Innate Immune Recovery Predicts CD4+ T Cell Reconstitution after Hematopoietic Cell Transplantation

Innate immune cells are the first to recover after allogeneic hematopoietic cell transplantation (HCT). Nevertheless, reports of innate immune cell recovery and their relation to adaptive recovery after HCT are largely lacking. Especially predicting CD4⁺ T cell reconstitution is of clinical interest, because this parameter directly associates with survival chances after HCT. We evaluated whether innate recovery relates to CD4⁺ T cell reconstitution probability and investigated differences between innate recovery after cord blood transplantation (CBT) and bone marrow transplantation (BMT). We developed a multivariate, combined nonlinear mixed-effects model for monocytes, neutrophils, and natural killer (NK) cell recovery after transplantation. A total of 205 patients undergoing a first HCT (76 BMT, 129 CBT) between 2007 and 2016 were included. The median age was 7.3years (range, .16 to 23). Innate recovery was highly associated with CD4⁺ T cell reconstitution probability (P < .001) in multivariate analysis correcting for covariates. Monocyte (P < .001), neutrophil (P < .001), and NK cell (P < .001) recovery reached higher levels during the first 200days after CBT compared with BMT. The higher innate recovery after CBT may be explained by increased proliferation capacity (measured by Ki-67 expression) of innate cells in CB grafts compared with BM grafts (P?=?.041) and of innate cells in vivo after CBT compared with BMT (P?=?.048). At an individual level, patients with increased innate recovery after either CBT or BMT had received grafts with higher proliferating innate cells (CB; P?=?.004, BM; P?=?.01, respectively). Our findings implicate the use of early innate immune monitoring to predict the chance of CD4⁺ T cell reconstitution after HCT, with respect to higher innate recovery after CBT compared with BMT.     

大鼠骨髓间质干细胞对同种骨髓移植后造血重建和免疫重建的作用

目的：探讨大鼠骨髓间质干细胞（MSC）对 同种异体骨髓移植造血重建和免疫重建的影响。方法:建立大鼠同种异 体骨髓移植模型，通过生存率分析、外周血象检测、免疫细胞计数和受体免疫功能检测，综 合评价MSC对骨髓移植(bone marrow transplantation,BMT)后造血重建和免疫重建的作用。 结果：(1) MSC可促进BMT后造血重建：移植后30 d，共移植组外周血白 细胞、淋巴细胞和血小板数均高于单纯骨髓移植组；共移植组骨髓细胞数也高于对照组。(2 )MSC可促进BMT后免疫重建：移植后30 d，共移植组胸腺细胞数、脾细胞总数均高于骨髓单 纯移植组；共移植组对ConA、LPS 刺激的淋巴细胞增殖反应以及对第三体来源的同种混合淋 巴细胞反应均强于单纯BMT组。结论：大鼠MSC与骨髓共移植对同种异体 骨髓移植造血重建和免疫重建有一定促进作用。     

Megakaryopoiesis and myelofibrosis in chronic myeloid leukemia after allogeneic bone marrow transplantation: an immunohistochemical study of 127 patients.

An immunohistochemical and morphometric study was performed on 363 trephine biopsies of the bone marrow derived from 127 patients with chronic myeloid leukemia at standardized end points before and after allogeneic bone marrow transplantation (BMT). The purpose of this investigation was to evaluate features of CD61+ megakaryopoiesis related to successful engraftment. Further, we tried to elucidate possible associations of this lineage, including precursor cells, with the platelet count and reticulin fibrosis during the pretransplant and, specifically, post-transplant periods. A significant correlation was recognizable between the quantity of CD61+ megakaryocytes and the platelet values before BMT and also after completed hematopoietic recovery. In the very early post-transplant period, which is associated with severe thrombocytopenia, patchy regeneration of disarranged hematopoiesis occurred, including dysplastic megakaryocytes. According to planimetric measurements after BMT, the atypical micromegakaryocytes characteristic for chronic myeloid leukemia disappeared, and the engrafted donor bone marrow revealed a prevalence of normal-size cells of this lineage. On the other hand, normalization of megakaryocyte size was absent in sequential examinations of the few patients with a leukemic relapse who had a predominance of atypical dwarf forms comparable with chronic myeloid leukemia. Before BMT occurred, reticulin fiber density was significantly correlated with the number of CD61+ megakaryocytes and its precursor cell population. In 34 patients with myelofibrosis that occurred after myelo-ablative therapy and BMT, an initial regression was followed by an insidious recurrence of fibers concentrated in the areas of regenerating hematopoiesis. This postgraft reappearance of reticulin fibrosis was significantly associated with the quantity of megakaryocytes. Regarding engraftment parameters, pretransplant presence of (reticulin) myelofibrosis exerted a distinctive impact because of a delayed hematopoietic reconstitution according to standard clinical criteria. In line with this finding, slowed engraftment was also significantly related with higher pretransplant megakaryocyte and platelet counts.     

