[Recent Progress on Pharmaceutical Properties of Extracellular Vesicles from Mesenchymal Stem Cells--Review].

Mesenchymal stem cells (MSCs) have been officially approved in many countries to treat graft-versus-host disease, autoimmune disorders and those associated with tissue regeneration after hematopoietic stem cell transplantation. Studies in recent years have confirmed that MSC acts mainly through paracrine mechanism, in which extracellular vesicles secreted by MSC (MSC-EV) play a central role. MSC-EV has overwhelming advantages over MSC itself in the setting of adverse effects in clinical application, indicating that MSC-EV might take the place of its parent cells to be a potentially therapeutic tool for "cell-free therapy". The pharmaceutical properties of MSC-EV largely depend upon the practical and optimal techniques including large-scale expansion of MSC, the modification of MSC based on the indications and the in vivo dynamic features of MSC-EV, and the methods for preparing and harvesting large amounts of MSC-EV. The recent progresses on the issues above will be briefly reviewed.

[Clinical Safety of NK Cell in the Prevention of Leukemia Relapse Post-transplantation and in Treatment of the Elderly Leukemia Patients].

OBJECTIVE: To observe the safety of donor NK cell infusions in the settings of hematopoietic stem cell transplantation and after consolidation chemotherapy in elderly patients with acute myeloid leukemia (AML). METHODS: Forty patients with AML were included, in which 21 patients aged over 60 years were at the stage of complete remission (CR) and 19 patients that received allogeneic hematopoietic stem cell transplantation (allo-HSCT). Mononucleated cells were isolated from peripheral blood from the donors (for allo-HSCT) or healthy immediate family members (elderly AML). The cells were seeded into the flasks pre-coated with NK cell specific activators, and expanded in media containing recombinant human IL-15 and IL-2 for 14 days. The cells were transfused intravenously after the identification of quality control. Trypan blue exclusion test was used for the determination of cell viability and counting. Flow cytometry analysis was performed to assess the surface antigenic profile. Seventy-eight infusions of the cell products were received by the elderly patients with AML after consolidation chemotherapy, 11 infusions were received by the patients during allo-HSCT and 32 infusions 3 moths after transplantation. The safety of cell therapy, body temperature, blood pressure and other indexes were observe during and 48 hours after cell transfusion. Meanwhile, the occurrence and severity of acute graft-versus-host disease (GVHD) were documented. RESULTS: Flow cytometry analysis showed that the proportion of NK cells (CD3-CD56+) in the mononucleated cells before culture was (14.10±4.22)% (n=121), and the proportion increased dramatically up to (87.29±8.75)% (n=121) after culture for 14 days, the number of NK cells increased to 753.47±140.13 times (n=121). The doses of the infused NK cells was (7.58±2.50)×107/kg per infusion. Moderate fever occurred in three cases after multiple infusions, and the temperature restored to normal on the same day after treatment. Fever was observed in one patient after every infusion of four times in total. The temperature reached to 38.5-39.0 ℃ and returned to normal within 1-2 hours after adequate antipyretic treatment, and then there was no discomfort. No GVHD was observed in the elderly AML patients, while 6 cases that received allo-HSCT developed moderate acute GVHD, among them grade I in 5 cases and grade II in 1 case. No other severe toxicities were observed. CONCLUSION: NK cell products with a high-purity could be obtained by ex vivo expansion with this protocol. The transfusion of these expanded cells is generally safe in the elderly patients with AML that have received chemotherapy or patients that received hematopoietic stem cell transplantation.

Infusion of haploidentical HSCs combined with allogenic MSCs for the treatment of ALL patients.

