Stem cell collection

This is the first stage where something is actually done to you. Stem cells are taken out of your blood so they can be edited in a laboratory, and it happens weeks or months before the treatment itself.

Mobilisation

Stem cells normally live in the bone marrow. Before they can be collected, medicines are given to push them out into the bloodstream where a machine can reach them. This is called mobilisation.

Which medicines are used is decided by your centre following national guidance rather than being fixed by the licence, and it can differ between sickle cell disease and thalassaemia. It is a reasonable thing to ask about, because the drugs have their own side effects.

Apheresis: the collection itself

The collection is done by a machine that takes blood out, separates off the stem cells, and returns the rest to you. The following describes how NHS units do this for stem cell collection generally, the procedure is the same one used here.

• A needle goes into the crook of one arm, blood flows out through tubing into the machine, and the remaining blood comes back through a cannula in your hand.

• If your veins are not up to it, a line can be placed in the groin instead. An existing Hickman line can be used, but a PICC line cannot, it does not give the machine enough flow.

• A session takes around four to six hours, and collection is usually finished in one or two days.

• You can eat and drink beforehand and during it. But once you are connected you cannot be disconnected until it finishes, so it is worth sorting out the practicalities first.

• You may feel tired afterwards and are advised to rest and drink plenty.

The tingling

The machine adds something to stop your blood clotting, and that can lower your calcium levels. It causes tingling around the lips, cheeks or fingertips. It is common, it is expected, and telling the nurse is the whole of the solution, they give calcium by tablet or through the drip and it settles.

Two things we could not find written down anywhere authoritative: whether the procedure hurts, and what people do to pass four to six hours attached to a machine. Ask your unit, and if you have been through it, this is exactly the sort of thing worth sharing with the person coming after you.

It may take more than one go

Enough cells have to be collected. There is a minimum dose for the treatment itself, and on top of that a separate back-up sample of your own untreated cells is always collected and kept, in case the treated cells fail to take hold later.

If the laboratory does not get enough cells to make the product, you go through mobilisation and collection again. Cycles have to be at least two weeks apart, so a second round adds meaningfully to the timeline.

This is worth expecting rather than being blindsided by. It is a known part of the process, not a sign anything has gone wrong.

Then you wait

Your cells go off to be edited and frozen. Nothing else happens to you during that time, and treatment does not begin until the product has been made and checked.

The NHS clinical procedure used at a lead centre puts manufacturing at roughly five to eight months, from the day your cells are collected to the day they go back in. That is a long time to hold your life open, and it is worth planning around rather than being surprised by.

Questions you might take to your team

• Which mobilising medicines will I have, and what are their side effects?

• Will I need a line, or can it be done through my arm?

• How many days should I plan for, and can I go home in between?

• What happens if you do not collect enough cells first time?

• How long will manufacturing take for me?

• Should someone come with me, and will I be able to get myself home?