Risk factors of respiratory infections in patients with hematopoietic stem cell transplantation at early stage

AIM:To investigate the pathological status, hematopoietic reconstitution and risk factors of respiratory infections(RI) in the patients with hematopoietic stem cell(HSC) transplantation at early stage. METHODS:The retrospective and case-control study, single-factor and Logistic analysis were performed to analyze the clinical data of 168 patients with HSC transplantation. RESULTS:The incidence rate of RI was 72.6%, upper RI was 44.0%, and lower RI was 28.6%. The cases with RI attacked before hematopoietic reconstitution were 81.1%. The risk factors of RI analyzed by single factor were age, origin of HSC, pretreatment, non-genetic transplantation, non-complete matching of human leukocyte antigen(HLA), hemogram recovery time, and independent risk factors were age and non-genetic transplantation. The risk factors of upper RI were age, origin of HSC, non-genetic transplantation, non-complete matching of HLA, hemogram recovery time, and independent risk factors were age and non-genetic transplantation. The risk factors of lower RI were the origin of HSC, non-genetic transplantation, non-complete matching of HLA, history of fungal pneumonia and graft-versus-host disease(GVHD), and independent risk factors were non-complete matching of HLA and history of fungal pneumonia. CONCLUSION:Higher incidence rate of RI exists at early stage of HSC transplantation, and independent risk factors include age, non-genetic transplantation, non-complete matching of HLA and history of fungal pneumonia.     

Construction of lentiviral vector carrying the Ang-1 gene and its expression in the rMSCs

AIM: To construct lentiviral vector carrying the angiopoietin-1 (Ang-1) gene,and make it express Ang-1 in the rat mesenchymal stem cells (rMSCs).METHODS: The cDNA encoding the CDS of Ang-1 gene was obtained from the placenta of the adult Fisher 344 rats with RT-PCR.After digestion with restrication endonuclease,the Ang-1 gene was recombined to construct the transfer plasmid PNL-Ang1-IRES2-EGFP.The three-plasmid system of lentiviral vector was consisted of PNL-Ang1-IRES2-EGFP,the packaging plasmid HELPER,and the envelope plasmid VSVG,which were co-transfected to 293T cells mediated by lipofectamin2000 to produce lentiviral particles.The rMSCs were infected by obtained lentiviral particles.The insertion of Ang-1 gene was detected by PCR,the mRNA expression of Ang-1 in rMSCs was detected with RT-PCR,the protein expression of Ang-1 was observed with immunocytochemistry and Western blotting methods.RESULTS: The result of sequencing showed that the cloned Ang-1 gene was consistent with the sequence reported in GenBank.After digestion with restrication endonuclease,the 1 512 bp fragment of Ang-1 gene and the 10.5 kb vector fragment of PNL-IRES2-EGFP were observed with gel electrophoresis.The insertion of Ang-1 gene in viral genome was confirmed.The EGFP expression was observed with the fluorescent microscope.In infected rMSCs,the mRNA and protein expressions of Ang-1 were confirmed.CONCLUSION: Lentiviral vector carrying Ang-1 gene has been successfully constructed.The infected rMSCs are able to express the Ang-1 mRNA and Ang-1 abundantly.This will facilitate the following exploratory development of Ang-1 gene-modified rMSCs.     

The stromal cells and the hematopoietic restitution of hematopoietic stem cell transplantation

As a major component of the hematopoietic microenvironment,stromal cells have been proved to support hematopoiesis. This review describes the constitution, origin of stromal cells and its mrechanism of regulate hematopoiesis, and then elaborates that the stromal cells play a important role in the hematopoietic restitution of hematopoietic stem cell transplantation.     

Restricted expansion of T cell receptor (TCR)Vβ genes in leukemic patients subjected to allogeneic hematopoeitic stem cell transplantation

AIM: To investigate restricted expansion of TCR Vβ gene repertoire in patients with leukemia following allogeneic hematopoietic stem cell transplantation. METHODS: TCR Vβ subfamily genes in peripheral blood mononuclear cells from 7 cases of leukemia was amplified using RT-PCR. RESULTS: Only two-eight fragments of Vβ genes were detected in samples from these patients, and the detected fragments are different in different patients. CONCLUSION: TCR complexes were abnormal in all patients, part of the genes were seletively expansed and part of them were suppressed after transplantation.     

