WO1994019459A1 - Method for obtaining an increased production of a producing celline by using a fusion protocol - Google Patents

Method for obtaining an increased production of a producing celline by using a fusion protocol Download PDF

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Publication number
WO1994019459A1
WO1994019459A1 PCT/SE1994/000123 SE9400123W WO9419459A1 WO 1994019459 A1 WO1994019459 A1 WO 1994019459A1 SE 9400123 W SE9400123 W SE 9400123W WO 9419459 A1 WO9419459 A1 WO 9419459A1
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Prior art keywords
celline
cell
protocol
fusion
cells
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Ceased
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PCT/SE1994/000123
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French (fr)
Inventor
Jack Spira
Lars Adamsson
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Pfizer Health AB
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Kabi Pharmacia AB
Pharmacia AB
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Priority to EP94907760A priority Critical patent/EP0684992B1/en
Priority to US08/505,189 priority patent/US5607845A/en
Priority to AU61197/94A priority patent/AU671195B2/en
Priority to AT94907760T priority patent/ATE192191T1/en
Priority to DE69424153T priority patent/DE69424153T2/en
Priority to JP6518882A priority patent/JPH08509363A/en
Application filed by Kabi Pharmacia AB, Pharmacia AB filed Critical Kabi Pharmacia AB
Priority to CA002156181A priority patent/CA2156181C/en
Priority to DK94907760T priority patent/DK0684992T3/en
Publication of WO1994019459A1 publication Critical patent/WO1994019459A1/en
Anticipated expiration legal-status Critical
Priority to GR20000401692T priority patent/GR3034006T3/en
Ceased legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K14/00—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof
    • C07K14/435—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from animals; from humans
    • C07K14/745—Blood coagulation or fibrinolysis factors
    • C07K14/755—Factors VIII, e.g. factor VIII C (AHF), factor VIII Ag (VWF)
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N5/00—Undifferentiated human, animal or plant cells, e.g. cell lines; Tissues; Cultivation or maintenance thereof; Culture media therefor
    • C12N5/10—Cells modified by introduction of foreign genetic material
    • C12N5/12—Fused cells, e.g. hybridomas
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N5/00—Undifferentiated human, animal or plant cells, e.g. cell lines; Tissues; Cultivation or maintenance thereof; Culture media therefor
    • C12N5/10—Cells modified by introduction of foreign genetic material
    • C12N5/12—Fused cells, e.g. hybridomas
    • C12N5/16—Animal cells

