Single-cell transcriptomics dissects hematopoietic cell destruction and T-cell engagement in aplastic anemia.

Aplastic anemia (AA) is a T cell-mediated autoimmune disorder of the hematopoietic system manifested by severe depletion of the hematopoietic stem and progenitor cells (HSPCs). Nonetheless, our understanding of the complex relationship between HSPCs and T cells is still obscure, mainly limited by techniques and the sparsity of HSPCs in the context of bone marrow failure. Here we performed single-cell transcriptome analysis of residual HSPCs and T cells to identify the molecular players from patients with AA. We observed that residual HSPCs in AA exhibited lineage-specific alterations in gene expression and transcriptional regulatory networks, indicating a selective disruption of distinct lineage-committed progenitor pools. In particular, HSPCs displayed frequently altered alternative splicing events and skewed patterns of polyadenylation in transcripts related to DNA damage and repair, suggesting a likely role in AA progression to myelodysplastic syndromes. We further identified cell type-specific ligand-receptor interactions as potential mediators for ongoing HSPCs destruction by T cells. By tracking patients after immunosuppressive therapy (IST), we showed that hematopoiesis remission was incomplete accompanied by IST insensitive interactions between HSPCs and T cells as well as sustained abnormal transcription state. These data collectively constitute the transcriptomic landscape of disrupted hematopoiesis in AA at single-cell resolution, providing new insights into the molecular interactions of engaged T cells with residual HSPCs and render novel therapeutic opportunities for AA.

Detection of lenalidomide metabolites in urine to discover drug-resistant compounds.

Lenalidomide is the first-line drug for the clinical treatment of multiple myeloma. However, its efficacy differs significantly among patients. Clinically, after lenalidomide treatment, few patients' conditions worsened, whereas others remained stable or improved. To clarify the reasons for this difference in efficacy, 20 patients with multiple myeloma who received maintenance treatment with lenalidomide were retrospectively included in this study. Lenalidomide metabolic compounds were detected in patient urine using mass spectrometry. A rapid and accurate ultra-performance liquid chromatography-time-of-flight tandem mass spectrometry (UPLC-TOF-MS/MS) method was used to characterize metabolites in the urine of different patients. Eleven metabolites, including four new compounds, were identified and characterized in all the samples. Among these, two metabolites were found to have obvious discrepancies in different groups of patients. One metabolite named Denitrified-2 glutarimide, a new potential compound, was only detected in the urine of ineffective and stable patients, whereas the other metabolite named 5-Hydroxy-lenalidomide was found only in the urine of effective patients.

Expansion of human megakaryocyte-biased hematopoietic stem cells by biomimetic Microniche.

Limited numbers of available hematopoietic stem cells (HSCs) limit the widespread use of HSC-based therapies. Expansion systems for functional heterogenous HSCs remain to be optimized. Here, we present a convenient strategy for human HSC expansion based on a biomimetic Microniche. After demonstrating the expansion of HSC from different sources, we find that our Microniche-based system expands the therapeutically attractive megakaryocyte-biased HSC. We demonstrate scalable HSC expansion by applying this strategy in a stirred bioreactor. Moreover, we identify that the functional human megakaryocyte-biased HSCs are enriched in the CD34+CD38-CD45RA-CD90+CD49f lowCD62L-CD133+ subpopulation. Specifically, the expansion of megakaryocyte-biased HSCs is supported by a biomimetic niche-like microenvironment, which generates a suitable cytokine milieu and supplies the appropriate physical scaffolding. Thus, beyond clarifying the existence and immuno-phenotype of human megakaryocyte-biased HSC, our study demonstrates a flexible human HSC expansion strategy that could help realize the strong clinical promise of HSC-based therapies.

Ixazomib-based maintenance therapy after bortezomib-based induction in patients with multiple myeloma not undergoing transplantation: A real-world study.