果胶降解相关酶与果实成熟软化

果胶降解相关酶广泛存在于植物体的各个部分,目前在果实组织中已发现多种,主要包括内切多聚半乳糖醛酸酶、外切多聚半乳糖醛酸酶、果胶甲酯酶、果胶裂解酶、B-半乳糖苷酶、α-L-阿拉伯呋喃糖苷酶和鼠李糖半乳糖醛酸酶,此类酶能使果胶多糖发生降解,进而使细胞间失去黏结作用,胞壁结构瓦解,从而导致果实组织松弛,质地下降.综述了果胶降...     

Supportive effects of human aorta-gonad-mesonephero stromal cells on the directed differentiation of embryonic stem cells into hematopoietic stem cells

AIM: To direct embryonic stem cells (ESCs) into hematopoietic stem cells (HSCs) in vitro by simulating the hematogenic microenvironment in human early embryonic aorta-gonad-mesonephero (AGM) region.METHODS: Murine E14 embronic stem cell line was used for two-step differentiation.In the first step of primary differentiation,E14 ESCs were seeded into semisolid methylcellulose-based medium containing bone morphogenesis protein 4 (BMP4) and vascular endothelial growth factor (VEGF) for embryoid body (EB) formation.On days 3,6,9,12 and 15,single EB cells were analyzed for Flk-1+ cells amount through flow cytometry.In the second step,single cell from EB containing most Flk-1+ cells was further co-cultured with human AGM stromal cells in non-contact system.On co-culture days of 3,6,9 and 12 days,cells were collected for cell count,flow cytometry for Sca-1+c-kit+ cells analysis,and colony forming cell assay.RESULTS: During the EB formation,BMP4+VEGF promoted Flk-1+ cell genesis on day 9 at peak pencentage value of 27.53%±2.84％,which was statistically higher than that in control group as 8.77±1.10 (P<0.05).Collagenase-disassociated single cell from day 9 EB was co-cultured with human AGM stromal cells of hAGMS3 or hAGMS4 for further hematopoietic differentiation.On day 6 Sca-1+c-kit+ cells got to peak value as 7.31%±1.21％ ［(2.57±0.48) folds］ and 7.62%±1.52％ ［(2.35±0.36) folds］ in hAGMS3 and hAGMS4 feeder systems,respectively,both of which were greater than those values of no-stroma groups at the same culture duration (P<0.05).Colonogenic cell assay showed that these Sca-1+c-kit+ cells had ability of forming multiple lineage hematopoietic colonies.CONCLUSION: BMP4 in combination with VEGF promotes Flk-1+ cell genesis during EB formation in vitro.Stromal cells from early human embryonic AGM region further enhance the directed differentiation of these primitive cells into HSCs.This two-step induction differentiation model can be used for molecular mechanism study of ESCs hematopoietic differentiation.     

《中国蔬菜品种志》

AIM: To characterize the gene expression of sortilin on adipogenic and osteogenic differentiation in mesenchymal stem cells (MSCs) in vitro and explore its significance.METHODS: MSCs derived from human bone marrow were isolated and cultured in vitro, then were stimulated in osteogenic medium and adipogenic medium, respectively. Osteopontin and lipoprotein lipase were detected by RT-PCR. Sortilin expression was analyzed by semiquantitative RT-PCR. RESULTS: 1.MSCs displayed the potential of differentiation into osteoblast and adipocyte. 2.Sortilin was upregulated one day after osteogenic induction and remained upregulated for a week. The expression of sortilin was significant increased on day 3(P＜0.01). 3. No significant changes of sortilin expression was found in adipogenic differentiation (P＞0.05).CONCLUSION: Sortilin may be useful to modulate the osteogenic differentiation and may not be necessary for adipocyte commitment in MSCs. The regulation of sortilin expression may provide new protocal and strategy for the treatment of osteoporosis and osteopenic disease.     

