2010 – the year of artificial organs
The world has suffered a year of regenerative medicine
Nadezhda Markina, Infox.ru
The past year can be called the year of regenerative medicine without exaggeration. Specialists are increasingly mastering the manipulation of stem cells and using this experience for the reconstruction of tissues and organs. The successes in restoring vision are also impressive.
Victory over blindnessTwo groups of studies, using different approaches, achieved the same result – they returned visual function to the eye with retinal dystrophy.
Scientists from the University of Tübingen (Germany) have created a microchip that is implanted under the retina. The microchip measures approximately 3 by 3 millimeters and consists of 1,500 active LEDs, each of which has its own stimulating electrode. The device was tested on 11 volunteers with absolute vision loss. After implantation of the microchip, some patients were able to distinguish and describe objects. So far, the chip needs to be changed every three months, but scientists are working on creating a permanent device.
Neuroscientists from Cornell Medical College in New York have created a molecular retinal prosthesis. However, so far it has been tested only on mice with model blindness. To do this, a transgenic mouse was created, in the optical neurons (ganglion cells) of which a light-sensitive protein from blue-green algae was introduced. In this way, scientists forced neurons to perceive information without intermediaries – without rods and cones of the retina. After such manipulation, the mice regained their sight, they were able to distinguish the outlines of stationary and moving objects. The authors of the technique believe that if the light-sensitive protein gene in the neurons of the human eye is made to work, it is possible to restore people's vision.
Obtaining stem cellsThe future of regenerative medicine is connected with stem cells, so the question of possible sources of these cells is very relevant.
In laboratories around the world, scientists are looking for ways to replace embryonic stem cells (ESCs) with other cells in order to reduce the risk of developing a cancerous tumor and circumvent ethical problems. The cells of an adult organism, which are manipulated to regain the ability to develop in different ways – pluripotency, are called induced pluripotent cells (IPCs). For the first time, a team from the Harvard University School of Medicine obtained IPC from peripheral blood cells. They began to behave like embryonic cells, having received unlimited possibilities of differentiation. The method attracts with the simplicity of obtaining stem cells – you do not need to take any biopsy, only blood.
But it is even easier to reprogram specialized tissue cells of an adult organism, directing differentiation along a different path, without returning them to the initial stage of pluripotence. Such an operation with fibroblasts was performed by scientists from McMaster University in Canada. By laboratory manipulations, they obtained erythrocytes and other blood cells from fibroblasts.
A similar transformation with heart cells was performed by specialists of the University of California. They successfully reprogrammed cardiac fibroblasts, obtaining cardiac muscle cells – cardiomyocytes from them. Just as in the previous work, they managed to get past the stage of pluripotence. The scientists isolated the proteins responsible for the transformation and tested the technique on mouse hearts. The use of fibroblasts as a source for cardiomyocytes will allow treating damage to the heart muscle in heart attacks and other pathologies.
Growing cells and organsNeuroscientists from the University of the District of Columbia managed to grow capable motor neurons from embryonic stem cells of a chicken.
Scientists transplanted chicken neurons obtained "in vitro" into the spinal cord of mouse embryos. In the spinal cord, neurons independently found the right place. Such surrogate neurons, scientists expect, can be used to treat paralysis.
The staff of the medical center of the Children's Hospital in Cincinnati managed to artificially grow an entire intestine from human pluripotent stem cells. To do this, the cells were treated with growth factor proteins to simulate the development of the intestine in the embryo. In a Petri dish, stem cells formed a tissue similar in three-dimensional architecture and cellular composition to intestinal tissue. The cells of the artificial intestine had suction and secretory properties. Experts hope that the ability to obtain intestinal tissue from stem cells will help patients with necrotic enterocolitis, inflammatory diseases and short bowel syndrome.
And researchers from Georgetown University Medical Center have proposed a way to grow insulin-producing pancreatic cells from testicular stem cells. In laboratory conditions, scientists managed to force the precursors of human sperm cells to differentiate into beta cells of pancreatic islets. To do this, spermatogonia did not need genetic modification, but only treatment with growth and differentiation factors. Transplanted into mice with a model of diabetes, they began to produce insulin and lowered the level of glucose in the blood of animals. In this way, patients with type I diabetes will be able to make up for the lack of insulin, using the reserves of their own body (though only for men).
Artificial organ transplantationAn artificial heart transplant was performed for the first time in Russia at the A.N.Bakulev Scientific Center of Cardiovascular Surgery of the Russian Academy of Medical Sciences.
The 60-year-old patient suffered from severe heart pathology, without a transplant she would have died. The operation was performed by cardiac surgeon Leo Bokeria. It was successful, the woman feels well after the operation, the artificial heart is working normally. The foreign–made device has only one drawback - the 10 kg battery is located outside, and it needs to be charged every 12 hours. According to specialists of the Bakulevsky Center, currently about 1.5 thousand residents of Russia need a heart transplant.
Organ reconstruction
Last year we learned about the unique technology of tracheal reconstruction, which was developed by the surgeon, head of the clinic of the University of Barcelona Paolo Macchiarini. At the first stage, he performed a trachea transplant on the patient, which was grown in a bioreactor using a skeleton from a deceased donor and the patient's own stem cells. At the second stage of technology development, Macchiarini abandoned the bioreactor and began using his own human body for this purpose. At the same time, the donor frame of the trachea is cleaned of cells, filled with undifferentiated bone marrow cells of the patient, treated with growth and differentiation factors and placed in the body instead of the damaged organ. Inside the body, stem cells form cells of the respiratory epithelium, after which the trachea begins to work.
Nine such operations have been carried out in Europe in three years. Professor Macchiarini presented his methodology in our country and organized an internship for Russian surgeons in Italy. And here is the result – on December 7, 2010, the operation was successfully performed in Russia, at the RSC of Surgery named after Academician B.V. Petrovsky of the Russian Academy of Medical Sciences. The patient is 25 years old, she has a severe tracheal lesion after an injury. The girl suffered from severe respiratory failure. And it was this patient who was lucky: she had an operation using the described technology. The surgeons transplanted the trachea from the donor frame with the addition of bone marrow cells of the patient during a six-hour operation. After two weeks, the girl could breathe normally, move actively and speak. This is an example of regenerative medicine, the purpose of which is to reconstruct an organ using the reserves of one's own body. The surgeons of the RSC of Surgery have four more patients on the waiting list who require such an operation.
In addition to achievements in the field of medicine, the draft federal law "On cellular biomedical Technologies" proposed by the Ministry of Health should be attributed to the results of 2010. The bill caused a negative assessment of doctors and researchers working in the field of cellular technologies, as well as heads of departments of the Russian Academy of Sciences and the Russian Academy of Medical Sciences. According to the general opinion, if this law is adopted in this form, it will greatly push Russia in one of the most promising areas of medicine. Experts' comments on the draft law Infox.ru will publish in the near future.
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13.01.2011