Hybrid 3D printer yields implantable cartilage

The printer is a combination of two low cost fabrication techniques: a traditional ink jet printer and an electrospinning machine. Combining these systems allowed the scientists to build a structure made from natural and synthetic materials. Synthetic materials ensured the strength of the construct and the natural gel materials provided an environment that promoted cell growth. In this study, the hybrid system produced cartilage constructs with increased mechanical stability compared to those created by an ink jet printer using gel material alone. The constructs were also shown to maintain their functional characteristics in the laboratory and a real life system. The key to this was the use of the electrospinning machine, which uses an electrical current to generate very fine fibres from a polymer solution. Electrospinning allows the composition of polymers to be easily controlled and therefore produces porous structures that encourage cells to integrate into surrounding tissue. "This is a proof of concept study and illustrates that a combination of materials and fabrication methods generates durable implantable constructs," said James Yoo, a professor at the Wake Forest Institute for Regenerative Medicine. "Other methods of fabrication, such as robotic systems, are currently being developed to further improve the production of implantable tissue constructs." Flexible mats of electrospun synthetic polymer were combined, layer by layer, with a solution of cartilage cells from a rabbit ear that were deposited using the traditional ink jet printer. The constructs were square with a 10cm diagonal and a 0.4mm thickness. The researchers tested their strength by loading them with variable weights and, after one week, tested to see if the cartilage cells were still alive. The constructs were also inserted into mice for two, four and eight weeks to see how they performed in a real life system. After eight weeks of implantation, the constructs appeared to have developed the structures and properties typical of elastic cartilage, demonstrating their potential for insertion into a patient. The researchers believe the cartilage constructs could one day be clinically applied by using an MRI scan of a body part, such as the knee, as a blueprint for creating a matching construct.