Supportive and expansive effects of aorta-gonad-mesonephros (AGM)-derived stromal cells on hematopoietic stem in vitro

AIM: To explore the supportive and expansive effects of aorta-gonad-mesonephros(AGM) region derived stromal cells on hematopoietic stem cells (HSC) in vitro.METHODS: The murine stromal cells were separated and cultured from AGM region of a 11 day postcoitum (dpc) mouse embryo and 6 week mouse. After identification by Wrights staining and flow cytometry, the stromal cells were co-cultured with the embryonic stem cell(ESC)-derived, cytokine-induced HSCs, and the maintenance and expansion of HSCs were evaluated by detecting CD34+，CD34+Sca-1+cells with flow cytometry.Blast colony-forming cell (BL-CFC) and high proliferative potential colony-forming cells(HPP-CFC) were determined by semi-solid medium clonal culture.RESULTS: AGM-derived and bone marrow(BM)-derived stromal cells were similar in morphology and phenotype, and had common character of stromal cells. Supported by AGM stromal cells or by BM stromal cells, more primitive progenitor cells HPP-CFC were expanded, but BL-CFC expansion was only detected in AGM-derived stromal cells. In the supporting of BM stromal cells CD34+ hematopoietic stem/progenitor cells were expanded 3-4 times, but no significant expansion in CD34+Sca-1+ cells was observed. While in the supporting of AGM stromal cells, both CD34+ hematopoietic stem/progenitor cells and CD34+Sca-1+ cells were expanded significantly from 4 to 5 times, respectively (P<0.05).CONCLUSION: AGM-derived stromal cells significantly support the expansion of HSC, and also maintain the self-renewal activity and multi-lineage differentiation of HSC in vitro.     

Construction of mouse pdx-1 gene eukaryotic expression vector and its expression in embryonic stem cells

AIM: To clone mouse pdx-1 gene and construct its eukaryotic expression vector for expression of pdx-1 in mouse embryonic stem cells.METHODS: Mouse pdx-1 cDNA fragment was amplified with polymerase chain reaction (PCR) from mouse pancreatic cDNA. The purified fragment was recombinated with a eukaryotic expression vector carrying enhanced green fluorescent protein, pEGFP-N1. The pdx-1 cDNA fragment was inserted into the multi-clone sites of the vector to construct a new plasmid, pEGFP/pdx-1. E.colli strain DH5α was transfected with the new recombinant plasmid to expand it. Plasmid DNA extracted from the expanded DH5α was identifed by cutting with Hind Ⅲ, BamHⅠ nuclease and by DNA sequencing. Identified plasmid DNA was transfected into mouse embryonic stem cell line MESPU13 by carrying with liposome. RESULTS: A 876 bp cDNA fragment was amplified from mouse pancreatic cDNA by PCR and it was inserted into the vector pEGFP-N1 correctly. The fragment was defined to be pdx-1 gene by nuclease digestion and DNA sequencing. Mouse embryonic stem cell line MESPU13 was transfected with the new recombinant plasmid DNA. The green fluorescent protein report gene and pdx-1 gene expressed in transfected mouse embryonic stem cells within 24 h. CONCLUSION: Mouse pdx-1 gene is cloned and its recombinant eukaryotic expression vector carrying green fluorescent protein is constructed successfully. It provides a useful tool for further research on the function of pdx-1.     

Protective effect of the bone marrow cells transfected with multidrug resistance gene on the reconstruction of murine hematopoietic function

AIM: To investigate the protective effect of the bone marrow cells transfected with human multidrug resistance gene (MDR1) on the reconstruction of murine hematopoietic function.METHODS: The mononuclear cells of the bone marrow from donors, BALB/C mice, treated with 5-Fu previously, were isolated and transfected with human multidrug resistance gene in vitro , then transplanted to the tertiary recipients. After lethal irradiation(8.5 Gy) and bone marrow transplantation, the recipients were selected with Taxol 7 mg/kg intraperitoneal injection, VCR 5 mg/kg or DNA 5 mg/kg intravenous injection. The survival rate and blood pictures of mice as well as the integration and expression of target gene MDR1 were studied. RESULTS: The lethal irradiated murine hematopoietic function could be reconstructed and protected from toxicity of high doses Taxol, VCR and DNR selection after reinfusing the hematopoietic progenitor cells containing human multidrug resistance gene (MDR1). The survival rate and survival time of experimental mice were higher than that in the control group. The integration and expression of MDR1 gene in recipients were confirmed by PCR, RT-PCR and FCM. CONCLUSION: The integration and expression of human multidrug resistance gene in recipients may play an important role in the reconstruction and protection of murine hematopoietic function.     

