Plasticity after allogeneic hematopoietic stem cell transplantation

The postulated almost unlimited potential of transplanted hematopoietic stem cells (HSCs) to transdifferentiate into cell types that do not belong to the hematopoietic system denotes a complete paradigm shift of the hierarchical hemopoietic tree. In several studies during the last few years, donor cells have been identified in almost all recipient tissues after allogeneic HSC transplantation (HSCT), supporting the theory that any failing organ could be accessible to regenerative cell therapy. However, the putative potential ability of the stem cells to cross beyond lineage barriers has been questioned by other studies which suggest that hematopoietic cells might fuse with non-hematopoietic cells and mimic the appearance of transdifferentiation. Proof that HSCs have preserved the capacity to transdifferentiate into other cell types remains to be demonstrated. In this review, we focus mainly on clinical studies addressing plasticity in humans who underwent allogeneic HSCT. We summarize the published data on non-hematopoietic chimerism, donor cell contribution to tissue repair, the controversies related to the methods used to detect donor-derived non-hematopoietic cells and the functional impact of this phenomenon in diverse specific target tissues and organs.     

T cell-mediated graft-versus-leukemia reactions after allogeneic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation represents the only curative approach for many hematological malignancies. During the last years the impact of the conditioning regimen has been re-assessed. With the advent of reduced-intensity conditioning the paradigm has changed from cytoreduction executed by high-dose radio-chemotherapy to immunological surveillance of leukemia by donor cells. Distinct subsets of T cells and NK cells contribute to graft-versus-leukemia reactions. So far, cytotoxic T lymphocytes are the mainstay of allogeneic immunotherapy. Here, we summarise the current knowledge of T cell-mediated graft-versus-leukemia reactions and present results from pre-clinical and clinical studies of T cell-based adoptive immunotherapy. We address the issues of feasibility and specificity of adoptive immunotransfer from a clinical point of view and discuss the prerequisites for successful clinical applications. Finally, the prospects for immunological research that have evolved with the increasing use of reduced-intensity conditioning and allogeneic stem cell transplantation are highlighted.     

Immune recovery after allogeneic stem cell transplantation: study of 19 patients

The aim of this study was to access average delays for novogeneration of myeloid and lymphoid cells after allogeneic bone marrow transplantation (BMT) outcome and factors affecting this organization. A prospective analysis over 2 years (01/01/07 to 31/12/08) enrolling 19 children treated with allogeneic intrafamilial bone marrow transplantation. Indications for bone marrow transplantation were: aplastic anemia (3 cases), bemoglobinopathies (9 cases), myelodysplastic syndrome (1 case) and primary immunodeficiency (6 cases). Different conditioning regiments were used according to the indication. The study of immune reconstitution was based on the quantitative determination of immunoglobulin and lymphocyte subpopulation. These tests were routinely requested to 1 month, 2 months, 3 months, 6 months, 9 months and 12 months. The average time of engraftment was 18 days (12-24). A rate of CD4+T lymphocytes>200/mm3 was provided within an average of 2,5 months (1-7). The average time to obtain CD8+T lymphocytes>200/mm3 was 2 months (1-5). The humoral immune reconstitution was made within an average of 2 months (1-4). A report of CD4+/CD8+T lymphocytes>I was obtained within 10 months and a half (1-24). Univaried analysis showed a correlation between the bone marrow sex matched and the faster reorganization of CD8+T cells (p=0.042). A quantity of CD34+>6 10(6)/kg was significantly associated with the recapture of a formula lymphocyte CD4+/CD8+T>1 (p=0.03) Immune recovery post bone marrow transplantation in children begins with myeloid lineage then lymphoid B then lymphoid T The inversion of the report CD4+/CD8+T lymphocytes, seems to be influenced by the high contain of CD34+cells in the graft as well as the type of conditioning.     

