[Preparation and characterization of monoclonal antibodies against recombinant human NDPK-A].

AIM: To prepare monoclonal antibodies (mAb) against recombinant human nucleoside diphosphate kinase-A(NDPK-A) and characterize their properties. METHODS: BALB/c mice were immunized with rhNDPK-A, and mAb was prepared by hybridoma technique. Ig subclass and specificity was analysed by double immunodiffusion and western blot respectively. The titres of mAbs in ascitic fluid, relative affinity and epitopes recognized by mAbs were determined by indirect ELISA. RESULTS: 6 hybridoma cell lines secreting anti-rhNDPK-A mAbs were obtained. Their Ig subclass belonged to IgG1. The titers of 6 mAbs in ascitic fluid were 1x10(-4)-5x10(-6). Relative affinity of mAbs were 4.5x10(-9)-2.8x10(-10) mol/L. They recognized 3 different epitopes on rhNDPK-A molecule. CONCLUSION: 6 mAbs against rhNDPK-A have been prepared successfully which provide useful reagent for clinical diagnosis and further research.

[In vivo transfection and expression of human coagulant factor VIII cDNA in mice].

The aim is to observe the expression of human factor VIII gene in mice tranduced in vivo and ex vivo. The vector pLNC-FVIII BD was generated by cloning a B-domain-deleted (760aa-1639aa) FVIII cDNA (FVIIIBD cDNA) into retroviral vector pLNCX. 2 x 10(6) of mouse bone marrow stroma cells transduced by LNC-FVIII BD were infused into 4-week-old BALB/c mice by tail-vein injection. pLNC-FVIII BD was conjugated with PAMAM dendrimer to form complex PAMAM-pLNC-FVIII BD, with which C57BL/6J were injected by tail vein (200 micro l contained 15 micro g/mouse) and sacrificed at days 1, 2, 7, 14, 21 and 28, respectively after injection. Tissue such as liver, spleen, lung and kindney were harvested, with which the transcription were detected by means of RT-PCR. In addition, blood was collected to be measured human FVIII Ag, human FVIIIc and anti-FVIII of human inhibitors. The results showed that the highest level of human FVIII in the recipient BALB/c mice was 8.6 +/- 1.44 ng/ml detected on the first day post-injection; anti-FVIII antibodies were detected from the first week post-injection, and then the level of FVIII Ag decreased and cannot be measured on the fourth week. In the C57BL/6J mice physiological level of human FVIII was expressed in plasma at 48 hours after injection and the average human FVIIIc was 0.62 U/ml and the average human FVIII Ag was 115.5 ng/ml, and gradually reduced later. Anti-FVIII of human inhibitors was not revealed all the time. Syngene image scanning demonstrated that the transcription of the human FVIII BD cDNA occurred mainly in spleen and lung, and secondarily in liver and kidney. No side effects of PAMAM-pLNC-FVIII BD were observed in mice tissue by pathological examination at 4 weeks. In conclusion, retrovirus-transduced bone marrow stroma cells effectively produced human FVIII after ex vivo transduction, but the development of anti-FVIII antibodies in recipient mice influenced the expression level. The human FVIII gene can successfully be transduced in vivo through injecting PAMAM-pLNC-FVIII BD cDNA into mice intravenously. There was physiological level expression of human FVIII in plasma at 48 hours after injection and the average human FVIIIc is 0.62 U/ml and the peak in the six mice was 0.89 U/ml, and gradually reduced later.

[Effective and stable in vitro expression of human coagulation factor VIII by retrovirus-based plasmid vector coupled with polyamidoamine dendrimer].

OBJECTIVE: To demonstrate the effectiveness of a retrovirus-based plasmid vector coupled with nanometer material-polyamidoamine (PAMAM) dendrimer in stable gene expression of FVIII in vitro and to study the cytotoxicity of PAMAM. METHODS: The retrovirus-based plasmid vector pLNC-FVIII BD was generated by cloning a B-domain-deleted (760aa - 1639aa) FVIII cDNA (FVIIIBD cDNA) into retroviral vector pLNCX. The complex that contained PAMAM and pLNC-FVIII BD transfer FVIII BD cDNA into NIH3T3 cell line. In day 2, 5, 10, 15, 30 after transferring, the antigen and procoagulant activity of human FVIII in the cell culture medium were measured by ELISA assay and one-stage method, respectively. RT-PCR was performed for the detection of FVIII BD mRNA. Inhibitory percentage of cell vitality was used for cytotoxicity of PAMAM. RESULTS: Human FVIII was expressed for 30 days by transfected cells. The mean procoagulant activity of secreted FVIII in these 30 days was 0.929 U/ml, and the FVIII antigen was 0.188 micro g/ml by 10(6) cells in 24 hours, respectively. The level of FVIII didn't significantly decreased during these days. Inhibitory percent of cell vitality was only 5.32%. CONCLUSION: PAMAM could effectively transfer pLNC-FVIII BD into NIH3T3 cells and FVIII could be stably and effectively expressed by the transfected cells. Cytotoxicity of PAMAM was low.