Definitions

  • the present invention relates to a method for obtaining a higher product expression in a producing mammalian celline characterized by treating the original celline with itself according to a fusion protocol, known in the art.
  • the production of protein products is performed in mammalian tissue culture, and the product could be therapeutic proteins or other molecules intended for human use.
  • this invention relates to the use of cell fusion methods to obtain a stable high producing celline.
  • a vector or virus containing necessary elements for expression of proteins in mammalian cells may be introduced in an appropriate cell.
  • a primary celline expressing a certain protein may be transformed to a continuous celline.
  • a primary celline such as a lymphocyte may be fused to a nonproducing celline and the resulting hybrid can be selected for expression of the wanted protein.
  • the protein of interest can be obtained from the culture medium or the cells themselves.
  • Hybrid cellines are usually characterized by presence of chromosomes or genes from the two different fusion parents and require some sort of selection procedure in order to eliminate the parental cells from the fusion mixture and allowing the emergence and outgrowth of the fused cell.
  • Cell fusion as a method of enhancing protein production has been described by Chenciner et al in Bio Technology vol 8, 1990:858-862. The authors produced classical hybrids between a liver cell and a transfected Vero cell. The stable hybrids produced an increased amount of the wanted product.
  • the above described prior art discloses the use of classical cellfusion of two different cells, as means of obtaining and increasing production of a particular product in a particular cell which is a fusion cell, a combination of the two parent cells.
  • the present invention relates to a method of obtaining a higher product expression in a producing celline by fusing the original cell with itself according to a fusion protocol, known in the art.
  • Cellfusion protocols suitable for the present invention are methods utilizing polyethylene glycol (PEG) or electrofusion, protoplast or Sendaivirus.
  • the cell could be a Chinese Hamster Ovary (CHO) derived celline, Baby Hamster Kidney (BHK) or Cos (an African green monkey derived celline) or any other commonly used mammalian celline.
  • CHO Chinese Hamster Ovary
  • BHK Baby Hamster Kidney
  • Cos an African green monkey derived celline
  • the product is preferably full length factor VIII, deletion derivatives of factor VIII or otherwise modified factor VIII but could also be another therapeutically active protein or molecule.
  • the resulting cellines could have a chromosome and DNA content identical or very similar to the original celline.
  • the cellfusion protocol is preferably performed without the presence of a selection protocol, but selection protocols could be used.
  • the fusion protocol could be performed on already fused cells.
  • the invention also relates to the use of a celline or cell which has been obtained by fusing the original cell with itself according to fusion protocol in the production of a protein or another molecule and preferably a celline in which the cellines have a chromosome and DNA content similar the original celline.
  • the present invention comprises thus the use of a cellfusion protocol to increase the productivity of a mammalian celline.
  • a preferred aspect of the present invention is the use of the method to increase the productivity of human recombinant factor VIII producing cellines.
  • the extent of increase of Factor VIII:C may be up to 2 fold, 10 fold and even 20 fold.
  • the method is applicable to many cellines but in particular CHO (Chinese Hamster Ovary) cells producing a full length factor VIII, deletion variants or otherwise modified factor VIII.
  • This invention shows that under the claimed cellfusion conditions, one can obtain high producing and stable cellines which are not classical hybrids.
  • Recombinant factor VIII was produced in CHO DG44 NY cells transfected with a cDNA encoding for a deletion variant of human factor VIII called factor VIII SQ.(r-VIII SQ) (see WO 91/09122 and WO 92/16557).
  • the following cellfusion protocol was used: The cells are cultured in a proprietary serumfree medium. 20-80x10 6 cells were washed, pelleted and a 50% (in medium) solution of PEG 4.000 was added dropwise to the pellet. After 1 minute the PEG-cell mixture was gently diluted by adding culture medium. The diluted mixture was gently centrifuged, new medium added and further cultivated in serumfree medium. No selective medium was used and only one type of cells were used.
  • Fusion of the cells were monitored by chromosome counting and flow cytometry.
  • Factor VIII activity is measured by the chromogenic substrate
  • Table 1 illustrates the r-VIII SQ expression one week after fusion.
  • the original r-VIII SQ producing celline "ADLA” was treated with PEG 4000 under standard fusion conditions, as described above under Materials and Methods, (ADLA PFT and PEG 1-5 in Table 1 ) and also when keeping the cells adhered to the plastic under subconfluency in order to prevent them from fusing (AD.LA PT in Table 1).
  • ADLA control had no PEG treatment. Cells were grown to confluence and tested for factor VII C.
  • Example 3 The already PEG fused celline (PEG 4) was again PEG fused with itself, and further subcultured for 10 days without any selective pressure.
  • the twice "fusion treated cells” expressed even higher levels of r-VIII SQ compared to the single fused cells.
  • PEG treatment can be performed repeatedly.
  • the celline PFT was further examined by chromosome counting and DNA content by fluorescence after propidium iodide staining.
  • Table 4 shows the results of chromosome analysis after 10-20 days in culture after fusion on two different occasions. At these timepoints an increased expression as described above was present. All cellines show a modal chromosome number of 20. All examined cells showed the presence of aberrant metaphase plates with subtetraploid chromosome numbers. There was however no differences comparing the fused cells to the control celline. This was further studied by propidiumidodine staining and analysis of DNA content fluorescence analysis on several occasions during the propagation of the cells.
  • the PEG treated cells did not have a higher DNA content compared to the non fused control cellines.

