Hematopoietic stem cell transplantation for thalassemia

Hematopoietic stem cell transplantation (HSCT) represents the only cure for patients with thalassemia. At present HSCT in younger patients from an HLA- matched sibling donor offers 80% to 87% probability of cure according to risk classes. However, results HSCT in adult patients continue to be inferior due to advanced of disease. High-resolution tissue typing techniques have enabled transplant centres to offer allogeneic HSCT from unrelated donors to patients with thalassemia who could not benefit from matched sibling donor transplantation with results comparable to those obtained using sibling donors. Advances in transplantation biology have made it possible to perform haploidentical HSCT in patients with thalassemia who lack a related or unrelated matched donor. Although limited number of patients, results of unrelated cord blood transplantation for thalassemia are encouraging. Patients with graft failure could now benefit from second transplantation using the same donor with a high disease-free survival rate. Most ex-thalassemics continue to have disease and treatment-related complications acquired before transplantation which require adequate treatment following BMT.     

Comparison analysis between haplo identical stem cell transplantation and matched sibling donor stem cell transplantation for high-risk acute myeloid leukemia in first complete remission

In order to compare the effect between haploidentical(HID) stem cell transplantation(HSCT) and matched sibling donor(MSD)stem cell transplantation for high-risk acute myeloid leukemia(AML) in first complete remission status(CR1), we retrospectively studied 170 cases who received stem cell transplantation from Jan 2008 to Jul 2015 in Peking University People's Hospital. We divided all cases into MSD group(43 cases) and HID(127 cases) group. Patients in HID and MSD group displayed similar baseline characteristics except for age distribution. There were no statistic differences for overall survival(OS), cumulative incidence of relapse, leukemia free survival(LFS), transplantation related mortality(TRM) between HID and MSD group. The 3-year OS, LFS for all patients was 63.9% and 59.7% respectively. Multivariate analysis showed that grade III-IV acute graft versus host disease(aGVHD) was an independent risk factor for treatment related mortality(HR=8.134, 95% CI:3.210–20.611, P0.001), monosomy/complex chromosomal karyotype and white blood cell count more than 50×109 L-1 were two independent factors for relapse(HR=1.533, 95% CI: 1.040–2.260, P=0.031)(HR=1.004, 95% CI: 1.001–1.008, P=0.015).Grade III-IV aGVHD was an independent factor for mortality(HR=3.184, 95% CI: 1.718–5.902, P0.001). These results demonstrated some risk factors for high-risk AML leukemia transplantation and indicated for AML patients in CR1 status, haplo stem cell transplantation could have the same therapeutic effect as MSD transplantation.     

Molecular monitoring of immune reconstitution after haploidentical stem cell transplantation

Haploidentical hematopoietic stem cell transplantation from a mismatched family member is an alternative treatment for transplant candidates who lack a HLA-matched related or an appropriate unrelated donor. One of main obstacles to successful haploidentical transplantation is slow immune reconstitution which significantly increases the risk of opportunistic infections, graft-vs-host-disease and disease relapse. Immune reconstitution is conventionally estimated by phenotypic recovery of immune cells according to lineage and/or by in vitro evidence of cell function. The limitations of these approaches include the sensitivity and specificity of phenotype markers, the availability of antibodies, the instability of long-term cell culture and the laborious nature of cell-function assays. Investigators have sought alternative approaches that are more sensitive, specific and simple, and that allow high-throughput testing for use in clinical transplantation. In this mini-review, we briefly introduce the concept of "molecular monitoring of immune-reconstitution" and discuss recent progress in this field achieved by our laboratory and other groups. We also propose future directions for clinical research incorporating these novel concepts.     

Immune reconstitution and strategies for rebuilding the immune system after haploidentical stem cell transplantation

Haploidentical hematopoietic stem cell transplantation is a curative alternative option for patients without an otherwise suitable stem cell donor. In order to prevent graft-versus-host disease (GvHD), different in vitro and in vivo T cell-depletion strategies have been developed. A delayed immune reconstitution is common to all these strategies, and an impaired immune function after haploidentical transplantation with subsequent infections is a major cause of deaths in these patients. In addition to in vitro and in vivo T cell-depletion methods, posttransplant strategies to rapidly rebuild the immune system have been introduced in order to improve the outcome. Advances in in vitro and in vivo T cell-depletion methods, and adoptive transfer of immune cells of the innate and specific immune system, will contribute to reduce the risk of GvHD, lethal infections, and the risk of relapse of the underlying malignant disease.     