Studies of the site and distribution of CD34+ cells in idiopathic myelofibrosis

The frequency and distribution of CD34+ cells in the bone marrow (BM) of patients with idiopathic myelofibrosis (IM) were determined using an immunohistochemical technique. The percentage and absolute number of circulating CD34+ cells were enumerated. Patients with IM exhibited a continuum of number of BM CD34+ cells ranging from 1 to 85 per 5 mm(2). The frequency of BM CD34+ cells was inversely related to the number of circulating CD34+ cells. The BM biopsy specimens obtained from 4 patients with IM who underwent allogeneic stem cell transplantation were examined sequentially. Quantitative measurement revealed that the reticulin fiber volume was progressively reduced after allogeneic stem cell transplantation. All 4 patients had normocellular marrow with normal numbers of BM CD34+ cells after transplantation. These findings suggest that the BM fibrosis and abnormal hematopoietic stem cell distribution in patients with IM is a consequence of the progeny of a malignant hematopoietic stem cell clone.     

Recipient-mediated effect of a traditional chinese herbal medicine,Ren-shen-yang-rong-tang (Japanese name: Ninjin-youei-to), on hematopoietic recovery following lethal irradiation and syngeneic bone marrow transplantation

Ren-shen-yang-rong-tang (Japanese name: Ninjin-youei-to, NYT), a traditional Chinese herbal medicine, was evaluated for recipient-mediated effect on hematopoietic recovery in a murine model of syngeneic bone marrow transplantation (BMT). BALB/c recipient mice were preconditioned with a lethal total body irradiation (TBI) at a dose of 6.5 Gy and transplanted with syngeneic bone marrow (BM) cells. NYT treatments, given intraperitoneally (i.p.) once per day for 3 consecutive days in a dose of 0.625 mg, were performed either before or after TBI and BMT to assess any recipient-mediated effect of this compound. NYT pretreatment was as effective as NYT posttreatment in enhancing the total number of colony-forming unit erythroid (CFU-E) and colony-forming unit granulocyte-macrophage (CFU-GM) per marrow and spleen after TBI and BMT. NYT pretreatment caused a significant increase in marrow and splenic CFU-E and CFU-GM numbers over a prolonged period following TBI and BMT, and affected late-stage erythropoiesis (CFU-E) more profoundly than early-stage erythropoiesis (burst-forming unit erythroid, BFU-E). NYT pretreatment significantly accelerate recovery of not only erythrocyte and leukocyte counts but also platelet counts after transplantation with a limited number (1 × 10⁵) of BM cells. The same treatment, however, was significantly less effective in hematopoietic recovery after transplantation with a minimal number (1 × 10⁴) of BM cells, indicating that NYT accelerates recovery of donor-derived rather than recipient-derived cells. The data are consistent with the idea that NYT has an enhancing effect on hematopoiesis via the recipient microenvironment, and suggest that NYT may have an important role in the acceleration of hematopoietic recovery of donor-derived cells following BMT.     

