Yongzhe Che

SDF-1/CXCR4 axis modulates bone marrow mesenchymal stem cell apoptosis, migration and cytokine secretion

Bone marrow mesenchymal stem cells (MSCs) are considered as a promising cell source to treat the acute myocardial infarction. However, over 90% of the stem cells usually die in the first three days of transplantation. Survival potential, migration ability and paracrine capacity have been considered as the most important three factors for cell transplantation in the ischemic cardiac treatment. We hypothesized that stromal-derived factor-1 (SDF-1)/CXCR4 axis plays a critical role in the regulation of these processes. In this study, apoptosis was induced by exposure of MSCs to H2O2 for 2 h. After re-oxygenation, the SDF-1 pretreated MSCs demonstrated a significant increase in survival and proliferation. SDF-1 pretreatment also enhanced the migration and increased the secretion of pro-survival and angiogenic cytokines including basic fibroblast growth factor and vascular endothelial growth factor. Western blot and RT-PCR demonstrated that SDF-1 pretreatment significantly activated the pro-survival Akt and Erk signaling pathways and up-regulated Bcl-2/Bax ratio. These protective effects were partially inhibited by AMD3100, an antagonist of CXCR4.We conclude that the SDF-1/CXCR4 axis is critical for MSC survival, migration and cytokine secretion.

Clinicopathological and Biological Significance of Human Voltage-gated Proton Channel Hv1 Protein Overexpression in Breast Cancer

Background: The voltage-gated proton channel Hv1 is specifically expressed in highly metastatic human breast tumor tissues and cell lines. Results: Hv1 overexpression is significantly correlated with clinicopathological parameters and contributes to breast carcinogenesis. Conclusion: High Hv1 expression is associated with poor progression and unfavorable clinical outcome of breast cancer. Significance: Hv1 is a potential biomarker for prognosis of breast cancer and a potential target for anticancer drugs in therapy. In our previous work, we showed for the first time that the voltage-gated proton channel Hv1 is specifically expressed in highly metastatic human breast tumor tissues and cell lines. However, the contribution of Hv1 to breast carcinogenesis is not well known. In this study, we showed that Hv1 expression was significantly correlated with the tumor size (p = 0.001), tumor classification (p = 0.000), lymph node status (p = 0.000), clinical stage (p = 0.000), and Her-2 status (p = 0.045). High Hv1 expression was associated significantly with shorter overall (p = 0.000) and recurrence-free survival (p = 0.000). In vitro, knockdown of Hv1 expression in the highly metastatic MDA-MB-231 cells decreased the cell proliferation and invasiveness, inhibited the cell proton secretion and intracellular pH recovery, and blocked the cell capacity of acidifying extracellular milieu. Furthermore, the gelatinase activity in MDA-MB-231 cells that suppressed Hv1 was reduced. In vivo, the breast tumor size of the implantation of the MDA-MB-231 xenografts in nude mice that were knocked down by Hv1 was dramatically smaller than that in the control groups. The results demonstrated that the inhibition of Hv1 function via knockdown of Hv1 expression can effectively retard the cancer growth and suppress the cancer metastasis by the decrease of proton extrusion and the down-regulation of gelatinase activity. Based on these results, we came to the conclusion that Hv1 is a potential biomarker for prognosis of breast cancer and a potential target for anticancer drugs in breast cancer therapy.

Specific expression of the human voltage-gated proton channel Hv1 in highly metastatic breast cancer cells, promotes tumor progression and metastasis

The newly discovered human voltage-gated proton channel Hv1 is essential for proton transfer, which contains a voltage sensor domain (VSD) without a pore domain. We report here for the first time that Hv1 is specifically expressed in the highly metastatic human breast tumor tissues, but not in poorly metastatic breast cancer tissues, detected by immunohistochemistry. Meanwhile, real-time RT-PCR and immunocytochemistry showed that the expression levels of Hv1 have significant differences among breast cancer cell lines, MCF-7, MDA-MB-231, MDA-MB-468, MDA-MB-453, T-47D and SK-BR-3, in which Hv1 is expressed at a high level in highly metastatic human breast cancer cell line MDA-MB-231, but at a very low level in poorly metastatic human breast cancer cell line MCF-7. Inhibition of Hv1 expression in the highly metastatic MDA-MB-231 cells by small interfering RNA (siRNA) significantly decreases the invasion and migration of the cells. The intracellular pH of MDA-MB-231 cells down-regulated Hv1 expression by siRNA is obviously decreased compared with MDA-MB-231 with the scrambled siRNA. The expression of matrix metalloproteinase-2 and gelatinase activity in MDA-MB-231 cells suppressed Hv1 by siRNA were reduced. Our results strongly suggest that Hv1 regulates breast cancer intracellular pH and exacerbates the migratory ability of metastatic cells.

