[Induction of hepatic specification of human adipose-derived stem cells (hADSCs) in vitro].

OBJECTIVE: To induce hepatic differentiation of human adipose-derived stem cells (hADSCs) in vitro. METHODS: hADSCs were isolated from human adipose tissue and treated with improved hepatic medium containing HGF, bFGF and FGF4. After 7 days of culture, OSM was added to the culture media. Cell growth during hepatic differentiation was evaluated by CCK8 assay. Morphology of differentiation was examined under light microscope. Liver specific genes and proteins were detected by RT-PCR analysis and immunohistochemical staining, respectively. And functional characteristics of hepatocytes were also examined. RESULTS: The number of hADSCs cultured in the improved hepatic media was increased significantly in comparison to hADSCs cultured in control media from 5 days to 21 days (t=6.59, 8.69, 15.94 and 24.64, respectively, P<0.05). The hADSCs-derived hepatocyte-like cells exhibited hepatocyte morphology, expressed hepatocyte markers, possessed hepatocyte-specific activities, such as uptake and excretion of indocyanine green, glycogen storage and albumin production. CONCLUSION: hADSCs can be induced into hepatocyte-like cells in this differentiation system. And this differentiation system promoted the growth of hADSCs.

Self-renewal and pluripotency is maintained in human embryonic stem cells by co-culture with human fetal liver stromal cells expressing hypoxia inducible factor 1alpha.

Human embryonic stem (hES) cells are typically maintained on mouse embryonic fibroblast (MEF) feeders or with MEF-conditioned medium. However, these xenosupport systems greatly limit the therapeutic applications of hES cells because of the risk of cross-transfer of animal pathogens. The stem cell niche is a unique tissue microenvironment that regulates the self-renewal and differentiation of stem cells. Recent evidence suggests that stem cells are localized in the microenvironment of low oxygen. We hypothesized that hypoxia could maintain the undifferentiated phenotype of embryonic stem cells. We have co-cultured a human embryonic cell line with human fetal liver stromal cells (hFLSCs) feeder cells stably expressing hypoxia-inducible factor-1 alpha (HIF-1alpha), which is known as the key transcription factor in hypoxia. The results suggested HIF-1alpha was critical for preventing differentiation of hES cells in culture. Consistent with this observation, hypoxia upregulated the expression of Nanog and Oct-4, the key factors expressed in undifferentiated stem cells. We further demonstrated that HIF-1alpha could upregulate the expression of some soluble factors including bFGF and SDF-1alpha, which are released into the microenvironment to maintain the undifferentiated status of hES cells. This suggests that the targets of HIF-1alpha are secreted soluble factors rather than a cell-cell contact mechanism, and defines an important mechanism for the inhibition of hESCs differentiation by hypoxia. Our findings developed a transgene feeder co-culture system and will provide a more reliable alternative for future therapeutic applications of hES cells.

Cells extract from fetal liver promotes the hematopoietic differentiation of human embryonic stem cells.

Here, we have now developed a new inducing system to promote the differentiation of human stem cells (hESCs) toward hematopoietic lineages by the treatment with cells extract of human fetal liver tissue (hFLT). The embryoid bodies (EBs) obtained from human H1 embryonic stem cells were exposed to buffer, hFLT cells extract, heated hFLT cell extract, and cell extract of human liver cells lines-LO2. Then, the feature of EBs in different groups was characterized by real-time RT-PCR and colony-forming assays. The results showed the treatment by hFLT cells extract could activate the hematopoietic genes expression and improve the capacity for hematopoietic progenitor development of hEBs. After that, we cocultured hFLT extract treated hEBs on the hFLSCs (human fetal liver stromal cells) feeder to differentiate them into hematopoietic cells. As a control, untreated hEBs were cocultured on hFLSCs feeder with cytokines. The feature of induced cells from hEBs was characterized by flow cytometry, Wright-Giemsa staining, and colony-forming assays. The results demonstrated that hFLT cells extract was capable of inducing hEBs into hematopoietic cells and combing it with hFLSCs feeder could largely promote hematopoietic differentiation of hESCs. This method may supply a new way to substitute the cytokines required in hematopoietic induction of hESCs.

