On Organ Donation

November 29, 2011

As of October 2011, a reported 112,178 patients in the U.S. were awaiting organ donations and every 11 minutes another individual is added to the waiting list. Though an average of 75 people per day receive organ transplants daily and more than 86 million people in the U.S. are registered as donors, a critical shortage of organs remains. Increasing information about the importance of donation could help to encourage new donors and save lives.

Organs and tissues including heart, kidneys, liver, lungs, skin, and corneas can all be donated and transplanted. According to experts, the organs and tissue from a single donor could help as many as 50 recipients. There are no age restrictions for donors, and depending on the type of donation, organs may come from a deceased or living donor. Current data indicates that as of October 7, 2011 there had been 113,693 living donors and 143,662 deceased donors since the tracking of organ donation was initiated.

Any individual is eligible to register as an organ donor, though the process for registering varies by state. If an individual who was not a registered donor dies due to massive trauma to the brain or is declared brain dead and cannot be revived, the individual’s family members must authorize the donation of the individual’s organs. Only organs with blood and oxygen flowing through them at the time of donation are viable for transplant, and each must be transplanted within hours to help prevent rejection by the recipient. When organs become available, they must tissue and blood typed to identify the appropriate individual on the transplant waiting list who is a match, as well as ensuring that they are the appropriate size for the recipient.

The recovery of organs for transplant is performed by a team of surgeons, nurses, and the transplant coordinator in the operating room where the donor received care. Just prior to removal, each organ is flushed free of blood and then placed in a sterile container for transportation to the recipient’s transplant center. Organs must be transplanted quickly – hearts and lungs within four hours, livers within 12-18, and kidneys within 24-48 hours of removal from the donor.

The risks associated with receiving an organ transplant are outweighed by the benefits as individuals receiving transplants are those who would not be able to survive without them. Though all organ recipients must take anti-rejection drugs following transplant, reports indicate that 15 percent still suffer some rejection in the first year. In addition, though the Centers for Disease Control and Prevention (CDC) reports that though the risk of disease transmission from donated organs is rather small, between 2007 and 2010 more than 200 cases of suspected transmission were investigated. To increase the safety of organ transplants, the CDC has drafted new guidelines for advanced organ testing which would screen for hepatitis B and C as well as HIV.

In 2010, 28,665 organ transplants were performed, but reports indicate that as many as 6,000 Americans die each year while waiting for a transplant. By encouraging individuals to consider registering as donors, it may be possible to save thousands of lives each year.

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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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