The new seed cells for hepatocyte transplantation

The prospect of liver disease treatment by hepatocyte transplantation is broad, but it is difficult to apply it in clinic therapy due to the restriction of source and proliferation of donor hepatocyte. The hematopoietic stem cell plasticity of trans-differentiation to hepatocyte provides a new source of seed cells for hepatocyte transplantation. In this review, we focus on advances in the seed cells for hepatocyte transplantation.     

Activation of vascular endothelial cells improves the homing of hematopoietic stem cells

AIM: To study the effect of endothelial cell activation on the homing of hematopoietic stem cells (HUHSC) during transplantation. METHODS: Human umbilical vein endothelial cells (HUVEC) were cultured to single layer and activated by vascular endothelial growth factor (EVGF), granulocyte colony stimulating factor (G-CSF) and lipopolysaccharide (LPS), respectively. The HUHSC, enriched by eliminating red blood cells, granulocytes, monocytes and lymphocytes from cord blood, were cocultured with activated HUVEC to make adhesion. The adhesive ability of activated HUVEC to C-Kit⁺ HUHSC was assayed by ELISA. Anti-VCAM-1 monoclonal antibody was used to detect the effect of activation on HUVEC and HUHSC interactions. RESULTS: Resting HUVEC had a little adhesive ability to HUHSC. A great enhancement of adhesive ability was showed when HUVEC was activated by VEGF, G-CSF and LPS. In the presence of anti-VCAM-1, the adhesive ability of activated HUVEC was decreased remarkablely. CONCLUSION: HUHSC homing may be related to the activation of endothelial cells and adhesion molecules.     

Effect of different PRA serum levels from patients with β-thalassemia on the proliferation and differentiation potential of the hematopoietic stem cells /progenitor cells of cord blood

AIM: To probe the effect of different panel reactive antibody(PRA) serum levels from patients with β-thalassemia on the proliferation and differentiation potential of the hematopoietic stem /progenitor cell of cord blood.METHODS: 1×105 mononuclear cells (MNCs) isolated from umbilical cord blood were incubated with different PRA serum levels (0 μL,50 μL,100 μL) respectively and complement,inoculated into the methylcellulose cultural system.The proliferation and differentiation potential of the hematopoietic stem /progenitor cell of cord blood by the colony formation assay were detected on day 7 and day 14,respectively.RESULTS: After culture of 7 days,the total colonies and CFU-GM were 88.20±9.41,79.00±11.39 in group A and 88.60±9.12,79.20±10.44 in group B,which were significantly higher than those of 20.60±7.39,15.20±4.66 in group C and those of 4.00±2.05,1.40±0.51 in group D (P<0.01).Meanwhile compared with group A and group E,no significant difference was found (P>0.05).After culture for 14 days,the total colonies and CFU-GM were 216.00±31.10,117.40±24.80 in group A and 213.20±31.06,116.00±19.75 in group B,which were significantly higher than those of 97.80±14.43,32.80±8.10 in group C and those of 31.40±13.41,8.40±4.30 in group D (P<0.01).The CFU-GEMMs were 45.60±8.51 in group A and 42.60±7.03 in group B,which were significantly higher than those of 20.80±6.96 in group C and those of 7.80±6.06 in group D (P<0.05).The BFU-MK was 12.80±4.42 in group A and 11.00±2.74 in group B respectively,which were significantly higher than that of 1.00±0.55 in group D (P<0.05).The CFU-E in group B 17.20±4.03 was significantly higher than that of 5.60±2.87 in group D (P<0.05).Meanwhile compared with group A and group E,no significant difference was found (P>0.05).By the Kendall test,there were negative correlations between the level of PRA serum and the total colonies,CFU-GM on day 7,the total colonies,CFU-GM,CFU-GEMM,BFU-E,BFU-MK on day 14 (tau-b=-0.793,-0.849,-0.808,-0.804,-0.645,-0.674,-0.624,P<0.01).There was a negative correlation between the level of PRA serum and CFU-MK on day 14 (tau-b=-0.466，P<0.05).CONCLUSION: PRA sera inhibit the colony in the colony cultures of the hematopoietic stem cells/progenitor cells in cord blood.The inhibition depends on the level of PRA sera.The higher the level of PRA sera,the stronger the inhibition is observed in our study.     

