造血干/祖细胞体外扩增的最新研究进展

造血干/祖细胞体外扩增方法的快速发展为造血干/祖细胞广泛应用于临床开辟了广阔的前景,就造血干/祖细胞体外扩增的方法和培养系统的最新进展做一综述。     

造血干/祖细胞体外扩增的最新研究进展

造血干/祖细胞体外扩增方法的快速发展为造血于/祖细胞广泛应用于临床开辟了广阔的前景,就造血干/祖细胞体外扩增的方法和培养系统的最新进展做一综述.     

CD34免疫亲合柱在脐血造血干/祖细胞分离与扩增中的应用

目的 :观察CD34免疫亲合柱对脐血造血干 祖细胞分离纯化的效果及纯化后CD34 细胞的增殖分化特性。方法 :采用CD34免疫亲合柱分离脐血单个核细胞 (MNC)中的CD34 细胞 ,流式细胞技术 (FACS)进行细胞表面标志测定。将分离前后的细胞加入造血生长因子进行液态扩增培养和多向祖细胞集落 (CFU GEMM)培养。结果 :经CD34免疫亲合柱分离后脐血中CD34 细胞为 49 6 2 %± 17 6 9% ,明显高于脐血MNC(1 17%± 0 6 8% ) ,细胞回收率为 5 4 38%± 11 91%。分离后CD34 细胞和脐血MNC经造血生长因子刺激培养 2 0d分别扩增 5 6 1 0 0倍和 44 44倍。培养至 12d时 ,免疫亲合柱分离组CD34 细胞阳性率为 5 3 38% ,对照组为 7 91%。分离组CFU GEMM产率明显高于对照组 (P <0 0 0 1)。结论 :CD34免疫亲合柱应用于脐血造血干 祖细胞的分离可充分富集CD34 细胞 ,且分离后的CD34 细胞具有明显的增殖效应和CFU GEMM形成能力。     

Direct Toll-like receptor-mediated stimulation of hematopoietic stem and progenitor cells occurs in vivo and promotes differentiation toward macrophages

As Toll-like receptors (TLRs) are expressed by hematopoietic stem and progenitor cells (HSPCs), they may play a role in hematopoiesis in response to pathogens during infection. We show here that TLR2, TLR4, and TLR9 agonists (tripalmitoyl-S-glyceryl-L-Cys-Ser-(Lys)4 [Pam3CSK4], lipopolysaccharide [LPS], and CpG oligodeoxynucleotide [ODN]) induce the in vitro differentiation of purified murine lineage negative cells (Lin(-) ) as well as HSPCs (identified as Lin(-) c-Kit(+) Sca-1(+) IL-7Rα(-) [LKS] cells) toward macrophages (Mph), through a myeloid differentiation factor 88 (MyD88)-dependent pathway. In order to investigate the possible direct interaction of soluble microorganism-associated molecular patterns and TLRs on HSPCs in vivo, we designed a new experimental approach: purified Lin(-) and LKS cells from bone marrow of B6Ly5.1 mice (CD45.1 alloantigen) were transplanted into TLR2(-/-) , TLR4(-/-) , or MyD88(-/-) mice (CD45.2 alloantigen), which were then injected with soluble TLR ligands (Pam3CSK4, LPS, or ODN, respectively). As recipient mouse cells do not recognize the TLR ligands injected, interference by soluble mediators secreted by recipient cells is negligible. Transplanted cells were detected in the spleen and bone marrow of recipient mice, and in response to soluble TLR ligands, cells differentiated preferentially to Mph. These results show, for the first time, that HSPCs may be directly stimulated by TLR agonists in vivo, and that the engagement of these receptors induces differentiation toward Mph. Therefore, HSPCs may sense pathogen or pathogen-derived products directly during infection, inducing a rapid generation of cells of the innate immune system.     

