Bone Marrow Transplantation for Non-Malignant Disease

A comprehensive analysis of cell-autonomous and non-cell-autonomous regulation of myeloid leukemic cells: The prospect of developing novel niche-targeting therapies

Leukemic cells (LCs) arise from the hematopoietic stem/and progenitor cells (HSCs/HSPCs) and utilize cues from the bone marrow microenvironment (BMM) for their regulation in the same way as their normal HSC counterparts. Mesenchymal stromal cells (MSCs), a vital component of the BMM promote leukemogenesis by creating a protective and immune-tolerant microenvironment that can support the survival of LCs, helping them escape chemotherapy, thereby resulting in the relapse of leukemia. Conversely, MSCs also induce apoptosis in the LCs and inhibit their proliferation by interfering with their self-renewal potential. This review discusses the work done so far on cell-autonomous (intrinsic) and MSCs-mediated non-cell-autonomous (extrinsic) regulation of myeloid leukemia with a special focus on the need to investigate the extrinsic regulation of myeloid leukemia to understand the contrasting role of MSCs in leukemogenesis. These mechanisms could be exploited to formulate novel therapeutic strategies that specifically target the leukemic microenvironment.

Safety of Cryopreserved Stem Cell Infusion through a Peripherally Inserted Central Venous Catheter

The management of patients undergoing stem cell transplantation requires a multipurpose central venous catheter (CVC) to facilitate drug administration, parenteral nutrition, transfusion of blood products, and collection of blood samples. Peripherally inserted central venous catheters (PICCs) appear to meet these requirements but are rarely used for stem cell infusion. We aimed to retrospectively assess the safety and feasibility of stem cell infusion through PICC and to evaluate its impact on transplantation kinetics. We retrospectively analyzed the outcomes of peripheral blood stem cell (PBSC) transplantation in patients receiving cryopreserved autologous or allogeneic PBSC by PICCs and compared the results with patients receiving transplants through a conventionally inserted central venous catheter (CICC). Despite statistically significant differences in CD34⁺ dose, infusion rate, and total length of administration, the clinical outcomes of transplantation, exemplified by platelet and neutrophil engraftment, along with the length of hospitalization, were not affected by the prolonged infusion time and lower infusion velocity in the PICC group. Our study showed that the clinical outcomes of PBSC transplantation did not differ between the PICC and CICC groups, suggesting that both types of catheters can be implemented in a PBSC transplantation setting.

Endocrinopathies in Inborn Errors of Immunity

Inborn errors of immunity (IEI), caused by hereditary or genetic defects, are a group of more than 400 disorders, in which the immune system, including lymphocytes, neutrophils, macrophages, and complements, does not function properly. The endocrine system is frequently affected by IEI as an associated clinical feature and a complex network of glands which regulate many important body functions, including growth, reproduction, homeostasis, and energy regulation. Most endocrine disorders associated with IEI are hypofunction which would be treated with supplementation therapy, and early diagnosis and appropriate management are essential for favorable long-term outcomes in patients with IEI. In this review, we aimed to comprehensively summarize and discuss the current understanding on the clinical features and the pathophysiology of endocrine disorders in IEI. This review is composed with three parts. First, we discuss the two major pathophysiology of endocrinopathy in IEI, autoimmune response and direct effects of the responsible genes. Next, the details of each endocrinopathy, such as growth failure, hypothyroidism, hypoparathyroidism, adrenal insufficiency, diabetes mellitus (DM) are specified. We also illustrated potential endocrinopathy due to hematopoietic stem cell transplantation, including hypogonadism and adrenal insufficiency due to glucocorticoid therapy.

The Relationship Between Busulfan Exposure and Achievement of Sustained Donor Myeloid Chimerism in Patients with Non-Malignant Disorders