Although haploidentical stem cell transplantation (haplo-HSCT) offers almost all acute lymphoblastic leukaemia (ALL) patients an opportunity for immediate transplantation, it exhibits a higher incidence of graft failure and graft versus host disease (GVHD). Mesenchymal stem cells (MSCs) are characterised by their haematopoiesis-promoting and immunomodulatory capacity. Thus, we designed a combination of haplo-HSCT and MSCs for ALL patients. ALL patients (n = 110) were given haploidentical HSCs combined with allogenic MSCs, and ALL patients without MSC infusion (n = 56) were included as controls. The 100-day cumulative incidences of grade ≥2 acute GVHD (aGVHD) and grade ≥3 aGVHD were 40.00% and 9.09% compared to 42.32% (P = 0.79) and 22.79% (P = 0.03) in patients without MSC infusion, respectively. The 3-year cumulative incidences of chronic GVHD (cGVHD) and extensive cGVHD were 22.27% and 10.27% compared to 32.14% (P = 0.19) and 22.21% (P = 0.04) in patients without MSC infusion, respectively. No significant differences in the 3-year relapse incidence, nonrelapse mortality, leukaemia-free survival or overall survival in groups with and without MSC cotransplantation were observed. Multivariate analysis showed that MSC infusion contributed to a lower risk of developing extensive cGVHD. Our data suggested that haplo-HSCT combined with MSCs may provide an effective and safe treatment for ALL patients.

Infusion of haploidentical hematopoietic stem cells combined with mesenchymal stem cells for treatment of severe aplastic anemia in adult patients yields curative effects.

BACKGROUND AIMS: Despite the great advances in immunosuppressive therapy for severe aplastic anemia (SAA), most patients are not completely cured. Haploidentical hematopoietic stem cell transplantation (haplo-HSCT) has been recommended as an alternative treatment in adult SAA patients. However, haplo-HSCT presents a higher incidence of graft failure and graft-versus-host disease (GVHD). The authors designed a combination of haplo-HSCT and umbilical cord-derived mesenchymal stem cells (UC-MSCs) for treatment of SAA in adult patients and evaluated its effects. METHODS: Adult patients (≥18 years) with SAA (N = 25) were given HLA-haploidentical hematopoietic stem cells (HSCs) combined with UC-MSCs after a conditioning regimen consisting of busulfan, cyclophosphamide, fludarabine and anti-thymocyte globulin and intensive GVHD prophylaxis, including cyclosporine, basiliximab, mycophenolate mofetil and short-term methotrexate. Additionally, the effects of the protocol in adult SSA patients were compared with those observed in juvenile SAA patients (N = 75). RESULTS: All patients achieved myeloid engraftment after haplo-HSCT at a median of 16.12 days (range, 11-26). The median time of platelet engraftment was 28.30 days (range, 13-143). The cumulative incidence of grade II acute GVHD (aGVHD) at day +100 was 32.00 ± 0.91%. No one had grade III-IV aGVHD at day +100. The cumulative incidence of total chronic GVHD was 28.00 ± 0.85%. The overall survival was 71.78 ± 9.05% at a median follow-up of 42.08 months (range, 2.67-104). Promisingly, the protocol yielded a similar curative effect in both young and adult SAA patients. CONCLUSIONS: The authors' data suggest that co-transplantation of HLA-haploidentical HSCs and UC-MSCs may provide an effective and safe treatment for adult SAA.

A study of human leukocyte antigen-haploidentical hematopoietic stem cells transplantation combined with allogenic mesenchymal stem cell infusion for treatment of severe aplastic anemia in pediatric and adolescent patients.

The clinical applications of human leukocyte antigen (HLA) haploidentical hematopoietic stem cells transplantation (haplo-HSCT) have offered most of the young severe aplastic anemia (SAA) patients an opportunity to accept curative therapy at the early stage of bone marrow lesions. However, the outcome of juvenile SAA patients received haplo-HSCT remain to be improved due to high incidence of graft failure and graft vs host disease (GVHD). Mesenchymal stem cells (MSCs) have been characterized by their hematopoiesis-supporting and immunomodulatory properties. In the current study, we designed a combination of haplo-HSCT with allogenic MSC for treatment of SAA in pediatric and adolescent patients and evaluated its effects. Juvenile patients (<18 years) with SAA (n = 103) were given HLA-haploidentical HSC combined with allogenic MSC after a conditioning regimen consisting of busulfan, cyclophosphamide, fludarabine, and antithymocyte globulin and an intensive GVHD prophylaxis, including cyclosporine, short-term methotrexate, mycophenolate mofetil, and basiliximab. Neutrophil engraftment was achieved in 102 of 103 patients in a median time of 14.3 days (range 9-25 days). The median time of platelet engraftment was 25.42 days (range 8-93 days). The cumulative incidence of II-IV acute GVHD at day +100 was 26.32% ± 0.19% and III-IV acute GVHD was 6.79% ± 0.06% at day +100, respectively. The cumulative incidence of chronic GVHD was 25.56% ± 0.26%. The overall survival was 87.15% ± 3.3% at a median follow-up of 40 (1.3-98) months. Our data suggest that cotransplantation of HLA-haploidentical HSC and allogenic mesenchymal stem cell may provide an effective and safe treatment for children and adolescents with SAA who lack matched donors.