Inhibition of p38 mitogen-activated protein kinase promotes ex vivo hematopoietic stem cell expansion

Hematopoietic stem cell (HSC) self-renewal is tightly regulated by a complex crosstalk between many cell-intrinsic regulators and a variety of extrinsic signals from the stem cell niche. In this study, we examined whether the p38 mitogen-activated protein kinase (p38) is one of the intrinsic regulators that can negatively regulate HSC self-renewal in vitro and whether inhibition of p38 activity with a small molecule inhibitor can promote HSC expansion ex vivo. The results from this study showed that sorted mouse bone marrow Lin(-)Sca1(+)c-kit(+) cells (LSK(+) cells) exhibited selective activation of p38 after culture in a serum-free medium supplemented with 100 ng/mL stem cell factor, thrombopoietin, and Flt3 ligand. The activation of p38 was associated with a significant reduction in HSCs and induction of apoptosis and cellular senescence in LSK(+) cells and their progeny. Addition of the specific p38 inhibitor SB203580 (SB, 5 μM) to the culture inhibited the activation of p38 in LSK(+) cells, which led to increase in HSC self-renewal and ex vivo expansion as shown by the cobblestone area forming cell assay, competitive repopulation, and serial transplantation. The increase in HSC expansion is likely attributable to SB-mediated inhibition of HSC apoptosis and senescence and upregulation of HoxB4 and CXCR4. These findings suggest that p38 plays an important role in the regulation of HSC self-renewal in vitro and inhibition of p38 activation with a small molecule inhibitor may represent a novel approach to promote ex vivo expansion of HSCs.     

Surface-aminated electrospun nanofibers enhance adhesion and expansion of human umbilical cord blood hematopoietic stem/progenitor cells

Interaction between hematopoietic stem/progenitor cells (HSPCs) and their extra cellular matrix components is an integral part of the signaling control for HSPC survival, proliferation and differentiation. We hypothesized that both substrate topographical cues and biochemical cues could act synergistically with cytokine supplementation to improve ex vivo expansion of HSPCs. In this study, we compared the ex vivo expansion of human umbilical cord blood CD34⁺ cells on unmodified, hydroxylated, carboxylated and aminated nanofibers and films. Results from 10-day expansion cultures showed that aminated nanofiber mesh and film were most efficient in supporting the expansion of the CD34⁺CD45⁺ cells (195-fold and 178-fold, respectively), as compared to tissue culture polystyrene (50-fold, p<0.05). In particular, aminated nanofiber meshes supported a higher degree of cell adhesion and percentage of HSPCs, as compared to aminated films. SEM imaging revealed the discrete colonies of cells proliferating and interacting with the aminated nanofibers. This study highlights the potential of a biomaterials approach to influence the proliferation and differentiation of HSPCs ex vivo.     

脐血造血干/祖细胞移植SCID小鼠的实验研究

目的 :检测扩增后脐血造血干 祖细胞的体内移植能力和造血活性 ,建立脐血细胞体外扩增优化方案和体内移植的SCID小鼠模型。方法 :采用无基质接触的液体悬浮培养方法扩增脐血CD34 细胞 ,将扩增前后的细胞移植给预先经过亚致死量辐照的SCID小鼠 ,4w后通过免疫荧光标记、PCR等检测存活小鼠体内的人源细胞。结果 :连续培养一定时间后 ,FL TPO SCF IL 6组脐血细胞得到持续扩增 ,并能维持一定比例的CD34 细胞 ;SCF IL 3 IL 6 GM CSF EPO组在第 2周时集落形成数已降低 ,第 4周时集落形成的细胞、CD34 细胞已基本检测不到。移植至少 4w后 ,在存活小鼠体内检测到人CD4 5 细胞和Alu基因。结论 :因子组合FL TPO CSF IL 6可以有效扩增脐血CD34 细胞 ,而且扩增后的细胞具有较高的移植效率和造血活性     

MCL1 increases primitive thymocyte viability in female mice and promotes thymic expansion into adulthood

