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.     

Granulocyte-macrophage colony-stimulating factor-based melanoma cell vaccines immunize syngeneic and allogeneic recipients via host dendritic cells

Subcutaneous injection of GM-CSF-expressing cancer cells into experimental animals results in protective cancer immunity. To delineate the mode of action of such vaccines, we used trinitrophenyl, the antigenic moiety of the contact allergen trinitrochlorobenzene, as surrogate Ag. Trinitrophenyl-derivatized bone marrow-derived dendritic cells were found to elicit a contact hypersensitivity response in syngeneic, but not in allogeneic recipients, compatible with their expected mode of direct Ag presentation. When expressing GM-CSF, haptenized M3 melanoma cells were also able to induce a contact hypersensitivity response but, in contrast to bone marrow-derived dendritic cells, not only in syngeneic but also in allogeneic recipients. This argues for a critical role of host APC. To identify their nature, we introduced the beta-galactosidase (betagal) gene into M3-GM cells. Their administration activated betagal-specific, L(d)-restricted CTL in syngeneic BALB/c mice. Evaluation of lymph nodes draining M3-GM-betagal injection sites revealed the presence of cells presenting the respective L(d)-binding betagal peptide epitope. Based on their capacity to activate betagal-specific CTL, they were identified as being CD11c(+) dendritic cells. These experiments provide a rational basis for the use of GM-CSF-based melanoma cell vaccines in an allogeneic setting.     

Granulocyte colony-stimulating factor exacerbates hematopoietic stem cell injury after irradiation

Background

Exposure to a moderate to high dose of ionizing radiation (IR) not only causes acute radiation syndrome but also induces long-term (LT) bone marrow (BM) injury. The latter effect of IR is primarily attributed to the induction of hematopoietic stem cell (HSC) senescence. Granulocyte colony-stimulating factor (G-CSF) is the only treatment recommended to be given to radiation victims soon after IR. However, clinical studies have shown that G-CSF used to treat the leukopenia induced by radiotherapy or chemotherapy in patients can cause sustained low white blood cell counts in peripheral blood. It has been suggested that this adverse effect is caused by HSC and hematopoietic progenitor cell (HPC) proliferation and differentiation stimulated by G-CSF, which impairs HSC self-renewal and may exhaust the BM capacity to exacerbate IR-induced LT-BM injury.

Methods

C57BL/6 mice were exposed to 4 Gy γ-rays of total body irradiation (TBI) at a dose-rate of 1.08 Gy per minute, and the mice were treated with G-CSF (1 μg/each by ip) or vehicle at 2 and 6 h after TBI on the first day and then twice every day for 6 days. All mice were killed one month after TBI for analysis of peripheral blood cell counts, bone marrow cellularity and long-term HSC (CD34-lineage-sca1+c-kit+) frequency. The colony-forming unit-granulocyte and macrophage (CFU-GM) ability of HPC was measured by colony-forming cell (CFC) assay, and the HSC self-renewal capacity was analyzed by BM transplantation. The levels of ROS production, the expression of phospho-p38 mitogen-activated protein kinase (p-p38) and p16^INK4a (p16) mRNA in HSCs were measured by flow cytometry and RT-PCR, respectively.

Results

The results of our studies show that G-CSF administration mitigated TBI-induced decreases in WBC and the suppression of HPC function (CFU-GM) (p < 0.05), whereas G-CSF exacerbated the suppression of long-term HSC engraftment after transplantation one month after TBI (p < 0.05); The increase in HSC damage was associated with increased ROS production, activation of p38 mitogen-activated protein kinase (p38), induction of senescence in HSCs.

Conclusion

Our findings suggest that although G-CSF administration can reduce ARS, it can also exacerbate TBI-induced LT-BM injury in part by promoting HSC senescence via the ROS-p38-p16 pathway.

     

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.     

Granulocyte-macrophage stimulating factor (GM-CSF) increases circulating dendritic cells but does not abrogate suppression of adaptive cellular immunity in patients with metastatic colorectal cancer receiving chemotherapy

Background  

Advanced cancer and chemotherapy are both associated with immune system suppression. We initiated a clinical trial in patients receiving chemotherapy for metastatic colorectal cancer to determine if administration of GM-CSF in this setting was immunostimulatory.     