CD34(+)-selected stem cell boost for delayed or insufficient engraftment after allogeneic stem cell transplantation

BACKGROUND: Poor graft function without rejection may occur after stem cell transplantation (SCT). CD34(+) stem cell boost (SCB) can restore marrow function but may induce or exacerbate GvHD. We therefore investigated the feasibility and efficacy of CD34(+)-selected SCB in some patients with poor graft function. We present the results for eight patients (median age 46 years) transplanted initially for myelofibrosis, acute leukemia, myeloma and NHL. Six patients had received HLA-matched and two mismatched grafts (PB, BM; n=5, 3). After a median of 128 days post-transplant, the median leukocyte and platelet counts were, respectively, 2.05/nL and 18/nL. None had achieved platelet counts >50/nL even though donor chimerism was >95% in seven recipients. METHODS: Positive selection of CD34(+) stem cells was performed on a CliniMACS device, observing GMP and achieving a median of 98.5% purity. The patients received a median of 1.7 x 10(6)/kg CD34(+) cells and 2.5 x 10(3)/kg CD3(+) T lymphocytes. RESULTS: Hemograms at days +30, +60 and +90, respectively, showed steadily increasing median leukocyte (2.55, 3.15 and 4.20/nL) and platelet (29, 39 and 95/nL) counts. After a median follow-up of 144 days, five patients remained alive. No patient had developed acute or chronic GvHD. One patient died of leukemic relapse and two others of systemic mycosis. DISCUSSION: These preliminary results point to the possibility of safely improving graft function using CD34(+) positively selected stem cells without necessarily increasing the incidence of GvHD in patients with poor graft function post-SCT. Experience with more patients and longer follow-up should clarify the optimal role for this procedure.     

Selective depletion strategies in allogeneic stem cell transplantation

Despite improved prophylaxis and treatment, GvHD remains a major limitation to optimal allogeneic stem cell transplantation. Ex vivo selective depletion (SD) is a strategy to prevent GvHD, in which host-reactive donor lymphocytes are selectively eliminated from a PBSC allograft while useful donor immune function is preserved. The elimination of alloreactive and thereby GvHD-mediating T cells has been shown to be feasible in both pre-clinical and more recently clinical studies. However, SD techniques and the translational research needed for clinical application are still under development. Here we summarize and discuss the following aspects of the SD approach: selection of an appropriate allogeneic stimulator; the responder population; the alloresponse; methods for removal of alloreacting T cells; product testing; clinical considerations. Our review highlights the diversity of possible approaches and the need to develop different techniques for specific clinical applications.     

异基因造血干细胞移植后并发自身免疫性溶血性贫血的治疗进展

异基因造血干细胞移植（HSCT）后自身免疫性溶血性贫血（AIHA）是HSCT后并不少见的并发症,其发病率约1﹪~ 6﹪,不同于一般的AIHA,HSCT后AIHA发病机制尚未完全明确,可能与HSCT后受者体内免疫失调相关。危险因素与移植患者年龄小、非恶性疾病、使用无关供者、半相合供者移植、脐血移植、去T细胞移植及移植后并发慢性移植物抗宿主病（GVHD）等有关。皮质激素作为一线治疗,疗效有限,难以持续缓解,需联合使用利妥昔单抗（RTX）、大剂量丙种球蛋白等,甚至需要联合霉酚酸酯、环磷酰胺、西罗莫司、阿伦单抗、依库丽单抗或蛋白酶体抑制剂硼替佐米等免疫抑制剂治疗,部分患者需行血浆置换,偶有行脾切除术者。移植后AIHA总死亡率常高达50﹪,总体预后差于单纯AIHA。该综述旨在总结HSCT后并发AIHA的最新治疗进展,供临床医师参考。     

Estimating the size of the dividing stem cell pool after allogeneic bone marrow transplantation

Currently the problem of estimation of the number of pluripotent stem cells reconstituting marrow grafts following bone marrow transplantation, or studies looking at questions of clonal dominance in hematopoietic cell populations, rely on indirect measurement and a simple application of the formula for the sampling variation of a binomial proportion. This approach, from a statistical viewpoint, can be seen to be flawed. It is very easily remedied though and only requires appropriate use of variance stabilizing transformations. These lead to a very simple estimator for the number of hematopoietic stem cells involved in repopulating the marrow and require little in the way of additional calculation. We give the distribution theory for this estimator as well as simple approximations for practical application. As an illustration we rework data recently gathered to address the question as to whether or not reconstitution of marrow grafts in the clinical setting is oligoclonal.     

