On the Uses of Stem Cells

October 27, 2009

Though their use remains controversial, new research and innovative procedures indicate that stem cells may be applicable in more situations than previously thought. Stem cells are immature cells with the ability to grow into any type of tissue. Scientists have worked for years to perfect methods of extracting and directing these cells to grow into different tissue types to heal injuries and cure diseases. In addition to human embryonic stem cells (hESCs), methods of using patient specific cells in regenerative medicine are being refined. Like embryonic stem cells, induced pluripotent stem cells (iPS cells) have the potential to become any type of cell in the body. Because iPS cells are made by “rewinding” adult cells to their pluripotent state – a state from which they can grow into other types of tissue – they can be created from a patient’s own tissues, thus lessening or eliminating the risk of rejection. According to the Los Angeles Times, iPS cells could be used to grow insulin-producing beta cells for patients with diabetes or nerve cells for patients with spinal cord injuries.

Amazing Image by Deborah Ervin

Using this type of “adult stem cells,” researchers at the Wayne State University School of Medicine have developed a procedure to increase mobility and quality of life for patients with spinal cord injuries. The process involves the use of progenitor cells from a patient’s own nasal tissue, thus lessening the chances of rejection, tumor formation, and disease transmission sometimes experienced when using donated tissue. Twenty patients with severe chronic spinal cord injuries took part in the Wayne State University study, led by Associate Professor Jean Peduzzi-Nelson. Each received a treatment of partial scar removal in combination with transplantation of nasal tissue and physical rehabilitation. Results from participants, including one paraplegic individual who is now able to ambulate with two crutches and knee braces, indicate that the transplantation of nasal tissue (an “olfactory mucosal autograft”) is an effective and safe treatment for individuals with chronic spinal cord injuries.

Other types of adult cells have also been used for transplantation to damaged tissues. At the Cincinnati Children’s Hospital Medical Center, fat stem cells from a 14-year-old boy were used to form cheekbones that the young patient lacked. This new technique has the potential to benefit approximately seven million people in the United States, including individuals with various forms of cancer, and those injured in conflict situations. A section of bone from a donated cadaver was shaped to resemble zygomatic bones and act as a support structure for the growth of new tissue. Mesenchymal stem cells from the patient’s fat and a growth-encouraging protein were injected into holes in this bone base. Before implantation, the research team wrapped the grafts in periosteum tissue, which helps encourage stem cells to produce bone tissue. Stem cells were harvested from fat tissue as they exist in similar proportions as in bone marrow tissue, but do not require invasive procedures to gather them.

Using embryonic stem cells from mice, researchers have been able to successfully create a “heart patch” to repair damage caused by heart disease. Bioengineers at Duke University created a 3D mold and used it to grow heart muscle cells or cardiomyocytes. In addition to the mold used to ensure that the cells would not grow as a disorganized mass, cardiac fibroblasts, which comprise up to 60 percent of the heart, were added. These cells helped to guide the growth of the patches and properly align the cells so that they would have properties similar to heart tissue. The heart patches created displayed critical features of heart muscle – the ability to contract and to conduct electrical impulses.

Studies indicate that transplants using pigment-containing visual cells derived from hESCs have also had some success. In individuals who underwent these procedures, structure and function of the light-sensitive lining and the eye (retina) were preserved. For millions who lose their sight or experience low-vision, this type of cell-replacement procedure could prove beneficial. Jennifer Elisseeff, associate professor in biomedical engineering at Johns Hopkins University, and her team have also utilized stem cells to repair damaged and deteriorating knee cartilage. In addition, Elisseeff’s team is working to enable stem cells to reconstruct muscle and fat lost during surgery or trauma and developing an eye patch constructed of special biomaterial derived from collagen to help repair damage to a patient’s cornea.

The use of hESCs remains controversial, though the Obama administration has lifted Bush-era restrictions on federal funding for research based on their use. iPS cells offer an alternative that may prove as beneficial or more so as there is no risk of rejection of the transplanted tissue. For patients with spinal cord injuries, deteriorating vision, compromised heart function, and many other health concerns, treatments using stem cells may offer an opportunity to heal that would otherwise not be available.

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