人源化NOD/SCID小鼠免疫细胞的动态变化与鉴定

目的： 比较脐血干细胞与单个核细胞移植NOD/SCID鼠所建立的人源化SCID模型，分析人源化淋巴细胞重建。方法： 磁珠分选法分离脐血中CD34⁺细胞，淋巴细胞分层液分离脐血单个核细胞，分别经尾静脉输入NOD/SCID小鼠。每隔2周采血至10周，流式细胞术动态检测人源淋巴细胞CD45、CD19、CD3抗原。第10周处死小鼠收集外周血、骨髓、胸腺组织，RT-PCR检测模型鼠组织中人β₂M基因及RAG2基因。结果： 两种类型细胞移植均可重建人源免疫细胞，人源淋巴细胞表达水平均在第8周达高峰。骨髓中人源淋巴细胞表达水平明显高于外周血。RT-PCR在外周血与骨髓检测到人β₂M基因及RAG2基因标志。结论： CD34⁺细胞移植重建人源化NOD/SCID免疫系统模型效果要好于脐血单个核细胞。人源T淋巴细胞在模型鼠骨髓中分化成熟。     

培养前后脐血CD34~＋细胞在NOD/SCID鼠体内造血重建功能的比较

目的:以NOD/SCID小鼠为模型, 经半致死剂量照射后输注新鲜或培养后的造血细胞, 以比较培养前后脐血CD34 细胞的造血重建功能.方法:从新鲜脐血中分离单个核细胞(MNC), 采用干细胞因子(SCF)、血小板生成素(TPO)、Flt3配体(FL)、白细胞介素3(IL-3)和白细胞介素6(IL-6)细胞因子组合体外培养14 d.通过MiniMACS免疫磁性吸附柱从新鲜或培养后的MNC中分离CD34 细胞, 4×105个CD34 细胞和5×106CD34-细胞混合后通过尾静脉输注入NOD/SCID小鼠中.饲养过程中动态观察外周血象恢复情况, 6周后检测小鼠骨髓和脾脏细胞中人源细胞及各系造血细胞的含量.结果:体外培养MNC 14 d后, 总细胞扩增了1.78倍;细胞移植6周后, 输注新鲜和培养后造血细胞的小鼠均存活, 在小鼠骨髓和脾脏中均可检测到人源细胞及各系人源血细胞和人特异ALU基因序列, 小鼠外周血象恢复到辐照前水平.培养后CD34 细胞在小鼠体内的植入水平与新鲜CD34 细胞的相近, 而其各系人源血细胞的含量高于新鲜CD34 细胞. 结论:体外培养14 d后的CD34 细胞仍保持了体内植入和重建造血的能力, 且其多系造血重建能力优于新鲜CD34 细胞.     

Transplantation of X-linked severe combined immunodeficient dogs with CD34+ bone marrow cells.

X-linked severe combined immunodeficiency (X-SCID) is the most common form of human SCID and is caused by mutations in the common gamma chain (gammac), a shared component of the interleukin (IL)-2, IL-4, IL-7, IL-9, IL-15, and IL-21 receptors. BMT for human X-SCID results in engraftment of donor T-cells and reconstitution of normal T-cell function but engraftment of few, if any, donor B-cells and poor reconstitution of humoral immune function. Canine X-SCID is also caused by mutations in the yc and has an immunological phenotype identical to that of human X-SCID. We have previously reported that transplantation of nonconditioned X-SCID dogs with unfractionated histocompatible bone marrow results in engraftment of both donor B- and T-cells and reconstitution of normal T-cell and humoral immune function. In this study, we assessed the ability of purified canine CD34+ bone marrow cells to reconstitute lymphoid populations after histocompatible BMT in 6 nonablated X-SCID dogs. All dogs showed engraftment of donor T-cells, with T-cell regeneration occurring through a thymic-dependent pathway, and had reconstituted normal T-cell function. In contrast to our previous studies, only 3 dogs had engraftment of donor B-cells and reconstituted normal antigen-specific B-cell function post-BMT. The variable donor B-cell engraftment and reconstitution of normal humoral immune function observed in this study are similar to the outcomes observed in the majority of human X-SCID patients following BMT. This study demonstrates that canine CD34+ cells contain progenitors capable of immune reconstitution and is the first study to document the ability of CD34+ bone marrow cells to reconstitute normal B- and T-cell function in a nonablated large-animal model of BMT. This study also demonstrates that the quality of immune reconstitution following CD34+ BMT may be dosage dependent Thus canine X-SCID provides a large-animal preclinical model that can be used not only to determine the optimal conditions for both donor B- and T-cell engraftment following CD34 BMT, but also to develop and evaluate strategies for gene therapy protocols that target CD34 cells.     