Effects of c-myb antisense RNA on the proliferation and collagen Ⅰ gene expression in cultured hepatic stellate cells

AIM:To investigate the effects of c-myb antisense RNA on the proriferation and collagen Ⅰ gene expression in cultured hepatic stellate cells(HSC) in rats.METHODS:The c-myb antisense gene recombinant retroviral vector(pDOR-myb) was constructed, and then was transfected into retroviral package cell line PA 317 by means of N-[1-(2,3-Dioleoyloxy) propyl]-N, N, N-trimethylammonium methyl-sulfate(DOTAP) liposomal transfection reagent. The pseudoviruses produced from the resistant PA317 cells selected with G418 were collected, with which HSCs isolated from rat liver were infected. The cell proliferation was measured by MTT method, c-myb, α₁-Ⅰ collagen mRNA expression and c-myb protein in HSCs were detected with semi-quantitative RT-PCR and western-blot, respectively.RESULTS:HSCs from rats were isolated successfully with the viability >98%. In the pDOR-myb infected HSCs, c-myb expression levels, the cell proliferation, and α₁-Ⅰ collagen mRNA expression were repressed significantly.CONCLUSIONS:c-myb plays a key role in the activation and proliferation of HSC. c-myb antisense RNA can inhibit cell proliferation and α₁-Ⅰ collagen mRNA expression in the infected HSC. These data suggest that inhibition of c-myb gene expression would be a potential way for the treatment of liver fibrosis.     

Generation of hematopoietic stem/progenitor cells with property of strengthened cell mediated immunity from an embryonic stem cell line

AIM:To induce lymphoid stem cells and/or T-cell precursors to differentiate into functional mature T lymphocyte, and to increase the surface marker of T lymphocytes such as CD₃⁺, while embryonic stem(ES) cells differentiated into hematopoietic stem/progenitor cells(HSPCs) in vitro. When they were injected into lethally irradiated mice, these differentiated cells had the advantage in immune reconstitution. METHODS:Embryonic stem cells formed embryoid bodies(EBs) in the medium containing methycellulose, hematopoietic growth factors(HGFs) was added to the culture system on the 6th day, thymopeptide was added at the same time. Flow cytometry were performed to detect the surface marker CD₃₄⁺ and CD₃⁺ of the differentiated cells. Finally the differentiated cells were injected into lethally irradiated mice, 60 days later, the incidence rate of graft versus host disease(GVHD) was taken as the mark of cell mediated immunity, PCR was performed to detect the sex determining region of the Y-chromosome(Sry) in bone marrow cells and spleen cells of the survival host female mice. RESULTS:The percentage of CD₃⁺ T lymphocytes was 10.52% and the incidence rate of GVHD was 0% on the 13th day, but they respectively rose up to 22.93% and 100% if thymopeptide was added in the procedure of inducing ES cells to differentiate into HSPC in vitro. CONCLUSION:The quantity of CD₃⁺ T lymphocytes increased in medium containing thymopeptide when ES cells differentiated into CD₃₄⁺ HSPC.     

Generation of thalassemia-specific integration-free induced pluripotent stem cells and determination of their differentiation ability

AIM: To generate thalassemia-specific integration-free induced pluripotent stem cells(iPSC) and to detect their ability of differentiation into hematopoietic precursors.METHODS: The plasmids pEB-C5 and pEB-Tg were transfected into the fibroblast cells from hemoglobin Bart's hydrops fetalis's skin by the method of nuclear transfection to reprogramm the cells into iPSC. The ability of the iPSC to differentiate into 3-germ layer cells was determined. The iPSC were cocultured with mouse OP9 cells to differentiate into hematopoietic precursors and the hematopoietic precursor specific antigens were detected. RESULTS: The integration-free iPSC from hemoglobin Bart's hydrops fetalis's skin fibroblasts were successfully derived, and had the ability to differentiate into 3 germ layers. When cocultured with OP9 cells for 9 d, the positive rate of hematopoietic progenitor cell marker CD34 was 18.7%, and the CD34 and CD45 double positive rate was 12.2%. CONCLUSION: Hemoglobin Bart's hydrops fetalis's skin fibroblasts can be successfully induced into "integration-free" iPSC. This cell line has the ability to differentiate into 3 germ layers, and can be differentiated into hematopoietic precursors when cocultured with OP9 cells.     

