Commentary: Pay Attention to Regenerative Medicine

As a veterinarian and cell biologist trained during the 1980s, I have witnessed firsthand the transformative impact that molecular biology has had on biomedical research, agriculture, and medicine. Characterizing molecular biology as "transformative" is appropriate. Consider how recombinant DNA methods, transgenics, and now genomics have impacted discovery science, farming practices, the pharmaceutical industry, and clinical diagnostics.

The process is not winding down--actually, just the opposite. We are entering an era of personalized medicine. Along with medical history, a clinical exam, and diagnostic tests, the evaluation and care of patients will increasingly include consideration of an individual's genome. Factoring in of the genome is already the case for known genetic markers with established disease associations. The full resequencing of a patient's DNA (genome), an overall evaluation of gene expression in clinical samples at the RNA or protein levels, and broad screening of metabolites all appear to be coming to clinical practice in the not-too-distant future. Veterinarians and physicians will use this information to help generate the differential diagnoses list for a patient, customize therapeutic strategies, and improve prognostic assessments.

In contrast to molecular biology, I have more recently recognized that cell biology also will likely have a transformative impact on the practice of medicine in a similar, not-too-distant time frame. Data are now accumulating from several medical disciplines that multipotent "stem cells" have the potential to facilitate tissue repair. I am not a stem cell expert by any stretch, but two broad mechanistic categories appear to be emerging.

The first category includes indirect mechanisms. Stem cells introduced into a patient have the potential to express and deliver the right mix of factors--such as cytokines (inflammatory mediators), chemokines (a type of small cytokine), and growth factors--at the correct concentrations and with the appropriate molecular structure to positively modulate the patient's immune response and tissue repair capabilities. The patient's own cellular resources for repair are mobilized and activated. Destructive catabolic (tissue breakdown) processes are switched to a self-sustaining anabolic (tissue growth) response. Interestingly, the introduced stem cells may not need to remain viable in the lesion area for very long to affect this switch.

The second category appears to be more challenging. It involves direct mechanisms in which the introduced stem cells themselves are expected to differentiate into the correct cell types, synthesize and organize the appropriate extracellular matrices, and regenerate normal tissue structures to achieve tissue repair. Both mechanisms work toward a restoration of tissue structure and function.

The take-home message that I now embrace and will encourage others to consider is "pay attention." Stem cells and regenerative medicine are poised to yield major clinical advances. As discussed by (Gregory L. Ferraro, DVM, associate director of the University of California, Davis, William R. Pritchard Veterinary Medical Teaching Hospital) in this issue (of Equine Disease Quarterly, Oct. 2011), many basic questions remain unanswered and there is much to learn. Our discovery process needs to be driven by rigorous scientific methods and hypothesis-driven experimental biology. However, through access to our diverse patient population, veterinary medicine has every opportunity to lead development and progress in these important areas. Yes--pay attention.

CONTACT: James MacLeod, VMD, PhD--859/ H. Gluck Equine Research Center, University of Kentucky, Lexington, Kentucky

This is an excerpt from Equine Disease Quarterly, funded by underwriters at Lloyd's, London, brokers, and their Kentucky agents.

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Equine Disease Quarterly

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