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Human Growth Hormone. CHEE450 By Leslie Davis. Human Growth Hormone. Simulates linear growth in humans Effects on the growth plates of the long bones Increased cell growth Increased protein, carbohydrate and lipid metabolism. Human Growth Hormone.
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Human Growth Hormone CHEE450 By Leslie Davis
Human Growth Hormone • Simulates linear growth in humans • Effects on the growth plates of the long bones • Increased cell growth • Increased protein, carbohydrate and lipid metabolism
Human Growth Hormone • Generally used to treat those with GH-deficiencies • Beneficial effects: burns, bone fractures and Turner’s syndrome • Shown promise in treating chemotherapy and AIDS • Increases body mass
Human Growth Hormone • Polypeptide • 191 amino acid residues • MW = 22125 daltons • Highly hydrophobic proteins
Historical Perspective • Isolated hGH in human pituitary 1956 • Proof of effectiveness 1958 • Obtained from human pituitary gland only • Urgent need to obtain human pituitary glands at autopsy • High cost • Cloned from human gene in 1980s
Recombinant DNA Synthesis of hGH • Cloning of human DNA • Adapting of the cloned gene for expression in Escherichia coli • E. coli did not have the biochemical machinery • 84 base pairs of ds DNA synthesized for direct expression
How it works • Chemical messenger produced by the pituitary gland • Promotes growth during childhood • Plays important metabolic role throughout adulthood Pituitary Gland
Production Process • Fermentation • Highly reproducible • Intracellular • E. coli W3110 with a pB322-derived plasmid coding • Antibiotic resistance of genetically modified E. coli strain • Typically tetracycline and ampicillin resistant
Production Process • Glucose and mineral salt medium • Exponentially growing cells in batch mode • Transferred from seed fermentor to production bioreactor • 10% of final volume • High cell density fermentation
Production Process • Fed-batch bioreactor • Glucose feed ~ 500-600 g/L • May use peptone for amino acid source • Temperature – near maximum tolerance of E. coli • Agitation generally ranges 1000-1500 rpm • Slightly positive pressure
Production Process • Purification • Cell disruption • Microfiltration • Chromatographic methods • Genentech adapted anion exchange chromatography and gel filtration technology (early 80s)
Production Process • Issues with scale up • Mass transfer through high density cells • Oxygen • Glucose feed • Inhibitory ion formation • Acetate and formate
Final Product • White lyophilized powder • Low oral bioavailability (<1%) • Intended for intravenous, subcutaneous or intramuscular administration • Sold in vials or cartridges containing • 4 - 24 mg of somatropin • Preservatives • Water for injection
Final Product • Approximately 28 day shelf life • Oxygen Sensitive • Must be refrigerated • Improve the solubility, sodium dodecyl sulfate (extremely surface active) or denaturing agents - urea and guanidine hydrochloride
Market U.S. Manufacturers • Genotropin by Pharmacia & Upjohn Company, Humatrope by Eli Lilly, Norditropin by Novo Nordisk, Saizen and Serostim by Serono Laboratories, Nutropin by Genentech
Market • Costs: $75 to $200 per week • World-wide sales of $1.6 billion • Approximately 20,000 U.S. children taking drug • Prescribed for non-GH-deficient children if (U.S.) • <3SD below mean for age category • <25% growth velocity
Discussion • Psychological issues • Cultural “heightism” • Increased metabolism, reduced fat, anti-aging, gain strength • Articles
References • Human Growth Hormone, edited by Salcatore Raiti and Robert A. Tolman, 1986 • Human Growth Hormone: Research and Clinical Practice, edited by Roy G. Smith and Michael O. Thorner • Influence of Scale-Up on the Quality of Recombinant Human Growth Hormone, Bylund, Castan, Mikkola, Veide and Larsson • Modelling the effects of Glucose Feeding on a recombinant E. coli Fermentation, Cockshott and Bogle • Further Studies Related to the Scale-up of High Cell Density Escherichia coli Fed-Batch Fermentations: The Additional Effect of a Changing Microenvironment When Using Aqueous Ammonia to Control pH
References • http://pi.lilly.com/us/humatrope-pi.pdf • http://www.hghnews.us/p/91.html • http://www.hgh-humangrowthhormone.com/hgh_human_growth_hormone_sitemap/hgh_manufacturer.html • http://www.novonordisk.com/therapy_areas/growth_hormone_therapy/default.asp • http://patft.uspto.gov/netacgi/ • http://www.genotropin.com/patients/growth_disorders/index.asp