[Establishment of A Novel Method to Activate and Expand Human NK Cells Ex Vivo].

OBJECTIVE: To develop a new method to activate and expand human NK cells ex vivo by using sodium hyaluronate as a major activating agent and to explore its related mechanism. METHODS: Mononuclear cells were isolated from 3 samples of peripheral blood from three healthy donors. New NK cell culture method and the control method were used to culture NK cells from each samples separately for 14 days. Flow cytometry was used to analyze the ratio of NK cells and CD69 expression. To measure the in vitro cytotoxicity of NK cells cultured by the two methods, the K562 cells were used as the targeting cells and flow cytometry combined with CFSE marker was used as the testing method. RESULTS: After culturing for 14 days, the number of NK cells obtained by new culture method for NK cells expanded by 188.63±3.83 times while the number of NK cells cultured by control method expanded by 152.77±5.77 times. The ratio of NK cells in new cell culture method was above 90%, while the ratio of NK cells in control method was about 70%. The ratio of CD69+ NK cells in new cell culture method was 32.37%±3.22%, while the ratio of CD69+ NK cells in control method was 17.29%±3.79%. The results of cytotoxicity experiment in vitro showed that NK cells cultured by the new method had a higher killing ability to the target cells as compared with NK cells cultured by the control method. CONCLUSION: New NK cell culture method using sodium hyaluronate as a major activating agent can expand NK cells more efficiently as compared with the cells cultured by control method, which may be related to the direct and/or indirect activation of sodium hyaluronate to NK cells, further causing the dominant expansion of the NK cells.

Tumor necrosis factor α in aGVHD patients contributed to the impairment of recipient bone marrow MSC stemness and deficiency of their hematopoiesis-promotion capacity.

BACKGROUND: Though accumulated evidence has demonstrated visceral organ involvement in acute graft-versus-host disease (aGVHD), how aGVHD influences the bone marrow (BM) niche and the reconstitution of hematopoiesis post-hematopoietic stem cell transplantation remains largely unknown. METHODS: In the current study, the cell morphology, immunophenotype, multi-differentiation capacity, self-renewal capacity, and hematopoiesis promotion of the MSCs from aGVHD and non-aGVHD patients were investigated. Additionally, the stemness and hematopoiesis-promoting property of healthy donor-derived MSCs were evaluated in the presence of BM supernatant from aGVHD patients. Mechanistically, antibodies targeting inflammatory cytokines involved in aGVHD were added into the MSC culture. Furthermore, a recombinant human tumor necrosis factor (TNF-α) receptor-Ig fusion protein (rhTNFR:Fc) was used to protect healthy donor-derived MSCs. Moreover, mRNA sequencing was performed to explore the underlying mechanisms. RESULTS: The aGVHD MSCs exhibited morphological and immunophenotypic characteristics that were similar to those of the non-aGVHD MSCs. However, the osteogenic and adipogenic activities of the aGVHD MSCs significantly decreased. Additionally, the colony formation capacity and the expression of self-renewal-related genes remarkably decreased in aGVHD MSCs. Further, the hematopoiesis-supporting capacity of aGVHD MSCs significantly reduced. The antibody neutralization results showed that TNF-α contributed to the impairment of MSC properties. Moreover, rhTNFR:Fc exhibited notable protective effects on MSCs in the aGVHD BM supernatants. The mRNA sequencing results indicated that the TNF-α pathway and the Toll-like receptor pathway may be activated by TNF-α. CONCLUSIONS: Thus, our data demonstrate MSCs as cellular targets of aGVHD and suggest a potential role of TNF-α blockage in maintaining the BM niche of aGVHD patients.

