Capillaries for tissue engineering
Breakthrough in regenerative medicine: blood vessels for bioengineered tissuesLifeSciencesToday based on Rice University materials:
Biomedical breakthrough: blood vessels for lab-grown tissues
Scientists at Rice University and Baylor College of Medicine (BCM) have destroyed one of the main obstacles to growing tissues for transplantation in the laboratory. They have found a way to grow blood vessels, including capillaries, necessary to maintain tissue life.
The new study (Covalently immobilized platelet-derived growth factor-BB promotes angiogenesis in biomimetic poly(ethylene glycol) hydrogels), which will be published in the January issue of the journal Acta Biomaterialia, is available online.
"The impossibility of vascularization – the formation of a vascular network – in laboratory–grown tissues is the main problem of today's regenerative medicine," says Jennifer West, the lead co-author of the article, professor of bioengineering and head of the department at Rice University. "If there is no blood supply, it is impossible to get a tissue structure thicker than a few hundred microns."
As a base material, a group of researchers led by West and BCM molecular physiologist Mary Dickinson chose polyethylene glycol (PEG), a non–toxic plastic widely used in medical devices and the food industry. Based on the 10-year experience of the West laboratory, scientists modified PEG, imitating the extracellular matrix of the body – a network of proteins and polysaccharides that make up a significant part of most tissues.
West, Dickinson and their colleagues combined modified polyethylene glycol with two types of cells, both of which are necessary for the formation of blood vessels. Using light that transforms PEG polymer filaments into a three-dimensional gel, they obtained a soft hydrogel containing living cells and growth factors. By marking both cell types with different fluorescent markers, the scientists were able to observe how the cells slowly form capillaries in the entire mass of the soft plastic gel. (The 13-second clip shows the growth of capillaries, which took 72 hours in real time.)
To test the new networks of blood vessels, scientists implanted a hydrogel into the cornea of the eye of mice, where there is no natural blood supply. The introduction of the dye into the blood of animals confirmed the existence of normal blood flow in the newly formed capillaries.
Another key achievement, published last November by West and graduate student Joseph Hoffmann, is the development of a new technology called "two–photon lithography" - an ultra-sensitive method of using light to create complex three-dimensional structures in soft PEG hydrogels. West believes that this technology will allow engineers to exercise fine control over where cells grow and where they move. In further experiments, also in collaboration with the Dickinson Laboratory, West and her group plan to use their method to grow a vascular network in gel matrices with a predetermined, not randomly formed structure.
Portal "Eternal youth" http://vechnayamolodost.ru
14.01.2011