Increasing the pool of cells at early T-cell developmental stages enhances thymopoiesis and is especially beneficial when T-cell production is compromised by radiation or aging. Within the immature double-negative (DN; CD4(-)CD8(-)) thymocyte subpopulation, the DN1 subset contains the most primitive cells including the rare early T-cell progenitors (ETPs). In the present study, a human MCL1 transgene, under the control of its endogenous promoter, resulted in enlargement of an undistorted thymus in C57/BL6 mice. Enlargement occurred in females but not males, being seen at 1 month of age and maintained during progression into adulthood as the thymus underwent involution. The small DN1 subset was expanded disproportionally (ETPs increasing from ～0.016 to 0.03% of thymocytes), while more mature thymocytes were increased proportionally (1.5-fold) along with the stroma. DN1 cells from transgenic females exhibited increased viability with maintained proliferation, and their survival in primary culture was extended. Exposure of transgenic females to γ-irradiation also revealed an expanded pool of radioresistant DN1 cells exhibiting increased viability. While the viability of DN1 cells from transgenic males was equivalent to that of their non-transgenic counterparts directly after harvest, it was enhanced in culture-suggesting that the effect of the transgene was suppressed in the in vivo environment of the male. Viability was increased in ETPs from transgenic females, but unchanged in more mature thymocytes, indicating that primitive cells were affected selectively. The MCL1 transgene thus increases the viability and pool size of primitive ETP/DN1 cells, promoting thymopoiesis and radioresistance in peripubescent females and into adulthood.     

血管内皮祖细胞的体外扩增特性研究

目的:探讨血管内皮祖细胞(EPCs)在体外扩增特性。方法:利用磁性活化细胞分选系统(MACS)系统富集CD34⁺细胞,在相同条件下与同批的单个核细胞(MNC)、CD34⁺和CD34^-混和细胞进行对照培养,比较EPCs体外扩增效果。另外研究血管内皮生长因子(VEGF)和传代培养对细胞分化、扩增动力学和细胞凋亡的影响。应用细胞免疫化学和流式细胞术对细胞定性定量分析。结果:MNC培养、CD34⁺和CD34^-细胞混和培养明显高于CD34⁺细胞单独培养EPCs扩增率(P＜0.05),一旦细胞形成线索样结构行传代培养明显低于未传代的细胞凋亡(P＜0.05)。VEGF对细胞凋亡(P＞0.05)无明显影响,这些分化的EPCs免疫细胞化学染色CD34、vWF、KDR、CD31阳性,并且吞噬乙酰化低密度脂蛋白(Ac-LDL)。培养7d流式细胞检查CD34⁺、AC133^＋分别占贴壁(AT)细胞的68.2%±6.3%(n=6)、57.2%±9.8%(n=6)。结论:MNC培养、CD34⁺和CD34^-细胞混和培养提高了EPCs扩增率,早传代使凋亡率明显降低。VEGF对EPCs体外扩增无明显影响。     

Human hematopoietic progenitor in bone marrow and peripheral blood

The ability to enhance the frequency of progenitors in the peripheral circulation has resulted in peripheral blood progenitor cell collections being the preferred procurement method for autologous transplants and an accepted alternative for allografts. In autografts, peripheral blood-derived progenitor cells appear to have an advantage over conventional marrow transplants in the form of earlier engraftment without compromising sustained marrow function. Studies were performed to evaluate the broad class of CD34+ progenitors and their subtypes in preparations of bone marrow and peripheral blood cells. As a result, peripheral blood appears to contain a larger quantity of more mature progenitors, which is the likely reason for a more rapid return of granulocytes and platelets. However, controveries continue to exist as to whether the measurements derived from these studies can be used to predict time to engraftment and subsequent reestablishment of a marrow reserve. Some of these issues have been addressed in pilot studies where allografts using G-CSF-mobilized peripheral blood progenitor cells were compared to conventionally harvested bone marrow and bone marrow obtained from G-CSF-stimulated donors. The time to engraftment of neutrophils and platelets were shortened when G-CSF-mobilized peripheral blood or marrow progenitor cells were used compared to case-matched grafts of steady-state marrow. The significance of the suggested differences between steady-state bone marrow grafts and mobilized peripheral blood cells remains to be determined. However, preparations of cytokine-mobilized peripheral blood progenitor cell preparations are being used with increasing frequency to replace conventional marrow harvests.     