[Effect of TGF-ß1 and IL-10 on the Immunoregulatory Function of Extracellular Vesicles Derived from Mesenchymal Stem Cells].

OBJECTIVE: To investigate the effect of immune regulatory molecules TGF-ß1 and IL-10 on the immunoregulatory activities of extracellular vesicles(EV) secreted from mesenchymal stem cells (MSCs). METHODS: MSC were isolated from human umbilical cord and expanded, then were treated with TGF-ß1 and IL-10 for 72h, and MSC-EVs in supernatants were isolated. The total protein content of all samples was determined by BCA methed. The morphological structure was observed by transmission electron microscopy. The surface markers of MSC-EV were analyzed by flow cytometry. The apoptosis of peripheral blood mononuclear cells(PBMNC) stimulated by ConA and the proportion of CD4+CD25+/CD127- (Treg) cells were detected by flow cytometry after incubation with MSC-EV for 72 h. The CBA and ELISA kit were used to detect the contents of IL2, IL4, IL6, IL10, IFN-γ, TNF-α, Th17A and TGF-ß1 in PBMC supernatants and MSC-EV. RESULTS: All the samples showed that the typical cup-shaped membrane-like structure was observed by transmission electron microscopy, and CD9, CD44, CD63 and CD81 expressed. After TGF-ß1 treatment, the MSC-EV displayed the strongest ability to promote PBMNC apoptosis（P<0.01）, and in all the samples the proportion of Treg cells increased. MSC-EV could increase the content of IL-10 in the supernatants of PBMNC culture, the content of TGF-ß1 in PBMNC supernatants after MSC treatment with TGF-ß1 was lower than that in untreated group(P<0.05). The content of IL-6 in MSC-EV increased significantly after treatment with TGF-ß1, and the content of TGF-ß1 decreased. CONCLUSION: TGF-ß1 alters the immnomodulatory function of MSC-EV and its underlying mechanisms need to be clarified in further investigations.

[System Amplifying NK Cells Using Mononuclear Cell Culture].

OBJECTIVE: To develop an easy method to amplify natural killer (NK) cells by using mononuclear cells in vitro, so as to lay the basis for NK cell therapy. METHODS: Umbilical cord blood from 3 healthy full-term pregnant women was collected, and the peripheral blood mononuclear cells (PBMNC) were harvested by density gradient centrifugation. Each sample of PBMNC was divided into 3 groups: CD16mAb, CD3 mAb and CD16mAb+CD3mAb- groups. The culture flasks were pre-coated with CD16, CD3 or CD3 plus CD16 mAb. The PBMNCs were cultured in serum-free media containing autologous plasma, recombinant human IL-2, IL-15 and IL-21 for 14 days under the same conditions. The total viable cell count was calculated. Flow cytometry was used to determine the ratio of CD56+CD3- cells, MTT assay was used to measure the killing rate of NK cells under different effector/target ratio, by using the K562 cells as the target cells. RESULTS: After 14 days of culture, the total cell numbers of CD16mAb, CD3mAb and CD16mAb +CD3mAb groups increased by 45.71±5.54, 87.41±19.77 and 4.88±51.84 times, respectively, and those of CD3mAb group were significantly higher than the other 2 groups (P<0.05). The ratio of CD56+CD3- cells before culture was 0.1663±0.0201, which was 0.8167±0.0500, 0.8077±0.0589 and 0.8077±0.0273 after incubation with CD16mAb, CD3mAb and CD16mAb +CD3mAb for 14 days, respectively (P>0.05). MTT test showed that the killing efficiencies were not significantly different among the 3 groups when the effector/target ratios were 1:1, 5:1 and 10:1 (P>0.05). CONCLUSION: By incubation with anti-CD3 monoclonal antibody, IL-2, IL-15 and IL-21, the highly purified NK cells can be obtained from mononucleated cells, thus providing a simple method for NK cell therapy.