[Cardiomyocyte-like differentiation of human bone marrow mesenchymal stem cells after exposure of 5-azacytidine in vitro].

To investigate the potential of adult mesenchymal stem cells (hMSCs) derived from human bone marrow to undergo cardiomyogenic differentiation after exposure of 5-azacytidine in vitro. A small bone marrow aspirate was taken from the iliac crest of human volunteers, and hMSCs were isolated by 1.073 g/mL Percoll and cultured in the right cell culturing medium as previously described. The phonotypes of hMSCs were identified by flow cytometry. The stem cells were cultured in cell culture medium (as control) and medium mixed with 5-azacytidine (5-aza, 3, 5, 10 micromol/L) (n=5, respectively) for cellular differentiation. We examined respectively with immunohischemistry at 21 days of inducement on desmin, cardiac-specific cardiac troponin I (cTnI), GATA4 & connexin43. The ultrastructures of induced cells were examined by transmission electron microscope. The results indicated that the hMSCs showed a fibroblast-like morphology with vortex distribution in their peak propagation, and express high level of CD44 but negative for CD34 and CD45. 20%-30% cells grown after 5, 10 microl/L 5-aza treatment connected with adjoining cells and coalesced into myotube structures after 14 days. After 21 days of culturing, immunohistochemistry revealed expression of desmin, GATA4, cTnI and connexin43 in 5, 10 micromol/L showed positive, but no cardiac specific protein were found in neither 3 micromol/L nor in control group. The ratio of cTnI positive stained cells in 10 micromol/L group were higher than that in 5 micromol/L group (65.3+/-4.7% vs 48.2+/-5.4%, p<0.05). Electron microscopy revealed myofilaments were formed. The results indicated that purified hMSCs from adult bone marrow can be differentiated into cardiac-like muscle cells with 5-aza inducement in vitro and the differentiation is in line with the 5-aza concentration.

[The maintenance of cord blood CD34+ progenitor cells with plant lectin FRIL in vitro and the expression of related cell cycle modulator HTm4 and HTm4S].

Ex vivo maintainance of human stem cells is crucial for many clinical applications. Current culture conditions provide some level support but cytokines induce most quiescent stem cells to proliferate and differentiate. Better control of primitive cells is needed to extend the time and range of manipulation of such cells. A recently identified plant lectin Flt3 receptor-interacting lectin (FRIL) present may a special ability to preserve primitive CB progenitors for extended periods in culture without exogenous cytokines. But the mechanisms of FRIL preserving quiescent primitive cells are still unknown. Recently a novel protein HTm4 and its alternatively spliced variant HTm4S, which serve as hematopoietic cell cycle regulators, have been identified. In this report we studied the effect of FRIL on the in vitro maintenance of quiescent human cord blood stem cells and the expression of the novel hematopoietic cell cycle regulator HTm4 and HTm4S in progenitor cells cultured in FRIL. We analyzed the proliferation and the HPP-CFC proportion of CD34(+) cells treated with FRIL. The human HTm4 and HTm4S mRNA expression was detected by semi-quantitative RT-PCR, and the cell cycle status of CB CD34(+) cells was analyzed by FACS. The results showed that incubation of CD34(+) cells in FRIL resulted in a low proliferation of progenitor cells and fewer cycling cells, but FRIL selectively maintained a higher number of primitive cells with proliferative potential in suspension culture. CB CD34(+) cells cultured in FRIL showed significant diversity in the expression of HTm4 and HTm4S during 0~14 d. On d 0, HTm4 was detected at high level, downregulated on d 1, but upregulated during d 3 to d 14, and reaching the highest level on d 7. But the expression levels of HTm4S changed little in the cells cultured in FRIL except the obviously increased expression on d 7. Exogenous expression showed that HTm4 was localized around the karyon while HTm4S scatted in the cytoplasm, respectively, which may be responsible for their difference in function. Thus, FRIL can preserve quiescent primitive CD34(+), and FRIL's ability to preserve quiescent primitive cells in a reversible manner may significantly expand the time and range of ex vivo manipulations of human stem cells for clinical applications. In other words, HTm4 and HTm4S may play a crucial role in the cell cycle modulation of CD34(+) progenitor cells maintained with FRIL in vitro.

