Article preview reprinted from Medtech Insight - January 2010
Brief summaries of recent advances in device research and clinical trials, including a neural interface for prosthetic limbs, new tools to detect cancer, and results of a multicenter study of the costs of treating MRSA. Read more...
Clinical Edge
Article preview reprinted from Medtech Insight - January 2010
Neural Interface for Prosthetic Limbs
A unique, implantable neural interface could usher in the next-generation of prosthetic limbs.
Researchers at the University of Michigan, led by Paul Cederna, MD, associate professor of plastic and reconstructive surgery, are developing an electrically active neural implant seeded with transplanted muscle cells that is designed to provide more natural movement control and feeling to prosthetic limbs. The implant, so far tested only in animals, acts as an interface between the transplanted muscle cells and the severed nerves at the amputation site, enabling nerve impulses to be transmitted to and from the prosthesis. In addition to motor impulses that impact prosthesis movement, the device may, for the first time, enable sensory input (through the use of heat or pressure sensors in the prosthesis) to be relayed from the prosthesis back to the brain.
A study of the device in rodents, presented at the 2009 American College of Surgeons meeting last October, demonstrated connection of severed neurons with the seeded muscle cells and transmission of nerve impulses across the connection. There was no evidence of scarring at six-month follow-up and new blood vessels formed in the tissue surrounding the interface to supply the transplanted muscle cells, according to a description of the research published in Massachusetts Institute of Technology's Technology Review. The research is being funded by the US Department of Defense's Defense Advanced Research Project Agency, which hopes to begin human testing of the device within three years.
New Tools to Detect CancerMass spectrometry may be the key to detecting cancer during surgery, while a new optical tool may one day allow doctors to create a high quality image of the brain for a virtual brain biopsy.
Researchers from Justus Liebig University Giessen, in Germany, are working on a scalpel that uses mass spectrometry to distinguish cancerous from normal tissue. For today's doctors, identifying cancer involves preoperative scans and studying tissue and cell samples under the microscope. A scalpel that can test tissues using mass spectrometry to compare the mass and charge of molecules could make it possible for physicians to test suspicious areas during an operation and instantly analyze the tissue.
It is widely known that cancerous and normal tissues have different molecular profiles, and previous research has shown that mass spectrometry is capable of differentiating between cancerous and healthy tissue. However, collecting samples for analysis has always had some limitations in the past. In order to prep molecules for evaluation, they have to be ionized before being pulled into the mass spectrometry machine. This involves bombarding a sample with charged particles. But those particles can be harmful to the human body, so standard methods could not be used in vivo during an operation.
The researchers avoided this problem in their modified scalpel by taking advantage of the natural byproduct of electroscalpels, which give off gaseous ions that are compatible with the mass spectrometry method. These byproducts are detrimental to the lungs and are typically collected during surgery to avoid harm. However, the new scalpel technology enables the gaseous ions to be sucked into the mass spectrometer and used to identify the sample based on the information available in a database.
Researchers at Purdue University are also studying mass spectrometry and how it can be useful in analyzing tissues. Their system, called DESI, involves coating tissue with a mist of charged particles, which can analyze a larger number of tissue characteristics than is possible with the method used by the German researchers. The German mass spectrometry system has already been tested in a variety of animals, such as rodents. However, cost may prove to be a barrier for this technology, as a traditional electrosurgery system costs about $8,000, but the mass spectrometry system would cost significantly more—about $120,000 by current estimates.
In related news, engineers at Johns Hopkins University are building a laser and optical fiber-based tool that has the potential to more clearly and less invasively image cancerous tissue in the brain. The goal of the technology is to be able to create high-resolution images of small portions of the brain without having to cut into it—a necessary element of a traditional biopsy. The new technology not only has the potential to eliminate surgical risks, but it could also help surgeons remove cancerous tissue more accurately during surgery.
The device employs optical fibers and optical coherence tomography to enable high-detail imaging. When light from optical fibers is focused on an area of the brain, the light bounces in mostly incoherent ways. However, through the use of optical coherence tomography, the light that is properly scattered can be successfully collected and converted into a detailed image of the tissue area, even to the level of cellular detail. Because these images are much sharper than anything produced through magnetic resonance imaging or ultrasound, surgeons should be able to better detect important blood vessels and healthy tissue that need to be preserved and thus remove cancerous tissue with greater accuracy. The new system is also expected to be significantly less expensive than traditional imaging systems, with a potential price tag under $10,000. The research is being funded by a two-year grant from the National Institutes of Health's Institute of Neurological Disorders and Stroke.
Novel Genetic Tool Holds Promise for Breast Cancer DiagnosisGene positioning analysis may offer a less invasive alternative to traditional pathology-based breast biopsy.
Researchers from the National Institutes of Health's National Cancer Institute, reporting in the December 14, 2009, issue of the Journal of Cell Biology, detailed a new genetic-based tool that may offer an important advance in breast cancer diagnosis. The researchers identified several genes inside the cell nucleus that appear to take on a disease-specific spatial arrangement in the nucleus that may be indicative of breast cancer. Scientists have long known that the spatial organization of genes inside the nucleus can change during a number of bodily processes, including disease states such as cancer, but this is the first time specific spatial arrangements and genes have been used successfully to differentiate normal cells from cancerous cells in the breast.
The scientists used fluorescent in situ hybridization (FISH) to locate specific DNA sequences in 11 normal and 14 malignant breast tissue specimens. They then identified eight genes with a high frequency of repositioning in the cancerous specimens. One gene in particular, known as HES5, enabled correct identification of invasive breast cancer tissue with nearly 100% accuracy. More testing will be needed to verify the results, but the technique opens up the possibility of an entirely new, less invasive approach to breast cancer diagnosis; one that would require only a small quantity of biopsy tissue—possibly as little as 100 to 200 cells, the researchers said. Moreover, because the method, unlike standard tissue pathology, does not rely on subjective analysis, it may reduce human error. The researchers said the new approach, if proven in further studies, could be a useful first-line diagnostic tool following an abnormal mammogram. Moreover, they believe it has the potential to be applied beyond breast cancer to any cancer type in which repositioned genes can be identified.
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Companies mentioned in this article:
Johns Hopkins University
Massachusetts Institute of Technology
National Institutes of Health
National Cancer Institute
Purdue University
US Department of Defense
University of Michigan
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Medtech Insight newsletter provides insights into the technology and market developments (devices, instrumentation, biomaterials, gene therapy, tissue engineering, etc.) impacting a wide range of surgical and non-surgical clinical practices.
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