Immunophenotype and functional characteristics of human primitive CD34-negative hematopoietic stem cells: the significance of the intra-bone marrow injection

The biology of hematopoietic stem cell (HSC) is a current topic of interest which has important implications for clinical HSC transplantation as well as for the basic research of HSC. The most primitive HSCs in mammals, including mice and humans, have long been believed to be CD34 antigen (Ag)-positive (CD34(+)) cells. In fact, bone marrow (BM), peripheral blood (PB), and cord blood (CB) stem cell transplantation studies indicate that a CD34(+) subpopulation in the BM, PB, or CB can provide durable long-term donor-derived lymphohematopoietic reconstitution. Therefore, CD34 Ag was used to identify/purify immature HSCs. However, Osawa et al. reported that murine long-term lymphohematopoietic reconstituting HSCs are lineage marker-negative (Lin(-)) c-kit(+)Sca-1(+)CD34-low/negative (CD34(low/-)), which are called CD34(low/-) KSL cells. Recently, human CB-derived CD34(-) HSCs, a counterpart of murine CD34(low/-) KSL cells, were successfully identified using an intra-bone marrow injection (IBMI) method. This review will update the concept of the immunophenotype and the functional characteristics of human primitive CD34(-) HSCs. In addition, the significance of the application of the IBMI technique in clinical HSC transplantation is also discussed. Recent rapid advances in understanding the biological nature of HSCs may make it possible to fully characterize the most primitive class of human HSCs in the near future.     

Ex vivo culture of human cord blood hematopoietic stem/progenitor cells adversely influences their distribution to other bone marrow compartments after intra-bone marrow transplantation

Intra-bone marrow injection is a novel strategy for hematopoietic stem cell transplantation. Here, we investigated whether ex vivo culture of cord blood hematopoietic stem/progenitor cells influences their reconstitution in bone marrow after intra-bone marrow transplantation. Freshly isolated AC133(+) cells or cells derived from AC133(+) cells cultured with cytokines (stem cell factor, flt-3 ligand, and thrombopoietin) for 5 days were injected into the bone marrow of the left tibia in irradiated NOD/SCID mice. In the bone marrow of the injected left tibia, the engraftment levels of human CD45(+) cells at 6 weeks after transplantation did not differ considerably between transplantation of noncultured and cytokine-cultured cells. However, the migration and distribution of transplanted cells to the bone marrow of other, noninjected bones were extremely reduced for cytokine-treated cells compared with noncultured cells. Similar findings were observed for engraftment of CD34(+) cells. Administration of granulocyte colony-stimulating factor to mice after transplantation induced the migration of cytokine-cultured cells to the bone marrow of previously aspirated bone but not to other intact bones. These data suggest that ex vivo manipulation of hematopoietic progenitor/stem cells significantly affects their migration properties to other bone marrow compartments after intra-bone marrow transplantation. Our data raise a caution for future clinical applications of the intra-bone marrow transplantation method using ex vivo-manipulated hematopoietic stem cells.     

Distinct phases in recovery of reconstituted innate cellular-mediated immunity after murine syngeneic bone marrow transplantation.

