Athena
04-26-2008, 05:58 AM
Biomagnetics speeds breast-cancer testing
Examining breast tissue samples for signs of cancer can be a laborious undertaking. Pathologists currently rely on tissue staining to determine whether a sample is normal or cancerous - a complex task that’s open to individual interpretation. Now, help may be at hand for the pathologists with the development of a nanotechnology-based detection system that automatically detects and quantifies cancerous cells in breast tissue.
Designed by researchers at University College London (UCL) in the UK, the HistoMag system uses magnetic nanoparticles in combination with a high-sensitivity magnetometer to detect cancerous cells in tissue samples. It works by exposing a biopsy sample to a solution of nanoparticle-tagged anti-HER2 antibodies. HER2 is a protein that’s over-expressed by early-stage breast cancer cells, thus the quantity of antibodies that adhere to the sample provides an accurate picture of the spread of cancerous cells.
HistoMagHistoMag uses a SQUID (superconducting quantum-interference device)-based magnetometer to measure the number of attached antibodies in the tissue. The tagged sample is sited between two coils:
a drive coil subject to a time-varying magnetic field and a pick-up coil. Any attached magnetic nanoparticles in the sample will disrupt the magnetic field and affect the voltage at the pick-up coil, enabling the system to automatically quantify the number of cancer cells present.
http://www6.0zz0.com/2008/04/26/02/783388948.jpg
Upper image: the magnetic microscope; the arrow points to a glass slide for mounting the biopsy tissue. Lower image: cross-section through the long axis of the glass slide, showing the bobbins for the applied magnetic field and the pick-up coils
"The magnetic nanoparticle tags carry a ’quantum’ of magnetic moment that we count using the HistoMag," explained team leader Quentin Pankhurst, professor of physics at UCL and deputy director of the London Centre for Nanotechnology. "The HistoMag scans the samples to pick up how many of the particles have been collected."
The technology could also help to identify the 15-30% of breast-cancer patients who are likely to benefit from treatment with the drug Herceptin (trastuzumab). The decision to treat with Herceptin is generally based on pathology results, Pankhurst told medicalphysicsweb. The tissue section is stained with immunoperoxidase dye and the pathologist decides whether or not there’s over-expression of HER2 on the basis of the colour of the section.
"Herceptin is used for addressing early-onset cancer, so you have to determine whether a patient has that particular type of cancer by examining the over-expression of HER2," Pankhurst explained. "We’re intending to add a bit more quantitative rigour to the process. HistoMag doesn’t give an absolute answer, but it’s a way of assisting the pathologist in determining whether there’s a reasonable probability that the patient will respond positively to Herceptin."
Pick-upThe UCL team recently won a Brian Mercer Feasibility Award from the Royal Society, worth £25,000. The cash will be used to re-engineer the HistoMag and increase its sensitivity before starting clinical trials next year. "The sensitivity can be enhanced through electronics and systems engineering to miniaturise the tip of the pick-up coil," Pankhurst explained. "This is the subject of the current project."
http://www5.0zz0.com/2008/04/26/02/393122676.jpg
The pick-up coils in the HistoMag contain 10 turns each, have an inner diameter of 1.0 mm and an outer diameter of 2.0 mm. Miniaturising the tip further will ramp the sensitivity of the system.
Other developments currently underway include adapting the device for use in vivo. Ultimately, such a scheme would involve injecting a patient with a magnetically-labelled, antibody-targeted dye and then scanning them with the HistoMag to determine whether there’s a measurable presence of magnetic particles at the site of a potential cancerous growth. Tagging the nanoparticles with different antibodies could also enable diagnosis of other disease, such as prostate or colorectal cancer, for example.
"We’re working on this at the moment, with oncologists at UCL and the Royal Free Hospital," said Pankhurst. "The biggest challenge here is that everything has to be physiologically safe. It’s a very harsh environment once you inject something into the bloodstream and activate the body’s immune response. We need to involve biochemists, biomedics and oncologists to design a system that will work in humans in vivo."
The researchers plan to make the in vitro HistoMag system generally available to pathologists in 2010 and are looking to engage with companies currently working in the histochemical arena. Pankhurst has previously commercialized a similar device, called SentiMag, through the university spin-out company Endomagnetics. SentiMag is a larger-scale version of Histomag that uses non-targeted magnetic nanoparticles to identify sentinel lymph nodes during surgical procedures.
