including secondary cancer (SC) with or without total body irradiation (TBI), in Asian patients receiving allogeneic hematopoietic stem cell transplantation (HSCT) using a nationwide database.

MATERIALS AND METHODS

We identified 4,554 patients receiving HSCT for leukemic disease from 2009 to 2016 using the healthcare bigdata system of Korea. Incidence rate ratios (IRRs) for SC, cataracts, hypothyroidism, chronic kidney disease (CKD), myocardial infarction, or strokes were compared, and standardized incidence ratios (SIR) of SC was also estimated.

RESULTS

TBI was conducted on 1,409 patients (30.9%). No overall survival differences based on TBI were observed. With a median follow-up duration of 58.2 months, 143 patients were diagnosed with subsequent SC (3.4%). Incidence rates per 1,000 person-year were 6.56 (95% confidence interval [CI], 4.8-8.8) and 7.23 (95% CI, 5.9-8.8) in the TBI and no-TBI groups, respectively (p = 0.594). Also, the SIR (95% CI) was not significantly increased by TBI (1.32 [0.86-1.94] vs. 1.39 [1.08-1.77] in the no-TBI group). In the young age group (0-19 years), SIRs were increased in both groups regardless of TBI (8.60 vs. 11.96). The IRRs of cataracts (1.60; 95% CI, 1.3-2.0), CKD (1.85; 95% CI, 1.3-2.6), and hypothyroidism (1.50; 95% CI, 1.1-2.1) were significantly increased after TBI. However, there were no significant differences in the occurrence of myocardial infarction and stroke according to TBI.

CONCLUSION

Our results suggest that modern TBI may not additionally increase the risk of SC after allogeneic HSCT, although increased risks of other diseases were noted. Physicians should carefully consider individualized risks and benefits of TBI, with a particular focus by age group.

Viral meningoencephalitis in pediatric solid organ or hematopoietic cell transplant recipients: a diagnostic and therapeutic approach

Neurologic complications, both infectious and non-infectious, are frequent among hematopoietic cell transplant (HCT) and solid organ transplant (SOT) recipients. Up to 46% of HCT and 50% of SOT recipients experience a neurological complication, including cerebrovascular accidents, drug toxicities, as well as infections. Defects in innate, adaptive, and humoral immune function among transplant recipients predispose to opportunistic infections, including central nervous system (CNS) disease. CNS infections remain uncommon overall amongst HCT and SOT recipients, compromising approximately 1% of total cases among adult patients. Given the relatively lower number of pediatric transplant recipients, the incidence of CNS disease amongst in this population remains unknown. Although infections comprise a small percentage of the neurological complications that occur post-transplant, the associated morbidity and mortality in an immunosuppressed state makes it imperative to promptly evaluate and aggressively treat a pediatric transplant patient with suspicion for viral meningoencephalitis. This manuscript guides the reader through a broad infectious and non-infectious diagnostic differential in a transplant recipient presenting with altered mentation and fever and thereafter, elaborates on diagnostics and management of viral meningoencephalitis. Hypothetical SOT and HCT patient cases have also been constructed to illustrate the diagnostic and management process in select viral etiologies. Given the unique risk for various opportunistic viral infections resulting in CNS disease among transplant recipients, the manuscript will provide a contemporary review of the epidemiology, risk factors, diagnosis, and management of viral meningoencephalitis in these patients.

Diagnostic clues in a stem cell transplant patient manifested with chronic central nervous system GVHD and IRIS

Transplant physicians should be aware of the immune deviation-related clinical conditions as allogeneic hematopoietic stem cell transplantation is widely used for the treatment of patients with malignant and non-malignant disorders. Neurological manifestations and graft-versus-host disease (GVHD) may commonly develop in transplant recipients. However, overlapping clinical immunological conditions may lead to diagnostic challenges. Herein, we discussed the differential diagnosis of a patient with immune reconstitution inflammatory syndrome (IRIS) developing on the basis of chronic GVHD.