Defects in immune reconstitution after hematopoietic stem cell transplantation confer extreme infection risk on to the transplant recipient. Perturbations in adaptive immune reconstitution have been well characterized, yet defects in reconstituted innate cellular-mediated immunity remain largely unstudied. Recovery in innate effector cells was defined by using an established murine model of autologous bone marrow transplantation. Cytokine induction after cell culture and systemic stimulation with pathogen-associated molecular patterns was also measured for control, transplant-recipient, and irradiated-only animals. Early reconstitution (7 to 14 days) of donor-derived macrophages, dendritic cells, and polymorphonuclear cells was associated with recovery in interleukin (IL)-12p70 and IL-6 production. Later reconstitution (21 days) of natural killer cells was associated with interferon (IFN)-gamma recovery. Hence, splenocyte innate cellular-mediated immunity recovered to normal levels in cellularity and IL-12p70, IFN-gamma, and IFN-alpha production by 21 days after transplantation. In contrast, levels of systemic cytokine production from transplant-recipient and irradiated-only animals were preserved despite incomplete or absent hematopoietic reconstitution. These results suggest that innate immune responses to systemic inflammatory challenges are largely intact after autologous bone marrow transplantation, whereas local innate cellular-mediated immunity within reconstituting lymphoid organs may be impaired. The disparate effects of autologous hematopoietic stem cell transplantation on host immune function may translate to differences in susceptibility to local versus systemic infectious challenges.     

CD34/QBEND10 immunostaining in the bone marrow trephine biopsy: a study of CD34-positive mononuclear cells and megakaryocytes

CONTEXT: The immunohistochemical detection of CD34 protein using QBEND10 antibody in bone marrow trephine biopsies was shown recently to be a precise method for quantitation of blasts and a possibly useful approach in diagnosis and classification of myelodysplastic syndrome. OBJECTIVES: To evaluate CD34+ cells in bone marrow biopsies with various diagnoses and to assess how counts obtained using this method correlate with blast counts obtained by traditional morphologic evaluation of bone marrow smears. DESIGN: Bone marrow trephine biopsies from 108 adult patients were evaluated by immunohistochemistry using anti-CD34 antibody (QBEND10). CD34+ mononuclear cells were counted and compared with the blast counts in the bone marrow aspirate smears or imprints. CD34+ mononuclear cell clusters and CD34+ megakaryocytes were also recorded. The type of positivity (membranous vs cytoplasmic) and the percentage of CD34+ megakaryocytes were evaluated because the presence of CD34+ megakaryocytes was recently suggested to be present in myelodysplastic syndrome, but not in myeloproliferative disease or nonneoplastic bone marrow. RESULTS: Six of 24 biopsies with partial involvement by non-Hodgkin lymphoma and 5 of 60 biopsies with reactive changes had 5% to 10% CD34+ mononuclear cells and were associated with lymphocytosis and increased hematogones. The CD34+ mononuclear cell clusters were found only in myelodysplastic syndrome and myeloproliferative disease. The CD34+ megakaryocytes were present in all diagnostic groups. CONCLUSION: The number of CD34+ mononuclear cells was often slightly higher than the number of myeloid blasts in the bone marrow smears, probably due to increased hematogones. The presence and the number of CD34+ megakaryocytes do not appear to have diagnostic value, but this finding should be further investigated in relation to clinical parameters.     

Intra-bone marrow injection of donor bone marrow cells suspended in collagen gel retains injected cells in bone marrow, resulting in rapid hemopoietic recovery in mice

We have recently developed an innovative bone marrow transplantation (BMT) method, intra-bone marrow (IBM)-BMT, in which donor bone marrow cells (BMCs) are injected directly into the recipient bone marrow (BM), resulting in the rapid recovery of donor hemopoiesis and permitting a reduction in radiation doses as a pretreatment for BMT. However, even with this IBM injection, some of the injected BMCs were found to enter into circulation. Therefore, we attempted to modify the method to allow the efficient retention of injected BMCs in the donor BM. The BMCs of enhanced green fluorescent protein transgenic mice (C57BL/6 background) were suspended in collagen gel (CG) or phosphate-buffered saline (PBS), and these cells were then injected into the BM of irradiated C57BL/6 mice. The numbers of retained donor cells in the injected BM, the day 12 colony-forming units of spleen (CFU-S) counts, and the reconstitution of donor cells after IBM-BMT were compared between the CG and PBS groups. The number of transplanted cells detected in the injected BM in the CG group was significantly higher than that in the PBS group. We next carried out CFU-S assays. The spleens of mice in the CG group showed heavier spleen weight and considerably higher CFU-S counts than in the PBS group. Excellent reconstitution of donor hemopoietic cells in the CG group was observed in the long term (>100 days). These results suggest that the IBM injection of BMCs suspended in CG is superior to the injection of BMCs suspended in PBS.     

