Compact Cell Settlers for Perfusion Cultures of Microbial (and Mammalian) Cells.

As microbial secretory expression systems have become well developed for microbial yeast cells, such as Saccharomyces cerevisiae and Pichia pastoris, it is advantageous to develop high cell density continuous perfusion cultures of microbial yeast cells to retain the live and productive yeast cells inside the perfusion bioreactor while removing the dead cells and cell debris along with the secreted product protein in the harvest stream. While the previously demonstrated inclined or lamellar settlers can be used for such perfusion bioreactors for microbial cells, the size and footprint requirements of such inefficiently scaled up devices can be quite large in comparison to the bioreactor size. Faced with this constraint, we have now developed novel, patent-pending compact cell settlers that can be used more efficiently with microbial perfusion bioreactors to achieve high cell densities and bioreactor productivities. Reproducible results from numerous month-long perfusion culture experiments using these devices attached to the 5 L perfusion bioreactor demonstrate very high cell densities due to substantial sedimentation of the larger live yeast cells which are returned to the bioreactor, while the harvest stream from the top of these cell settlers is a significantly clarified liquid, containing less than 30% and more typically less than 10% of the bioreactor cell concentration. Size of cells in the harvest is smaller than that of the cells in the bioreactor. Accumulated protein collected from the harvest and rate of protein accumulation is significantly (> 6x) higher than the protein produced in repeated fed-batch cultures over the same culture duration. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:913-922, 2017.

Anti-NeuGcGM3 antibodies, actively elicited by idiotypic vaccination in nonsmall cell lung cancer patients, induce tumor cell death by an oncosis-like mechanism.

1E10 is a murine anti-idiotypic mAb specific for an idiotypic mAb that reacts with NeuGc-containing gangliosides, sulfatides, and Ags expressed in some human tumors. In melanoma, breast, and lung cancer patients, this anti-idiotypic Ab was able to induce a specific Ab response against N-glycosylated gangliosides, attractive targets for cancer immunotherapy as these glycolipids are not naturally expressed in humans. A clinical study with nonsmall cell lung cancer patients showed encouraging clinical benefits. Immunological studies performed in 20 of these patients suggested a correlation between the induction of Abs against NeuGcGM3 and longer survival times. The induced anti-NeuGcGM3 Abs recognized and directly killed tumor cells expressing the Ag, by a mechanism independent of complement activation. In the present work, we show that this cytotoxicity differs from apoptosis because it is temperature independent, no chromatin condensation or caspase 3 induction are detected, and the DNA fragmentation induced has a different pattern than the one characteristic for apoptosis. It is a very quick process and involves cytosqeleton reorganization. The Abs induce cellular swelling and the formation of big membrane lesions that allow the leakage of cytoplasm and the loss of the cell membrane integrity. All of these characteristics resemble a process of oncotic necrosis. To our knowledge, this is the first report of the active induction in cancer patients of NeuGcGM3-specific Abs able to induce complement independent oncotic necrosis to tumor cells. These results contribute to reinforcing the therapeutic potential of anti-idiotypic vaccines and the importance of NeuGcGM3 ganglioside as antitumor target.

Structure-activity relationship studies of new acronine analogues as suggested by molecular descriptors.

This work describes the results of an investigation on the structure-activity relationships of a series of acronine (CAS 7008-42-6) analogues which possess cytotoxic and antitumor activity. The results were obtained employing a commercially available software, which correlates structure and activity through calculations with different descriptors. The best results, obtained with electrostatic descriptors, led to propose new structures which present higher calculated activity than that of acronine.

Killing of lymphoblastic leukemia cells by nitric oxide and taxol: involvement of NF-kappaB activity.

Nitric oxide (NO) and taxol are cytotoxic towards leukemia and tumor cells and interfere with the transcription factor NF-kappaB activity. NO and taxol inhibited NF-kappaB activity and were cytotoxic to human and murine leukemia cells, but at a different magnitude (30% cell killing and 80% inhibition of NF-kappaB). Sub-effective concentrations of SNAP and taxol synergized in killing L-1210 cells but either alone or in combination completely inhibited NF-kappaB. Pyrrolidine dithiocarbamate (PDTC) was cytotoxic on its own and inhibited NF-kappaB activity. It potentiated NO and taxol killing but again there was no direct relationship between inhibition of NF-kappaB and cell killing. Neither NO nor taxol cytotoxicity was related to the cytoskeleton. Our results show that NO, taxol and PDTC induced apoptosis and NF-kappaB inhibition in leukemic cells but their cytotoxicity either alone or in combination, does not seem to be dependent on the inhibition of NF-KB activity.