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  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Genetics & Genomics (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Zoology (AREA)
  • Biomedical Technology (AREA)
  • Biotechnology (AREA)
  • Bioinformatics & Cheminformatics (AREA)
  • Wood Science & Technology (AREA)
  • General Health & Medical Sciences (AREA)
  • Biochemistry (AREA)
  • General Engineering & Computer Science (AREA)
  • Microbiology (AREA)
  • Cell Biology (AREA)
  • Medicinal Chemistry (AREA)
  • Gastroenterology & Hepatology (AREA)
  • Biophysics (AREA)
  • Hematology (AREA)
  • Molecular Biology (AREA)
  • Proteomics, Peptides & Aminoacids (AREA)
  • Toxicology (AREA)
  • Preparation Of Compounds By Using Micro-Organisms (AREA)
  • Micro-Organisms Or Cultivation Processes Thereof (AREA)
  • Peptides Or Proteins (AREA)
  • Data Exchanges In Wide-Area Networks (AREA)
  • Medicines Containing Material From Animals Or Micro-Organisms (AREA)
  • Immobilizing And Processing Of Enzymes And Microorganisms (AREA)
  • Apparatus Associated With Microorganisms And Enzymes (AREA)

Abstract

The invention relates to a method for obtaining a higher product expression in a producing mammalian celline characterized by treating the original celline with itself according to a fusion protocol known in the art. The production of protein products is performed in mammalian tissue culture, and the product could be therapeutic proteins or other molecules intended for human use. In particular this invention relates to the use of cell fusion methods to obtain a stable high producing celline.

