The researchers hope to develop biohybrid limbs that would allow amputees to control prosthetic arms and legs with muscle and nerve cells. They will try to lengthen bones, regenerate cartilage, blend skin with metal and power artificial joints with implants in the brain and microchips in the muscle.
The project draws together five disparate research programs - four at Brown University and one at the Massachusetts Institute of Technology—to find ways to restore natural function to amputees, especially those who lost limbs in Iraq.
Nine out of 10 soldiers injured in the Iraq war survive, the highest survival rate ever, thanks to body armor and improvements in casualty care. But many survivors have disabling injuries, especially lost limbs. The Walter Reed Army Medical Center, in Washington, D.C., has treated about 200 people who suffered traumatic amputations in Iraq, and there might be others treated in other Army hospitals. Any number of them could participate in the Brown-VA project.
“They want to go back to their units,” said Dr. Roy K. Aaron, a Brown professor of orthopedics and the project’s leader. “These are people who have their whole lives ahead of them. We owe a lot to them.”
Although the financing is for five years, the researchers intend to make the Center for Restorative and Regenerative Medicine a permanent part of Brown University and the Providence VA Medical Center. In addition to the $7.2 million, the VA has committed $6 million to build a rehabilitation research center at its Providence hospital, making Providence the 14th such center in the VA system.
Today, amputees cope with prosthetic limbs that can be awkward or painful, and that often poorly mimic what real limbs do. The researchers will try to develop better ways to connect the prostheses to the body, to establish two-way communication between the nervous system and the limb, and to regenerate lost or damaged tissue, especially cartilage.
“We’re trying to create a limb that better senses the intent of the user,” Aaron said.
Iraq war amputees will be recruited to come to the Providence VA hospital for surgery and fitting of the prosthetics. Others who have lost their limbs will also be eligible. But much of the work, especially in the beginning, will take place in the laboratory.
The project harnesses expertise from distant corners of science—pairing metallurgists and cellular biologists, computer scientists and physicians, neuroscientists and engineers.
“We had the pieces. It was just a matter of bringing them all together,” said Regina Correa-Murphy, administrative officer for research and development at the Providence VA Medical Center.
“This group at Brown has brought a set of skills, ideas, talent and expertise that is in some respects unique and complements what is already going on in the system,” said Dr. Stephan Fihn, acting director of research and development for the Department of Veterans Affairs.
“The mantra in rehab research for the VA, and all of our research, is to get patients back to a functional, useful productive life.”
These are the main areas of research:
Robotics: Hugh Herr, of the MIT Media Laboratory, will be working on prosthetic knees and ankles that are controlled by the patient’s nervous system. Wireless microchips the size of a grain of rice will be injected into leg muscle, where they pick up signals from nerves and transmit them to the knee or ankle, telling the joint to move. Sensors on the artificial foot will relay information about ground conditions to a microprocessor that will guide movement.
Herr lost both legs in a climbing accident when he was teenager, and has devoted his career to building better prosthetic legs.
Brain Sensors: Dr. John P. Donoghue and colleagues have developed a brain implant that picks up nerve signals in the brain, processes them through a bank of computers, and translates them into commands that a personal computer can understand. His implant, called BrainGate, is being tested in a quadriplegic man, who has used his personal computer to control his television and pick up e-mail. (The man, Matthew Nagle, was featured in the Nov. 14 Providence Sunday Journal.)
Now, Donoghue and others will try to use the BrainGate system to operate robotic limbs. He envisions signals from the brain implant traveling through a hair-thin fiber-optic cable to a small processor implanted in the chest. Sensory information from the robotic limb would be relayed to the brain.
Limb Lengthening: When someone loses a limb just below the joint, the remaining piece might be too small to fit a prosthetic. Dr. Michael Ehrlich, Brown’s chairman of orthopedics, has lengthened the limbs of children with birth defects such as dwarfism, through a process in which wires are threaded through skin and bone and tied to a metal frame. Now, he and Aaron will work on better developing this procedure in adults, stretching limbs by three or four inches.
Tissue Engineering: Cartilage, the essential cushion in every joint, stops growing at adulthood, and can crumble with age. Getting cartilage to grow will be the first goal of a team that hopes eventually to regenerate muscles, ligaments, skin and bone.
Michael Lysaght, director of Brown’s Center for Biomedical Engineering, has developed a method for delivering growth factors, the proteins that instruct tissue to grow. He has encapsulated them inside biodegradable beads derived from seaweed, each the size of a grain of salt. If applied to polymer “scaffolding,” it is hoped these beads will release growth factors in the right quantity and sequence to spur and sustain tissue growth.
Melding Tissue With Metal:The researchers want to implant a bolt in the bone that protrudes through the skin, where the prosthetic could be attached. Titanium bolts have been successfully incorporated into bone, such as in dental implants, but they don’t fare well in skin. The skin will not adhere to titanium, but tries to grow under it as if to eject it like a splinter, resulting in infection.
Clyde Briant, Brown’s dean of engineering, will work on developing forms of porous titanium that will integrate skin cells. Jeffrey Morgan, professor of medicine science, will try to alter the skin cells so that they will multiply and spread on metal.
Measuring Outcomes:Community health professors Linda Resnick and Vincent Mor will evaluate the methods for measuring the amputees’ functioning, considering such factors as mobility, satisfaction with the limb and quality of life. They’ll use their findings to track the project’s performance in improving the amputees’ lives.
The VA project is a feather in the cap for Brown University, which has not been known as a major research center but has recently committed to boosting its research funding.
Although geared toward amputees, the research has potential applications to many other conditions. If cartilage can be grown, for example, knee and hip replacement surgery wouldn’t be needed. Getting skin to accept a protruding device can improve the safety of catheters.
“The potential is essentially unlimited,” Aaron said, “if we play this right.”
Copyright 2004 Providence Publications, LLC
Copyright © 2002 LexisNexis, a division of Reed Elsevier Inc.