Multiple Tumor-Associated MicroRNAs Modulate the Survival and Longevity of Dendritic Cells by Targeting YWHAZ and Bcl2 Signaling Pathways

Tumors use a wide array of immunosuppressive strategies, such as reducing the longevity and survival of dendritic cells (DCs), to diminish immune responses and limit the effect of immunotherapy. In this study, we found that tumors upregulate the expression of multiple microRNAs (miRNAs), such as miR-16-1, miR-22, miR-155, and miR-503. These tumor-associated miRNAs influenced the survival and longevity of DCs by affecting the expression of multiple molecules that are associated with apoptotic signaling pathways. Specifically, miR-22 targeted YWHAZ to interrupt the PI3K/Akt and MAPK signaling pathways, and miR-503 downregulated Bcl2 expression. The result of the increased expression of miR-22 and miR-503 in the tumor-associated DCs was their reduced survival and longevity. Thus, tumor-associated miRNAs can target multiple intracellular signaling molecules to cause the apoptosis of DCs in the tumor environment. Use of miR-22 and miR-503 as inhibitors may therefore represent a new strategy to improve DC-based immunotherapies against tumors.

Antigen Presentation by Dendritic Cells in Tumors Is Disrupted by Altered Metabolism that Involves Pyruvate Kinase M2 and Its Interaction with SOCS3

Dendritic cell (DC) function is negatively affected by tumors and tumor-derived factors, but little is known about the underlying mechanisms. Here, we show that intracellular SOCS3 in DCs binds to pyruvate kinase type M2 (M2-PK), which plays a critical role in ATP production through glycolysis. The interaction of SOCS3 with M2-PK reduced ATP production and impaired DC-based immunotherapy against tumors. Thus, SOCS3, which has been shown to be upregulated by tumor-derived factors, interacts with M2-PK to decrease ATP production, causing DC dysfunction. These dysfunctional DCs have a reduced ability to present antigens. Alteration of DC metabolism mediated by SOCS3 represents a novel mechanism for DC dysfunction in the tumor microenvironment.

Functionalization of electrospun poly(ε-caprolactone) scaffold with heparin and vascular endothelial growth factors for potential application as vascular grafts

In this study, a heparin-conjugated poly(ε-caprolactone) electrospun fiber was constructed to develop a functional scaffold for controlled release of vascular endothelial growth factors. The immobilization of vascular endothelial growth factor was achieved through affinity binding between heparin and vascular endothelial growth factor molecules. The sustained release of vascular endothelial growth factor from the scaffold was followed for up to 15 days. The endothelial cell adhesion and proliferation assay demonstrated that immobilized vascular endothelial growth factor maintained its activity. The blood compatibility of the scaffold was evaluated by activated partial thromboplastin time, platelet adhesion test, and arteriovenous shunt, and the functionalized scaffold showed improved anticoagulation properties. The biocompatibility was evaluated by subcutaneous implantation. Results showed that this vascular endothelial growth factor–releasing scaffold stimulated neovascularization with minimum immunological rejection compared to the unmodified poly(ε-caprolactone) scaffold. The present study demonstrated a new strategy of building bioactive scaffolds for the development of small-diameter vascular graft.

Granulocyte colony-stimulating factor exacerbates cardiac fibrosis after myocardial infarction in a rat model of permanent occlusion

AIMS Controversy exists regarding the effects of granulocyte colony-stimulating factor (G-CSF) on post-infarction remodelling, which is regulated by matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs). The aim of this study was to investigate the impact of G-CSF administration on cardiac MMP/TIMP ratios and long-term remodelling in a rat model of acute myocardial infarction (MI). METHODS AND RESULTS Sprague-Dawley rats underwent coronary ligation to produce MI. Rats surviving the MI for 3 h were randomized to receive G-CSF (50 microg/kg/day for 5 consecutive days, n = 16) or saline (n = 10). Sham-operated animals received no treatment (n = 10). G-CSF injection significantly increased circulating white blood cells, neutrophils, and monocytes. Western blotting revealed that the ratios of MMP-2/TIMP-1 and MMP-9/TIMP-1 were significantly decreased in the infarcted myocardium. At 3 months, echocardiographic and haemodynamic examinations showed that the G-CSF treatment induced left ventricular (LV) enlargement and dysfunction. Histological analysis revealed that the extent of myocardial fibrosis and infarct size were larger in the G-CSF group than in the Saline group. Furthermore, G-CSF treated animals showed a significantly lower post-MI survival during the study period. CONCLUSION Decrease of cardiac MMP/TIMP ratios by G-CSF after infarction may be important as a mechanism in promotion of myocardial fibrosis, which further facilitates infarct expansion and LV dysfunction.