G-CSF诱导移植物抗白血病效应治疗异基因造血干细胞移植后复发白血病的研究

目的观察应用G-CSF诱导移植物抗白血病效应治疗异基因造血干细胞移植后复发白血病的疗效。方法对2011年7月至2013年2月该科异基因造血干细胞移植后40例复发的白血病患者,进行输注粒细胞集落刺激因子动员后供者外周血单个核细胞治疗。其中-CR3髓系有4例,细胞混合有6例,-CR2淋巴细胞有10例,-CR2髓系有16例,髓系加速期慢性有4例。在异基因造血干细胞移植后,半年内,40例患者均复发,予G-CSF动员后,供者外周血单个核细胞输注,每次输注细胞量逐级增加,每次输注间隔4周。结果 24例患者再次缓解完全,未缓解的16例。患者输注后,6例发生急性移植物抗宿主病Ⅰ~Ⅱ度,24例发生慢性移植物抗宿主病,5例未发生并发症。结论 G-CSF诱导移植物抗白血病效应治疗后,白血病复发有较好的疗效,不良反应小,值得临床推广。     

Adoptive transfer of T-cell precursors enhances T-cell reconstitution after allogeneic hematopoietic stem cell transplantation

Immunoincompetence after allogeneic hematopoietic stem cell transplantation (HSCT) affects in particular the T-cell lineage and is associated with an increased risk for infections, graft failure and malignant relapse. To generate large numbers of T-cell precursors for adoptive therapy, we cultured mouse hematopoietic stem cells (HSCs) in vitro on OP9 mouse stromal cells expressing the Notch-1 ligand Delta-like-1 (OP9-DL1). We infused these cells, together with T-cell-depleted mouse bone marrow or purified HSCs, into lethally irradiated allogeneic recipients and determined their effect on T-cell reconstitution after transplantation. Recipients of OP9-DL1-derived T-cell precursors showed increased thymic cellularity and substantially improved donor T-cell chimerism (versus recipients of bone marrow or HSCs only). OP9-DL1-derived T-cell precursors gave rise to host-tolerant CD4+ and CD8+ populations with normal T-cell antigen receptor repertoires, cytokine secretion and proliferative responses to antigen. Administration of OP9-DL1-derived T-cell precursors increased resistance to infection with Listeria monocytogenes and mediated significant graft-versus-tumor (GVT) activity but not graft-versus-host disease (GVHD). We conclude that the adoptive transfer of OP9-DL1-derived T-cell precursors markedly enhances T-cell reconstitution after transplantation, resulting in GVT activity without GVHD.     

Antigen-specificity of oligoclonal abnormal protein bands in multiple myeloma after allogeneic stem cell transplantation

Myeloma patients may develop oligoclonal immunoglobulins, so-called abnormal protein bands (APB), after stem cell transplantation. APB do not correspond to the patient's paraprotein and confer a good prognosis. We set out to investigate whether such APB represent a humoral anti-myeloma immune response by screening immunoglobulins of 15 myeloma patients after allogeneic stem cell transplantation and a control group of healthy donors for reactivity with myeloma protein extracts. While the immunoglobulins of healthy donors did not react with myeloma protein extracts, patient-derived immunoglobulins showed variable levels of interaction, depending on the presence of APB on immunofixation. Most commonly, we detected interactions with heat-shock proteins, followed by neutral alpha-glucosidase, alpha-enolase and vimentin, as well as proliferating cell nuclear antigen and MAGEA4. More than 80% of targets were upregulated in myeloma. Heat-shock protein 60 (HSP60) was subsequently evaluated as an exemplary antigen. We found that HSP60 was aberrantly displayed on the surface of primary myeloma cells. Indeed, patient-derived APB-containing immunoglobulins recognized surface HSP60 suggesting that this antigen becomes accessible to the immune system after aberrant membrane exposition. We conclude that immunoglobulin fractions with APB recognize recurrent myeloma antigens and that this humoral response may contribute to the more favorable prognosis in patients with APB.     

Inflammatory cytokines and dendritic cells in acute graft-versus-host disease after allogeneic stem cell transplantation

The wider use of allogeneic stem cell transplantation (allo-SCT) is still limited by the immunologic recognition and destruction of host tissues, termed graft-versus-host disease (GVHD). The role of inflammatory cytokines such as TNF-alpha and IL-1, and their impact on immune effectors (mainly CD4+ and CD8+ T) cells has been extensively studied in the context of GVHD occurring after standard myeloablative allo-SCT. However, recent data suggested that GVHD pathophysiology is likely to involve more complex interactions where antigen-presenting cells, especially dendritic cells (DCs), may play a major role at time of initiation of acute GVHD. In addition, the wider use of reduced intensity and less toxic conditioning (RIC) regimens prior to allo-SCT would allow better visualization of the fine functions of immune effectors, thereby offering a window of opportunities to better decipher the intimate pathophysiological mechanisms underlying GVHD. The aim of this work is to review the available research evidence on the role of DCs as in vivo regulators of alloimmune reactivity, and their interactions with other immune effectors.     