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。     

Number of megakaryocytic progenitors and adhesion molecule expression of stem cells predict platelet engraftment after allogeneic hematopoietic stem cell transplantation

BACKGROUND: The mechanism of platelet recovery after hematopoietic stem cell transplantation and the factors that influence its time-course are not fully understood. Rapid hematopoietic recovery results in a reduction of transplantation-related complications. In the present study, we questioned and analyzed whether there were important factors predicting the speed of platelet engraftment. METHODS: Thirty-seven patients with various hematologic diseases transplanted with allogeneic BM between January 2002 and December 2005 were included. We investigated the differences in mononuclear cell counts (MNC), numbers of infused CD34(+), CD34(+) CD41(+) and CD34(+) CD61(+) cells and phenotypic analysis of homing-associated cell adhesion molecules (CXCR4, CD49d and CD49e). The number of megakaryocytes formed in vitro (colony-forming unit-megakaryocytes; CFU-Mk) was also measured. RESULTS: Median days of ANC >/=0.5x10(9)/L and platelet count >/=20x10(9)/L were 14.8 and 17.3, respectively. The number of infused CD34(+) CD41(+) and CD34(+) CD61(+) cells correlated much better with the time to platelet engraftment than that of infused CD34(+)cells (P<0.05 each). Rapid platelet recovery also occurred in patients receiving both higher homing-associated cell adhesion molecule doses and CFU-Mk (P<0.05 each). DISCUSSION: Rapid platelet recovery has several advantages, including reducing the cost of supportive therapy and reducing the risk of fatal bleeding as a result of severe thrombocytopenia. Our findings suggest that phenotypic and clonogenic assessment of infused progenitor cells can identify patients in whom platelet engraftment is likely to be significantly delayed, and new strategies to overcome related problems might be employed in the very near future.     

Mesenchymal stem cells in hematopoietic stem cell transplantation

Mesenchymal stromal/stem cells (MSC) of bone marrow (BM) origin not only provide the supportive microenvironmental niche for hematopoietic stem cells (HSC) but are capable of differentiating into various cell types of mesenchymal origin, such as bone, fat and cartilage. In vitro and in vivo data suggest that MSC have low inherent immunogenicity, modulate/suppress immunologic responses through interactions with immune cells, and home to damaged tissues to participate in regeneration processes through their diverse biologic properties. MSC derived from BM are being evaluated for a wide range of clinical applications, including disorders as diverse as myocardial infarction and newly diagnosed diabetes mellitus type 1. However, their use in HSC transplantation, either for enhancement of hematopoietic engraftment or for treatment/prevention of graft-versus-host disease, is far ahead of other indications. Ease of isolation and ex vivo expansion of MSC, combined with their intriguing immunomodulatory properties and their impressive record of safety in a wide variety of clinical trials, make these cells promising candidates for further investigation.     

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.     

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。     

Determining Toxoplasma high-risk autologous and allogeneic hematopoietic stem cell transplantation patients by systematic pre-transplant PCR screening of stem cell originated buffy coat

The diagnosis of Toxoplasma infection or disease in hematopoietic stem cell transplantation (HSCT) patients is achieved mainly by PCR screening; however screening did not find wide field of use in practice due to costly expenditures of PCR. This study aimed to determine patients at high risk of Toxoplasma infection or disease before transplantation by stem cell originated buffy coat PCR and subsequently to screen them. Buffy coats collected from 12 autologous and 18 allogeneic HSCT patients' donors were investigated by PCR before transplantation. After transplantation, blood and sera collected at fixed time intervals were screened by two PCR methods and serological assays. Screening results first time assessed a toxoplasmosis incidence level as 25% in autologous HSCT patients and increased incidence level in allogeneic HSCT patients to 22%. Importantly, buffy coat PCR was first time performed before transplantation, to determine the risk of toxoplasmosis. Buffy coat PCR results showed that four patients were at high risk of toxoplasmosis before transplantation. After transplantation, these patients experienced toxoplasmosis. In conclusion, for the determination of patients at risk of toxoplasmosis, clinicians should consider buffy coat PCR in combination with serology before transplantation. After transplantation, PCR screening can be initiated in high risk patients upon clinical suspicion.     

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.