All sources of stem cells have their pros and cons. But what if stem cell replacement therapies weren’t needed at all? What if we could manipulate the existing stem cells; promote them to proliferate and develop while still within the patient? This may seem far-fetched, but scientists are learning more about the niches that stem cells inhabit, and the signals and epigenetic mechanisms that control their fate. Such an approach might not be far-fetched for long.

Epigenetic research is of key importance to stem cell technology. It asks, what makes a stem cell a stem cell? And how do they develop into specific tissues? Each cell in the adult body contains exactly the same DNA (the same genes). The difference between cell types, then, lies in the particular subset of genes which are used. Epigenetics can be thought of as the chemical modifications to DNA which control this gene usage.

Research by Amanda Fisher’s group (London, UK) and others suggests that as cells develop towards specific fates, regions of their genome are ‘closed-down’ by various epigenetic modifications. This restricted access is then manifest in their restricted potential. Since stem cells are able to give rise to all cell types it is thought, and indeed studies indicate, that their DNA is more open to instruction and manipulation i.e. their epigenetic instructions are missing (not yet enforced).

By deciphering the nature of these instructions – how epigenetic modifications are established and maintained and how they are influenced by the cells’ environment – researchers hope to improve culture techniques, for converting stem cells into specific types. And ultimately stem cells might be directly manipulated in the patient using carefully targeted drugs.

With the various technical, ethical and practical limitations like the US resistance to funding, certain cell-based therapies might be a long time coming. But understanding the epigenetic secrets of stem cells will certainly underlie their future therapeutic use. The European Epigenome Network has a particularly crucial role to play in this respect.