It's a well-known fact that our skin protecting us from diseases. And when it's damaged by severe burns or injuries, we need to replace it by healthy tissue, which is not always possible. But now, researchers at the University of Sheffield have developed a dissolvable scaffold for growing new areas of skin. These microscopic 3-dimensional scaffolds, made from specially developed polymers, look similar to tissue paper but have fibers 100 times finer. Skin cells are put on these scaffolds and grow over them. After enough skin is grown, the scaffold is put over the wound and dissolves over several weeks without any risk of rejection. The researchers think that this technology will move out of the lab in a few years. But read more...
Before going further, here is a diagram of our full dermal structure (Credit: Barry Kaye, CookandKaye, via the University of Sheffield). Such a structure is beyond current technology, but useful engineered tissues have been developed, and are in clinical use.
But why using scaffolds to develop 3D tissues?
To mimic natural tissues, communities of cells of many different phenotypes must develop at pre-determined locations in three dimensions. Tissue engineers try to replicate this development in vitro using scaffolds. Two different types of tissue-engineering approach are being followed:
Smart scaffolds include chemical and/or biochemical markers that encourage cell differentiation or colonisation. These markers may be localised, in an attempt to prepare fully differentiated tissues in vitro.
Dumb scaffolds are chemically homogeneous. Preparing tissues in vitro using these relies on 'smart cells' to differentiate according to their location in the 3D matrix, or using simple stratagems, such as inoculating different areas or surfaces of the scaffold with different types of cells.
After this introduction, let's move to the University of Sheffield news release to learn how these new microscopic scaffolds work.
This ultra-fine, 3-dimensional scaffold, which is made from specially developed polymers, looks similar to tissue paper but has fibres 100 times finer. Before it is placed over a wound, the patient's skin cells (obtained via a biopsy*) are introduced and attach themselves to the scaffold, multiplying until they eventually grow over it. When placed over the wound, the scaffold dissolves harmlessly over 6 to 8 weeks, leaving the patient's skin cells behind.
This new approach to skin reconstruction has been developed by a team of chemists, materials scientists and tissue engineers at the University of Sheffield, with funding from the Engineering and Physical Sciences Research Council (EPSRC). It is designed primarily for cases involving extensive burns where surgeons are unable to take enough skin grafts from elsewhere on the body to cover the damaged areas. Currently, bovine collagen or skin from human donors is used in these cases, but these approaches have potential health and rejection risks.
Below is a microscope image of skin cells growing on scaffold fibers (Credit: University of Sheffield and EPSRC). "In this (fluorescent) image, the fibers are red and the cell nuclei blue."
And when this technology will be used in the real world?
The next step in the research is to develop the skin reconstruction technology for clinical use, hopefully in the next few years. The technology also offers possibilities for testing the toxicity of cosmetic and similar products, using materials grown in the laboratory that closely resemble natural skin.
For more information about this research effort, you can visit the Sheffield Polymer Centre web site. And you can read in particular these two pages about tissue engineering, here and there.
Sources: University of Sheffield news release, June 27, 2006; and various web sites
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