Description

METHOD FOR OBTAINING AN INCREASED PRODUCTION OF A PRODUCING CELLINE BY USING A FUSION PROTOCOL
Field of invention
The present invention relates to a method for obtaining a higher product expression in a producing mammalian celline characterized by treating the original celline with itself according to a fusion protocol, known in the art. The production of protein products is performed in mammalian tissue culture, and the product could be therapeutic proteins or other molecules intended for human use. In particular this invention relates to the use of cell fusion methods to obtain a stable high producing celline.
Description of the Related art.
Expression of proteins in heterologous mammalian cells is usually performed in one of the following three ways, well known to the artisan in the field.
1 ) A vector or virus containing necessary elements for expression of proteins in mammalian cells may be introduced in an appropriate cell.
2) A primary celline expressing a certain protein may be transformed to a continuous celline.
3) A primary celline, such as a lymphocyte may be fused to a nonproducing celline and the resulting hybrid can be selected for expression of the wanted protein.
By further cultivation of cells derived from 1-3 above the protein of interest can be obtained from the culture medium or the cells themselves.
The latter technique 3 is the most common one and is used for production of monoclonal antibodies by hybridoma cells. Hybrid cellines are usually characterized by presence of chromosomes or genes from the two different fusion parents and require some sort of selection procedure in order to eliminate the parental cells from the fusion mixture and allowing the emergence and outgrowth of the fused cell. Cell fusion as a method of enhancing protein production has been described by Chenciner et al in Bio Technology vol 8, 1990:858-862. The authors produced classical hybrids between a liver cell and a transfected Vero cell. The stable hybrids produced an increased amount of the wanted product.
Different cell fusion protocols are well known in the art. The use of polyethylene glycol (PEG), protoplast or Sendaivirus can be mentioned as examples and reference is here given to Cell culture by William B Jakoby and Ira H Pastan, Methods in Enzymology Vol. LVIII, Academic Press, 1979. Electrofusion is another method that also can be used and reference is here given to Electromanipulation in hybridoma technology, Laboratory manual, by Carl A K Borrbaeck and Inger Hagen, Stockman Press, 1989 and Guide to Electroporation and Electrofusion, Chang et al, Academic Press, 1992. By variations of e.g. the used amount of cells, time, temperature etc., each laboratory often has its own protocol.
In summary the above described prior art discloses the use of classical cellfusion of two different cells, as means of obtaining and increasing production of a particular product in a particular cell which is a fusion cell, a combination of the two parent cells.
We have now found a method that can be used in the establishment of a protein producing celline. The method will increase the production of the wanted product of the celline. Although the method resembles cellfusion it is not a classical cellfusion and the cellines obtained are, to our great surprise, stable over a prolonged period.
Summary of the invention.
The present invention relates to a method of obtaining a higher product expression in a producing celline by fusing the original cell with itself according to a fusion protocol, known in the art.
Cellfusion protocols suitable for the present invention are methods utilizing polyethylene glycol (PEG) or electrofusion, protoplast or Sendaivirus. The cell could be a Chinese Hamster Ovary (CHO) derived celline, Baby Hamster Kidney (BHK) or Cos (an African green monkey derived celline) or any other commonly used mammalian celline.
The product is preferably full length factor VIII, deletion derivatives of factor VIII or otherwise modified factor VIII but could also be another therapeutically active protein or molecule.
The resulting cellines could have a chromosome and DNA content identical or very similar to the original celline.
The cellfusion protocol is preferably performed without the presence of a selection protocol, but selection protocols could be used. The fusion protocol could be performed on already fused cells.
The invention also relates to the use of a celline or cell which has been obtained by fusing the original cell with itself according to fusion protocol in the production of a protein or another molecule and preferably a celline in which the cellines have a chromosome and DNA content similar the original celline.
The present invention comprises thus the use of a cellfusion protocol to increase the productivity of a mammalian celline. A preferred aspect of the present invention is the use of the method to increase the productivity of human recombinant factor VIII producing cellines. The extent of increase of Factor VIII:C may be up to 2 fold, 10 fold and even 20 fold. The method is applicable to many cellines but in particular CHO (Chinese Hamster Ovary) cells producing a full length factor VIII, deletion variants or otherwise modified factor VIII.
This invention shows that under the claimed cellfusion conditions, one can obtain high producing and stable cellines which are not classical hybrids.
Description of the preferred embodiment. Materials and Methods.
Recombinant factor VIII was produced in CHO DG44 NY cells transfected with a cDNA encoding for a deletion variant of human factor VIII called factor VIII SQ.(r-VIII SQ) (see WO 91/09122 and WO 92/16557). The following cellfusion protocol was used: The cells are cultured in a proprietary serumfree medium. 20-80x106 cells were washed, pelleted and a 50% (in medium) solution of PEG 4.000 was added dropwise to the pellet. After 1 minute the PEG-cell mixture was gently diluted by adding culture medium. The diluted mixture was gently centrifuged, new medium added and further cultivated in serumfree medium. No selective medium was used and only one type of cells were used.
Fusion of the cells were monitored by chromosome counting and flow cytometry.
For measurement of factor VIII:C activity the growth medium was exchanged to a production medium and VIII.C measured as it accumulated in the supernatant (without medium changes) for the number of days indicated in the tables. Factor VIII activity (VIII:C) is measured by the chromogenic substrate
(Chromogenix Mόlndal) after various time points.
Example 1
This example (Table 1) illustrates the r-VIII SQ expression one week after fusion. The original r-VIII SQ producing celline "ADLA" was treated with PEG 4000 under standard fusion conditions, as described above under Materials and Methods, (ADLA PFT and PEG 1-5 in Table 1 ) and also when keeping the cells adhered to the plastic under subconfluency in order to prevent them from fusing (AD.LA PT in Table 1). ADLA control had no PEG treatment. Cells were grown to confluence and tested for factor VII C.
Table 1. Expression of PEG treated cells compared to control cells (ADLA).
Figure imgf000006_0001
Results
Cells treated under "standard" fusion conditions expressed as a mean 457%, 140% and 153% of control values day one to three after the fusion treatment. Cells PEG-treated under subconfluent conditions did only express an enhanced VIII.C activity (ADLA PT) day one after treatment. The table also shows that there are considerable differences between individual experiments and that expression is highest immediately, day one, after fusion.
Example 2.
To test the stability of the not selected, PEG-treated population one of the above cellines (PEG 4) was further subcultured without any selective pressure for a period of 2 month and was then re-evaluated for factor VIII activity. These cells still expressed a higher amount of rVIII SQ.
Table 2. Stability of increased expression capability of PEG treated cells. VIII:C expression compared to control after 60 days in culture.
Day Day Day Day Day Day Day Day 61 62 63 64 65 66 67 68
Control 100% 100% 100% 100% 100% nt. nt 100%
PEG 4 100% 907% 1892 1541 1187 nt nt 294% % % %
Result
The expression from day 62 to 68 after fusion, kept under nonselective conditions was between 294 % and 1892 % of the control values.
Example 3 The already PEG fused celline (PEG 4) was again PEG fused with itself, and further subcultured for 10 days without any selective pressure.
Table 3. Vll C expression aft er retreati ng PEG treated cells (PEG 4) with PEG compared to non treated con trol cells.
Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7
Control 100% 100% 100% 100% 100% 100% 100%
PEGx2 100% 1933% 1884% 1799% nt nt 490% Result
The twice "fusion treated cells" expressed even higher levels of r-VIII SQ compared to the single fused cells. Thus PEG treatment can be performed repeatedly.
Example 4
The celline PFT was further examined by chromosome counting and DNA content by fluorescence after propidium iodide staining. Table 4 shows the results of chromosome analysis after 10-20 days in culture after fusion on two different occasions. At these timepoints an increased expression as described above was present. All cellines show a modal chromosome number of 20. All examined cells showed the presence of aberrant metaphase plates with subtetraploid chromosome numbers. There was however no differences comparing the fused cells to the control celline. This was further studied by propidiumidodine staining and analysis of DNA content fluorescence analysis on several occasions during the propagation of the cells.
Table 4. Chromosome an alysi. s. No of metaphases with the indicated chromosome number in 1 he P EG treated cells and in the control
Chrom numb 18 19 20 21 22 24 32 34 36 37 38 39
Control 6 8 4 1 1
ADLA PFT 1 2 2 7 3 1 2 1 1
ADLA PFT 2 1 3 11 2 1 1 1
Result
The PEG treated cells did not have a higher DNA content compared to the non fused control cellines. These analysis, together with the fact that the high expression levels were stable after long time non selective cell culture indicate that the high producer cells were not the result of a classical cellfusion process. Discussion
Cellfusion is a well-known process. The examples presented here are though not typical for classical cellfusion. Firstly the PEG treated cells contained neither more DNA nor chromosomes and secondly there were no selective steps involved in subculturing the population. Furthermore the regular fusion frequencies of 10*4-10"5 are to low for cellfusion as explanation of the long term persistence of the increased productivity. Taken together these results indicate that cellfusion with PEG treatment induce a stable change in the expression capability of the cells. As such this method is applicable to different cells and different agents.

