Makoto Yamanaka

Efficient production of recombinant IgG by metabolic control and co-expression with GLUT5 in a fructose-based medium.

A fructose-based cell culture is suitable for the process control of protein production because of slow sugar consumption rate and low lactate accumulation. The fructose transporter, GLUT5, mediates its incorporation into cells and is required for the fructose-based culture. In order to produce efficiently recombinant IgG by metabolic control and co-expression with GLUT5 in a fructose-based medium, an IgG and GLUT5 co-expression vector was constructed and transfected into the human myeloma derived cell line, SC-01MFP, which produced stably recombinant proteins. The cell proliferation in the fructose-based medium was improved by the GLUT5 gene transfection. The recombinant IgG production of the cells cultured in the fructose-based medium exhibited about two-fold increase of that in the glucose-based medium. Flow cytometoric analysis indicated that the GLUT5 protein expression level in cell surface was increased in the fructose-based medium. An exogenous but not endogenous GLUT5 transcription activator remarkably raised IgG productivity in the fructose-based medium when compared to that in the glucose-based medium, suggesting that exogenous GLUT5 expression may be involved in it. The GLUT5 co-expression system may be useful for efficient production of recombinant proteins by the fructose-based cell culture.

Induction of cell size vesicles from human lymphoma cell lines and their application to drug carriers

Sodium butyrate (NaB) induced the membrane enclosed cell size vesicles from several IgM producing cell lines. We considered the application of the cell-derived vesicles (CDVs) to drug delivery system (DDS) using the lung cancer specific IgM producing AE6 cell line. Microscopic observation showed that the DiI fluorescence labeled AE6 vesicles were incorporated into the lung cancer cell line A549. The anticancer drug, actinomycin D (actD), contained in AE6 and Ramos vesicles decreased the A549 cell viability to 46 and 62% of control without actD, respectively. The cytotoxic effect in AE6 vesicles was superior to that in the Ramos vesicles that have the lung cancer non-specific IgM on their surfaces. However, the result of the Ramos vesicles suggests that the surface molecules other than IgM may interact with the A549 cells. In our method for vesicle production, more specific and abundant antibodies mounted vesicles can be generated by transfection of their genes into cells followed by NaB treatment. These suggest that the CDVs may be useful for the development of a drug carrier for DDS.

Characterization of Cell-Sized Vesicles Induced from Human Lymphoid Cell Lines

We developed that induced with a sodium butyrate mass production of cell-size vesicles from several human lymphoma cells. Ramos, a human burkitt lymphoma was the best induction rate among several human cell lines. However, all cells were dead after NaB treatment. The trypan blue dye staining showed the leakless of the vesicle. Therefore, it is suggested that the vesicle could be available for a drug carrier. The immunostaining analysis showed the retainment of surface antigen such as IgM, implying the possibility of specific vesicle production by transfection of desired gene into viable cells followed by the NaB treatment. This study is applicable to membrane protein isolation, drug delivery system, and microreactor development.