[Clinical Study on Treatment of Juvenile Myelomonocytic Leukemia with Haploidentical-Hematopoietic Stem Cell Transplantation].

OBJECTIVE: To analyze the therapeutic efficacy of haploidentical-hematopoietic stem cell transplantation (hi-HSCT) for patients with juvenile myelomonocytic leukemia (JMML). METHODS: The engraftment of hematopoietic stem cells, incidence of graft versus host disease (GVHD), infection, relapse, and survival of 6 JMML patients received hi-HSCT were retrospectively analyzed. RESULTS: Six (6 males) JMML patients received hi-HSCT from haplo-HLA-matched related donors. The results showed that the hematopoictic stem cells in all 6 patients were grafted successfully. Two cases of JMML died of pulmenary infections, other 4 cases survive without disease. Acute GVHD occurred in 3 patients and chronic GVHD occurred in 1 patients. The overall survival, disease free survival and relapse rates were 66.7%, 66.7%, 0%, respectively. CONCLUSION: The hi-HSCT is an effective method for treatment of patients with JMML, but there also is a serial problems to be resolved.

The epigenetically-regulated miR-34a targeting c-SRC suppresses RAF/MEK/ERK signaling pathway in K-562 cells.

Previous reports show that miR-34a suppressed K-562 cell proliferation and contributed to megakaryocytic differentiation of K-562 cells. Here, we reported that miR-34a, a tumor suppressor gene, is down-regulated in the K-562 cells and chronic myeloid leukemia (CML) patients due to aberrant DNA hypermethylation. c-SRC is a target of miR-34a. Restoring miR-34a expression resulted in down-regulation of c-SRC and phosphorylated (Tyr416) c-SRC protein in K-562 cells, which consequently triggered suppression of the RAF/MEK/ERK signaling pathway to decrease cell proliferation.

The absolute number of regulatory T cells in unmanipulated peripheral blood grafts predicts the occurrence of acute graft-versus-host disease post haplo-identical hematopoietic stem cell transplantation.

CD4+CD25+Foxp3+ regulatory T cells (Tregs) have been reported to play a central role in suppressing acute graft-versus-host disease (aGVHD), but whether the Treg contents of grafts correlates with the occurrence of aGVHD post haplo-identical hematopoietic stem cell transplantation (haplo-HSCT) remains unclear. In the present study, changes in Tregs in peripheral blood (PB) were followed before and after granulocyte colony-stimulating factor (G-CSF) mobilization. In addition, functional analyses of Tregs in PB grafts and bone marrow (BM) grafts were performed. To probe the prognostic value of Tregs for aGVHD, an analysis of Tregs in haplo-identical grafts was conducted in 61 patients. Moreover, univariate and multivariate analyses of both clinical variables and cellular subsets were performed. The results showed that both the percentage Tregs of CD4+ T cells and absolute numbers of Tregs per 106 total nucleated cells significantly increased after G-CSF administration. Additionally, Tregs in PB grafts exhibited a stronger inhibitory effect on antigen-specific T cell proliferation than did Tregs in BM grafts. Strikingly, patients receiving more Tregs in PB grafts had a lower cumulative incidence of aGVHD II-IV (36% versus 58%, P=0.046). Further, in a multivariate analysis, the number of Tregs in PB grafts was significantly associated with a lower occurrence of aGVHD II-IV (P=0.02). In contrast, the number of Tregs in BM grafts was not associated with the occurrence of aGVHD in the current study. Further analysis showed that the Treg content in grafts did not affect Treg reconstitution, infection rate, or incidence of chronic GVHD after haplo-HSCT. Moreover, no significant correlations between cell types in grafts and the survival end points or relapse rates were found in the present study. In conclusion, our results suggest that a high number of Tregs in PB grafts is associated with reduced risk of aGVHD in haplo-HSCT in our transplant setting.

Hepatocyte growth factor enhances the inflammation-alleviating effect of umbilical cord-derived mesenchymal stromal cells in a bronchiolitis obliterans model.

