Stem cells: what the phrase actually covers

The definition

A stem cell is an unspecialised cell that can renew itself and can give rise to at least one more specialised cell type. That single definition covers cells with very different capabilities, from embryonic stem cells that can become almost any tissue to adult tissue-specific cells with a narrow repertoire.

Most cells sold commercially in this field are mesenchymal stromal cells, often abbreviated MSCs. They are not the blood-forming cells used in transplant medicine, and the scientific literature increasingly stresses that their main observed activity is signalling to surrounding tissue rather than turning into it.

Where the cells come from

Sourcing changes almost everything downstream: what the product contains, how it is regulated, how long it takes to prepare and what it costs.

• Autologous — taken from your own body, usually bone marrow or fat, often processed and returned the same day.
• Allogeneic — taken from a donor, most commonly umbilical cord tissue donated after a live birth.
• Culture-expanded — grown in a laboratory before use, which in most jurisdictions moves the product into the category of a manufactured medicine.
• Minimally manipulated — processed only in limited ways, which in some jurisdictions keeps it inside a surgical-procedure exemption.

Studied uses versus marketed uses

These are not the same list, and the gap between them is the single most useful thing to understand before spending money.

In the United States the FDA states that the only approved stem cell products are cord-blood-derived hematopoietic progenitor cells, approved for certain disorders of the blood-forming system. Everything else being sold as a stem cell treatment is unapproved for that use in that jurisdiction, whatever the clinic calls it.

Outside that approved category there is a large research literature. Much of it is early-phase, single-arm, small, or conducted with a product that differs from the one a given clinic sells. A published paper about mesenchymal cells in general is not evidence about a specific clinic's specific preparation.

Evidence and regulatory reality

The ISSCR's patient guidance makes a point worth repeating: a treatment being available for purchase, in any country, tells you nothing about whether it has been shown to work. Clinics operating under a national registration or permit are complying with a process requirement. Registration is not a finding of efficacy.

Regulatory status also varies by jurisdiction and by product. The same preparation can be a permitted procedure in one country and an unapproved drug in another.

Questions worth asking a provider

• Exactly which cell type is being used, and from which tissue?
• Autologous or donor-derived? If donor-derived, how were donors screened?
• Was the product culture-expanded, where, and under what quality standard?
• What dose will I receive, how is it measured, and can I see a certificate of analysis for my lot?
• Under which regulatory pathway is this offered here, and is it approved for my condition?
• Which published studies used this same product, at this dose, in patients like me?

What this guide is not

This is educational information, not medical advice, and not a recommendation to pursue any procedure. Whether anything described here is appropriate for you is a clinical judgement to make with a qualified healthcare professional.