Regeneration in mammals: new data
The ability of primitive organisms, from coelenterates to reptiles, to "resurrect" from several cells or at least grow new limbs or tails left to a predator is well known, and its mechanisms are well studied. In mammals, regenerative abilities are much weaker, and they are much worse studied.
Liver tissue can increase in size when part of the organ is removed, which is often mistakenly called regeneration. However, this term is not entirely correct, since the preserved liver tissue simply increases in size in order to compensate for partially lost functions. Regeneration, on the contrary, is a process that results in the exact restoration of the size, shape and functions of the lost organ or its fragment.
Data obtained by researchers at the Institute of Regenerative Medicine at Wake Forest Baptist Medical Center during an earlier study indicate that rats are able to regenerate the removed part (up to 75%) of the bladder within 8 weeks.
If specialists manage to understand the mechanisms that ensure the regeneration of the bladder in rats, the data obtained can help in the development of methods for the restoration of other organs and tissues, the preservation of the structure of which is necessary for normal functioning, such as the intestine, spinal cord and heart.
In their new work, scientists led by Professor George Christ demonstrated that removing most of the bladder increased the rate of division and growth of certain cells in the body of rats. The most noticeable proliferative reaction was initially observed in the urothelium, a layer of tissue lining the inner surface of the bladder. When the proliferative activity of these cells weakened, it was replaced by the proliferation of cells of the muscular layer of the bladder and the fibrous ligament separating the urothelium from the muscular layer.
A drawing from an article by Charles C. Peyton et al. Characterization of the Early Proliferative Response of the Rodent Blade to Subtotal Cystectomy: A Unique Model of Mammalian Organ Regeneration, published in the journal PLOS ONE.
The authors have formulated several hypotheses explaining this process. According to one of them, urothelial cells transform and turn into stem cells capable of giving rise to all types of cells that form the bladder. It is also possible that the cells of the urothelium give signals to other cells to divide, while the damage itself stimulates the migration of stem cells into the bladder, which also contribute to its recovery.
In the future, the researchers plan to decipher the subtle mechanisms of the regenerative process and repeat the experiment on a mouse model. The ability to create lines of mice that do not have certain genes will allow us to find out the roles belonging to various genes and their protein products in the regenerative process, as well as to develop therapies that promote regeneration.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of Wake Forest Baptist Medical Center:
Scientists Identify Mammal Model of Bladder Regeneration.
18.10.2012