Antibody titer and viable cell density (VCD) are two important parameters that need to be closely monitored during the process of cell line development and manufacturing of therapeutic antibodies. Typically, determination of each parameter requires 10–100 μL of supernatant sample, which is not suitable for small scale cultivation. In this study, we demonstrated that as low as 2 μL of culture supernatants were sufficient for the analysis using UV-Vis spectrum assisted with partial least squares (PLS) model. The results indicated that the optimal PLS models could be used to predict antibody titer and VCD with the linear relationship between reference values and predicted values at R2 values ranging from 0.8 to > 0.9 in supernatant samples obtained from four different single clones and in polyclones that were cultured in various selection stringencies. Then, the percentage of cell viability and productivity were predicted from a set of samples of polyclones. The results indicated that while all predicted % cell viability were very similar to the actual value at RSEP value of 6.7 and R2 of 0.8908, the predicted productivity from 14 of 18 samples were closed to the reference measurements at RSEP value of 22.4 and R2 of 0.8522. These results indicated that UV-Vis combined with PLS has potential to be used for monitoring antibody titer, VCD, and % cell viability for both online and off-line therapeutic production process.
Graphical abstract
Background:
Cancer is a noncommunicable disease with increasing incidence and mortality rates both worldwide and in Thailand. Its apparent lack of effective treatments is posing challenging public health issues.
Introduction: Encouraging research results indicating probable anti-cancer properties of the Delonix regia flower extract
(DRE) have prompted us to evaluate the feasibility of developing a type of product for future cancer prevention or
treatment.
Methods and Results:
In the present report, using High Performance Liquid Chromatography (HPLC), we demonstrate in
the DRE, the presence of high concentrations of three identifiable flavonoids, namely rutin 4.15±0.30 % w/w, isoquercitrin
3.04±0.02 %w/w, and myricetin 2.61±0.01 % w/w respectively while the IC50 of DPPH and ABTS assay antioxidation activity was 66.88±6.30 µg/ml and 53.65±7.24 µg/ml respectively.
Discussion:
Our cancer cell line studies using the MTT assay demonstrated DREs potent and dose dependent inhibition of
murine leukemia cell line (P-388: 35.28±4.07% of cell viability remaining), as well as of human breast adenocarcinoma
(MCF-7), human cervical carcinoma (HeLa), human oral cavity carcinoma (KB), and human colon carcinoma (HT-29) cell
lines in that order of magnitude.
Conclusion:
Three identifiable flavonoids (rutin, isoquercitrin and myricetin) with high antioxidation activity and potent
and dose dependent inhibition of murine leukemia cell line and five other cancer cell lines were documented in the DRE.
The extract’s lack of cytotoxicity in 3 normal cell lines is a rare advantage not usually seen in current antineoplastic agents.
Yet another challenge of the DRE was its low dissolution rate and long-term storage stability, issues to be resolved before a
future product can be formulated.
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