Development of immunity in human severe primary T cell deficiency following haploidentical bone marrow stem cell transplantation

Recent advances in the prevention of graft-vs-host disease (GVHD) have allowed the use of haploidentical bone marrow cells for correction of lethal genetic defects of the immune system. Sequential analyses of blood lymphocyte phenotypes and functions were done before and after transplantation of haploidentical marrow stem cells into 17 infants with severe primary T cell deficiencies. The marrow was depleted of post-thymic T cells and most other mature marrow cells by soy lectin agglutination and sheep erythrocyte rosetting. The studies were performed to define the time course and extent of appearance of immune function, and to identify factors leading to resistance to engraftment. No pretransplant immunosuppression was used. T cell function was detected between 34 and 287 days after transplantation, but a sharp rise usually occurred between 84 and 115 days, and normal function was reached between 113 and 210 days. Fifteen of the patients are alive from 6 to 41 mo post-transplantation, 12 have improved or have normal T lymphocyte function, and nine have proven T cell chimerism. Increased immunoglobulins of several isotypes have been noted in 11 patients and specific antibodies in seven patients, although B cell chimerism has been detected in only one patient. B cell function required 2 to 2.5 yr for normalization. No GVHD occurred in 14 patients, and the other three had only transient mild skin rashes. Two patients died of viral infections. Failure to engraft was correlated with some pre-transplant lymphocyte responses to mitogens and allogeneic cells (three cases), but not with the presence of pre-transplant natural killer cell function (five cases) nor with the presence of purine salvage pathway enzyme deficiencies (four cases). The latter, however, was associated with poor lymphoid function in two patients. These studies indicate that the thymic microenvironment of most infants with severe combined immunodeficiency disease is capable of differentiating donor stem cells to mature and functioning T lymphocytes which can cooperate with apparently normal host B cells for antibody production.     

Gene therapy strategies to facilitate organ transplantation.

Organ transplantation is now the definitive therapy for many forms of end-organ disease, but chronic allograft rejection, the side effects of chronic immunosuppressive therapy and the severe donor organ shortage continue to limit its success. Gene therapy has the potential to prevent graft rejection by manipulating the immune response in the microenvironment of the graft or by facilitating the induction of tolerance. Genetic manipulation of stem cells to create transgenic and/or knockout animals that could serve as organ or cell donors could be combined with gene therapy approaches to overcome the problem of limited allogeneic donor organ supply.     

An ISCT Stem Cell Engineering Committee Position Statement on Immune Reconstitution: the importance of predictable and modifiable milestones of immune reconstitution to transplant outcomes

Allogeneic stem cell transplantation is a potentially curative therapy for some malignant and non-malignant disease. There have been substantial advances since the approaches first introduced in the 1970s, and the development of approaches to transplant with HLA incompatible or alternative donors has improved access to transplant for those without a fully matched donor. However, success is still limited by morbidity and mortality from toxicity and imperfect disease control. Here we review our emerging understanding of how reconstitution of effective immunity after allogeneic transplant can protect from these events and improve outcomes. We provide perspective on milestones of immune reconstitution that are easily measured and modifiable.     

Hematopoietic stem cell transplantation with umbilical cord multipotent stromal cell infusion for the treatment of aplastic anemia—a single-center experience

Background aimsThe purpose of this study was to observe the outcome of co-transfusion of umbilical cord multipotent stromal cells (UC-MSC) and allogeneic hematopoietic stem cells in the treatment of heavily-transfused patients with severe aplastic anemia.MethodsOf the 22 patients, eight cases received haploidentical hematopoietic stem cells from granulocyte colony-stimulating factor–primed bone marrow and peripheral blood grafts; the other patients received granulocyte colony-stimulating factor–mobilized peripheral blood grafts from human leukocyte antigen–matched related (six cases) and unrelated donors (eight cases). MSCs were intravenously infused at a mean dose of 1.2 × 10⁶/ kg (range, 0.27–2.5 × 10⁶/kg). Fludarabine-based conditioning was conducted, and graft-versus-host disease prophylaxis containing cyclosporine A, methotrexate and mycophenolate mofetil with or without addition of anti-CD25 monoclonal antibody was performed. Hematopoietic engraftment, the occurrence of graft-versus-host disease (GVHD) and infections and overall survival were documented.ResultsAll patients had rapid engraftment; mean time for neutrophil and platelet recovery was 13.95 d and 20.27 d, respectively. No acute toxicity associated with UC-MSC transfusion was observed. Acute GVHD developed in seven cases (grade I–II), and none had development of chronic GVHD. Cytomegalovirus reactivation was observed in 11 cases. One patient died of pulmonary complication 6 months after transplantation. Twenty-one patients are currently alive, at a median follow-up of 15 months; they are transfusion-independent and reached full donor chimerism at the time of reporting.ConclusionsUC-MSC infusion might be an alternative option to promote hematopoietic engraftment and reduce the occurrence of GHVD in hematopoietic stem cell transplantation in the treatment of heavily transfused patients with severe aplastic anemia.     