In utero transplantation of human hematopoietic stem/progenitor cells partially repairs injured liver in mice

The aim of this study is to establish a novel mouse model with high achievement and chimerism by in utero transplantation of human hematopoietic stem/progenitor cells and to explore the possibility that human adult hematopoietic stem/progenitor cells can differentiate into hepatocyte-like cells and partially repair the liver damage induced by carbon tetrachloride (CCl(4)). Mononuclear cells (MNCs) were isolated from fresh human umbilical cord blood (hUCB) and CD34(+) cells were enriched from the MNCs by magnetic cell isolation. These cells were injected respectively into the fetal mice at 11-13 days of gestation. At one month after birth, the specific markers of human cells, human alpha-satellite sequence (h17alpha), CD14, CD34, CD45, and GPA were detected by PCR and FACS. At three and six months after birth, the established human-mouse chimeras were administered with CCl(4) by intraperitoneal injection. The biochemical markers (ALT, AST, ALP, albumin) in serum were determined and human hepatocyte-specific proteins, such as human albumin, hepatocyte nuclear factor-4, hepatocyte-specific antigen, tryptophan 2,3-dioxygenase and alpha fetoprotein were analyzed by PCR, RT-PCR, real-time PCR and immunohistochemistry staining, respectively. More than 77% of recipients demonstrated human-mouse chimera. Significantly, hUCB hematopoietic stem/progenitor cells may differentiate into human hepatocyte-like cells with evidence of the expression of human hepatocyte-specific proteins as well as partially repair or protect liver damage induced by CCl(4). The mouse model described in this article provides a useful tool for the studies of regeneration of human hepatocyte-like cells from adult hematopoietic stem/ progenitor cells as well as facilitates the therapeutic potential for liver diseases or damage by in utero transplantation.     

Androstenediol stimulates myelopoiesis and enhances resistance to infection in gamma-irradiated mice

The ionizing radiation-induced hemopoietic syndrome is characterized by defects in immune function and increased mortality due to infections and hemorrhage. Since the steroid 5-androstene-3beta, 17beta-diol (5-androstenediol, AED) modulates cytokine expression and increases resistance to bacterial and viral infections in rodents, we tested its ability to promote survival after whole-body ionizing radiation in mice. In unirradiated female B6D2F1 mice, sc AED elevated numbers of circulating neutrophils and platelets and induced proliferation of neutrophil progenitors in bone marrow. In mice exposed to whole-body (60)Co gamma-radiation (3 Gy), AED injected 1 h later ameliorated radiation-induced decreases in circulating neutrophils and platelets and marrow granulocyte-macrophage colony-forming cells, but had no effect on total numbers of circulating lymphocytes or erythrocytes. In mice irradiated (0, 1 or 3 Gy) and inoculated four days later with Klebsiella pneumoniae, AED injected 2 h after irradiation enhanced 30-d survival. Injecting AED 24 h before irradiation or 2 h after irradiation increased survival to approximately the same extent. In K. pneumoniae-inoculated mice (irradiated at 3-7 Gy) and uninoculated mice (irradiated at 8-12 Gy), AED (160 mg/kg) injected 24 h before irradiation significantly promoted survival with dose reduction factors (DRFs) of 1.18 and 1.26, respectively. 5-Androstene-3beta-ol-17-one (dehydroepiandrosterone, DHEA) was markedly less efficacious than AED in augmenting survival, indicating specificity. These results demonstrate for the first time that a DHEA-related steroid stimulates myelopoiesis, and ameliorates neutropenia and thrombocytopenia and enhances resistance to infection after exposure of animals to ionizing radiation.     

