Daniel I. C. Wang

Massachusetts Institute of Technology

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Trends

Author Order

Document Type

Co-Authors

Matthew S. Croughan

Keck Graduate Institute

Jean‐François P. Hamel

Massachusetts Institute of Technology

Gregory Stephanopoulos

Massachusetts Institute of Technology

Gregg Nyberg

Merck & Co., Inc., Rahway, NJ, USA (United States)

R. Robert Balcarcel

Bayer (United States)

Brian D. Follstad

Amgen (United States)

Bryan J. Harmon

Eli Lilly (United States)

William G. Thilly

Massachusetts Institute of Technology

Xuejun Gu

Anhui Institute of Optics and Fine Mechanics

Tzyy‐Wen Chiou

National Dong Hwa University

Cooperative Institutions

Massachusetts Institute of Technology

Amgen (United States)

Eli Lilly (United States)

Purdue University West Lafayette

IIT@MIT

Karolinska Institutet

John Wiley & Sons (United States)

Sinocelltech Group (China)

Chinese Academy of Medical Sciences & Peking Union Medical College

Sino Biological (China)

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Field

Fiber bed reactor design for animal cell culture

Biotechnology and Bioengineering (1989)

Steven D. Perry Daniel I. C. Wang

Center (category theory)

Engine department

10.1002/bit.260340102

Cite

Citations (35)

Immobilized Animal Cell Bioreactors

CRC Press eBooks (1994)

Matthew S. Croughan Tzyy‐Wen Chiou Daniel I. C. Wang

To initiate a culture of animal cells, one removes the cells from the animal and often then immobilizes the cells on an appropriate surface [1,2]. If the subsequent culture environment is suitable, the cells will grow to cover the surface and can be used to inoculate a new, larger surface. The initial growth surface is generally the interior bottom wall of a simple vessel, such as a T-flask or petri plate [1,2]. For large-scale operations, which require billions of cells or more,extensive surface area is often provided through highly engineered reactors. The design of such reactors is the topic of this chapter.

10.1201/9781482277470-15

Cite

Citations (0)

Hydrodynamic effects on animal cells grown in microcarrier cultures

Biotechnology and Bioengineering (2006)

Matthew S. Croughan Jean‐François P. Hamel Daniel I. C. Wang

Abstract Hydrodynamic phenomena in microcarrier cultures are investigated with regard to the development of improved reactor designs for large‐scale operations. New concepts and theoretical models that describe new data as well as previously published data are presented. © 2006 Wiley Periodicals, Inc.

Microcarrier

10.1002/bit.21158

Cite

Citations (22)

Metabolic Effects on Recombinant Interferon-γ Glycosylation in Continuous Culture of Chinese Hamster Ovary Cells

IBM Journal of Research and Development (2000)

Gregg Nyberg R. Robert Balcarcel Brian D. Follstad Gregory Stephanopoulos Daniel I. C. Wang

Asparagine linked (N-linked) glycosylation is an important modification of recombinant proteins, because the attached oligosaccharide chains can significantly alter protein properties. Potential glycosylation sites are not always occupied with oligosaccharide, and site occupancy can change with the culture environment. To investigate the relationship between metabolism and glycosylation site occupancy, we studied the glycosylation of recombinant human interferon-γ (IFN-γ) produced in continuous culture of Chinese hamster ovary cells. Intracellular nucleotide sugar levels and IFN-γ glycosylation were measured at different steady states which were characterized by central carbon metabolic fluxes estimated by material balances and extracellular metabolite rate measurements. Although site occupancy varied over a rather narrow range, we found that differences correlated with the intracellular pool of UDP-N-acetylglucosamine + UDP-N-acetylgalactosamine (UDP-GNAc). Measured nucleotide levels and estimates of central carbon metabolic fluxes point to UTP depletion as the cause of decreased UDP-GNAc during glucose limitation. Glucose limited cells preferentially utilized available carbon for energy production, causing reduced nucleotide biosynthesis. Lower nucleoside triphosphate pools in turn led to lower nucleotide sugar pools and reduced glycosylation site occupancy. Subsequent experiments in batch and fed-batch culture have confirmed that UDPsugar concentrations are correlated with UTP levels in the absence of glutamine limitation. Glutamine limitation appears to influence glycosylation by reducing amino sugar formation and hence UDP-GNAc concentration. The influence of nucleotide sugars on site occupancy may only be important during periods of extreme starvation, since relatively large changes in nucleotide sugar pools led to only minor changes in glycosylation.

