HEALING PROCESS

The global search to improve the growth process of bone tissue could be over with new advances by the Royal College of Surgeons of Ireland.

A NEW technique to accelerate the growth of bone tissue has been developed by engineers from Siemens and researchers from the Royal College of Surgeons of Ireland (RCSI).

Prof Fergal O'Brien, an associate professor in the anatomy department at the RCSI, said the project aims to halve the time required to produce bone tissue for use in some of the four million bone replacement procedures performed each year.

"Usually when someone has a fracture that won't heal or a cancer-related surgery, bone has to be taken from elsewhere in the body by way of a bone graft," he says.

"The problem with this is that there is very little spare bone in the body. As an alternative, bone can be taken from a donor, but this process comes with a higher risk of transferring an infectious disease," he said.

Due to these difficulties there is a global search to improve the growth process of tissue engineered bone grafts using cells taken from a patient's bone marrow so the treatment can be delivered more quickly.

Three things are required to engineer bone tissue in a laboratory: tissue cells, a carrier material made of collagen and a bio-reactor.

The cells are encouraged to grow by pumping a nutrient solution over the collagen scaffold which is encased in a bioreactor - an enclosed vessel that provides the optimum environmental conditions for biochemical engineering.

However, to date, the growth process has taken around six weeks, which means a long wait for patients.

Over time, researchers discovered that the cells grew faster when the flow was regulated, but the tricky part was to establish exactly what flow sequence produced the best results and this formed the basis of the research by O'Brien and Siemens.

O'Brien said months or even years could have been spent carrying out trial-and-error experiments to discover the best pattern.

However, thanks to a computational and mathematical modelling system designed by Siemens engineers, this time-consuming approach was not necessary.

Heinrich Huber, project manager with Siemens Ireland, explains a three-dimensional simulator was designed to show the changing condition of the cells as they were subjected to different stimuli. This allowed the team to run massive volumes of simulations to find out what factors were most effective in encouraging the cells to grow.

"We used the computational model to determine the optimal biophysical stimuli required to achieve the goal of producing tissue-engineered bone graft in the shortest possible time," says Huber. The model was built using the engineering principles of computational fluid dynamics. It involved so many permutations that it required a number of parallel computers running for 13 days to complete the task.

The project started over a year ago and has been part-funded by Science Foundation Ireland and Siemens. The precision offered by the model has allowed the researchers to develop bigger and more productive bioreactors.

Initial tests suggest that the improved bioreactors can halve the growth time of the bone tissue from six to three weeks.

O'Brien and Siemens are now considering the commericalisation of the research.

Huber says the calculations from the three-dimensional models may also be used by Siemens for the development of next generation diagnostic equipment.