Examining breast tissue samples for signs of cancer can be a laborious undertaking. Pathologists currently rely on tissue staining to determine whether a sample is normal or cancerous - a complex task that’s open to individual interpretation. Now, help may be at hand for the pathologists with the development of a nanotechnology-based detection system that automatically detects and quantifies cancerous cells in breast tissue.
Designed by researchers at University College London (UCL) in the UK, the HistoMag system uses magnetic nanoparticles in combination with a high-sensitivity magnetometer to detect cancerous cells in tissue samples. It works by exposing a biopsy sample to a solution of nanoparticle-tagged anti-HER2 antibodies. HER2 is a protein that’s over-expressed by early-stage breast cancer cells, thus the quantity of antibodies that adhere to the sample provides an accurate picture of the spread of cancerous cells.
HistoMagHistoMag uses a SQUID (superconducting quantum-interference device)-based magnetometer to measure the number of attached antibodies in the tissue. The tagged sample is sited between two coils:
a drive coil subject to a time-varying magnetic field and a pick-up coil. Any attached magnetic nanoparticles in the sample will disrupt the magnetic field and affect the voltage at the pick-up coil, enabling the system to automatically quantify the number of cancer cells present.
http://www6.0zz0.com/2008/04/26/02/783388948.jpg
Upper image: the magnetic microscope; the arrow points to a glass slide for mounting the biopsy tissue. Lower image: cross-section through the long axis of the glass slide, showing the bobbins for the applied magnetic field and the pick-up coils
"The magnetic nanoparticle tags carry a ’quantum’ of magnetic moment that we count using the HistoMag," explained team leader Quentin Pankhurst, professor of physics at UCL and deputy director of the London Centre for Nanotechnology. "The HistoMag scans the samples to pick up how many of the particles have been collected."
The technology could also help to identify the 15-30% of breast-cancer patients who are likely to benefit from treatment with the drug Herceptin (trastuzumab). The decision to treat with Herceptin is generally based on pathology results, Pankhurst told medicalphysicsweb. The tissue section is stained with immunoperoxidase dye and the pathologist decides whether or not there’s over-expression of HER2 on the basis of the colour of the section.
"Herceptin is used for addressing early-onset cancer, so you have to determine whether a patient has that particular type of cancer by examining the over-expression of HER2," Pankhurst explained. "We’re intending to add a bit more quantitative rigour to the process. HistoMag doesn’t give an absolute answer, but it’s a way of assisting the pathologist in determining whether there’s a reasonable probability that the patient will respond positively to Herceptin."
Pick-upThe UCL team recently won a Brian Mercer Feasibility Award from the Royal Society, worth £25,000. The cash will be used to re-engineer the HistoMag and increase its sensitivity before starting clinical trials next year. "The sensitivity can be enhanced through electronics and systems engineering to miniaturise the tip of the pick-up coil," Pankhurst explained. "This is the subject of the current project."
http://www5.0zz0.com/2008/04/26/02/393122676.jpg
The pick-up coils in the HistoMag contain 10 turns each, have an inner diameter of 1.0 mm and an outer diameter of 2.0 mm. Miniaturising the tip further will ramp the sensitivity of the system.
Other developments currently underway include adapting the device for use in vivo. Ultimately, such a scheme would involve injecting a patient with a magnetically-labelled, antibody-targeted dye and then scanning them with the HistoMag to determine whether there’s a measurable presence of magnetic particles at the site of a potential cancerous growth. Tagging the nanoparticles with different antibodies could also enable diagnosis of other disease, such as prostate or colorectal cancer, for example.
"We’re working on this at the moment, with oncologists at UCL and the Royal Free Hospital," said Pankhurst. "The biggest challenge here is that everything has to be physiologically safe. It’s a very harsh environment once you inject something into the bloodstream and activate the body’s immune response. We need to involve biochemists, biomedics and oncologists to design a system that will work in humans in vivo."
The researchers plan to make the in vitro HistoMag system generally available to pathologists in 2010 and are looking to engage with companies currently working in the histochemical arena. Pankhurst has previously commercialized a similar device, called SentiMag, through the university spin-out company Endomagnetics. SentiMag is a larger-scale version of Histomag that uses non-targeted magnetic nanoparticles to identify sentinel lymph nodes during surgical procedures.