The NG2 proteoglycan promotes oligodendrocyte progenitor proliferation and developmental myelination

The NG2 proteoglycan has been shown to promote proliferation and motility in a variety of cell types. The presence of NG2 on oligodendrocyte progenitor cells (OPCs) suggests that the proteoglycan may be a factor in expansion of the OPC pool to fill the entire CNS prior to OPC differentiation to form myelinating oligodendrocytes. Comparisons of postnatal cerebellar myelination in wild type and NG2 null mice reveal reduced numbers of OPCs in developing white matter of the NG2 null mouse. Quantification of BrdU incorporation shows that reduced proliferation is a key reason for this OPC shortage, with the peak of OPC proliferation delayed by 4–5 days in the absence of NG2. As a result of the subnormal pool of OPCs, there is also a delay in production of mature oligodendrocytes and myelinating processes in the NG2 null cerebellum. NG2 may promote OPC proliferation via enhancement of growth factor signaling or mediation of OPC interaction with unmyelinated axons.     

The Notch pathway mediates expansion of a progenitor pool and neuronal differentiation in adult neural progenitor cells after stroke

Molecular mechanisms by which stroke increases neurogenesis have not been fully investigated. Using neural progenitor cells isolated from the subventricular zone (SVZ) of the adult rat subjected to focal cerebral ischemia, we investigated the Notch pathway in regulating proliferation and differentiation of adult neural progenitor cells after stroke. During proliferation of neural progenitor cells, ischemic neural progenitor cells exhibited substantially increased levels of Notch, Notch intracellular domain (NICD), and hairy enhancer of split (Hes) 1, which was associated with a significant increase of proliferating cells. Blockage of the Notch pathway by short interfering ribonucleic acid (siRNA) against Notch or a γ secretase inhibitor significantly reduced Notch, NICD and Hes1 expression and cell proliferation induced by stroke. During differentiation of neural progenitor cells, Notch and Hes1 expression was downregulated in ischemic neural progenitor cells, which was coincident with a significant increase of neuronal population. Inhibition of the Notch pathway with a γ secretase inhibitor further substantially increased neurons, but did not alter astrocyte population in ischemic neural progenitor cells. These data suggest that the Notch signaling pathway mediates adult SVZ neural progenitor cell proliferation and differentiation after stroke.     

Effect of heparin addition on expansion of cord blood hematopoietic progenitor cells in three-dimensional coculture with stromal cells in nonwoven fabrics

Primary human cord blood mononuclear cells (CB MNCs) were inoculated into layers of primary human bone marrow stromal cells prepared in a nonwoven fabric porous carrier [three dimensional (3-D)] or on a dish [two dimensional (2-D)] using a cytokine-free medium and were cultured for 7 days with or without the addition of heparin. The number of progenitor cells increased threefold during the 3-D coculture, whereas it decreased in the 2-D culture. Heparin addition to the 3-D coculture further increased the number of progenitors twofold, whereas the addition of desulfated heparin had no effect. The heparin effect was also observed in a 3-D culture of CB MNCs without stromal cells when conditioned medium was employed. The coating of the carrier with N-(O--(6-O-sulfogalactopyranosyl)-6-oxyhexyl)-3,5-bis (dodecyloxy)-benzamide instead of heparin addition also increased the number of progenitor cells in the 3-D culture of CB MNCs without stromal cells when the conditioned medium was employed. The 3-D coculture constructed with nonwoven fabrics and stromal cells was clearly superior to the 2-D culture because of the expansion of CB hematopoietic progenitor cells without cytokine addition. Heparin addition to the 3-D coculture further increased the number of progenitor cells, which may result from a synergistic effect of soluble cytokines produced by stromal cells with the sulfur group of heparin.