On the Uses of Stem Cells

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.

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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The Flu Vaccine

As new cases and concerns about seasonal flu and swine flu (H1N1) continue to spread worldwide, two vaccines have recently been made available. Both the nasal spray vaccine and injectable vaccine for seasonal flu have proven effective for specific portions of the population, however distribution is still slow. For the H1N1 (swine flu) virus, The Baltimore Sun reports, availability is still an issue and many areas have not yet received enough doses to meet the demand. While many in the developed world do not yet have access to the H1N1 vaccine, Dr. Bernadine Healy notes that the problem is even greater in the developing world. To help these nations fight the pandemic, the United States has agreed to donate 10 percent of its vaccination supply to the World Health Organization (WHO) – eight other nations will make similar donations.

Inoculating individuals for both viruses is complicated by the time frame in which the vaccinations can occur. If one chooses nasal spray for both seasonal and swine flu, they must wait four weeks between doses, while if one is injected for one virus and uses nasal spray for the other, they can be administered together. Discovery Health reports that doctors recommend annual flu shots to lessen the chances of becoming ill. Individuals as young as six months can be inoculated, according to the Centers for Disease Control and Prevention (CDC) and side effects are reported to be minor. Because the virus used to make the seasonal flu vaccine is dead, it is not possible to contract flu from a flu shot, however one may expect a low-grade fever 8 to 24 hours following injection, a swollen or tender area around the injection site, a slight headache or chills within 24 hours.

The seasonal flu shot is an inactivated vaccine, and contains three influenza viruses – one A(H3N2) virus, one regular seasonal A(H1N1) virus (which differs from the 2009 H1N1 virus), and one B virus. The viruses used change annually based on international surveillance which track infection trends and scientists estimations about which strains will circulate during the year. In contrast to the flu shot, the nasal-spray flu vaccine contains a weakened but still living flu virus, sometimes called LAIV (live attenuated influenza vaccine). These nasal mists are approved for use in healthy individuals ages two to 49 who are not pregnant. In addition to nasal sprays, Discovery Health reports that researchers at Stanford University and the University of Alabama at Birmingham have been working with naked DNA in an effort to develop a vaccine that could be delivered via shampoo or dermal patch.

Three recent large-scale studies, including a study led by Dr. Arnold S. Monto of the University of Michigan, indicate that while the seasonal flu shot is more effective for adults and safe for women who are pregnant, the intranasal vaccine (nasal spray) is more effective at preventing flu in children. These studies showed 35 to 53 percent fewer cases of flu in children who were given the nasal spray vaccine than those who received injected vaccines. The Los Angeles Times reports that injectable vaccines prevent roughly 50 percent more seasonal flu in healthy adults than the nasal spray vaccines.

Due to the relative newness of the H1N1 vaccine, health authorities have implemented a number of tracking measures to ensure its safety. The Associated Press reports that Harvard Medical School scientists are working to link insurance databases covering 50 million people with vaccination registries to allow them to determine if people visit a doctor after being vaccination as well as the reason for the visit. Johns Hopkins University and the CDC are also working to ensure that any side effects are noted and addressed quickly. These efforts include emailing individuals who have been vaccinated recently to see how they are feeling (Johns Hopkins), and preparing take-home cards asking vaccine recipients to report any side effects to the nation’s Vaccine Adverse Event Reporting system (CDC). These measures are being undertaken as in the Internet-age, the Associated Press notes, one person updating their Facebook status to say that they got a flu shot and feel sick could cause a wave of similar reports.

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Associated Press on the Nasal Spray Flu Vaccine - The New York Times on CDC Side Effect Tracking Measures