Effect and mechanism of human dental pulp stem cells-derived exosomes on lipopolysaccharide induced acute lung injury / 军事医学

Objective To investigate the protective role and underlying mechanism of human dental pulp stem cells (DPSCs)-derived exosomes against lipopolysaccharide ( LPS) induced acute lung injury ( ALI) in pulmonary alveolar macrophage(PAM) cells of rats.Methods DPSCs were cultured in the complete culture medium , and their supernatants at passage 6 were collected after serum-free medium treatment for 24 hours.Exosomes were extracted and purified with ultracentrifugation .Rat PAM NR8383 was cultured in 12-well plate and treated with LPS of 1μg/ml alone or together with exosomes.The supernatants were then collected at 0, 6, 12 and 24 h respectively after treatment .Inflammatory cytokine levels of tumor necrosis factor-α(TNF-α)and interleukins (IL-1βand IL-6) in the supernatant were measured by ELISA assay and the expression and phosphorylation level of MAPK (p44/42), NF-κB and IκBαin cell lysates were detected with Western-blotting.Results Compared with control group , the content of TNF-α,IL-1βand IL-6 increased significantly in LPS group (P<0.05), which indicated that the inflammatory cell model was induced successfully .The levels of TNF-αand IL-1βwere obviously attenuated after a high doses of exosomes treatment (P<0.05), and the expression of IL-6 was markedly suppressed after low and high doses of exosomes treatment (P<0.05), compared with the group of LPS treatment alone.The phosphorylation of NF-κB, IκBαand p44/42 was significantly inhibited after treatment with the DPSCs-derived exosomes.Conclusion DPSCs-derived exosomes may have a potential protective effect on LPS-induced ALI, and the underlying mechanism is that the activity of MAPK (p44/42) and NF-κB/IκBαpathways are eliminated by DPSCs-derived exosomes.

Human mesenchymal stem cells modified by hepatocyte growth factor gene promote chicken embryonic angiogenesis / 中国实验血液学杂志

This study was purposed to investigate the angiogenesis-promoting activities of human mesenchymal stem cells (hMSCs) modified by hepatocyte growth factor (HGF) and the underlying mechanisms. The hMSCs were transfected by recombinant adenoviral vector carrying human HGF gene and seeded onto the chicken chorioallantoic membrane. Three days later, the number of blood vessels was counted and their angiogenic response was compared with those of hMSCs of same generation, recombinant basic fibroblast growth factor (bFGF) and alpha-MEM as control. The expression levels of bFGF, VEGF, angiopoietin-1 and angiopoietin-2 were evaluated by RT-PCR assay. The results showed that gene-modified hMSCs exhibited greatest activity to promote angiogenesis while the angiogenic response was nearly same between groups treated by hMSCs and bFGF, all of which were significantly higher than that observed in control (p < 0.01). RT-PCR analysis revealed that hMSCs constitutively expressed multiple angiogenesis-associated growth factors and their levels seemed up-regulated by HGF gene transfer. It is concluded that HGF gene-modified hMSCs show a potent angiogenesis-promoting function and may be useful in the treatment of ischemic disorders.

Research progress in hirudin fusion protein--review / 中国实验血液学杂志

Natural hirudin extracted from the secretion of medical leech salivary gland is a single-chain peptide containing 65 aminoacid residues with molecular weight of 7000 D, and exists in three isomers of HV1, HV2 and HV3. Hirudin possesses three disulfide bridges forming the structure of core cyclic peptides, which binds to the catalytic site of thrombin so as to inhibit the catalysis of thrombin. Its c-terminus rich in acidic aminoacid residues possesses hydrophilicity, and is free on the molecular surface, and can bind with fibrin recognition site of hirudin. The minimal segment of 12 - 16 C-terminal acidic residues keeps the minimal activity of anti-thrombosis. Thus, hirudin, as a potent and specific inhibitor of thrombin, can be used to protect from and to treat clinically thrombosis. As it has some disadvantages such as short half-life, bleeding side-effect and mono-function, and so on, hirudin has been fused with some other functional proteins in recent years. The obtained fusion proteins can prolong the half life of hirudin, or relieve it bleeding side effect, or bring new functions, such as thrombolysis, inhibiting the platelet aggregation, targeting specifically. The research progress in hirudin fusion protein was summarized in this review.

Purification of Recombinant Fusion Protein Staphylokinase-Hirudin Expressed by Escherichia coli and Analysis of its Dimer / 中国生物工程杂志

The recombinant fusion protein staphylokinase-hirudin(rSFH) was purified from the high density-fermented engineered E.coli by means of ion-exchange chromatography (IEC) and gel filtration (GF). The purity of rSFH reached to more than 98% determined by RP-HPLC and SDS-PAGE, and the yield was up to 0.7g per liter of fermentation broth. The analysis of homologous dimmer of rSFH appeared during the purification and calculation of the surface hydrophobic area had been carried out by means of hydrophobic chromatography and MALD-TOF. The influence of sodium chloride and temperature on the behavior of rSFH reversible dimerization was analyzed by high performance sized- exclusive chromatography(HPSEC). It is concluded that the hydrophobic interaction played an important role in the reversible dimerization of rSFH.

Design and Functional Investigation of a Novel Anti-coagulative Fusion Protein by Hirudin With a Recognizing Sequence of FXa / 中国生物工程杂志

Hirudin (HV) is known as the most potent and specific inhibitor of thrombin. Although hirudin has many advantages , it has the bleeding side effect and this is the great shortage of hiudin for clinical application. In order to alleviate bleeding side effect of hirudin, fusion protein, named as FHV (fusion hirudin linked with FXa recognition peptide) was designed. The fusion protein gene ( fhv) was cloned into plasmid pPIC9K. FHV engineered Pichia pastoris containing high copies was chosen for fermentation and purification at 30 L fermentor scale, finally, FHV with purity of above 97% was obtained. To investigate the function of FHV in vivo, mouse tail thrombosis model was used. In the mice thrombus tail model induced by carrageenan, FHV decreased the length of tail thrombus significantly, similar to that of HV control, and had no obvious effects on the TT, PT and APTT. In conclusion, FHV is constructed and expressed in yeast. FHV fusion proteins is obtained by fermentation and purification. FHV has antithrombotic effects not influencing IT, PT and APTT after administration immediately in animal models. Therefore, FHV is a promising anticoagulant and antithrombotic drug.