Supportive effects of human AGM region and fetal liver stromal cells on differentiation of murine embryonic stem cells into hematopoietic stem cells and in vivo hematopoietic reconstitution

AIM: To investigate the differentiation of murine embryonic stem cells (ESCs) into hematopoietic stem cells (HSCs) by the supportive effects of human aorta-gonad-mesonephros (AGM) region and fetal liver (FL) stromal cells.METHODS: E14 ESCs were induced into embryoid body (EB) first. Then the cells from EB were further co-cultured with human AGM region and FL stromal cells in non-contact system. On day 6, the cells derived from EB were collected for Sca-1⁺c-Kit⁺ cell analysis by flow cytometry, colony forming unit (CFU) assay and teratoma formation checking. BALB/c female mice conditioned with lethal dose of γ-ray irradiation were transplanted with EB cells from different culture systems. The survival rates, engraftment of donor cells, reconstitution of hematopoietic were monitored.RESULTS: Sca-1⁺c-Kit⁺ cells in EB cells co-cultured with human AGM region and FL stromal cells had the value of (21.96±2.54)%, and the total CFU was as (520±52)/10⁵ cells, which were statistically greater than those in EB cells only cultured with human AGM region stromal cells (P＜0.05). No teratoma was found in NOD-SCID mice after subcutaneous injection of EB cells co-cultured with human AGM region and FL stromal cells. In BALB/c female mice transplanted of EB cells co-cultured with human AGM region and FL stromal cells, the survival rate was 77.8%, and the peripheral blood cell count was obviously improved on day 14. PCR results showed the recipients all had sry gene copies from donor in bone marrow. The recipient mice transplanted with EB cells only cultured with human AGM region stromal cells all died within 15 days.CONCLUSION: Stromal cells from human AGM region and FL enhance the directed differentiation of ESCs into HSCs which can reconstruct hematopoiesis in vivo.     

Distribution and identification of immunocytes in humanized SCID mouse model

AIM: Humanized-NOD/SCID(hu-NOD/SCID) mouse model was established and the level of immune reconstitution was assessed in this model. METHODS: Mononuclear cells (MNC) and CD34⁺ cells were isolated or sorted from cord blood(CB). Human CD45, CD19, CD3 markers on cells from NOD/SCID murine peripheral blood(PB), bone marrow(BM), thymus were detected by FCM from 4 to 10 weeks after hematopoietic stem cell transplantation. After 10 weeks, the gene expressions of the human β₂M and RAG2 were detected by RT-PCR in PB or bone marrow of mice model. RESULTS: Human CD45, CD19, CD3 cells populations in PB and BM were found by flow cytometry in mice model transplanted with CD34+ cells or CB MNC from 4 to 10 weeks. The highest positivity of human lymphocytes was at 8 week after transplantation. The levels of human cell engraftment in mice transplanted with CD34⁺ cells were higher than those in mice transplanted with CB MNC. The mRNA of human β₂M and RAG2 were found by RT-PCR in BM.CONCLUSION: The higher level of human lymphocyte engraftment is established in NOD/SCID mouse model transplanted with CD34⁺ compared with CB MNC. The maturation of T lymphocytes could be happened in bone marrow of mice model.     

Effect of ex vivo short time expansion with SCF and IL-6 on the adhesion and transmigration activities of hematopoietic stem/progenitor cells

AIM:To investigate the expression and function of homing related molecules and transmigration ability of human cord blood CD34+ hematopoietic stem/progenitor cells after short time stimulation with cytokine SCF and IL-6.METHODS:CD34+ cells were separated by Ficoll density gradient centrifugation and stimulated by SCF and IL-6 cytokines for 48 h. The changes of CD49d (VLA-4), CD11a (LFA-1), CD62L (L-selectin) and CD184 (CXCR4) were analyzed by flow cytometry. The adherent and migration activities of CD34+ cells were evaluated in human fibronectin (FN) coated microplates (96 wells) and transwell system.RESULTS:The numbers of CD34+ cell expanded to 3 folds and the percentages of CD34+ cells that were positive expressions for CD49d, CD11a, CD62L or CD184 increased 1 to 2 folds after the cytokine stimulation. The spontaneous adhesion between CD34+, FN and SDF-1 induced migration increased after SCF+IL-6 stimulated.CONCLUSION:SCF+IL-6 can improve the most of the homing related characteristics and activities in the short time expansion of CD34+ hematopoietic stem/progenitor cells, which may be partly related to the increased intrinsic homing potential.