MicroTransponder Inc. Spins Off UT Dallas Technology for Neurotech Applications

by David Pope, editorial director

MicroTransponder Inc., a small startup in Dallas, TX, has set out to develop tiny, implantable, wireless “neurotransponders” that may open the way to substantial miniaturization of neurostimulation devices. Perhaps more important in the long run is the potential of these neurotransponders to fundamentally transform how researchers detect and stimulate nerve impulses in vivo.

Initially, MicroTransponder is focusing on developing an implantable device for alleviating peripheral-nerve pain, and has begun work on adapting the technology for wireless vagus nerve stimulation with the goal of generating specific neural plasticity in the brain that could be used to treat disorders such as tinnitus, chronic orofacial pain, anxiety, and stroke-induced functional impairments. The VNS and brain plasticity effort seeks to apply the research of Michael Kilgard, who heads the University of Texas at Dallas’ cortical plasticity lab. The company also is developing a platform for implanting neurotransponders in organs and inside sensory and motor nerves in almost any part of the body.

The company has a patent pending for a delivery system for implanting an array of neurotransponders next to a peripheral nerve by means of a hypodermic needle. The individual transponders can be linked together to form a cluster, and to make removal simpler. Each neurotransponder is the size of a grain of salt (about 1 mm in length and 0.25 mm in diameter), small enough for dozens to be implanted simultaneously in a single location.

Within the transponder is a microcoil and a tiny integrated circuit that includes a rectifier, capacitor, and a junction field-effect transistor that is used as a switch. The wireless part of the transponder is based on a well-established commercial technology called RFID (Radio Frequency Identification Device). The micro-coil in the transponder receives electromagnetic energy from an external coil that is placed on the skin, and can transmit data signals to the external coil. Neural activity is detected by electrodes in grooves on the transponder. The electrodes also can be used to stimulate nerves.

MicroTransponder’s technology was invented at UTD by Larry Cauller, who heads the cortical connections lab. The first wireless transponder was developed under a DARPA Revolutionizing Prosthetics grant to create a bi-directional neural interface for a prosthetic hand. A Texas company, Zyvex Corp., made the transponders using its atomically precise manufacturing technology. Cauller and Zyvex were awarded a patent in 2005 for a wireless transponder that interfaced cellular matter with a machine. Cauller credits Will Rosellini for seeing that this technology had wider application than prosthetics—specifically, that it could be developed into a wireless neurostimulator platform. In 2007 Rosellini, Cauller, and Richard Weiner, a Dallas neurosurgeon and pioneer in implanting nerve stimulators, founded the company and licensed the technology from UTD.

Rosellini now serves as CEO of MicroTransponder, Cauller is chief neuroscientist, and Weiner is chief medical officer. President and COO is Jordan Curnes, a long time associate of Rosellini, as is Frank McEachern, who is CFO and executive chairman of the board of directors. The company has attracted two top experts in implanted neurostimulation systems. Chief technology officer Scott Armstrong managed development of Cyberonics’ neurostimulation platforms as director of electrical design engineering. Armstrong previously was director of R&D at Dentsply International and an engineer at St. Jude Medical. Microtransponder’s chief scientific officer, Paul McArthur, formerly served as chief scientist at Advanced Bionics and directed the BION 3 project.

The BION is an injectable, wireless neurostimulator that is considerably larger (about 10x2x2 mm) than the neurotransponder. It was developed by engineers at the Alfred Mann Foundation in concert with Jerry Loeb, then at Queens University, and Phil Troyk at IIT. Neuromodulation rights to the BION were acquired by Boston Scientific when it purchased Advanced Bionics from Mann in 2004. Three years later Boston Scientific agreed to return Advanced Bionics to Mann, but certain rights for the BION microstimulator remained with Boston Scientific’s neuromodulation group. Both Mann’s companies and Boston Scientific are conducting clinical trials with versions of the BION.

Rounding out the management staff are Navzer Engineer, vice president of preclinical affairs. Engineer received his Ph.D. from UTD and worked as a senior researcher in UTD’s cortical plasticity lab. Dave Makanani, vice president of regulatory affairs, worked for the U.S. Food & Drug Administration for 10 years and spent another 26 years in the healthcare industry successfully guiding implantable devices through the FDA approval process. Reema Casavant, vice president of research operations, worked at the Naval Health Research Center as a project manager and researcher.

During its first years, MicroTransponder bootstrapped its finances, operating in part from the $75,000 won in several business plan competitions, $500,000 in capital investment, and a $1.38 million grant from the Texas Emerging Technology Fund. UTD is reported to have started with a 15 percent stake in the company.

In March 2009, MicroTransponder closed a $2.2 million Series A round of funding. CEO Rosellini said the funding would enable the company to complete its wireless platform and to conduct pilot trials. Another funding round is planned for the near future, and the company also is exploring other options including, strategic partners, venture capital, and angel investors.

MicroTransponder has already garnered a number of Small Business Innovation Research grants from the National Institutes of Health, including a grant in 2008 for developing “Neuro-MicroTransponders for a Minimally Invasive Peripheral Nerve Interface,” and 2009 grants for work on developing a wireless neurostimulation treatment for chronic orofacial pain, and another for testing the feasibility of reducing tinnitus by pairing vagus nerves stimulation with tone presentations to reorganize the auditory cortical map.

Some neuroscientists have expressed doubts about the ability of the tiny neurotransponders to stimulate nerves in the body. They point out that the voltages used with needle electrodes is much higher than the transponder can handle. Researchers at MicroTransponder point out that their implants are in intimate contact with the cellular matter around nerves and that this subcutaneous tissue readily conducts electrical signals so strong voltages are not required to stimulate a neuron. They point out that an array of neurotransponders can have linked electrodes so that they function as a single stimulator. Recently, a working prototype device was tested in rats and proved effective in stimulating peripheral nerves.

MicroTransponder also is developing a wireless platform that can be used to stimulate deep peripheral nerves or muscles and organs such as the bladder or stomach. A transponder that can be implanted inside a nerve fiber is being developed. Deep implants could be powered by implanting a large transfer coil near the transponders. The transfer coil would pick up electromagnetic energy from a surface coil and pass it on to the transponders.