DNA immunization against tissue-restricted antigens enhances tumor immunity after allogeneic hemopoietic stem cell transplantation

Malignant relapse remains a major problem for recipients of allogeneic hemopoietic stem cell transplantation (HSCT). We hypothesized that immunization of allogeneic HSCT recipients against tissue-restricted Ags using DNA vaccines would decrease the risk of relapse without enhancing graft-vs-host disease (GVHD). Using the mouse B16 melanoma model, we found that post-HSCT DNA immunization against a single tumor Ag induces tumor rejection that is significantly greater than HSCT alone in a T cell-depleted MHC-matched minor Ag-mismatched allogeneic HSCT model (LP --> B6). In treatment models, post-HSCT DNA immunization provides significantly greater overall survival than the vaccine alone. Donor leukocyte infusion further enhances tumor-free survival, including in treatment models. There was no GVHD in HSCT recipients treated with DNA vaccination and donor leukocyte infusion. Further analysis demonstrated that these effects are dependent on CD8+ T cells of donor origin that recognize multiple epitopes. These results demonstrate that DNA immunization against tissue-restricted Ags after allogeneic T cell-depleted HSCT can induce potent antitumor effects without causing GVHD.     

Potential of glycosylation research in graft versus host disease after allogeneic hematopoietic stem cell transplantation

BackgroundGlycans, complex oligosaccharides, are directly involved in almost every biological process, have a fundamental role in the immune system, and are probably involved in nearly every human disease. However, glycosylation has been greatly ignored in the area of allogeneic hematopoietic stem cell transplantation (alloHSCT) and graft versus host disease (GVHD). Both acute and chronic GVHD are multisystemic debilitating immunological disturbances arising after alloHSCT.Scope of reviewIn this paper, we review the glycosylation research already done in the field of alloHSCT and GVHD and evaluate further potential of glycan analysis in GVHD by looking into resembling inflammatory and autoimmune conditions.Major ConclusionsGlycan research could bring significant improvement in alloHSCT procedure with reduction in following complications, such as GVHD. Identifying glycan patterns that induce self-tolerance and the ones that cause the auto- and allo-immune response could lead to innovative and tissue-specific immunomodulative therapy instead of the current immunosuppressive treatment, enabling preservation of the graft-versus-tumor effect. Moreover, improved glycan pattern analyses could offer a more complete assessment and greatly needed dynamic biomarkers for GVHD.General significanceThis review is written with a goal to encourage glycan research in the field of alloHSCT and GVHD as a perspective tool leading to improved engraftment, discovery of much needed biomarkers for GVHD, enabling an appropriate therapy and improved monitoring of therapeutic response. This article is part of a Special Issue entitled "Glycans in personalised medicine" Guest Editor: Professor Gordan Lauc.     

CAR19/22 T cell cocktail therapy for B-ALL relapsed after allogeneic hematopoietic stem cell transplantation

B cell acute lymphocytic leukemia (B-ALL) patients who have relapsed after hematopoietic stem cell transplantation (HSCT) have a poor prognosis, and there is currently no standard approach available. Chimeric antigen receptor (CAR)-T cells induce high rates of initial response and long-term remission among patients with B-cell malignancies, especially B-ALL. Meanwhile, sequential infusion of CAR19/22 T cells has been proven to be effective at preventing tumor immune escape. In the present study, we retrospectively analyzed 23 B-ALL patients who relapsed after allogeneic (allo)-HSCT and underwent sequential infusion of CAR19/22 T cells, including nine donor-derived and 14 recipient-derived, in our center from July 2016 to July 2020, to evaluate the safety and efficacy of the cocktail of two single-specific CAR-T cells in B-ALL patients relapsed after transplantation. Except for one patient refusing evaluation, the remaining 22 patients achieved minimal residual disease (MRD)-negative complete remission within 30 days after CAR-T infusion. Most toxicities were slight and reversible. The estimated 12-month progression-free survival (PFS) rate was 59.2% (95% confidence interval [CI], 35.9% to 76.5%), and the estimated 12-month overall survival (OS) rate was 67.4% (95% CI, 43.2% to 83.1%). Only two patients had CD19-negative recurrence. In addition, early recurrence after transplantation, graft-versus-host disease (GVHD) and severe infection after CAR-T infusion were poor prognostic factors. Our results indicate that sequential infusion of CAR19/22 T cells is safe and effective for relapsed ALL patients after HSCT. This trial was registered at www.chictr.org.cn as #ChiCTR-OPN-16008526.