Nucleotide sugar

N-linked glycosylation

10.1147/rd.445.0770

Cite

Citations (2)

Hydrodynamic effects on animal cells grown in microcarrier cultures

Biotechnology and Bioengineering (2000)

Matthew S. Croughan Jean‐François P. Hamel Daniel I. C. Wang

Hydrodynamic phenomena in microcarrier cultures are investigated with regard to the development of improved reactor designs for large-scale operations. New concepts and theoretical models that describe new data as well as previously published data are presented.

Microcarrier

10.1002/(sici)1097-0290(20000320)67:6<841::aid-bit19>3.0.co;2-k

Cite

Citations (21)

Optimization of growth surface parameters in microcarrier cell culture

Biotechnology and Bioengineering (1979)

David Levine Daniel I. C. Wang William G. Thilly

Abstract The microcarrier technique for the growth of anchorage‐dependent animal cells has been studied and significantly improved. Excellent cell growth (up to 5 × 10 6 cells/ml) has been obtained on a newly synthesized microcarrier optimized with respect to substitution with a positively charged exchange moiety. Various parameters of microcarrier culture were examined in order to identify the source of reported “toxicities” associated with this technique. The hypothesis that bead adsorption of nutrients is responsible for such “toxicities” was found to be inconsistent with our results, which suggest that microenvironmental effects are critical for cell propagation on microcarriers.

Microcarrier

Moiety

10.1002/bit.260210507

Cite

Citations (151)

Metabolism of peptide amino acids by Chinese hamster ovary cells grown in a complex medium

Biotechnology and Bioengineering (1999)

Gregg Nyberg R. Robert Balcarcel Brian D. Follstad Gregory Stephanopoulos Daniel I. C. Wang

Metabolic flux analysis is a useful tool for unraveling relationships between metabolism and cell function. Material balancing can be used to provide estimates of major metabolic pathway fluxes, provided all significant metabolite uptake and production rates are measured. Potential sources of metabolizable material in many serum-free media formulations are low molecular weight digests of biological material such as yeast extracts and plant or animal tissue hydrolysates. These digests typically contain large amounts of peptides, which may be utilized as amino acids. This article demonstrates the need for accounting for amino acids liberated from peptides in order to accurately estimate pathway fluxes in Chinese hamster ovary cells grown in a complex (hydrolysate containing) medium. A simplified model of central carbon metabolism provides the framework for analyzing external metabolite measurements. Redundant measurements are included to ensure the consistency of data and assumed biochemistry by comparing redundant measurements with their predicted values from a minimum data set, and by expressing the degree of agreement using a statistical "consistency index." The consistency index tests whether redundancies are satisfied within expected experimental error. For chemostat steady states of CHO cultures grown in a hydrolysate-supplemented medium, consistent data were obtained only when amino acids liberated from peptides were taken into account.

Metabolic flux analysis

Chemostat

10.1002/(sici)1097-0290(19990205)62:3<324::aid-bit9>3.0.co;2-c

Cite

Citations (126)

Growth and death in overagitated microcarrier cell cultures

Biotechnology and Bioengineering (1989)

Matthew S. Croughan Daniel I. C. Wang

Abstract The effects of hydrodynamic forces on cell growth are investigated for animal cells growing on microcarriers. A reduction in net growth was observed with high levels of agitation. DNA measurements indicated that the reduction in net growth was due entirely to cell death, from hydrodynamic forces. No inhibition or enhancement of cell replication appeared to occur with high levels of agitation.