Transplantation of parthenogenetic embryonic stem cells ameliorates cardiac dysfunction and remodelling after myocardial infarction

AIMS Parthenogenetic embryonic stem cells (pESCs) derived from artificially activated oocytes without fertilization presumably raise minimal ethical concerns and may serve as attractive candidates for regenerative medicine. Here we investigated whether pESCs could repair myocardial infarction (MI), in comparison to embryonic stem cells (ESCs). METHODS AND RESULTS A total of 89 mice that survived coronary artery ligation randomly received an intramyocardial injection of undifferentiated pESCs, ESCs, or saline. Sham-operated mice (n = 21) that received no treatment served as control animals. After 7 days, transplantation of pESCs increased expression of pro-angiogenic factors and reduced leucocyte infiltration. By 14 and 30 days post-MI, similar to treatment with ESCs, treatment with pESCs efficiently prevented cardiac remodelling and enhanced angiogenesis, in contrast to saline-treated hearts. Improved heart contractile function was also notable 30 days following transplantation of pESCs. Immunofluorescence staining revealed that tissues regenerated from pESCs in the infarcted myocardium were positive for markers of cardiomyocytes, endothelial cells, and smooth muscle cells. Unlike ESC-treated mice, which exhibited a high incidence of teratoma (6 of 34), the pESC-treated mice showed no teratomas (0 of 30) 30 days following transplantation. CONCLUSION Transplantation of pESCs could attenuate cardiac dysfunction and adverse ventricular remodelling post-MI, suggesting that pESCs may provide promising therapeutic sources for MI in females.

Bone marrow-derived cells can acquire renal stem cells properties and ameliorate ischemia-reperfusion induced acute renal injury.

BackgroundBone marrow (BM) stem cells have been reported to contribute to tissue repair after kidney injury model. However, there is no direct evidence so far that BM cells can trans-differentiate into renal stem cells.MethodsTo investigate whether BM stem cells contribute to repopulate the renal stem cell pool, we transplanted BM cells from transgenic mice, expressing enhanced green fluorescent protein (EGFP) into wild-type irradiated recipients. Following hematological reconstitution and ischemia-reperfusion (I/R), Sca-1 and c-Kit positive renal stem cells in kidney were evaluated by immunostaining and flow cytometry analysis. Moreover, granulocyte colony stimulating factor (G-CSF) was administrated to further explore if G-CSF can mobilize BM cells and enhance trans-differentiation efficiency of BM cells into renal stem cells.ResultsBM-derived cells can contribute to the Sca-1+ or c-Kit+ renal progenitor cells population, although most renal stem cells came from indigenous cells. Furthermore, G-CSF administration nearly doubled the frequency of Sca-1+ BM-derived renal stem cells and increased capillary density of I/R injured kidneys.ConclusionsThese findings indicate that BM derived stem cells can give rise to cells that share properties of renal resident stem cell. Moreover, G-CSF mobilization can enhance this effect.

Co-Transplantation of Skin-Derived Precursors and Collagen Sponge Facilitates Diabetic Wound Healing by Promoting Local Vascular Regeneration

Background/Aims: Impaired diabetes wound healing can often lead to serious complications and remains a major health concern due to the lack of effective therapeutic approaches. Compromised angiogenesis, disrupted growth factor and cytokine activity are all attributable to diabetic wound healing impairment. The skin-derived precursors (SKPs) have been shown to differentiate into vascular and nerve cells, both of which are crucial components for wound repair. Given their easy accessibility and multipotency, the SKPs were proposed as an ideal therapeutic candidate for diabetic wound healing. Since the efficacy of cell therapy is limited by poor cell survival, collagen sponge was employed for better SKPs delivery. Methods: SKPs were isolated and transplanted directly to the wound areas of diabetic mice in the absence and presence of collagen sponge. The effects of SKPs and/or collagen sponge on diabetic wound healing were examined histologically as well as immunostaining of isolectin and α-SMA. Mechanisms via which the SKPs facilitate wound healing were then investigated by transplanting SKPs that have been pre-labelled with a fluorescence dye, Dil. Expression patterns of Dil and an SKP marker, nestin, was also examined. Results and Conclusion: Accelerated wound healing and enhanced local capillary regeneration could be observed 14 days after skin ablation from both SKPs and collagen sponge co-transplanted and collagen sponge only groups. Subsequent analyses further revealed superior pro-angiogenic effects from the SKP and collagen sponge co-delivered group, which are mainly attributable to in vivo transdifferentation and paracrine signalling of the SKPs.