Claims

1. A method of obtaining a higher product expression in a producing celline characterized by fusing the original cell with itself according to fusion protocol.
2. A method according to claim 1 characterized by using Polyethylenglycol (PEG) in the fusion protocol.
3. A method according to claim 1 characterized by using electrofusion, protoplast or Sendaivirus in the fusion protocol.
4. A method according to any of claims 1-3, in which the cell is a Chinese Hamster Ovarian (CHO) derived celline.
5. A method according to any of claims 1-3, in which the cell is Baby Hamster Kidney (BHK) or Cos or any other mammalian celline commonly used foe protein production.
6. A method according to any of claims 1-5, in which the product is a therapeutically active protein or molecule.
7. A method according to claim 6 in which the product is full length factor VIII, deletion derivatives of factor VIM or otherwise modified factor VIII.
8. A method according to any of claims 1-7, in which the resulting cellines have a chromosome and DNA content identical or very similar to the original celline.
9. A method according to any of claims 1-8, in which the cellfusion protocol is performed without the presence of a selection protocol.
10. A method according to any of claims 1-8, in which a selection protocols is used.
11. A method according to any of claims 1-10, in which the fusion protocol is performed on already fused cells.
12. Use of a celline or cell which has been obtained by fusing the original cell with itself according to a fusion protocol in the production of a protein or another molecule.
13. Use of a celline according to claim 12 in which the cellines have a chromosome and DNA content is identical or very similar to the original celline.
PCT/SE1994/000123 1993-02-16 1994-02-15 Method for obtaining an increased production of a producing celline by using a fusion protocol Ceased WO1994019459A1 (en)

Priority Applications (9)

