Disappearing Materials Advance Medical Devices

New materials technology - particularly with resorbable compounds - is leading to significant advances in medical devices.

A drug-eluting absorbable metal scaffold was recently implanted in the first patient by Dr. Michael Haude in Neuss, Germany. Most absorbable stents developed to date have been made from polymers.

Developers of the new technology say that the magnesium metal alloy provides mechanical advantages over plastics, while providing a reliable degradation profile in which it slowly returns to its natural physiology.

The new device is combined with a slow-release drug and is intended to open vessels and to keep them from reclogging, while avoiding the longer-term disadvantages associated with permanent metal stents such as "late stent thrombosis."

The safety and biocompatibility of bare magnesium scaffolds have been proven in previous Biotronic studies. A global pioneer in absorbable magnesium, Biotronic says it has refined this technology for more than 10 years based on physicians' input to deliver the optimal balance between vessel scaffolding, degradation profile and drug-elution characteristics.

"DREAMS (drug-eluting absorbable metal scaffold) is different than a drug-eluting stent because it offers a promising solution for currently unmet clinical needs," says Alain Aimonetti, vice president marketing and sales with Biotronic. "Many physicians anticipate that the absorbable aspect will initiate a true revolution in interventional cardiology."

Metals typically use for stents have been nickel titanium alloy (nitinol), cobalt chromium, titanium, tantalum or steel, such as 316 L.

Spinal Scaffold

Another interesting materials' development comes from InVivo Therapeutics of Cambridge, MA, whose MIT-developed polymer technologies provide a novel approach to the treatment of spinal cord injuries.

A resorbable polymer-based medical device is used for the repair of spinal cord tissue for open- and closed-wound spinal cord injuries.

Dr. Robert  Langer, institute professor at MIT, and Dr. Yang (Ted) Teng of Harvard's Neurosurgery Dept. said in a research study: "We have designed an implant modeled after the intact spinal cord consisting of a multi-component polymer scaffold."

At 70 days post-injury, animals implanted with scaffold plus stem cells exhibited coordinated, weight-bearing hind limb stepping. Analysis suggested that this recovery may have been due to a reduction in tissue loss from secondary injury processes as well as in diminished glial scarring.

InVivo Therapeutics has worked with MIT professors to commercialize the technology, and hope to begin a human trial in the next few months.