Diabetes

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Making human insulin

For many years, insulin was obtained by purifying it from the pancreas of cows and pigs slaughtered for food. This was expensive, difficult and the insulin could cause allergic reactions.

Once the structure of human insulin had been found, in 1955, the cow and pig insulin could be chemically modified to be the same as human insulin. It is now made by genetically-engineered microbes. They produce human insulin in a pure form that is less likely to cause allergic reactions.

Producing human insulin

Human insulin is produced in a very controlled and clean environment.

Genetically-engineered bacteria are grown in large stainless steel fermentation vessels. The vessel contains all the nutrients needed for growth.

When the fermentation is complete, the mixture containing the bacteria is harvested. The bacteria are filtered off and broken open to release the insulin they have produced. It is then purified and packaged into bottles for distribution.

All the equipment is kept sterile so that contamination cannot get into the medicine. Regular checks make sure that all the processes are working properly and the insulin meets the required quality.

Fermentation vessel in a factory

Production and packaging of insulin pens

Insulin pens

Images courtesy of Novo Nordisk

Question 4

Drag these processes into the correct order for making human insulin from genetically engineered bacteria.

Put genetically-engtineered bacteria into fermentation vessels

Allow genetically-engineered bacteria to grow

Harvest bacteria and break open to release insulin

Clean fermentation vessel and add solution containing nutrients

Purify and package human insulin

Insert gene for human insulin into bacteria

Autoimmune disease

A disorder where the body's immune system behaves abnormally and starts attacking its own cells

Autopsies

The study of the human body to investigate how a disease or injury lead to death

Cardiovascular disorders

Diseases linked to the heart and its blood vessels, for example heart disease and stroke

Embryo

The name for a group of cells that are developing into a fetus. In humans this is from implantation to the 8th week of development

Glossary

A list of often difficult or specialized words with their definitions

Fermentation

Process where microorganisms are cultured so that they reproduce and increase in quantity

Gene

A short piece of DNA which is responsible for the inheritance of a particular characteristic. It codes for the production of a specific protein

Gene therapy

A new, experimental method of fighting disease by replacing a defective gene with a healthy gene

Genetic engineering

A general name for the processes which scientists use to produce desired characteristics or substances that are in short supply, such as human insulin

Glucagon

A hormone produced by the pancreas. It causes the liver to convert glycogen back to glucose and to release glucose into the bloodstream.

Glucose

A type of sugar: a mono saccharide with 6 carbon atoms (a hexose sugar)

Harvested

The process by which a useful substance is extracted

Home Office

The UK government department responsible for regulating the use of animals in scientific research

Hormone

A chemical messenger produced by a particular gland or cells of the endocrine system. Hormones are transported throughout the body in the blood stream but they produce a response only in specific target cells

Hyperglycaemic

This is the term used when the blood glucose level is too high (more than 10 mmol/l)

Hypoglycaemic

This is the term used when the blood glucose level is too low (less than 4 mmol/l)

Immune system

The body's own system for protecting it against disease (where it produces antibodies to attack invading pathogens)

In vitro fertilisation

A process where the egg is fertilised outside of the body and then transferred back into the uterus to develop normally

Insulin

A hormone produced by the pancreas. It allows cells in the body to take in and store glucose.

Liver

A large organ in the upper abdomen which manufactures, stores and breaks down substances as required by the body

Non-animal alternatives

Processes such as cell culture, computer modelling, imaging and microdosing of human volunteers that can give information on potential harmful effects of a substance

Obesity

A disorder where an excessive amount of fat has accumulated in the body. It results when the energy taken in as food is stored in the body instead of being used up through activity

Pancreas

An endocrine gland which produces insulin

Respiration

The biochemical process by which the cells in the body releases energy

Sterile

Uncontaminated by microorganisms

UK Law [for animal testing]

Animal welfare is regulated in the UK by the Animal (Scientific Procedures) Act 1986