Histopathology of bone marrow reconstitution after allogeneic bone marrow transplantation

In order to study haematopoietic reconstitution in allogeneic bone marrow transplantation we investigated bone marrow histology in 61 biopsies of 37 patients, treated with HLA-compatible bone marrow grafts for leukaemia or severe aplastic anaemia. The biopsies were taken from the day of transplantation until 100 d after transplantation. Stromal changes, in particular oedema, fibrosis and granulomas, were found during the whole period of observation. These changes were more prominent in biopsies from leukaemia patients than from patients with aplastic anaemia. The cellularity in the biopsies increased until 28 d after bone marrow transplantation and was stable thereafter. Initially, only clusters of cells belonging to a single cell lineage were seen, suggesting that the first outgrowth of haematopoietic cells is by proliferation of committed precursor cells. Long-lasting abnormalities in localization of haematopoietic cells in the bone marrow space and of the myeloid: erythroid ratio were seen; dyserythropoiesis was common.     

Lack of self-renewal capacity in Fancc-/- stem cells after ex vivo expansion

Treatments of the hematological manifestation in Fanconi anemia (FA) are first supported by attempts to stimulate hematopoiesis with androgens or hematopoietic growth factors. However, the long-term curative treatment of the hematological manifestation in FA patients is bone marrow (BM) or cord blood stem cell transplantation. The success rate for BM transplantation is fairly high with HLA-matched sibling donors but is, unfortunately, low with HLA-matched unrelated donors. An alternative curative treatment for those patients with no sibling donors might be gene transfer into hematopoietic stem cells. Because FA patients have reduced numbers of stem/progenitor cells, ex vivo expansion of hematopoietic stem cells would be a crucial step in gene transfer protocols. Using the FA mouse model, Fancc-/-, we tested the ability of CD34- hematopoietic stem cells to support ex vivo expansion. We determined that Fancc-/- CD34- stem cells have reduced reconstitution ability and markedly reduced self-renewal ability after culture, as shown by secondary transplants. These results indicate that FA stem cells may not be well suited for ex vivo expansion before gene transfer or transplantation protocols.     

Immunologic and hematopoietic effects of recombinant human prolactin after syngeneic bone marrow transplantation in mice.

The period of immune deficiency following bone marrow transplantation (BMT) results in a susceptibility to opportunistic infections and remains a growing obstacle in improving the efficacy of BMT. Neuroendocrine hormones have been shown to affect numerous immunologic and hematologic responses after in vivo administration. We investigated whether neuroendocrine hormones, notably prolactin (PRL), could be administered after BMT and result in improved immunologic recovery. Mice were given lethal total body irradiation followed with a congeneic or a syngeneic BMT. Some groups then received recombinant human PRL (rhPRL) daily for 3 weeks. Effects on immune reconstitution and function were then monitored. The results show that PRL could increase thymic cellularity and donor T-cell reconstitution after congeneic BMT. Increases in B cells and myeloid progenitors were also observed. Mitogenic responses by both T and B cells were observed after PRL treatment. These results suggest that PRL may be of use to promote immune and myeloid reconstitution after BMT.     

Comparable Long-Term Outcome of Unrelated Cord Blood Transplantation with Related Bone Marrow or Peripheral Blood Stem Cell Transplantation in Patients Aged 45 Years or Older with Hematologic Malignancies after Myeloablative Conditioning

We investigated whether bone marrow or peripheral blood stem cells from older sibling donors or cord blood from unrelated donors provided a better outcome in allogeneic hematopoietic stem cell transplantation for relatively older patients who were candidates for myeloablative conditioning. Clinical outcomes of 97 patients aged 45 years or older with hematologic malignancies who received unrelated cord blood transplantation (CBT) (n = 66) or bone marrow transplantation (BMT) or peripheral blood stem cell transplantation (PBSCT) from related donors (n = 31) were compared. The cumulative incidences of grades III to IV acute and extensive chronic graft-versus-host diseases were similar between both groups. Although transplant-related mortality was significantly lower after CBT compared with BMT/PBSCT from related donors (hazard ratio [HR], .29, P = .04), overall mortality (HR, .72, P = .47) and relapse (HR, 2.02, P = .23) were not significantly different after CBT and BMT/PBSCT from related donors. These data suggest that CBT could be as safe and effective as BMT/PBSCT from older related donors for relatively older patients when it is used as a primary unrelated stem cell source.     

