An interesting attribute of biomedical engineering is its constant evolution in conjuncture with theory. A previous article on this site describes the tissue engineering technique of cell sheet layering (pioneered in 2003). This technique has developed much since then, and several advances has been made by the same laboratory responsible for the original research.
As stated previously, one main challenge of cell sheet engineering is vascularization of three dimensional tissue constructs. The researchers at Tokyo Women’s Medical University have continued developing their technique, and have recently (2011) found a way for the cells in cell sheet layers to assist in their own vascularization. They found that creating a micropattern on the surface of thermoresponsive polymer culture dishes caused human fibroblast cells to align, altering their physical and biochemical action. Alignment is caused by intracellular receptors which bind to the cell’s environment and relay information about the culture surface back to the cell. This physical feedback has a powerful effect on the chemistry of the cell, and in this case causes human fibroblasts to release a protein known as VEGF (Vascular Endothelial Growth Factor). VEGF is widely recognized as the main activator in angiogenesis, and inducing its expression is a critical step forward in engineering vascular 3D tissue.
The presence of VEGF alone, however, is not enough to promote angiogenesis (though it is the first step in a complicated process). The biochemical environment of the body is extremely complex, so researchers must find ways to combine the correct cell types, growth factors, and mechanical stimuli to induce and maintain blood vessel growth in engineered tissues. Once this strategy matures, the implications are immense. Already, scientists have successfully fabricated many types of tissue at a basic level such as heart, lung, and neural tissue. Once it becomes possible to create fully vascularized tissues, the restrictions in place now will be greatly reduced, allowing for the development of much more complex tissue cultures such as fully functional, biologically engineered organs.
To learn more about cell sheet engineering, click here