BACKGROUND AIMS: Specific and effective therapy for prevention or reversal of bronchiolitis obliterans (BO) is lacking. In this study, we evaluated the therapeutic effect of hepatocyte growth factor (HGF) gene modified mesenchymal stromal cells (MSCs) on BO. METHODS: A mouse model of experimental BO was established by subcutaneously transplanting the tracheas from C57BL/6 mice into Balb/C recipients, which were then administered saline, Ad-HGF-modified human umbilical cord-MSCs (MSCs-HGF) or Ad-Null-modified MSCs (MSCs-Null). The therapeutic effects of MSCs-Null and MSCs-HGF were evaluated by using fluorescence-activated cell sorting (FACS) for lymphocyte immunophenotype of spleen, enzyme-linked immunosorbent assay (ELISA) and real-time polymerase chain reaction (rt-PCR) for cytokine expression, and histopathological analysis for the transplanted trachea. RESULTS: The histopathologic recovery of allograft tracheas was improved significantly after MSCs-Null and MSCs-HGF treatment and the beneficial effects were particularly observed in MSCs-HGF-treated mice. Furthermore, the allo-transplantation-induced immunophenotype disorders of the spleen, including regulatory T (Treg), T helper (Th)1, Th2 and Th17, were attenuated in both cell-treated groups. MSCs-HGF treatment reduced expression and secretion of inflammation cytokines interferon-gamma (IFN-γ), and increased expression of anti-inflammatory cytokine interleukin (IL)-4 and IL-10. It also decreased the expression level of the profibrosis factor transforming growth factor (TGF)-ß. CONCLUSION: Treatment of BO with HGF gene modified MSCs results in reduction of local inflammation and promotion in recovery of allograft trachea histopathology. These findings might provide an effective therapeutic strategy for BO.

[Mesenchymal Stem Cells Combined with Budesonide, Almeterol and Azithromycin for the Treatment of Bronchiolitis Obliterans Syndrome after Hematopoietic Stem Cell Transplantation].

OBJECTIVE: To evaluate the safety and effectiveness of a novel therapeutic regimen for bronchiolitis obliterans sydrome (BOS) affter hematopoietic stem cell transplantation (HSCT). METHODS: Seven patients who had received HSCT and had been diagnosed as BOS were enrolled in this study. They received weekly intravenous injection of umbilical cord-derived mesenchymal stem cells (MSC) at a dose of 1 × 10(6)/kg for 4 weeks. Budesonide was given orally at a daily dose of 0.25 g, and salmeterol was inhaled at a dose of 4.5 µg for 3 times per day. Methylprednisolone was given at a dose of 1 mg/(kg·d) for 2 weeks when respiratory failure occured. The dose of methylprednisolone was tapered to 0.25 mg/(kg·d) after 4 weeks and was adjusted according to the occurrence and severity of chronic graft-versus-host disease (cGVHD). RESULTS: The therapy was generally safe and no severe acute toxicity was observed. One patient died of heart failure during the treatment, the other 6 patients were alive and the pulmonary function parameters including FEV1, FEV1/FVC, PaO2 and AaDO2 were significantly improved after 6 months as compared with the baseline parameters (P < 0.05). CONCLUSION: MSC combined with budesonide, almeterol and azithromycin has been confirmed to be generally safe and can reduce the dose of glucocorticoid in treatment of BOS after HSCT.

[The effect of rosuvastatin therapy on CCR2 expression in mononuclear cells and its upstream pathway].

