"Elixir of youth" for nerve stem cells
Scientists from the University of Hong Kong and the Massachusetts Institute of Technology published an article entitled "Forever Young" in the December issue of the journal Cell Transplantation: How to Control the Elongation, Differentiation, and Proliferation of Cells Using Nanotechnology", containing the results of work on the study of the possibility of maintaining the "eternal youth" of stem cells by slowing their growth, differentiation and proliferation.
According to the authors, the storage and implantation of viable stem cells to repair damage to the nervous system is quite a difficult task, compounded by the fact that the restoration of nervous tissue itself is associated with certain difficulties. They claim that the creation of a special microenvironment that controls the activity of cells by slowing down their proliferation and maturation will help to solve these problems for tissue engineering specialists. As the main component of such a microenvironment, they suggest using a self-assembling nanofiber scaffold (SAPNS), which not only regulates cell division and tissue growth, but also protects implanted cells from inhospitable conditions of the recipient's body.
As a material for the frame, the researchers used the RADA16-I oligopeptide developed several years ago at the Center for Biomedical Engineering at the Massachusetts Institute of Technology. It consists of a four-fold repeated sequence of amino acids arginine (R), alanine (A), aspartic acid (D) and again alanine (the letter designations of amino acids are adopted by the International Union of Theoretical and Applied Chemistry). In an aqueous solution, these amino acid chains are assembled into a gel in which the distances between the fibers depend on the concentration of the oligopeptide.
Such a framework, imitating the intercellular matrix, not only provides the implanted neural stem cells with a substrate for adhesion and migration, but also limits the invasion of cells from the tissues surrounding the transplant. It also slows down the rate of cell growth and differentiation, which facilitates their "acclimatization" in new conditions and allows them to maintain their ability to divide indefinitely for a long time.
Under laboratory conditions, changes in cell density and SAPNS fiber concentration allowed scientists to change the nanoenvironment of PC 12 cells (a cell line derived from transplantable rat cells reacting to nerve growth factor), Schwann cells (glial cells that ensure the viability of peripheral nerve fibers) and precursor nerve cells, as well as control their proliferation, elongation, differentiation and maturation.
Experiments on animals implanted with cells and nanocars in brain and spinal cord injuries have also shown good results. The picture shows the state of the brain areas after a rather large (scale size – 0.1 mm) incision made with a scalpel. On the left is a section of the brain tissue of a control animal that was injected with only a saline solution into the wound, on the right is an incision into which a 1% RADA solution was injected, 2 months after the injury, almost filled with new cells.
The researchers concluded that the use of a combination of SAPNS and stem cells makes it possible to abandon the use of immunosuppressants when using cellular implants to repair damage to the central nervous system. They believe that their proposed technique will eventually allow not only to restore injuries to the central nervous system, but also to rejuvenate aging brains.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on ScienceDaily: 'Fountain of Youth' for Stem Cells?
13.01.2010