On each of the four days before you donate, you will receive injections of granulocyte colony-stimulating factor (G-CSF). This is a naturally occurring hormone that increases the number of stem cells your body produces.

You’ll then come to one of our collection centres (in London, Oxford, Sheffield or Manchester), where a doctor will insert a tiny tube in your arm, draw out your blood, and pass it through a machine to collect the stem cells.

Donating only takes 4-5 hours for most people. At the end, a nurse will check how many stem cells you’ve donated. There is a chance that you’ll be asked to come back the next day to donate more.

You won’t need a general anaesthetic or to stay in hospital overnight.