BACKGROUND: Maintenance therapy with proteasome inhibitors (PIs) can improve outcomes of multiple myeloma (MM) patients, however, the neurotoxicity and parenteral route of bortezomib limit its long-term use. An efficacious, tolerable, and convenient PI option is needed. METHODS: In this single-center, real-world study, we retrospectively analyzed the outcome and safety profile of ixazomib-based maintenance therapy in patients who plateaued with the responses of steady disease or better after bortezomib-based induction therapy in MM patients not undergoing transplantation. RESULTS: Of all the 71 patients, 37 cases (52.1%) were newly diagnosed MM (NDMM) and 34 cases (47.9%) were relapsed and/or refractory MM (RRMM). The overall response rate (ORR) was 81.7%, including 34 patients (47.9%) with a very good response rate or better (≥VGPR) after a median of nine cycles (6-14) of bortezomib-based induction therapy. Then the ORR was transformed to 74.6% including 39 patients of ≥VGPR (54.9%) after a median of six courses (2-25) of ixazomib-based maintenance therapy. Of these, 18 patients (25.4%) exhibited responses deepened. With 26.5 months median follow-up, median progression-free survival (PFS) was 28.4 and 16.5 months from the start of bortezomib and 16.2 and 10.0 months from the initiation of ixazomib in NDMM and RRMM group, respectively. Moreover, responses deepened during the maintenance phase (hazard ratio: 0.270, p = 0.007), and responses of ≥VGPR during the induction phase (hazard ratio: 0.218, p < 0.001) were confirmed to independently predict longer PFS after multivariate analyses. Severe adverse events (grade 3/4) were relatively rare. Bortezomib-emergent peripheral neuritis (PN) was significantly relived after the transition to ixazomib (p < 0.001). CONCLUSION: This real-world analysis has demonstrated oral ixazomib is a favorable option of long-term administration for maintenance with efficacy and feasibility and confirmed the association between deepening responses with ixazomib and prolonged PFS.

[Screening and Verification of Antioxidant Small Molecular Compounds for Expansion of Human Hematopoietic Stem Cells Ex Vitro].

OBJECTIVE: To screen the antioxidant small molecular compounds with optimal efficiency of expansing the human hematopoietic stem cells (hHSC) In vitro based on antioxidant small molecular compound database of LKT laboratory, and to verify the effects of these compounds on the biological functions of hHSC. METHODS: The umbilial cord blood CD34+ cells were enriched by using the MACS beads; the absolute number and percentage of CD34+ cells and CD34+ CD49f+ cells were detected by high throughput flow cytometry after culture of hHSC with compounds in vitro for 1 week, the SR1 (1 µmol/L) was used as positive control, the candidate compounds were screened out; then 4 compounds were selected for follow-up experiments by comprehensive evaluation of concentration, safety and expansion efficacy, the optimal used concentrations of selected compounds were determined through the concentration gradient analysis, and CFC short-term colony-forming cell test was performed by using the determined concentration so as to verify the effect of compounds on the self-renewal, multilineage differentiation. RESULTS: Out of 85 antioxidant small molecular compounds, 4 compounds (C2968, D3331, B1753 and B3358) with obvious expansion efficacy for CD34+ cells and CD34+ CD49f+ cells were screened out by high throughput flow cytometry; their optimal concentrations of 4 compounds were 0.5 µmol/L for C2968, 1.5 µmol/L for D3331 and 1.5 µmol/L for B1753 and 15 µmol/L for B3358. The CFC assay showed the colony formation number in compound-treated group significantly increased as compared with control group, moreover the self-renewal and multilineage differentiation were maintained. CONCLUSION: The antioxidant small molecular compounds C2968 (0.5 µmol/L), D3331 (1.5 µmol/L), B1753 (1.5 µmol/L) and B3358 (1.5 µmol/L) possess good expansion efficacy for hHSC, they can maintain hHSC self-renewal, at the same time ensure the multilineage differentiation potentiality of hHSC.

[Ex vivo Culture System of Single Human Hematopoietic Stem Cell Used to Screan the Small Molecular Compounds].

OBJECTIVE: To explore an efficient, stable system and method to verify the regulation effect of small molecule compounds on human hematopoietic stem cells (hHSC). METHODS: By using combination of flow cytometry with study results of surface markers on hHSC, and optimation of sorting process for further studying the effect of small molecular compounds on stem property of hHSC, the single hHSC was treated with published small molecular compounds such as SR1 and UM171 which possess the expansion effect. After treating with hHSC for 14 d, the flow cytometric analysis of cell phenotypes and cell morphologic observation were performed, at the same time the hematopoietic function of cultured hHSC was verified by colony-forming cell (CFC) test and cobblestone area forming cell (CAFC) test. RESULTS: The effects of SR1 and UM171 and their compositions in multi-cell culture were consistent with the published data, therefore the useful concentration of compounds were obtained. The results of multiparameter sorting of single cell (CD34+ CD38- CD45RA- CD90+ CD49f+) and ex vivo culture were consistent with the results of bulk cell culture. The results of cell phenotype analysis was in accordance with flow cytometric results. In addition, CFC test and CAFC test revealed that the colony-forming ability in treated group was significantly higher than that in control group (P<0.05). CONCLUSION: The rapid, efficient stably amplified and short-time culture system for single hHSC and method for varifying the effect of small molecular compounds are established, which provides platform for screening small molecular compounds and lays the foundation for further study of hHSC expansion.