Stability validation of seeding cell control parameters in large-scale hybridoma cell culture

Effects of passage number on growth and productivity of hybridoma secreting MRSA anti-PBP2a monoclonal antibodies

Monoclonal antibodies (mAb) are high added value glycoproteins recommended for immunotherapy, diagnosis, and also for the treatment of bacterial infections resistant to multiple drugs such as Methicillin Resistant Staphylococcus aureus (MRSA). In addition to environmental conditions related to cell cultures, the intrinsic characteristics of hybridoma cells, like the secretion stability of monoclonal antibodies by the cells through successive subcultures, are relevant for the characterization of cell lines related to the productivity of mAb. The rate of mAb production differs significantly between different cell lines and different passage numbers, and it is an important variable in characterization of cell lines. In order to find a more robust, faster-growing, and higher-productivity cell line of hybridoma, cultivations in 24-well plates were performed in different subculture periods, or cell passages (P), of hybridoma cells producing MRSA anti-PBP2a monoclonal antibodies [MRSA-antiPBP2a (mAb)]. The objective of this study was to study the effects of cell growth and production of MRSA-antiPBP2a mAb secreted by murine hybridoma cells grown in different passages as well as determine the which passages the hybridomas can be cultivated without harming their growth and productivity. So, cell growth profiles of hybridomas secreting MRSA-antiPBP2a (mAb) and the production of MRSA-antiPBP2a mAb in different subculture periods or cell passages (P) were studied. Cell growth tests, monoclonal antibody productivity, and metabolite characteristics revealed substantial differences in those cells kept between P10 and P50. Similarities in the secretion of monoclonal antibody, growth, and metabolic profiles, were noted in the MRSA-antiPBP2a mAb producing hybridoma cells kept between P10 and P20. Also, glucose consumption (g/L) and lactate production (g/L) in the latter cell cultures were monitored daily through biochemical analyzer. As of P30, it was observed a 4.4 times reduction in productivity, a 13 % reduction in metabolic yield, and a significant change in cell growth. Secretion of MRSA-antiPBP2a mAb should be obtained through the culture of hybridomas up to P20 in order to keep its stability.

A chimeric antibody targeting CD147 inhibits hepatocellular carcinoma cell motility via FAK-PI3K-Akt-Girdin signaling pathway

CD147 is expressed at low levels in normal tissues but frequently highly expressed in a wide range of tumor types such as lung, breast, and liver and therefore it is a potentially unique therapeutic target for these diverse tumor types. We previously generated a murine antibody HAb18 which suppresses matrix met al.loproteinase-2 and matrix metalloproteinase-9 secretion, attenuates cell invasion by blocking the CD147 molecule in tumor cells. Here, we generated a chimeric antibody containing the variable heavy and variable light chains of murine HAb18 and the constant regions of human IgG1γ1 and human κ chain as a potential therapeutic agent (designated cHAb18). Quantitative measurement of cHAb18 antibody affinity for antigen CD147 with surface plasmon resonance showed the equilibrium dissociation constant KD was 2.66 × 10(-10) mol/L, similar to that of KD 2.73 × 10(-10) mol/L for murine HAb18. cHAb18 induced antibody-dependent cell-mediated cytotoxicity in two hepatocellular carcinoma cell lines, SMMC-7721 and Huh-7 cells. It inhibited cancer invasion and migration in hepatocellular carcinoma cells by specifically blocking CD147. Except for the depression of matrix metalloproteinase-2 and matrix metalloproteinase-9 expressions, cHAb18 antibody suppressed cell motility by rearrangement of actin cytoskeleton, which was probably induced by decreasing the phosphorylation of focal adhesion kinase, phosphatidylinositide-3 kinase (PI3K), Akt, and Girdin in the integrin signaling pathway. In an orthotopic model of hepatocellular carcinoma in BALB/c nude mice, cHAb18 treatment effectively reduced the tumor metastasis in liver and prolonged the survival. These findings reveal new therapeutic potential for cHAb18 antibody targeting CD147 on tumor therapy.

Label-free hybridoma cell culture quality control by a chip-based impedance flow cytometer

Impedance flow cytometry (IFC) was evaluated as a possible alternative to fluorescence-based methods for on-line quality monitoring of hybridoma cells. Hybridoma cells were cultured at different cell densities and viability was estimated by means of IFC and fluorescence-based flow cytometry (FCM). Cell death was determined by measuring the impedance phase value at high frequency in low conductivity buffer. IFC data correlate well with reference FCM measurements using AnnexinV and 7-AAD staining. Hybridoma cells growing at different densities in cell culture revealed a density-dependent subpopulation pattern. Living cells of high density cultures show reduced impedance amplitudes, indicating particular cellular changes. Dead cell subpopulations become evident in cultures with increasing cell densities. In addition, a novel intermediate subpopulation, which most probably represents apoptotic cells, was identified. These results emphasize the extraordinary sensitivity of high frequency impedance measurements and their suitability for hybridoma cell culture quality control.

Heparin promotes suspension adaptation process of CHO-TS28 cells by eliminating cell aggregation

While heparin has been shown to eliminate cell aggregation in suspension adaptations of insect and HEK293 cells for virus-based cell cultures, the role of heparin in long period serum-free suspension adaptation of the anchorage-dependent Chinese hamster ovary (CHO) cell lines remains inconclusive. In this paper, we explore the potential application of heparin in suspension adaptation of CHO cell line which produces an anti-human chimeric antibody cHAb18. Heparin showed a concentration-dependent inhibition of CHO-TS28 cell-to-cell adhesion, with a significant inhibitory effect occurring when the concentration exceeded 250 μg/ml (P < 0.001). Heparin also exhibited a cell aggregation elimination role at all concentrations (P < 0.001). Furthermore, heparin promoted cell growth and antibody secretion, with the highest cell density ((99.83 ± 12.21) × 10(4) cells/ml, P = 0.034) and maximum antibody yield ((9.46 ± 0.94) mg/l, P < 0.001) both occurring at 250 μg/ml heparin. When agitated, cell aggregates were effectively dispersed by 250 μg/ml heparin and a single-cell suspension culture process was promoted. In suspension adapted CHO-TS28 cells, cell growth rates and specific antibody productivity were maintained; while antigen-binding activity improved slightly. Together, our results show that heparin may promote suspension adaptation of anchorage-depended CHO cells by resisting cell aggregation without reducing cell growth, antibody secretion, and antigen-binding activity.