Impaired Interferon-Alpha Production by Plasmacytoid Dendritic Cells after Cord Blood Transplantation in Children: Implication for Post-transplantation Toll-Like Receptor Ligand–Based Immunotherapy

Plasmacytoid dendritic cells (pDCs) initiate both innate and adaptive immune responses, making them attractive targets for post-transplantation immunotherapy, particularly after cord blood transplantation (CBT). Toll-like receptor (TLR) agonists are currently studied for pDC stimulation in various clinical settings. Their efficacy depends on pDC number and functionality, which are unknown after CBT. We performed a longitudinal study of pDC reconstitution in children who underwent bone marrow transplantation (BMT) and single-unit CBT. Both CBT and unrelated BMT patients received antithymocyte globulin as part of their graft-versus-host disease prophylaxis regimen. pDC blood counts were higher in CBT patients than in healthy volunteers from 2 to 9 months after transplantation, whereas they remained lower in BMT patients. We showed that cord blood progenitors gave rise in vitro to a 500-fold increase in functional pDCs over bone marrow counterparts. Upon stimulation with a TLR agonist, pDCs from both CBT and BMT recipients upregulated T cell costimulatory molecules, whereas interferon-alpha (IFN-α) production was impaired for 9 months after CBT. TLR agonist treatment is thus not expected to induce IFN-α production by pDCs after CBT, limiting its immunotherapeutic potential. Fortunately, in vitro production of large amounts of functional pDCs from cord blood progenitors paves the way for the post-transplantation adoptive transfer of pDCs.     

Antioxidant intervention: a new method for improving hematopoietic reconstitution capacity of peripheral blood stem cells

In peripheral blood stem cell transplantation, bone marrow hematopoietic stem cells (BM HSCs) are collected as they are released from the hypoxic bone marrow, then infused into peripheral blood with higher oxygen concentration after mobilization. In some cases, in vitro amplification culture under normal oxygen may be required, and homing into the hypoxic bone marrow is further carried out after intravenous re-infusion, thereby resulting in constant changes in the reactive oxygen species (ROS). The high-level ROS can damage the hematopoietic reconstitution capacity of HSCs. Thus, the application of antioxidant intervention in the in vivo mobilization of BM HSC and the in vitro culture process of peripheral blood stem cells may be effective against the negative effects of ROS on BM HSC. Antioxidant intervention may also better protect the hematopoietic reconstitution capacity of HSCs, as well as improve the success rate of transplantation.     

Characterization of phenotypically distinct B-cell subsets and receptor-stimulated mitogen-activated protein kinase activation in human cord blood B cells

Human cord blood (CB) is a valuable source of hematopoietic stem cells, but clinical reports have indicated slow recovery of B-cell development and function after CB transplantation. To investigate the basis of these B-cell defects in reconstitution, we characterized B cells purified from CB. We compared B-cell receptor activation and B-cell subsets in CB, bone marrow (BM), and peripheral blood (PB). We found that in CB B cells activation of extracellular signal-regulated kinase (ERK) and p38 following ligation of CD40 but not of the B-cell antigen receptor (BCR) was inefficient. The patterns of expression of CD5, CD34, and CD40 in the B-cell population of CB were similar to those in PB rather than in BM. The B cells in CB contained an increased proportion of B cells expressing a high level of CD24 and a low proportion of B cells expressing CD27, pointing to the presence of circulating CD24high immature transitional and CD27(-) naive B cells. CD40-mediated activation of ERK and p38 was also minimal in these B cells of CB. These findings may account for the functional defects of B cells in transplanted CB.