[Migration and differentiation of exogenous rat mesenchymal stem cells engrafted into normal and injured hearts of rats].

OBJECTIVE: To investigate the effects of different microcircumstances on the migration and differentiation of grafted rat mesenchymal stem cells (rMSC) in host myocardium and the feasibility of treatment of myocardial infarction by exogenous adult stem cells. METHODS: rMSC were isolated from the femurs and tibiae of a male Wistar rat and then purified, made into cell suspension, and labeled with DAPI. 35 female Wistar rat were divided randomly into four groups: acute myocardial infarction control group (AMI group, n = 10, the descending anterior branch of left coronary artery was ligated), acute myocardial infarction + rMSC transplantation group (AMI + rMSC group, n = 10, 1 - 3 hours after the ligation DAPI-labeled rMSC were injected into the peri-infarct tissues), normal heart + rMSC transplantation group (normal heart + MSC group, n = 10, DAPI-labeled rMSC were injected into the corresponding myocardium), and mono-nuclear cells transplantation group (AMI + MNCS, n = 5 DAPI-labeled mononuclear cells were injected into he periinfarct tissues). Ten weeks after the implantation, the rats were killed and their hearts were harvested. Immunohistochemistry was used to examine the troponin, GATA-4 and connexin-43. RESULTS: No lymphocyte proliferation and immonologic rejection were seen in the cardiac tissues of the rats implanted with rMSC. DAPI-labeled rMSC with blue nuclei were distributed extensively in the myocardium of the AMI + rMSC group, ovoid in shape and arranged in parallel with the cardiac muscle fibers, and were distributed sporadically like islands in the myocardium of the normal heart + rMSC group, irregular in shape and not arranged in parallel with the cardiac muscle fibers. No blue nucleus was seen in the cardiac tissues of the hearts implanted with DAPI-labeled mononuclear cells. Troponin and GATA4 were positive immunohistochemically in the implanted rMSC with blue nuclei and the host cardiac muscle cells of the AMI group and AMI + rMSC group, however, were negative in the implanted rMSC with blue nuclei and normal cardiac muscle cells of the normal heart + rMSC group. CONCLUSION: Purified rMSC are immunologically tolerable and can be used as donor cells for exogenous cells therapy. Capable of surviving and homing in both in normal and injured hearts, exogenous rMSC migrate and differentiate into cardiac muscle cell-like cells in myocardium with infarction, however, not in normal heart.

[Identification of differentially expressed genes in Lin-CD34- and Lin-CD34+ cells].

OBJECTIVE: To identify genes that differentially expressed in Lin(-)CD(34)(-) and Lin(-)CD(34)(+) cells. METHODS: With Lin(-)CD(34)(-) cells as tester and Lin(-)CD(34)(+) cells as driver, cDNA subtractive library for Lin(-)CD(34)(-) cells was constructed using suppression subtractive hybridization technique. Part of clones in the library were sequenced and the homologue analysis was conducted against the DNA database in GenBank. RESULTS: 593 clones containing an average of 300 - 500 bp insert were identified. Of them, 53 randomly selected ESTs were sequenced. Homologue analysis revealed that 37 ESTs represented 10 known genes, and the other 16 ESTs represented 4 novel sequences. CONCLUSION: Part of specifically expressed genes in Lin(-)CD(34)(-) cells were identified, which maybe related to Lin(-)CD(34)(-) cells' specific characteristics.

