To understand how cell therapy works, it helps to understand the role of cells in the body. Cells are the basic building blocks of the human body. These tiny structures compose the skin, muscles, bones and all of the internal organs. They also hold many of the keys to how our bodies function. Cells serve both a structural and a functional role in the body, performing an almost endless variety of actions to sustain the body's tissues and organs. [Source: Stem Cell Research Foundation].

There are hundreds, perhaps thousands, of different specialized cell types in the adult body. All of these cells perform very specific functions for the tissue or organ they compose. For example, specialized cells in the heart muscle "beat" rhythmically through the conduction of electrical signals, while the cells of the pancreas produce insulin to help the body convert food to energy. These adult/tissue cells have been differentiated, or dedicated, to performing their special tasks. Scientists believe that under normal conditions, once a cell has become specialized, it cannot be changed into a different type of cell.

Like the body itself, cells have a finite life span; they eventually die. Most of the body's cells divide and duplicate throughout life, but some cells either don't replenish themselves or do so in such small numbers that they cannot replace themselves fast enough to combat disease [Source: Stem Cell Research Foundation]. Other cells accumulate toxic proteins, as in Alzheimer's Disease.

While cells perform all the vital functions for the body, they can also exist outside the body. They can live and divide in "cultures," in special solutions in petri dishes in incubators. This ability of certain cell types to live isolated from other cells under controlled conditions has allowed scientists to study them independently of the organ they are normally a part of. Through the isolation and manipulation of cells, scientists are finding ways to identify young, regenerating stem cells that can be used to replace damaged or dead cells in diseased organs. This therapy is similar to the process of organ transplant, only the treatment consists of the transplantation of cells rather than organs. This form of therapy is also referred to as regenerative medicine [Source: Stem Cell Research Foundation].

Even though most of the work done in this field has been experimental, most scientists find cell therapy so promising that they believe it is only a matter of time before its use becomes routine. And while many of the hoped for uses of cell therapy sound futuristic, there are a few forms of this technique that have already been in use for years. Bone marrow transplants are an example of cell therapy in which the stem cells in a donor's marrow are used to replace the blood cells in patients after they are treated for leukemia and other cancers. Cell therapy is also being used in experiments to graft new skin cells to treat serious burn victims, and to grow new corneas for the sight-impaired. In all of these uses, the goal is for the healthy cells to become integrated into the body and begin to function like the patient's own cells.

So far, the results of such experiments have exceeded expectations. In a recent advance, pancreatic cells isolated from cadavers have been implanted successfully in juvenile diabetes patients to restore insulin-producing cells. Even though cell therapy is a new science, early results like the above have caused great optimism in the scientific community. However, there are several scientific challenges that must be overcome before we can truly harness the power of stem cells.

One of the first challenges that must be overcome for stem cell therapies to become more commonplace is the difficulty of identifying tissue stem cells in cultures of adult tissues, which contain numerous types of cells. While scientists are discovering new cell types almost every day, they estimate that there could literally be thousands of human cell types. The process of identifying any desired type of stem cell will involve painstaking research, which is ongoing. Second, once stem cells are identified and isolated, the right biochemical solution must be developed to cause these early cells to change into the desired cell type. This too will require a great deal of experimentation and is the topic of many research laboratories.

Assuming that the above obstacles have been overcome, new issues arise when the cells are implanted into a person. The cells must be integrated into the patient's own tissues and organs and "learn" to 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.

Yet another challenge is 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. Organ recipients must take drugs to suppress their immune systems for the rest of their lives.

Yet another concern is the possible risk of cancer. Cancer results when cells lose their internal "brakes" and keep dividing when further proliferation is no longer desirable. Researchers must find the delicate balance between fostering the growth of new cells to replenish damaged tissues and making sure that cells don't overgrow and become cancerous. However, most scientists believe that, with the appropriate research, these obstacles can be overcome. [Source: Stem Cell Research Foundation].

Despite the many challenges, most scientists believe that cell therapy will revolutionize medicine. With the use of cell therapies, we may have new treatments for cancer, Parkinson's, diabetes, kidney disease, multiple sclerosis, macular degeneration and a host of other diseases. Cell therapies have also shown promise in helping to repair catastrophic spinal injuries, and helping victims of paralysis regain movement. While we will undoubtedly encounter the limits of cell therapy one day, there is every reason to hope that this revolutionary new approach will result in radically improved ways to treat disease [Source: Stem Cell Research Foundation].

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