Reduced Intensity Conditioning,Combined Transplantation of Haploidentical Hematopoietic Stem Cells and Mesenchymal Stem Cells in Patients with Severe Aplastic Anemia

We examined if transplantation of combined haploidentical hematopoietic stem cells (HSC) and mesenchymal stem cells (MSC) affected graft failure and graft-versus-host disease (GVHD) in patients with severe aplastic anemia (SAA). Patients with SAA-I (N = 17) received haploidentical HSCT plus MSC infusion. Stem cell grafts used a combination of granulocyte colony-stimulating factor (G-CSF)-primed bone marrow and G-CSF-mobilized peripheral blood stem cells of haploidentical donors and the culture-expanded third-party donor-derived umbilical cord MSCs (UC-MSCs), respectively. Reduced intensity conditioning consisted of fludarabine (30 mg/m²·d)+cyclosphamide (500 mg/m²·d)+anti-human thymocyte IgG. Transplant recipients also received cyclosporin A, mycophenolatemofetil, and CD25 monoclonal antibody. A total of 16 patients achieved hematopoietic reconstitution. The median mononuclear cell and CD34 count was 9.3×10⁸/kg and 4.5×10⁶/kg. Median time to ANC was >0.5×10⁹/L and PLT count >20×10⁹/L were 12 and 14 days, respectively. Grade III-IV acute GVHD was seen in 23.5% of the cases, while moderate and severe chronic GVHD were seen in 14.2% of the cases. The 3-month and 6-month survival rates for all patients were 88.2% and 76.5%, respectively; mean survival time was 56.5 months. Combined transplantation of haploidentical HSCs and MSCs on SAA without an HLA-identical sibling donor was safe, effectively reduced the incidence of severe GVHD, and improved patient survival.     

Perspectives on establishing a public cord blood inventory in South Africa

The South African population is highly diverse, both ethnically and genetically. This diversity is particularly true for the African ancestry and various mixed ancestry population groups. These groups are under-represented in national and international bone marrow and peripheral blood donor registries, making it challenging to identify HLA-matched and mismatched unrelated donors when patients from these groups require allogeneic hematopoietic stem and progenitor cell transplantation. In most high-income countries, banked cord blood (CB) units provide an attractive source of hematopoietic progenitor cells for genetically diverse populations. SA does not have a public CB inventory, leaving many patients without access to this important treatment modality. Haploidentical transplantation provides an alternative. In recent years, the use of post-transplant cyclophosphamide has significantly reduced the incidence of graft-versus-host disease after haploidentical transplantation and has improved transplantation outcomes. However, it is difficult to identify suitable haploidentical donors in SA because of family disruption and a high prevalence of HIV. Here the authors provide a brief historical overview of the ethnic and genetic diversity of the country and region. The authors provide a southern African perspective on HLA diversity, consider the allogeneic hematopoietic stem and progenitor cell transplantation landscape and explore the need to establish a public CB bank (CBB) in SA. The health policy and regulatory frameworks that will impact on a CBB in the country SA are also explored. Finally, the authors discuss several matters we believe require attention when considering the establishment of a sustainable public CBB in the South African context.     

Bone marrow transplantation and approaches to avoid graft-versus-host disease (GVHD)

Haematopoietic stem cell transplantation (HSCT) offers promise for the treatment of haematological and immune disorders, solid tumours, and as a tolerance inducing regimen for organ transplantation. Allogeneic HSCTs engraftment requires immunosuppression and the anti-tumour effects are dependent upon the immune effector cells that are contained within or generated from the donor graft. However, significant toxicities currently limit its efficacy. These problems include: (i) graft-versus-host disease (GVHD) in which donor T cells attack the recipient resulting in multi-organ attack and morbidity, (ii) a profound period of immune deficiency following HSCT, and (iii) donor graft rejection. Currently available methods to prevent or treat GVHD with systemic immunosuppression can lead to impaired immune recovery, increased opportunistic infections, and higher relapse rates. This review will provide an overview of GVHD pathophysiology and discuss the roles of various cells, pathways, and factors in the GVHD generation process and in the preservation of graft-versus-tumour effects. Variables that need to be taken into consideration in attempting to extrapolate preclinical results to the clinical paradigm will be highlighted.     