[Development of the human/rat chimera model with neonatal rats].

The purpose of this study was to transplant neonatal rat with human cord blood Lin(-) cells to test the possibility of this xenograft model. The Lin(-) cells were purified from human cord blood (CB) using negative selection strategy based on different lineage-specific antigens. The Lin(-) cells were injected into the liver of neonatal rats using a microinjector at an average of 5 x 10(5) cells for each. Peripheral blood (PB) and spleen were collected at 2,4 and 8 weeks after injection. Flow cytometry was performed to detect human cells in the rat PB, PCR was used to detect human cells in PB as well as spleen. The results showed that a definite proportion of human cells existed in peripheral blood of chimeric rat and the human specific beta2 microglobulin gene fragments were detected in spleen genomic DNA of chimeric rat. It is concluded that human/rat chimera model can be developed with neonatal rats. Human/rat xenograft model may provide a useful and convenient method for human hematopoietic stem cell assay in vivo.

[Migration and differentiation of human bone marrow mesenchymal stem cells in the rat brain].

Bone marrow mesenchymal stem cells (MSCs) are multipotent tissue stem cells that can be induced in vitro to differentiate into a variety of cells such as osteoblasts, chondrocytes and adipocytes. MSCs are useful vehicles for both cell and gene therapy for a variety of diseases. Here, we injected human MSCs with enhanced green fluorescent protein (EGFP) into the striatum of Parkinson disease (PD) rat and examined their survival, migration, differentiation, and the behavior changes in PD rats, which will provide a theoretical foundation and technical method for clinic PD therapy by stem cells. The results showed that human bone marrow MSCs can survive in rat brain for a long time (exceeding 70 d). MSCs were found in multiple areas of the rat brain including the striatum, the corpus callosum, contralateral cortex and even the brain vascular wall. Immunocytochemical staining suggested that implanted cells expressed human neurofilament (NF), neuron-specific enolase (NSE) and glial fibrillary acid protein (GFAP). At the same time, remission in abnormal behavior of the PD rats appeared. Rotation scores decreased gradually from 8.86+/-2.09 r/min pre-transplantation to 4.87+/-2.06 r/min 90 d post-transplantation (statistic result showed P<0.05).

[Effect of Tpo and/or IL-11 gene modified stromal cells on the expansion of CD34+ CD38- hematopoietic primitive progenitor cells].

OBJECTIVE: To investigate the effects of Tpo and/or IL-11 gene modified stromal cells on the expansion of CD(34)(+) hematopoietic stem/progenitor cells in cord blood. METHODS: Retroviral vectors containing Tpo or IL-11 gene were constructed and used to transfect the stromal cell line HFCL. Tpo and/or IL-11 mRNA was assayed by Northern blot. Non-modified stromal cells were used, CD(34)(+) hematopoietic stem/progenitor cells from cord blood were expanded on gene-modified stromal cells for 7 days. The phenotype of CD(34)(+)CD(38)(-) primitive progenitors was detected by flow cytometry. RESULTS: HFCL expressed Tpo and/or IL-11 mRNA after transfected by the retroviral vectors. The percentages of CD(34)(+)CD(38)(-) primitive progenitors in the cultures of Tpo, IL-11 and Tpo + IL-11 modified HFCL were (1.8 +/- 0.24)%, (1.62 +/- 0.23)%, and (2.45 +/- 0.28)%, respectively, which were higher than that in the control [(0.8 +/- 0.23)%]. CONCLUSION: The stromal cells modified by Tpo and/or IL-11 gene were able to enhance ex vivo expansion of CD(34)(+) and CD(34)(+)CD(38)(-) hematopoietic stem/progenitor cells from cord blood.

[Study on granulocytes derived from induction of committed differentiation of hematopoietic stem/progenitor cells ex vivo].

