Regenerative Medicine has been ‘defined’ in numerous ways. Any single definition is too restricting on what is a very diverse and fast-changing field. A better word might be ‘characterised’.

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RM embraces:

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• Cell- and molecular-based therapies: replacement of compromised cells/tissue, stimulation of endogenous response, delivery of genetic or molecular therapies 

• Gene therapy: use of DNA as a pharmaceutical agent to treat disease

• Biologics and small molecules: stimulation of dormant or endogenous cells to regain their regenerative properties

• Tissue engineering (TE): scaffolds created from synthetic and bio-based materials

• Biobanking: the collection, storage and distribution of bio-tissue

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The other field is stem cell biology. This is the study of unspecialised cells that can give rise to one or more different types of specialised cells. For instance, after adult marrow-derived Mesenchymal Stem Cells (MSCs) have divided, their progeny are capable of further division and differentiation into one of several mesenchymal phenotypes including osteoblasts, chondrocytes, myocytes, marrow stromal cells, tendon-ligament fibroblasts, and adipocytes. That is, the original stem cells have the capability to differentiate into a variety of phenotypes and so provide the foundation for numerous potential therapies to treat chronic illnesses and traumatic injuries.

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Further, it has become recognised that the beneficial effects of stem cells go further than those arising solely from differentiation:

 

Stem cells can secrete combinations of trophic factors including cytokines and growth factors. These modulate, via paracrine action, the molecular composition of the environment to evoke responses from resident cells. MSCs, for instance, secrete bioactive factors that suppress the local immune system, inhibit fibrosis (scar formation) and apoptosis (‘normal’ or programmed cell death), enhance angiogenesis (blood vessel formation), stimulate mitosis (division of a parent cell to produce two identical daughter cells) and differentiation of reparative cells or stem cells.

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Researchers are working to understand such processes more fully and thus set the scene for innovative new therapies that will undoubtedly emerge. Further, the author suggests that future therapies may well comprise an intimate combination of both differentiation-based mechanisms and trophic mechanisms, where ‘superior’ outcomes can be demonstrated and where regulatory requirements, not least for trophic factors’ Modes of Action, can be met.