Making bones about it

Replacement skin, cartilage, bone and membranes could be made to order using a Bioplotter, an automated device capable of producing 3D replicas.

Replacement skin, cartilage, bone and membranes could be made to order using an automated device capable of producing 3D replicas.

The Bioplotter, under development by German tissue engineering firm Envisiontec, acts in a similar way to a rapid prototyping machine and uses cultures of the patient’s own cells to build new structures layer by layer.

Imaging technology, such as ultrasound, computer-aided tomography (CAT) or magnetic resonance imaging (MRI), is used to provide physical data to a CAD software system.

From these scans the Bioplotter creates a digital data model of the structure to be built. It then dispenses cells producing a 3D arrangement of biological and biocompatible material, said the managing director of Envisiontec, Hendrik John.

The company is expecting to receive approval from government agencies such as the US Federal Drug Administration in the next few years.

‘Bioplotter is still in the R&D stage,’ said John. ‘It will take a couple of years to develop into an industrial process and gain approval from the FDA and others. There is still a lot of work to do, and we need surgeons and chemists who are experts in biomaterials.’

The device builds replacement tissue in two stages. A ‘scaffold’ is made from a porous biocompatible material, such as collagen, silicon or a thermoplastic, and cultured cells, originally drawn from the patient, are laid over it.

The human tissue can then be separated from the supporting structure and transplanted into the patient. Alternatively, biodegradable scaffolding could be used and the entire object could be transplanted. It breaks down within the body and as it does so the material is replaced by the cells as they grow and multiply.

Researchers at Leicester University are developing scaffold material for knee injuries using a polymer which degrades in the body into naturally-occurring hyaluronic acid.

In the case of bone, the biodegradable polymer and cell structure would be transplanted into the patient and new bone would grow into the scaffold, eventually replacing it completely after one to two years, said John.

As the process uses the patient’s own cells, the resulting body parts will not be rejected in the way that traditional tissue grafts are. These usually come from other people and sometimes other species. The immune system attacks this tissue as it is ‘foreign’ so the patients must take immune suppressant drugs for the rest of their lives.

Researchers at the University of Sussex are also aiming to use rapid prototyping technology to create artificial body parts from biocompatible plastics or titanium.

Patients needing an artificial hip, knee joint or skull fragment would be scanned using MRI, CAT or ultrasound to produce a 3D image of the area. The rapid prototyping system, under development by Dr Panos Diamantopoulos, would then be used to model the replacement part.