Education and Training

Ph.D. University of California, Berkeley, 1993
Chemical Engineering

B.S. with honors, California Institute of Technology, Pasadena, CA, 1987
Chemical Engineering

Postdoctoral Research Assistant, School of Medicine, University of California, Los Angeles, April 1994-September 1996

Postdoctoral Research Assistant, Department of Chemical Engineering, University of California, Berkeley, March 1993-April 1994

Contact

E-mail: sharfs@rpi.edu
Website: http://www.eng.rpi.edu/chme/faculty_details.cfm?facultyID=sharfs
Tel: (518) 276-2166
Fax: (518) 276-4285

Office: Biotech Center 2nd floor

Rensselaer Polytechnic Institute
110 8th Street
Troy, NY 12180

Research Interests

Mammalian cell biotechnology and bioprocessing focused on recombinant biopharmaceutical production.

The primary focus of my research activities is on developing a fundamental understanding of the role of culture conditions and cell physiology on the yield and quality of recombinant proteins produced in mammalian cell cultures. The protein therapeutics market is currently greater than $50 billion dollars a year and growing at a rate of ~20% annually [1]. Approximately 40 protein therapeutics are on the market today, with 700 more in clinical development, 150-200 in late stage trials [2]. Of those molecules, 60-70% are produced in mammalian cells in order to achieve proper folding, glycosylation, assembly, and other post-translational modifications. Despite their significant advantages, mammalian cell cultures are limited by relatively low cell densities and specific productivities when compared with microbial cultures, raising concerns about production capacity limitations as more biopharmaceuticals enter the market. Within the biotechnology/biopharmaceutical industry, strict product timelines dictate 12 to 18 months from the time when a candidate molecule enters process development to the time the molecule enters phase-I clinical production, allowing little time for process science. With limited fundamental understanding of how process conditions affect production, the majority of process development is done empirically and cell-line selection is done by extensive, labor-intensive clone screening. 

My group has made significant advances in providing this fundamental understanding by focusing on the effects of osmolarity on protein production, cell line characterization to understand what makes a cell line a “good producer”, and understanding the effects of culture conditions on protein glycosylation.

• Understanding cellular responses to osmolarity: It has been widely shown that increasing osmolarity increases specific productivity for recombinant proteins produced in cultured mammalian cells. However, increased osmolarity adversely affects cell growth, limiting the applicability of this technique. We are seeking a mechanistic understanding of this phenomenon using cell and molecular biology techniques and gene expression (microarray analysis). Ultimately, we intend to identify candidate genes for cellular engineering to improve osmotolerance.
• Cell line characterization to understand factors that control antibody productivity: We have been characterizing a collection of industrially derived cell clones that all produce the same recombinant monoclonal antibody to determine why some cell lines exhibit higher productivities than others.
• Analysis of the effects of culture conditions on protein glycosylation: It is well known that culture conditions affect glycosylation of recombinant proteins. We are trying to understand mechanistically what effect specific culture conditions have on the glycosylation pathways.

Selected Publications

Z. Jiang and S.T. Sharfstein, Sodium Butyrate Stimulates mAb Over-expression in CHO Cells by Improving Gene Accessibility, Biotechnology and Bioengineering, in press

A. Venkiteshwaran, P. Heider, S. Matosevic, A. Bogsnes, A. Staby, S. Sharfstein, and G. Belfort  Optimized removal of soluble host cell proteins for the recovery of met-human growth hormone inclusion bodies from Escherichia Coli cell lysate using crossflow microfiltration, Biotechnology Progress, 23: 667-672. (2007). 

J.H. Nam M. Ermonval, and S.T. Sharfstein, Cell attachment to microcarriers affects growth, metabolic activity, and culture productivity in bioreactor culture,  Biotechnology Progress, 23: 652 -660 (2007)

D. Shen and S.T. Sharfstein, Genome-Wide Analysis of the Transcriptional Response of Murine Hybridomas to Osmotic Shock, Biotechnology and Bioengineering, 93: 132-145 (2006).

Z. Jiang, Y. Huang, and S.T. Sharfstein, Regulation of Recombinant Monoclonal Antibody Production in Chinese Hamster Ovary Cells: A Comparative Study of Gene Copy Number, mRNA Level and Protein Expression, Biotechnology Progress, 22: 313-318 (2006). One of the 10 most accessed articles of 2006 from Biotechnology Progress

K.M. McNeeley, Z. Sun, and S.T. Sharfstein, Techniques for Dual Staining of DNA and Intracellular Immunoglobulins in Murine Hybridoma Cells: Applications to Cell-Cycle Analysis of Hyperosmotic Cultures, Cytotechnology, 48: 15-26 (2005).

Z. Sun, R. Zhou, S. Liang, K.M. McNeeley, and S.T. Sharfstein, Hyperosmotic Stress in Murine Hybridoma Cells: Effects on Antibody Transcription, Translation, Posttranslational Processing, and the Cell Cycle, Biotechnology Progress, 20: 576-589 (2004).