Microcarrier

Replication

10.1002/bit.260330611

Cite

Citations (99)

Influence of Primatone RL supplementation on sialylation of recombinant human interferon-γ produced by Chinese hamster ovary cell culture using serum-free media

Biotechnology and Bioengineering (1997)

Xuejun Gu Liangzhi Xie Bryan J. Harmon Daniel I. C. Wang

Although serum-free media have been widely used in mammalian cell culture for therapeutic protein production, the effects of serum-substitutes on product quality have not been extensively examined. This study observed an adverse effect of Primatone RL, an animal tissue hydrolysate commonly used as a serum-substitute to promote cell growth, on sialylation of interferon-γ (IFN-γ) derived from Chinese hamster ovary (CHO) cell culture in both batch and fed-batch modes. In batch cultures, decreased sialylation was observed at each of the glycosylation sites (i.e., Asn25 and Asn97) of IFN-γ with the use of elevated concentrations of the peptone. Although poorest sialylation was obtained with the use of a growth-inhibiting concentration of Primatone RL, diminished sialylation was observed at the optimal peptone concentration for cell growth and product yield. Since incubation of the product in Primatone RL-supplemented acellular medium did not result in decreased sialylation, the negative effect of Primatone RL could not be attributed to extracellular desialylation of IFN-γ by components of the peptone. In the fed-batch mode, a culture utilizing a serum-free feeding medium supplemented with Primatone RL demonstrated poorer sialylation than a similar culture not fed the peptone. The results of both the batch and fed-batch experiments indicate that the adverse effect of the peptone was not due solely to ammonia accumulation. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 56: 353–360, 1997.

Fed-batch culture

10.1002/(sici)1097-0290(19971120)56:4<353::aid-bit1>3.0.co;2-n

Cite

Citations (36)

Metabolic effects on recombinant interferon-? glycosylation in continuous culture of Chinese hamster ovary cells

Biotechnology and Bioengineering (1999)

Gregg Nyberg R. Robert Balcarcel Brian D. Follstad Gregory Stephanopoulos Daniel I. C. Wang

Asparagine linked (N-linked) glycosylation is an important modification of recombinant proteins, because the attached oligosaccharide chains can significantly alter protein properties. Potential glycosylation sites are not always occupied with oligosaccharide, and site occupancy can change with the culture environment. To investigate the relationship between metabolism and glycosylation site occupancy, we studied the glycosylation of recombinant human interferon-γ (IFN-γ) produced in continuous culture of Chinese hamster ovary cells. Intracellular nucleotide sugar levels and IFN-γ glycosylation were measured at different steady states which were characterized by central carbon metabolic fluxes estimated by material balances and extracellular metabolite rate measurements. Although site occupancy varied over a rather narrow range, we found that differences correlated with the intracellular pool of UDP-N-acetylglu- cosamine + UDP-N-acetylgalactosamine (UDP-GNAc). Measured nucleotide levels and estimates of central carbon metabolic fluxes point to UTP depletion as the cause of decreased UDP-GNAc during glucose limitation. Glucose limited cells preferentially utilized available carbon for energy production, causing reduced nucleotide biosynthesis. Lower nucleoside triphosphate pools in turn led to lower nucleotide sugar pools and reduced glycosylation site occupancy. Subsequent experiments in batch and fed-batch culture have confirmed that UDP-sugar concentrations are correlated with UTP levels in the absence of glutamine limitation. Glutamine limitation appears to influence glycosylation by reducing amino sugar formation and hence UDP-GNAc concentration. The influence of nucleotide sugars on site occupancy may only be important during periods of extreme starvation, since relatively large changes in nucleotide sugar pools led to only minor changes in glycosylation. © 1999 John Wiley & Sons, Inc. Biotechnol Bioeng 62: 336–347, 1999.

Nucleotide sugar

N-linked glycosylation

10.1002/(sici)1097-0290(19990205)62:3<336::aid-bit10>3.0.co;2-n

Cite

Citations (125)