The overall objective of allogeneic hematopoietic cell transplantation (HCT) in patients with non-malignant conditions involves replacing a dysfunctional or absent cell or gene product for disease correction. It is unclear whether lower busulfan exposure may be sufficient in this population to facilitate durable myeloid engraftment and limit toxicity. Given that neither the ideal level of mixed myeloid chimerism for specific non-malignant diseases nor how to condition a patient to achieve stable mixed myeloid chimerism is fully known, we sought to analyze the relationships among busulfan exposure, myeloid chimerism, and outcomes in patients with non-malignant conditions receiving busulfan as a part of combination pretransplant conditioning at our institution. This was a single-center, retrospective study including pediatric patients with a variety of non-malignant disorders who underwent allogeneic HCT at the University of California San Francisco Benioff Children's Hospital from March 2007 to June 2018. The busulfan cumulative area under the curve (cAUC) was estimated using a validated population pharmacokinetic model and nonlinear mixed effects modeling. Median busulfan cAUC for all patients was 70 mg·h/L (range, 53 to 108). All of the 29 patients with a busulfan cAUC of ≥70 mg·h/L achieved long-term disease correction with full or stable mixed (>20%) myeloid chimerism, compared to 78.5% (22/28) of patients with a cAUC of <70 mg·h/L (P = .01). Overall ksurvival was evaluated up to 3 years and was identical in patients with busulfan cAUC < 70 mg·h/L and patients with busulfan cAUC ≥70 mg·h/L (96% versus 93%; P = .92). Only three patients died, at days 65, 164 and 980 days post-HCT. Severe busulfan-related toxicities and graft-versus-host-disease (GVHD) were rare, with veno-occlusive disease occurring in four patients (7%), acute respiratory distress syndrome in three patients (5%), and GVHD in five patients (9%). These results demonstrate excellent outcomes and extremely low rates of toxicity across our entire cohort. Based on the results of this study, we recommend a busulfan exposure target of 75 mg·h/L (range, 70 to 80) in all non-malignant patients receiving allogeneic HCT to ensure optimal exposure for achievement of high-level stable myeloid chimerism.

Posttransplant Lymphoproliferative Disorder in Children: A 360-degree Perspective

An earlier incorrect version of this article appeared online. This article was corrected on December 17, 2019.

Gonadal failure among female patients after hematopoietic stem cell transplantation for non-malignant diseases

In addition to malignant diseases, hematopoietic stem cell transplantation (HSCT) is also a vital option as a curative therapy for non-malignant diseases, such as immunodeficiency, and other hematological disorders. Not only for malignant diseases, but for non-malignant diseases, cytotoxic therapy of conditioning regimens are associated with high risks of adverse effects; however, clinical details regarding the long term outcomes of cytotoxic therapy for non-malignant diseases are not documented yet. To clarify the endocrinological consequences of pediatric HSCT for non-malignant disease patients, we conducted a retrospective analysis. From 1983 to 2014, 75 patients that underwent HSCT for non-malignant diseases were selected for this study. Of these, 23 patients (19 men, 4 women) were continuously followed up in our institute, with regular health check-ups for late effects. Based on a multiple linear regression analysis, the glucocorticoid treatment duration for chronic graft-versus-host disease (cGVHD) and the conditioning regimen were found to be independent predictors of growth retardation. All four female patients developed hypogonadism, and required hormone replacement therapy. The conditioning regimen for the four female patients with hypogonadism was based on the use of alkylating agents, and two female patients were treated with a reduced-intensity conditioning (RIC) regimen. Our study revealed that even the RIC regimen was toxic for the gonads in female patients, and that the survivors of both non-malignant and malignant diseases should be followed up carefully after pediatric HSCT.

In vivo engineering of bone tissues with hematopoietic functions and mixed chimerism

Synthetic biomimetic matrices with osteoconductivity and osteoinductivity have been developed to regenerate bone tissues. However, whether such systems harbor donor marrow in vivo and support mixed chimerism remains unknown. We devised a strategy to engineer bone tissues with a functional bone marrow (BM) compartment in vivo by using a synthetic biomaterial with spatially differing cues. Specifically, we have developed a synthetic matrix recapitulating the dual-compartment structures by modular assembly of mineralized and nonmineralized macroporous structures. Our results show that these matrices incorporated with BM cells or BM flush transplanted into recipient mice matured into functional bone displaying the cardinal features of both skeletal and hematopoietic compartments similar to native bone tissue. The hematopoietic function of bone tissues was demonstrated by its support for a higher percentage of mixed chimerism compared with i.v. injection and donor hematopoietic cell mobilization in the circulation of nonirradiated recipients. Furthermore, hematopoietic cells sorted from the engineered bone tissues reconstituted the hematopoietic system when transplanted into lethally irradiated secondary recipients. Such engineered bone tissues could potentially be used as ectopic BM surrogates for treatment of nonmalignant BM diseases and as a tool to study hematopoiesis, donor-host cell dynamics, tumor tropism, and hematopoietic cell transplantation.