Application Number Priority Date Filing Date Title
US08/505,189 US5607845A (en) 1993-02-16 1994-02-15 Method for obtaining an increased production of a producing cell line by using a fusion protocol
AU61197/94A AU671195B2 (en) 1993-02-16 1994-02-15 Method for obtaining an increased production of a producing celline by using a fusion protocol
AT94907760T ATE192191T1 (en) 1993-02-16 1994-02-15 METHOD FOR IMPROVED PRODUCTION OF A PRODUCING CELL LINE USING A FUSION PROTOCOL
DE69424153T DE69424153T2 (en) 1993-02-16 1994-02-15 METHOD FOR IMPROVING THE PRODUCTION OF A PRODUCING CELL LINE BY USING A FUSION PROTOCOL
JP6518882A JPH08509363A (en) 1993-02-16 1994-02-15 How to obtain increased production of developmental serine by using fusion protocols
EP94907760A EP0684992B1 (en) 1993-02-16 1994-02-15 Method for obtaining an increased production of a producing celline by using a fusion protocol
CA002156181A CA2156181C (en) 1993-02-16 1994-02-15 Method for obtaining an increased production of a producing celline by using a fusion protocol
DK94907760T DK0684992T3 (en) 1993-02-16 1994-02-15 Process for achieving increased production in a producing cell line using fusion protocol
GR20000401692T GR3034006T3 (en) 1993-02-16 2000-07-24 Method for obtaining an increased production of a producing celline by using a fusion protocol.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9300509-8 1993-02-16
SE9300509A SE9300509D0 (en) 1993-02-16 1993-02-16 PEG TREATMENT

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US (1) US5607845A (en)
EP (1) EP0684992B1 (en)
JP (1) JPH08509363A (en)
AT (1) ATE192191T1 (en)
AU (1) AU671195B2 (en)
CA (1) CA2156181C (en)
DE (1) DE69424153T2 (en)
DK (1) DK0684992T3 (en)
ES (1) ES2147781T3 (en)
GR (1) GR3034006T3 (en)
NZ (1) NZ261936A (en)
PT (1) PT684992E (en)
SE (1) SE9300509D0 (en)
WO (1) WO1994019459A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5888815A (en) * 1993-11-01 1999-03-30 Pharmacia & Upjohn Aktiebolag Cell cultivation method and medium

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10329594B1 (en) * 2015-09-03 2019-06-25 CHO Plus, Inc. Cell lines for high level production of protein-based pharmaceuticals
US11649449B2 (en) 2015-09-03 2023-05-16 CHO Plus, Inc. Hybrid cell lines for high level production of a target protein

Citations (1)

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Publication number Priority date Publication date Assignee Title
US4659663A (en) * 1984-10-01 1987-04-21 Board Of Regents, University Of Texas System Methods for isolating cell fusion products

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US4822470A (en) * 1987-10-09 1989-04-18 Baylor College Of Medicine Method of and apparatus for cell poration and cell fusion using radiofrequency electrical pulses
US4832814A (en) * 1987-12-28 1989-05-23 E. I. Du Pont De Nemours And Company Electrofusion cell and method of making the same
GB8807271D0 (en) * 1988-03-26 1988-04-27 Preece A W Cell fusion apparatus
SE465222C5 (en) * 1989-12-15 1998-02-10 Pharmacia & Upjohn Ab A recombinant human factor VIII derivative and process for its preparation
SE468050C (en) * 1991-03-15 1998-04-27 Pharmacia & Upjohn Ab Recombinant human factor VIII derivative

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Publication number Priority date Publication date Assignee Title
US4659663A (en) * 1984-10-01 1987-04-21 Board Of Regents, University Of Texas System Methods for isolating cell fusion products

Non-Patent Citations (1)

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Title
Bio/Technology, Volume 8, Sept 1990, NICOLE CHENCINER et al., "Enhancement of Gene Expression by Somatic Hybridization with Primary Cells: High-Level Synthesis of the Hepatitis B Surface Antigen in Monkey Vero Cells by Fusion with Primary Hepatocytes", page 858 - page 862. *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5888815A (en) * 1993-11-01 1999-03-30 Pharmacia & Upjohn Aktiebolag Cell cultivation method and medium

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DE69424153T2 (en) 2000-11-16
CA2156181C (en) 2004-09-21
DK0684992T3 (en) 2000-09-18
US5607845A (en) 1997-03-04
CA2156181A1 (en) 1994-09-01
AU6119794A (en) 1994-09-14
JPH08509363A (en) 1996-10-08
DE69424153D1 (en) 2000-05-31
AU671195B2 (en) 1996-08-15
ES2147781T3 (en) 2000-10-01
GR3034006T3 (en) 2000-11-30
EP0684992B1 (en) 2000-04-26
SE9300509D0 (en) 1993-02-16
EP0684992A1 (en) 1995-12-06
NZ261936A (en) 1996-05-28
ATE192191T1 (en) 2000-05-15

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