Combining the capabilities of your basic desktop inkjet printer and those of a cotton candy maker, scientists have produced artificial cartilage that may one day help people regrow cartilage lost due to injury or the long-term wear of osteoarthritis.
This new work, by researchers at the Wake Forest Institute for Regenerative Medicine, builds upon previous bioprinting efforts, which used a technique of laying down tissues cells in a gel medium, similar to how an inkjet printer lays down ink on the page as it prints. They added to the process what's called 'electrospinning' — using electric charge to spin very fine, nanoscale fibres from a polymer liquid, similar to how a cotton candy maker spins sugar solution into a fluffy, fibrous treat — to produce a kind of 'scaffold' to support the printed cells.
This new hybrid technique allowed the research team, led by Dr James Yoo, to print cartilage structures that were far stronger and more durable than those produced only with the 'inkjet' method. The fine control provided by the electrospinning machine also allowed them to produce fibres that were porous, which would help the implants to integrate with the person's body.
To test their method, the researchers laid down successive layers of electrospun polymer sheets and bioprinted cartilage cell solution, creating small mats of the material. These were left for a week and then tested with a series of weight to see if the cartilage cells were still alive. They found that 80 per cent of the cells survived, and those survivors thrived in the polymer 'scaffold'.
Further tests with implanting the hybrid tissues into mice found that they held up well and, after eight weeks, demonstrated the properties typical of elastic cartilage. According to the team, this indicated that these structures showed promise for implantation into human patients.
"This is a proof of concept study and illustrates that a combination of materials and fabrication methods generates durable implantable constructs," said Yoo. "Other methods of fabrication, such as robotic systems, are currently being developed to further improve the production of implantable tissue constructs."
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