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Regenerative medicine will lead to the creation of fully biologic or biohybrid (part biologic, part synthetic) tissues and organs that will enable doctors to replace damaged tissue with healthy tissue that is accepted by the body and functions normally.

Cell-based tissue regeneration, or cellular therapy, is one of the most promising and exciting areas of biomedical research. Its goal is to repair damaged and diseased tissues by transplanting healthy new cells to the affected site. Bone marrow transplant, which has been used for more than 50 years to treat leukemia, is a widely used, successful form of cellular therapy.

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Cell-based tissue regeneration has exploded in recent years due to the identification of new sources and types of stem cells, discovery of new differentiation pathways, and advances in purification, culture, and other technologies.

Opportunities

There can be no discussion of cellular therapy without stem cells, which are often considered the fundamental tool of regenerative medicine. Stem cells are the progenitors of all cells within the body, have the ability to self-renew for long periods, and are pluripotent — able to be directed to differentiate into various tissue types. This offers enormous promise for regenerating various tissues compromised by disease, trauma and aging.

There are a number of congenital defects and acquired diseases for which there are no effective drug therapies. It is for these conditions that, perhaps, cellular therapies represent the most hope: diseases such as Duchenne Muscular Dystrophy, epilepsy and Parkinson’s Disease, but also chronic conditions such as coronary artery disease, sexual dysfunction and diseases of the immune system.

Challenges

Despite its promise, cellular therapy research is still a young field of study. Most of the encouraging data has come from laboratory studies. There remain many challenges to be addressed before it becomes a widely viable treatment, including:

• Directing cells to the proper place. Consider the prospect of injecting stem cells into the body by way of the circulatory system. How many of these cells will eventually find their way to the target tissue? How many will survive the journey and remain in good health?
• Integrating cells with the patient’s own tissue so that they function in concert with the body’s natural cells. Cardiac cells that beat in a cell culture, for example, may not beat in rhythm with a patient's own heart cells. And neurons injected into a damaged brain must become "wired” into the brain's intricate network of cells and their connections in order to work properly.
• Overcoming the phenomenon of tissue rejection. Just as in organ transplants, the body's immune cells will recognize transplanted cells as "foreign," setting off an immune reaction that could cause the transplant to fail and possibly endanger the patient. Cell recipients would have to take drugs to temporarily suppress their immune systems, which in itself could be dangerous.