Successful gene therapy of mice with congenital erythropoietic porphyria

Porphyrias are a group of disorders due to a genetic deficiency in one of the heme biosynthetic pathway enzymes. Congenital erythropoietic porphyria (CEP) is the most severe type characterized by a deficiency in uroporphyrinogen III synthase (UROS) activity. Bone marrow transplantation represents a curative treatment for patients, as long as human leucocyte antigen-compatible donor is available. We used a recently obtained murine model to check the feasibility of gene therapy in this disease. Lentivirus-mediated transfer of the human UROS cDNA into hematopoietic stem cells (HSCs) from Uros(mut 248) mice resulted in a complete and long-term enzymatic, metabolic and phenotypic correction of the disease, favored by a survival advantage of corrected red blood cells. These results demonstrate for the first time that the cure of this mouse model of CEP at moderate transduction level supports the proof of concept of a gene therapy in this disease by transplantation of genetically modified HSCs.     

人类白细胞抗原半相合供者外周血细胞因子诱导的杀伤细胞治疗晚期原发性肝癌二例

目的 观察半相合供者细胞因子诱导的杀伤细胞(CIK)治疗晚期肝癌的临床疗效.方法 2 例无法手术且无法耐受化疗的晚期肝癌患者分别选取人类白细胞抗原(HLA)半相合健康供者体外培养CIK,14 d 后分次回输给相应患者,观察患者治疗前后瘤体大小、肿瘤标志物、免疫指标、临床症状、生活质量和卡氏评分等的变化.结果 2 例患者...     

The evolution of MHC restrictions in antigen recognition by T cells in a haploidentical bone marrow transplant recipient

We have longitudinally followed the major histocompatibility complex (MHC) restrictions that govern the response of T lymphocytes to specific Ag in a child with severe combined immunodeficiency who was successfully transplanted by using T cell depleted haploidentical maternal bone marrow cells and immunized shortly afterwards with tetanus toxoid (TT) Ag. In the first year post-transplant, monocytes were of both donor and recipient origin whereas T and B cells were of donor origin. Three years after transplant, all monocytes and T and B cells were of donor origin. T lymphocytes taken from the child at that time and depleted in vitro of alloreactivity to paternal Ag proliferated in response to TT presented by maternal as well as paternal monocytes. A TT-specific T cell line established from these cells in the presence of maternal monocytes cooperated with maternal but not with paternal monocytes, whereas a TT-specific T cell line established in the presence of paternal monocytes cooperated with paternal but not with maternal monocytes and with monocytes derived from a paternal uncle who shared the haplotype inherited by the recipient from her father. These results show that long-term memory T cells restricted to recipient MHC Ag not shared with the bone marrow donor continue to circulate long after the disappearance of accessory cells of recipient origin. These T cells could potentially participate in a secondary immune response because they were shown to recognize TT presented by recipient fibroblasts induced to express class II MHC molecules following treatment with IFN-gamma.     

Allogeneic mesoangioblasts give rise to alpha-sarcoglycan expressing fibers when transplanted into dystrophic mice

Cell therapy for muscular dystrophy involves transplantation of either genetically modified autologous cells or normal donor cells that will be rejected unless the host is adequately immune suppressed. The extent of the immune response appears to be mitigated in this case of stem cells, by immune-suppressive and tolerogenic molecules that they release. We previously reported significant morphological and functional amelioration of a mouse model of limb-girdle muscular dystrophy by transplantation of mesoangioblasts. These are vessel-associated stem cells that can be propagated in vitro and differentiate into several types of mesoderm including skeletal muscle. In these experiments, both donor cells and host were syngeneic (C57Bl/6J) and thus possible immune reaction to the donor cells could not be appreciated. To address this question, we transplanted H2-mismatched mesoangioblasts (BalbC) in the same dystrophic mice, and in addition, we treated the host with different pharmacological drugs (rapamycin, IL-10 or both). The results showed that donor cells give rise to fibers that express the mutated gene product (alpha-sarcoglycan) even in the absence of immune suppression; however, the combined action of rapamycin and IL-10 increases the number of alpha-sarcoglycan expressing fibers while reducing the levels of inflammatory cytokines. These results indicate that transplantation of mesoangioblasts into immunologically unrelated host leads to long-term survival of donor cells and this may be further enhanced by appropriate protocols of immune modulation, thus setting the stage for experimentation in large animals and in patients.     