OBJECTIVE: To investigate the effect of rosuvastatin therapy on C-C chemokine receptor(CCR2)expression in mononuclear cells in patients with carotid atherosclerosis and explore the possible upstream mechanism. METHODS: Twenty patients without previous statin treatment were enrolled. Rosuvastatin were given 5 to 20 mg/day for 3 months. At baseline and 12 weeks, lipid profile and plasma monocyte chemotactic protein-1 (MCP-1) levels were examined. The mRNA and protein expressions of CCR2 in the mononuclear cells were measured with RT-PCR and flow cytometry, respectively. The mRNA and protein expression of peroxidase proliferator-activated receptor(PPAR ß) were detected with RT-PCR and Western blot, respectively. RESULTS: After 3-months rosuvastatin treatment, the patients' low-density lipoprotein cholesterol (LDL-C) levels decreased significantly (P<0.01). Compared with baseline, the mRNA and protein expressions of CCR2 in the mononuclear cells showed significantly decrease, as well as plasma MCP-1 levels (P<0.05). Both mRNA and protein expressions of PPAR ß in the mononuclear cells increased (P<0.05). CONCLUSIONS: Rosuvastatin may attenuate MCP-1/CCR2 through PPARß upstream pathway.

[Progesterone Promotes Human Bone Marrow Mesenchymal Stem Cells to Synthesize Fibronectin via ERK Pathway].

OBJECTIVE: To investigate whether the progesterone can promote fibronection (FN) synthesis by human bone marrow mesenchymal stem cells (MSCs) and to explore the potential underlying mechanism. METHODS: The human bone marrow MSCs were cultured in a serum-free medium with progesterone for 72 hours, the MTT test was performed to observe the proliferation status and adhension ability of the treated cells. Western blot was used to detect the content of FN in MSDs with GAPDH as the internal reference, the phosphorylation of ERK1/2, as well as the FN content in MSC treated by PD98059, a specific inhibitor of ERK1/2. RESULTS: The progesterone at a range of certain doses not effect on the proliferation of human bone marrow MSCs. Progesterone (25 µg/L) treatment enhanced the FN expression and adherent ability of marrow MSCs. Progesterone could induce prompt phosphorylation of ERK 1/2 and its promoting effects on FN synthesis was reversed by PD98059. CONCLUSION: The progesterone can promote FN synthesis by human bone marrow MSCs via ERK 1/2 pathway, and it might be used to culture MSCs in serum-free medium.

[Silymarin Protects Umbilical Cord-Derived Mesenchymal Stem Cells against Apoptosis Induced by Serum-Deprivation].

OBJECTIVE: To investigate the protection of silymarin against the human mesenchymal stem cell (MSC) apoptosis induced by serum deprivation and its underlying mechanism. METHODS: Human umbilical cord MSCs were cultured in the absence of serum, and the silymain of different concentration (1-10 µg/ml) was added into the medium. MTT test was performed to observe the cell proliferation status. After being cultured for 72 hours, the cells were collected, and flow cytometry with Annexin-V-PI double-staining was used to detect the apoptotic cells from the control and silymarin-treated groups. Furthermore, the intracellular contents of BAX and BCL-2 were detected by Western blot for exploring the potential mechanism. RESULTS: The silymarin promoted the proliferation of human UC-MSCs in a dose-dependent manner, reaching its maximal at a dose of 5 µg/ml. Moreover, silymarin could inhibit the serum deprivation-induced apoptosis of MSCs and, the inhibitory rate reached up to 30% when it was added at a concentration of 5 µg/ml. The content of intracellular BAX was obviously elevated after serum-deprivation treatment, and this increase could be blunted by the addition of silymarin. Meanwhile, the content of BCL-2 was not obviously changed. CONCLUSION: The silymarin can stimulate MSC growth and inhibit the apoptosis of MSCs probably by the mitochondria pathway.

Easily-handled method to isolate mesenchymal stem cells from coagulated human bone marrow samples.

