The unique nature of biotechnology processes adds to the complexity and difficulty of scale-up. Successful scale-up means a shortened cycle to full-scale production, competitive advantage, and cost savings. The many pitfalls as well as actual and potential scale-up problems are reviewed. Emphasis is placed on covering all areas of concern in planning, executing, and documenting key studies. Needs in technology transfer are discussed and regulatory requirements are incorporated into scale-up needs. A review of the recent literature is coupled with actual case studies; problem avoidance is stressed. Problems in asepsis, in construction, and in validation are discussed and potential solutions given. Organizational problems are noted. Finally, checklists are given for project planning, for a safety audit, and for timely attainment of successful scale-up. Eighty-two references are included.

Problems in Scale-Up of Biotechnology Production Processes

Preparative chromatography continues to be the dominant purification technique in the 
production of biological compounds, especially in the pharmaceutical and 
biotechnological industries. However, the conceptual complexity of a purely theoretical 
approach to preparative chromatography is formidable, because we are dealing with 
systems of highly coupled, nonlinear partial differential equations [1, 2]. Although 
theoretical work is progressing, it can currently capture predictively only a few aspects of 
realistic biotechnological separations, especially given the extremely complex 
biochemical feedstocks often used in these applications. It is not entirely coincidental that 
the current approach to scale-up and optimization in industry is highly empirical. 
Although this is natural, especially given the constraints of process validation, the first 
few chapters of this book attempt to show that current theoretical understanding does 
give insight into the practical issues involved in scale-up and optimization. These 
chapters show that a careful combination of basic theory with experiments can reduce the 
time needed to achieve an effective scale-up of a realistic chromatographic separation.

An Overview of Scale-Up in Preparative Chromatography

DNA breaks and repair in mouse leukemia L1210 cells treated with 3 different types of cross-linkers, mitomycin C (MMC), 1-(4-amino-2-methyl-5-pyrimidinyl)-methyl-3-(2-chloroethyl)-3-nitroso ure a hydrochloride (ACNU) and SN-07 (a macromolecular antibiotic), were studied. Measured in D37 values, MMC gave the highest number of cross-links per lethal 'hit' directly after the 1-h treatment in the alkaline elution assay, followed by ACNU and SN-07. A good dose-response increase in induced interstrand DNA cross-linking frequency was observed in cells treated with 2.5-10 micrograms/ml MMC and with 10-100 micrograms/ml ACNU for 1 h with and without 24-h post-incubation. After 6-h post-incubation, the highest frequency of cross-linking was observed in cells treated with 2.5 micrograms/ml MMC and 30 micrograms/ml ACNU, while cross-link production continued in the cells treated with SN-07 for 12-h post-incubation. No significant increase in DNA breaks was observed in cells treated with MMC throughout 24-h post-incubation. The highest frequency of single-strand DNA breaks in cells treated with ACNU was observed immediately after the treatment and they disappeared after 6-h post-incubation. After 24-h post-incubation, a marked enhancement of the DNA breaks was observed in cells treated with SN-07 and the cells contained double-strand DNA breaks also. RNA synthesis was not affected in the cells treated with 10 micrograms/ml MMC and slightly inhibited to 70% of control in those treated with 100 micrograms/ml ACNU, while DNA synthesis in both cells was significantly inhibited after 24-h post-incubation. By contrast, both RNA and DNA synthesis were completely inhibited in cells treated with 8.0 micrograms/ml SN-07.

DNA breaks and repair in the mouse leukemia L1210 cells exposed to three different types of interstrand DNA cross-linkers.

5 - Protein Inactivations During Chromatographic Methods of Separation

The mechanisms of action of a novel macromolecular antitumor antibiotic (SN-07) were examined using cultured mouse lymphoid leukemia L1210 cells. A shoulder exponential-type cytotoxicity was observed when the cells were treated with 3.13 to 100 ng/ml SN-07 for 1 hr and surviving colonies were counted after a 14-day incubation. It was found that 500 ng/ml SN-07 inhibited both RNA and DNA syntheses significantly at 40 and 80 min, respectively, while 8,000 ng/ml did not affect protein synthesis at 80 min. Treatment with a low concentration (80 ng/ml) of SN-07 for 1 hr inhibited both RNA and DNA syntheses after a 24-hr post-incubation. The alkaline elution technique revealed that 8,000 ng/ml SN-07 induced DNA interstrand cross-links time-dependently for 1 to 4 hr, and a 1-hr treatment with 80 to 8,000 ng/ml SN-07 induced DNA breaks after a 24-hr post-incubation. According to flow cytometric analysis, most L1210 cells progressed to the G2 phase in the cell cycle at a cytostatic concentration (25 ng/ml) of SN-07, and typical inhibition of the cell cycle progression was observed at a cytocidal concentration (200 ng/ml).

Mechanisms of Action of a Novel Macromolecular Antitumor Antibiotic,SN-07,on Mouse Leukemia L1210 Cells in Culture

Scale-up of hydrophobic interaction chromatography for purification of SN-07 was studied. The height equivalent to a theoretical plate of the adsorbent gel (Sepabeads FP-PH 12) was kept constant for various superficial liquid velocities and column diameters. The efficiency of purification was also constant for the Sepabeads FP-PH 12 columns ranging from 16 mm to 113 mm in inner diameter. Effects of the ligand concentration on the adsorption capacity were also studied, and the adsorption capacity increased with an increase in the ligand concentration. These effects resulted in decreasing the required amount of salt to purify SN-07.

E. Sada

Papers

Scale-up of hydrophobic interaction chromatography for purification of antitumor antibiotic SN-07