Graft versus host disease (GVHD) represents a major complication of allogeneic hematopoietic stem cell transplantation (allo HCT). Graft cellular manipulation has been used to mitigate the risk of GVHD. The αβ T cells are considered the primary culprit for causing GVHD therefore depletion of this T cell subset emerged as a promising cellular manipulation strategy to overcome the human leukocyte antigen (HLA) barrier of haploidentical (haplo) HCT. This approach is also being investigated in HLA-matched HCT. In several studies, αβ T cell depletion HCT has been performed without pharmacologic GVHD prophylaxis, thus unleashing favorable effect of donor’s natural killer cells (NK) and γδ T cells. This article will discuss the evolution of this method in clinical practice and the clinical outcome as described in different clinical trials.

Human mesenchymal stromal cells (MSCs), particularly Wharton's jelly-derived MSCs (WJMSCs), offer significant therapeutic potential for complex immune conditions such as graft versus host disease (GVHD), in part through their secreted small extracellular vesicles (sEVs). These sEVs exhibit crucial immunomodulatory properties, including suppression of T-cell activation demonstrated both in healthy donor cells and in pathologic contexts. Despite this promise, widespread clinical application is impeded by substantial challenges in developing robust, scalable, and Good Manufacturing Practice (GMP)-compliant manufacturing processes for MSC-derived sEVs to meet clinical demand. To address the critical barriers in sEV production, this study details the development and validation of a reliable and scalable manufacturing platform for WJMSC-derived sEVs. The process utilized GMP expanded WJMSC culture medium, generated from cultured low-passage cells and processed in scalable 2-L and 6-L batch volumes. This platform employed a sequential approach involving tangential flow filtration (TFF) for efficient initial concentration followed by size-exclusion chromatography (SEC) for comprehensive final purification of sEVs. The integrated TFF-SEC manufacturing approach resulted in a significant enrichment of nanoparticles, demonstrating up to a 16.9- and 36-fold increase in particle concentration post-TFF from the 2-L and 6-L batches, respectively. Two batches of purified sEVs demonstrated very similar mean size ranges, from 142 ± 2 nm to 156 ± 2 nm, and displayed the markers CD9 and CD81 while not expressing the negative marker calnexin. Those WJMSC-derived sEVs maintained their biological activity, effectively suppressing - cell activation in vitro. Furthermore, the purified sEVs from both 2-L and 6-L batches demonstrated an intact structure observed by cryogenic electron microscopy (cryo-EM), positivity for the inhibitory immune checkpoint ligand PD-L1. In this study, we report a reliable large-scale manufacturing framework that combines TFF and SEC to manufacture WJMSC-derived sEVs. The established standard operating procedures (SOPs) will help guide the design and establishment of industrial-scale, clinical-grade WJMSC-derived sEV manufacturing. This work significantly advances the field by offering a practical pathway that is anticipated to facilitate the broader development and accelerate the clinical translation of these WJMSC-derived sEVs as potent, cell-free therapeutic agents for various human diseases.

CXC chemokine CXCL12 is involved in the pathological development of rheumatoid arthritis (RA) through abnormal migration of peripheral immune cells in the joint. Although low dose methotrexate (MTX) is clinically used to treat RA patients, CXCL12 signaling responses to MTX-mediated treatments is still not well understood. In this study, we examined the expression of CXCR4 (cognatic receptor for CXCL12) in peripheral T cells from RA patients and arthritis mice models received from low dose MTX therapies. The effects of low dose MTX on CXCR4 were further determined via both in vitro CD3+ T cells and Cxcr4 conditional knockout (CKO) arthritis mice models. Our clinical data shows that low dose MTX treatment was clinically associated with down-regulated expression of chemokine receptor CXCR4 on patient peripheral T cells. In vitro, low dose MTX significantly decreased cell transmigration through down-regulated CXCR4’s expression in CD3+ T cells. Consistently, CD3+ T cells treated with low dose MTX demonstrated an increased genomic hypermethylation across the promoter region of Cxcr4 gene. Furthermore, our preclinical studies showed that low dose MTX-mediated downregulation of CXCR4 significantly improved the pathological development in mouse arthritis models. Conditional disruption of the Cxcr4 gene in peripheral immune cells potentially alleviated inflammation of joints and lung tissue in the arthritis mice, though genetic modification itself overall did not change their clinical scores of arthritis, except for a significant improvement on day 45 in CXCR4 CKO arthritis mice models during the recovery phase. Our findings suggest that the effect of low dose MTX treatment could serve to eliminate inflammation in RA patients through impairment of immune cell transmigration mediated by CXCR4.

Extracellular vesicles (EVs) contribute to the development of cancer in various ways. Non-Hodgkin lymphoma (NHL) is a cancer of mature lymphocytes and the most common hematological malignancy globally. The most common form of NHL, diffuse large B-cell lymphoma (DLBCL), is primarily treated with chemotherapy, autologous stem cell transplantation (ASCT), and/or chimeric antigen receptor T-cell (CAR-T) therapy. With NHL disease progression and its treatment, extracellular vesicles play remarkable roles in influencing outcomes. This finding can be utilized for therapeutic intervention to improve patient outcomes for NHL. This review focuses on the multifaceted roles of EVs with NHL and its potential for guiding patient care.

Anti-BCMA CAR T-cell therapy, specifically ciltacabtagene autoleucel, has significantly improved outcomes for relapsed/refractory multiple myeloma (RRMM). While early-onset immune-effector cell–associated neurotoxicity syndrome (ICANS) is a recognized complication, delayed-onset and non-ICANS neurological syndromes, such as movement and neurocognitive toxicity (MNT), present unique diagnostic and therapeutic challenges.

Severe refractory alloimmune thrombocytopenia is a challenging and life-threatening complication in patients with hematologic disorders who are undergoing allogeneic hematopoietic stem cell transplantation. This study aimed to investigate the utility of continuous intravenous immunoglobulin and platelet transfusions as a therapeutic approach for alloimmune thrombocytopenia in patients undergoing allogeneic transplants. A single-center retrospective analysis was conducted of ten adult allogeneic transplant patients hospitalized with transfusion-refractory alloimmune thrombocytopenia. Intravenous immunoglobulin (2 g/kg) was administered as a slow continuous infusion over 48 h along with a continuous apheresis platelet infusion (one apheresis unit over eight hours). Clinical response was defined as the resolution of bleeding or patients being able to undergo the required procedure without bleeding complications. The median time after the transplant was 27.5 (range: 7-299) days. Myeloablative and reduced-intensity conditioning were performed in 5 (50 %) and 5 (50 %) patients, respectively. The median platelet count at the time of infusion was 4.5 × 10⁹/L. All patients were able to achieve clinical response with the median maximum platelet count within ten days of the infusion being 41.0 × 10⁹/L. The median time to best response was three days with a median platelet count of 27.0 × 10⁹/L. Continuous intravenous immunoglobulin and platelet infusions over 48 h may be able to overcome life-threatening refractory alloimmune thrombocytopenia in transplant patients and may provide a bridging measure until platelet engraftment or for life-threatening hemorrhage or invasive procedures with high bleeding risk.