To evaluated the feasibility of preventing infection after high dose chemotherapy and radiotherapy using the granulocytes derived from differentiated from hematopoietic stem/progenitor cells ex vivo, human CD34-positive cells were isolated from umbilical cord blood by using a high-gradient magnetic cell sorting system (MACS), and the cells committedly differentiated with hematopoietic cytokines (SCF + IL-3 + IL-6 + G-CSF) in a liquid culture system. The expanded cell number, ratio of the viable cells, chromosome and phenotype of the differentiated cells and safety analysis of expanded cells were detected by using cell count, trypan blue exclusion test, karyotype analysis, flow cytometry and tumorigenic model of nude mice, respectively. The results showed that the combination of cytokines increased cell number by (1006.4 +/- 103.2) folds and flow cytometric analysis showed myeloid marker CD11b expressed in the about 60% cells. The growth peak of differentiated cells was at 14 days of culture and decreased at about 33 days. No abnormality was found in the karyotype analysis of expanded cells. No tumor was found in the nude mice injected with expanded cells after 35 days and the expanded cells had the ability of phagocytizing bacteria. It is concluded that the cells, differentiated from CD34(+) cells, expanded ex vivo possess the function of granulocyte and it was safe for clinical trial.

[Expression of telomerase during induction of committed differentiation of human cord blood hematopoietic stem/progenitor cells in vitro].

To investigate the expression of telomerase in cord blood hematopoietic stem/progenitor cells during their committed differentiation in vitro and provide an index of monitoring the proliferating potential of the hematopoietic stem/progenitor cells and security for clinical application. Human CD34 positive cells were isolated from umbilical cord blood by using magnetic cell sorting system (MACS), and were induced to differentiation with hematopoietic growth factors (SCF + IL3 + IL6 + GCSF and SCF + IL3 + IL6 + EPO) in a liquid culture system. The telomerase activity and the cytalytic subunit of telomerase (hTERT) of the cells were analysed during different periods of culture by using TRAP-PCR, TRAP-ELISA, Western blot and RT-PCR techniques, respectively. The results showed that a peak of cell growth was achieved on day 14 - 21 during induction of differentiation in vitro. Total cell number could increase 1006.4 +/- 103.2 times and could not increase there after. Telomerase activity and hTERT expression were low in freshly isolated cord blood CD34(+) cells and increased after about 7 days of culture in addition of cytokine combinations of SCF + IL3 + IL6 + GCSF and SCF + IL3 + IL6 + EPO, respectively. The telomerase activity and hTERT decreased after 14 days of culture and were not detected after 28 days of culture. It was concluded that the hematopoietic stem/progenitor cells can be expanded in large number in vitro and do not have the character of immortality and the telomerase activity could be a useful index in hematopoiesis regulation.

[Construction of fetal mesenchymal stem cell cDNA subtractive library].

UNLABELLED: To identify differentially expressed genes between fetal mesenchymal stem cell (MSC) and adult MSC, especially specified genes expressed in fetal MSC, a cDNA subtractive library of fetal MSC was constructed using suppression subtractive hybridization (SSH) technique. At first, total RNA was isolated from fetal and adult MSC. Using SMART PCR synthesis method, single-strand and double-strand cDNAs were synthesized. After Rsa I digestion, fetal MSC cDNAs were divided into two groups and ligated to adaptor 1 and adaptor 2 respectively. Results showed that the amplified library contains 890 clones. Analysis of 890 clones with PCR demonstrated that 768 clones were positive. The positive rate is 86.3%. The size of inserted fragments in these positive clones was between 0.2 - 1 kb, with an average of 400 - 600 bp. CONCLUSION: SSH is a convenient and effective method for screening differentially expressed genes. The constructed cDNA subtractive library of fetal MSC cDNA lays solid foundation for screening and cloning new and specific function related genes of fetal MSC.