ASIAN INNOVATION AWARDS: THE WINNERS 2004: GOLD AWARD

Healing Heads

Doctors and engineers in Singapore have found a safer way to mend damaged skulls and to help bone regrow in other parts of the body

By Barry Wain/SINGAPORE

Issue cover-dated October 21, 2004

ACCIDENT VICTIMS who end up with a damaged skull are usually fitted with a titanium plate or bone taken from another part of the body. Soon, they will have the option of being treated with a biodegradable plastic plug that fits neatly into the hole and allows the bone to regenerate and the hair to grow back.

Replacement bone must be taken from a patient's hip, which requires a painful operation, or obtained from a cadaver, which could transfer bacteria and viruses. The new plastic mesh is almost half the price of titanium and doesn't carry the risk of infection. Moreover, it allows the patient to regain a natural look and feel, as the material fuses with the patient's head.

The breakthrough comes from a group of six engineers and doctors from the National University of Singapore and the National University Hospital in collaboration with the city's Temasek Polytechnic. S.H. Teoh, T.C. Lim, D.W. Hutmacher, J.T. Schantz, N. Chou and K.C. Tan have won the Gold in this year's Asian Innovation Awards.

Encouraged by their success, the team is now experimenting to see if the mesh can help grow bone and other tissue around the eye socket, jaw, spine, chest and legs.

Their achievement is a triumph for tissue engineering, which aims to restore tissue and organ functions with minimal host rejection. It is a multidisciplinary field that integrates engineering principles, basic life science and cell biology, and it has been heralded as likely to revolutionize the health-care-biotechnology industry.

"This is the new wave," says Teoh, a principal member of the team and a professor in the university's department of mechanical engineering. "It will change the way surgeons--plastic surgeons, neurosurgeons--treat patients."

Teoh says the three engineers and three clinicians, who teamed up in 1999, shared a vision to create a "platform" for tissue and organ regeneration. "It is a foundation for us to build many products out of one technology," he says.

A basic material is polycaprolactone (PCL) polymer, which is used as a structure in which cells can grow. PCL is bio-reabsorbable, meaning it can be digested by the body and disposed of without trace. Although this is the first time such a material has been used for tissue engineering for the skull, PCL has long been approved by the United States Food and Drug Administration for other medical uses.

Using medical imaging, biomaterials and advanced manufacturing, the team has been able to produce the mesh in an exact, three-dimensional shape without the use of a mould. That cuts costs and reduces the risk of infection.

This is particularly useful when doctors have drilled one or two holes in the skull of an accident or stroke patient to remove blood clots. As an alternative to closing the wounds with titanium mesh, the team has designed a plug from the PCL mesh shaped like a flattened button mushroom to fit into the openings.

With all 13 patients who so far have been fitted this way, the plug integrated into the skull bone and new bone grew back over the holes so that there was no depression, or any other sign of the drilling. It took two years for the material to degrade completely, and none of the patients suffered ill effects.

Teoh says he expects these so-called burr plugs to be most useful in developing countries, which usually lack medical imaging equipment, which means doctors sometimes drill as many as four holes in a patient's skull before finding the right entry point.

The mesh also can be fabricated to fit a patient's defect precisely, and is easily cut to size by hand. The team produced a massive "scaffold," as the fashioned mesh is sometimes called, for a construction worker who lost a third of his skull in an accident three years ago. Not only did the bone regenerate, but his hair grew back, restoring his appearance completely.

The team has already produced a second generation of the material containing a calcium compound that promotes faster bone growth and healing, which wasn't in the first generation.

"It's a clinically friendly technology," says Teoh, displaying small sheets of the material. "It's so simple." He demonstrates his point by immersing spaghetti-like strands of the material in hot water, and fashioning it into various shapes by hand. When it cools, it regains its firmness and stays in place, sticking to other surfaces.

After lab trials on animals, patients with facial injuries are now being treated with a so-called sinus plate, which helps restore damage around the eyes. Other prospective products are for people with cardiovascular, orthopaedic and dental problems. The team has patented the process, and has filed another two patents for products.

The six researchers have established a company, Osteopore International, to sell their products. They have already made some overseas sales, but they are waiting for approval by the U.S. Food and Drug Administration before tackling major markets. A strong selling point is affordability. The burr plug, for example, goes for S$600 ($356) compared with S$1,000 or more for the best titanium plate.

Osteopore is looking for investors to take equity in the company and provide the commercial savvy. "We are strong technically, but we need management and marketing," says Teoh. He estimates the venture needs an infusion of about $6 million to go fully commercial.

But Teoh doesn't want just any investors. He's looking for those who will buy into the vision he and his five colleagues share. He figures Osteopore will have a two-year window of opportunity to exploit the market after its gets FDA approval, which it hopes to obtain within six months. Patents notwithstanding, "I worry about copying," Teoh says. "Somebody will copy it."
 

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