Modified responses to recipient and donor B cells by genetically donor T cells from human haploidentical bone marrow chimeras

After administration of haploidentical stem cells to infants with severe combined immunodeficiency disease (SCID), mature T cells of donor karyotype appear later in the recipient without causing graft-vs-host disease (GVHD). To investigate the effect of the host microenvironment on these genetically donor T cells, mixed leukocyte cultures were carried out. Unfractionated mononuclear cells (MNC) from eight infants with SCID immunologically reconstituted by haploidentical bone marrow stem cells responded in the same pattern as MNC from non-chimeric individuals to autologous and allogeneic irradiated MNC, even though they contained all genetically donor T cells and all genetically patient B cells and monocytes. This included surprisingly vigorous proliferative responses of the patients' MNC to the original donors' irradiated MNC. This autoreactivity could be detected as soon as T cell function appeared post-transplantation and appeared to increase with time. It could be blocked by the addition of monoclonal antibodies to HLA Class II antigens. Responses of most patients' MNC were similar whether stimulated by irradiated MNC from the donor or non-donor parent or by those from unrelated normal controls. Purified genetically donor T cells that had matured from stem cells in the patient's microenvironment responded vigorously to purified donor B cells. These same cells responded much less to patient B cells. In six cases, such genetically donor T cells responded less to patient B cells than fresh donor T cells did to donor B cells in the autologous mixed leukocyte response. By contrast, T cells of donor karyotype from three of the patients responded more vigorously to donor B cells than fresh donor T cells did. Thus, genetically donor T lymphocytes that had matured from stem cells in the recipient microenvironment behaved differently from those that had matured in the donor. The hyporesponsiveness of genetically donor T cells from the patient to patient B cells does not appear to be due to T suppressor cells.     

Hematopoietic stem cell transplantation from alternative donors for high-risk acute leukemia: the haploidentical option

Much progress has been made in the clinical, biological and technical aspects of the T-cell-depleted full-haplotype mismatched transplants for acute leukemia. Our experience demonstrates that infusing a megadose of extensively T-cell-depleted hematopoietic peripheral blood stem cells after an immuno-myeloablative conditioning regimen in acute leukemia patients ensures sustained engraftment with minimal graft-vs-host disease (GvHD) without the need of any post-transplant immunosuppressive treatment. Since our first successful pilot study, our efforts have concentrated on developing new conditioning regimens, optimizing the graft processing and improving the post-transplant immunological recovery. The results we have so far achieved in more than 200 high-risk acute leukemia patients show that haploidentical transplantation is now a clinical reality. Because virtually all patients in need of a hematopoietic stem cell transplant have a full-haplotype mismatched donor, who is immediately available, a T-cell depleted mismatched transplant should be offered, not as a last resort, but as a viable option to high risk acute leukemia patients who do not have, or cannot find, a matched donor.     

Rapid reconstitution of antibody responses following transplantation of purified allogeneic hematopoietic stem cells

Allogeneic hematopoietic cell transplantation has broad clinical applications extending from the treatment of malignancies to induction of immunologic tolerance. However, adaptive cellular and humoral immunity frequently remain impaired posttransplantation. Here, recovery of T-dependent and T-independent Ab responses was evaluated in mice transplanted with purified hematopoietic stem cells (HSCs) devoid of the mature immune cells believed to hasten immune recovery. Mixed and full donor chimeras were created by conditioning recipients with sublethal or lethal irradiation, respectively, across different donor/host genetic disparities. By 6 wk posttransplantation, all animals demonstrated robust T-independent Ab responses, and all mixed chimeras and recipients of MHC-matched or haploidentical HSCs with a shared MHC haplotype had T-dependent Ab responses equivalent to those of untransplanted controls. Full chimeras that received fully MHC-disparate HSCs showed delayed T-dependent Ab responses that recovered by 12 wk. This delay occurred despite early reconstitution and proper migration to germinal centers of donor-derived T(follicular helper) (T(FH)) cells. Congenic transplants into T(FH)-deficient CD4(-/-) mice revealed restoration of T-dependent Ab responses by 6 wk, leading us to conclude that MHC disparity caused delay in humoral recovery. These findings, together with our previous studies, show that, contrary to the view that depletion of graft lymphocytes results in poor posttransplant immunity, elimination of immune-suppressing graft-versus-host reactions permits superior immune reconstitution. This study also provides insight into the regeneration of T(FH) cells and humoral immunity after allogeneic HSC transplantation.