American College of Physicians: Internal Medicine — Doctors for Adults ®


Panelists highlight advances in pharmacogenetics, tissue engineering

Pharmacogenetics--the study of how genetic differences among patients are reflected in their responses to medications--has the potential to make individualized medicine a reality, one of the promises of the Human Genome Project.

The ability to tailor medication regimens to specific patients "should improve efficacy and decrease the side effects of prescribed drugs," said Matthew R.G. Taylor, MD, PhD, a panelist in this morning's session, "Exciting research advances: Skeletal tissue engineering and pharmacogenetics. "It will move us away from our current one-size-fits all model in which typically all patients receive the same medication at the same dose."

Familiar drugs that work reliably in most patients can be ineffective in others, and even potentially harmful, said Dr. Taylor, director of adult clinical genetics at the University of Colorado Health Sciences Center in Denver. The genetic causes of these variabilities are beginning to be identified in recent research.

Dr. Taylor will discuss two widely used drugs/drug classes, Coumadin (warfarin sodium) and beta-blockers, as examples of advances in the field. His presentation will attempt to answer the question, "Which pharmacogenetic tests are ready (or nearly ready) for the clinic?"

Researchers in the field of pharmacogenetics are now poised to identify a number of genetic variants that influence how patients respond to commonly prescribed medications, said Dr. Taylor.

"Until recently, examples of pharmacogenetic markers for drug response had been restricted to relatively rare diseases and circumstances," he said. "However, there are accumulating data identifying these types of variants in more common diseases, and these findings will have a broader relevance."

Tissue engineering

A promising approach to the treatment of osteoarthritis lies in the replacement of damaged cartilage through tissue engineering. Articular cartilage, once damaged, lacks the ability to repair itself. Cartilage tissue engineering is focused on meeting the load-bearing demands of this tissue in the human body.

Rocky Tuan, PhD

Rocky Tuan, PhD

"Tissue engineering is an exciting, emerging scientific field that combines the principles of life sciences and engineering for the purpose of developing new tissues to replace diseased or damaged tissue and restore function," said session panelist Rocky S. Tuan, PhD, chief of the Cartilage Biology and Orthopaedics Branch of the National Institute of Arthritis, and Musculoskeletal and Skin Diseases. "The aims of tissue engineering are twofold: to develop tissue de novo and to induce tissue regeneration. Regenerative medicine, as a new paradigm, should greatly expand treatment options for patients suffering from degenerative joint diseases."

That's especially relevant as the U.S. population ages and joint problems become more widespread. According to the Arthritis Foundation, osteoarthritis affects an estimated 21 million Americans and results in more than 50% of the country's total joint replacements.

Recent work by Dr. Tuan and others has focused on several areas:

  • the selection and culture expansion of appropriate cells, such as adult mesenchymal stem cells, for cartilage tissue engineering;

  • the design and fabrication of novel scaffolds, with materials including nanofibers and hydrogels, to be used in cell-based, three-dimensional tissue engineering;

  • the controlled stimulation of stem cell growth and differentiation into chondrocytes with appropriate bioactive molecules such as growth factors; and

  • articular cartilage repair in animal models using tissue-engineered cartilage constructs.

"At present, total joint replacement using metallic/polymer implants is the treatment of choice for end-stage osteoarthritis," said Dr. Tuan. "In comparison to arthroplasty, the biological nature of the tissue engineering/regeneration approach opens an additional window of opportunity for pharmacological therapeutics that may be targeted to the new tissue to improve the clinical outcome."

David E. Steward, MACP

David E. Steward, MACP

Both sessions will be moderated by David E. Steward, MACP, professor and chairman of the department of medicine at Southern Illinois University.

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