As an intern at COSMOS Online:
A new technique that uses electricity to engineer human tissue may have the potential to tailor-make bone marrow.
The technique uses electric fields to build up layers of cells to form a tissue. It is based on a phenomenon called dielectrophoresis, which is essentially the electrical equivalent of the attraction of iron filings to the poles of a magnet.
"The use of electricity enables greater control over the position of the cells than conventional techniques," said Gerard Markx of the University of Manchester, who is developing the technique.
Conventional tissue engineering typically involves either creating a polymer scaffold onto which cells are grown, or starting with a liquid suspension of cells that later hardens to form a gel. There is little control over the position of the cells, which is a significant drawback in engineering multicellular tissues in which cells have to be specifically positioned.
Markx and his team use a "bottom-up" approach, in which tissues are painstakingly built up in layers. Each layer is designed using dielectrophoresis; cell positioning is controlled by an electric field that is stronger in some areas and weaker in others. The electric field is supplied via microelectrodes measuring between 50 to 250 microns in size, and is dispelled once the cells are suitably placed.
Because the technique relies predominantly on the structure of the electric field, it may be applied in wide range of tissue engineering. According to Markx, "as long as you can get the cells in suspension, you can use the technique to build tissues with them".
"In theory, it is possible to make reactors in which blood is produced," he said. "This could be useful for example for the production of rare blood types or cell types."
The team has already built tissue of up to 200 microns thick and created some basic haematon structures in the laboratory. Haematon is a multicellular structure found in bone marrow with the ability of creating all types of blood cells that can be found in the body, and is thought to be dysfunctional in patients suffering from bone marrow diseases like leukaemia.
The success of tissue engineering will allow organs to be grown on spec, avoiding waiting lists for organ donations, as well as problems from immune reactions towards transplanted organs. The creation of haematon may also answer a number of questions about stem cell biology.
"We have shown that we can recreate [haematon] with dielectrophoresis," Markx said. "The next step is to vary the composition of the haematon, and the position of the cells in particular, to find out how this affects stem cell development."