AIM: To establish an easily-handled method to isolate mesenchymal stem cells (MSCs) from coagulated human bone marrow samples. METHODS: Thrombin was added to aliquots of seven heparinized human bone marrow samples to mimic marrow coagulation. The clots were untreated, treated with urokinase or mechanically cut into pieces before culture for MSCs. The un-coagulated samples and the clots were also stored at 4 °C for 8 or 16 h before the treatment. The numbers of colony-forming unit-fibroblast (CFU-F) in the different samples were determined. The adherent cells from different groups were passaged and their surface profile was analyzed with flow cytometry. Their capacities of in vitro osteogenesis and adipogenesis were observed after the cells were exposed to specific inductive agents. RESULTS: The average CFU-F number of urokinase-treated samples (16.85 ± 11.77/10(6)) was comparable to that of un-coagulated control samples (20.22 ± 10.65/10(6), P = 0.293), which was significantly higher than those of mechanically-cut clots (6.5 ± 5.32/10(6), P < 0.01) and untreated clots (1.95 ± 1.86/10(6), P < 0.01). The CFU-F numbers decreased after samples were stored, but those of control and urokinase-treated clots remained higher than the other two groups. Consistently, the numbers of the attached cells at passage 0 were higher in control and urokinase-treated clots than those of mechanically-cut clots and untreated clots. The attached cells were fibroblast-like in morphology and homogenously positive for CD44, CD73 and CD90, and negative for CD31 and CD45. Also, they could be induced to differentiate into osteoblasts and adipocytes in vitro. CONCLUSION: Urokinase pretreatment is an optimal strategy to isolate MSCs from human bone marrow samples that are poorly aspirated and clotted.

[Putrescine Promotes Human Marrow Mesenchymal Stem Cells to Differentiate along Osteogenic Pathway].

OBJECTIVE: To investigate the effects of putrescine on the growth and differentiation of human bone marrow mesenchymal stem cells (MSC) to develop a new inductive medium mixture for their osteogenic differentiation. METHODS: Human bone marrow MSC were collected from three healthy donors and were used to observe the growth-promoting activity of putrescine with MTT test. Experiments were divided into 3 groups: (1) putrescine group, (2) positive control group (presence of dexamethasone, ascorbate, and glycerol phosphate) and negative group (d-alpha with 5% FCS). The cellular expression level of Runx-2 was detected by PCR assay after the culture was maintained for 1 week. After 2 weeks, the intracellular activity of alkaline phosphatase was revealed by histochemistry staining, the phosphatase activity, and the protein concentration in the cell lysates were also detected. Furthermore, MSC were cultured in the presence of putrescine for 2 weeks and Oil-red O staining was performed to reveal the differentiated adipocytes; the cells induced by the standard agent cocktail were used as the positive control. RESULTS: Putrescine promoted the proliferation of human marrow MSC in a dose-dependent manner. MSC exposed to putrescine at a concentration of 100 µmol/L for 1 week expressed greatly higher level of Runx-2, compared with the negative control. Alkaline phosphatase activity was evidently observed after MSC were maintained in the presence of putrescine for 2 weeks. The phosphatase activity contrasted to the protein content in putrescine-treated MSC was significantly higher than that of the control cells (0.87±0.012 vs 0.52±0.010) (P<0.01), and also greatly higher than that of the positive control (0.83±0.029) (P=0.02). Oil red O staining showed that MSC treated by putrescine did not differentiate into adipoblasts. CONCLUSION: Putrescine can promote the proliferation and osteogenic differentiation of MSC, suggesting the potential application of putrescine as a novel inductive agent for in vitro osteogenesis of MSC.

[Investigation on the internalization pathway of microparticles into human umbilical cord endothelial cells].

OBJECTIVE: To investigate the mechanisms underlying the incorporation of microparticles(MP) derived from human bone marrow mesenchymal stem cells (MSCs) into human umbilical cord endothelial cells (HUVECs). METHODS: MPs were isolated from the supernatants of MSCs which had exposed to a hypoxia/serum-deprivation condition. Electron microscope was used to identify the MPs. The surface molecule profile was evaluated with the bead-based flow cytometry technique. The expression level of the phosphatidylserine receptor (PSR) was detected by immunofluorescence cytochemistry. MPs were co-cultured with HUVECs in the presence or absence PSR-antibody, and the internalization of MPs was observed with laser scanning microscopy. RESULTS: The MPs derived from MSCs expressed highly PS, while PSR expressed on the surface of HUVECs. The confocal result revealed that MPs could quickly be uptaken by the endothelial cells, and mainly distributed in the cytoplasm surrounding of the nuclei. The internalization of MPs reduced significantly after PSR specific blockage. CONCLUSION: The reaction between PS on the MP and the PSR of HUVECs plays an important role in the internalization of MSC-MPs.