Effects of hepatocyte growth factor-mediated activation of Dll4-Notch-Hey2 signaling pathway.

BACKGROUND: Hepatocyte growth factor (HGF) treats ischemic disease by promoting arteriogenesis, however, its mechanism of action is not known. The notch signaling pathway plays an important role in neovascularization. The relationship between the proliferation and migration ability of artery endothelial cells and the Dll4-Notch-Hey2 signaling pathway in the process of arteriogenesis was investigated as a mechanism of action of HGF. METHODS: Based on the prophase study cells and supernatant were harvested at the indicated time after human femoral artery endothelial cells (HFAECs) were infected with adenovirus-HGF (Ad-HGF) at 200 pfu/cell. Cells were analyzed for HGF expression and Notch1, Dll4 and Hey2 expression by ELISA and reverse transcription-PCR (RT-PCR). The changes in the proliferation and migration ability of HFAECs were observed by MTT and Transwell migration experiments. Ad-GFP-infected HFAECs were used as control. RESULTS: Compared with the control group the Ad-HGF group's HGF expression was not increased with time, and the induction by HGF of Notch1, Dll4 and Hey2 gene transcription was not enhanced with an increase of HGF. The proliferation ability of Ad-HGF-transduced HFAECs was enhanced and their migration ability was also enhanced in the presence of HGF. CONCLUSIONS: Through activating the Dll4-Notch-Hey2 signaling pathway, HGF indirectly promotes the proliferation and migration ability of cells, so that offspring artery branches are formed.

Effects of mesenchymal stem cells transfected with human hepatocyte growth factor gene on healing of burn wounds.

OBJECTIVE: To explore the effects of bone marrow-derived mesenchymal stem cells (BMSCs) transfected with adenoviral vector carrying hepatocyte growth factor (HGF, Ad-HGF) on burn wound healing. METHODS: BMSCs from male Wistar rats were separated and purified with Percoll separating medium by density gradient centrifugation and cultured with DMEM containing 20% fetal bovine serum (FBS). Then BMSCs were transfected with Ad-HGF at the optimal gene transduction efficiency of 100 multiplicity of infection (MOI). The efficiency of transfection and the expression of HGF in the suspension were detected by flow cytometry and enzyme linked immunosorbent assay (ELISA) respectively. Thirty-two female rats were subjected to 90 degree centigrade water for 12 seconds to induce a partial thickness skin burn. The animals were randomly divided into mesenchymal stem cells (MSCs) treatment group (Group A), Ad-HGF treatment group (Group B), Ad-HGF-modified MSCs treatment group (Group C) and saline control group (Group D). On days 3, 5, 7, 14 and 21 postburn, HE and Sirius red stain were performed to observe the burn wound healing and collagen content. The content of hydroxyproline in wounds was also detected. Transplanted cells and the expression of (sex-determining region Y) SRY gene were detected by in situ hybridization and polymerase chain reaction (PCR), while the expression of HGF in wound tissues was detected by ELISA. RESULTS: The result of flow cytometry showed that the transfection efficiency was 86.41% at 100 MOI. Compared with the control group, the content of HGF in the supernatant after transfection increased time-dependently and peaked at 48 h, showing significant differences at 24 h, 48 h, 72 h and 96 h (P less than 0.01). Results of HE stain revealed that the range of re-epidermidalization in Group C was significantly larger than that in other groups in the first week. Three weeks postburn, the epidermis was significantly thicker in Group C than in other groups and the nails of dermis inserted into the derma of burn wounds. Sirius red stain showed that the content of collagen I in Group C was much less compared with that in other groups 21 days postburn. In situ hybridization revealed an expression of SRY gene in burned female rats, consistent with the finding of PCR. Immunohistochemistry demonstrated the largest increase of HGF expression in Group C, whose contents of hydroxyproline, however, decreased on day 7 postburn. Compared with other groups, the content of HGF in the wounds of Group C increased obviously on day 14 after transfection (P less than 0.05) and there was no significant difference among Groups A, B and D. CONCLUSION: Our study suggests that transplantation of MSCs modified with Ad-HGF has positive effects on the healing of burn wounds probably through differentiation and release of relevant cytokines.

[Prokaryotic expression, polyclonal antibody preparation and subcellular localization of CIB].

AIM: To construct the prokaryotic expression vector pET32a-CIB, prepare the specific polyclonal antibody against CIB and study the subcellular localization of CIB. METHODS: CIB was amplified by RT-PCR from human brain tissue and cloned into prokaryotic expression vector pET32a-CIB. The CIB fusion protein was expressed in BL21 (DE3)/pET system and identified by SDS-PAGE. The mice were immunized with the polyacrylamide gel particles containing the CIB fusion protein for polyclonal antibody preparation. The antibody was purified by affinity chromatographic column matrix coupled with protein G, antigen respectively and then identified by Western blot and immunohistochemistry. RESULTS: The protein of CIB was obtained by recombination expression. The specificity of polyclonal antibody was obtained by immunizing BALB/c mice with polyacrylamide gel particles containing the fusion protein of CIB and purification. The results of immunohistochemistry demonstrated that CIB was localized predominantly in the cytoplasm of SHG44 and Hhu7 cells. CONCLUSION: The protein of CIB has been cloned and expressed successfully. The specific polyclonal antibody against the protein of CIB has been obtained, which can be used for further research into the function of CIB.

[Maturation regulation of dendritic cells pulsed with hepatocellular carcinoma cell soluble antigens].

OBJECTIVE: To research the maturation regulation of dendritic cells (DCs) pulsed with hepatocellular carcinoma (HCC) cell soluble antigens. METHODS: BCG HSP 70 was purified by SDS-PAGE electrophoresis and its biological activity was determined with ELISA. Phenotypes of DCs pulsed with antigens or with both antigens and BCG HSP 70 were analysed with flow cytometry. MTT assay was used to estimate the proliferation of self lymphocytes and the mixed lymphocyte reaction (MLR) of BCG HSP 70 primed DCs. RESULTS: The characteristics of DCs had changed after loaded with soluble antigens of HCC. There were about 10% DCs which had lost their specific markers. The expression levels of CD54, CD83, CD86 molecules and the stimulatory ability in allogeneic MLR decreased. However, after being activated by BCG HSP 70, the DCs pulsed with antigens could keep their special markers and the expression levels of CD54, CD83, CD86 molecules increased too. The stimulatory abilities in allogeneic MLR and proliferation of self lymphocytes also improved. CONCLUSION: This study shows that BCG HSP 70 can induce DCs pulsed with antigens maturation and improve their antigen-presenting ability, which may be a useful maturation inducer for dendritic cells.