A Close-Up Look at Metastasis

By Medical Discovery News

May 29, 2015

A Close-Up Look at Metastasis

One of the things that make cancer cells so deadly is metastasis, their ability to dislodge from their original location and migrate to other tissues. Most people who die of cancer are victims of this process. Even if a tumor is removed surgically, doctors can’t be certain that some of the tumor cells haven’t already metastasized, hence the need for treatments such as chemotherapy to target those cells. Unsurprisingly, metastasis is a subject of intense research, and luckily scientists now have a new tool to help them understand how tumor cells move.

While most tumors have the ability to metastasize to many different tissues, they prefer to spread to certain ones, like those in the bones, liver, and lungs. Cancer begins to spread by invading nearby tissue, then through a process called intravasation, tumor cells enter a blood or lymphatic vessel, allowing them to circulate to other parts of the body.

When tumor cells stop moving in a tiny blood vessel called a capillary, the can move out of the blood vessel and into the tissue, which is called extravasation. They will proliferate in this new location and release signals to stimulate the production of new blood vessels to satisfy the oxygen and nutrient demands of the tumor, a process called angiogenesis. Not all cells of the tumor are equally capable of metastasizing, and depending on the new environment they may not be able to grow in their new locations. In general, cells in metastatic tumors acquire additional genetic mutations that make them better able to relocate to other sites in the body. In some cancers, the metastatic cells have evolved to be remarkably different from the original tumor cells, which may contribute to the failure of treatments, the identity of the original cancer, and the recurrence of cancer.

Engineers and scientists at Johns Hopkins University have reproduced the 3-D extracellular matrix (ECM) that surrounds human cells. They also created an artificial blood vessel that runs through the matrix to simulate the flow of blood or lymph. They then added breast cancer cells either individually or in clumps.

Using fluorescent microscopy, they studied how the tumor cells interacted with the model to investigate how tumor cells get into and out of vessels, a key step in metastasis. They found that the tumor cells first dissolved some of the ECM to form a tunnel. The cells moved back and forth within this tunnel, occasionally coming into contact with the vessel. Then the cancer cells attached to the vessel through a long process, finally sitting on the surface of the blood vessel. They appear to change shape and move along the outer surface of the blood vessel. After a few days, the cancer cells force their way between the outer cells of the vessel and are swept away by the fluid moving through it.

About 60-70 percent of cancer patients are already at the stage of metastasis by the time they have been diagnosed. This new device will allow scientists to gain a better understanding of the processes and molecular players in metastasis, which will hopefully lead to new interventions or therapies that could interrupt or prevent this process.

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I Spy for Heart Disease

Aug. 29, 2014

By Medical Discovery News

Heart in chest

While a shrink ray like the kind used in science fiction is still stuck in the future, miniature devices are not. Tiny devices have been created to perform a variety of tasks, from an implantable telescope to improve vision in those with macular degeneration to the new pacemaker in clinical trials that is about the size of a large vitamin pill. Now, researchers have developed a catheter-based device smaller than the head of a pin that can provide real-time 3D images of the heart, coronary arteries, and other blood vessels. This is an important invention as the casualties of heart disease continue to rise. Statistically, one in four people will have a heart attack. 

Many Americans are at risk for developing coronary artery disease (CAD) due to the buildup of cholesterol and plaque. If there is a rupture or breakage of the plaque, creating a blood clot, that can result in a heart attack with little to no warning. Traditional diagnostic tests such as stress tests and echocardiograms show how much blood is flowing to the heart. If there are regions of the heart that are not getting as much blood as others, it might be a sign of clogged coronary arteries. However, blood flow can also appear to be normal even with plaque buildup.

Currently, there are a variety of methods that provide images of what is going on inside arteries, including magnetic resonance imaging (MRI), multi-detector Computerized Tomography (CT) scans, and injecting an iodine-based contrast agent into arteries through a catheter. But all these look at the inside of the body from the outside, which is why this new device gives an unprecedented way of viewing the heart.

This invention combines ultrasound imaging with computer processors on a single chip only 1.4 millimeters wide. The body’s signals are processed on the chip then transmitted through 13 tiny cables to a computer monitor, so doctors have a visual of the heart and arteries. The prototype took 60 images per second using very little power, therefore generating little heat. This would allow cardiologists to take real-time images of blood vessels in and around the heart to more precisely determine the extent of blockages. These images also have much higher resolution compared to those taken with machines outside the body.

The next step is to conduct studies using the device on animals to determine its safety and efficacy and to develop potential applications of this technology. Eventually, this data will be submitted to the Food and Drug Administration (FDA) to gain permission to perform clinical trials on humans. Extensive testing will be required before the FDA will approve the device for general use. The developers, a group of engineers at the Georgia Institute of Technology, are also working to shrink the device even further to .4 millimeters so it can generate images of even smaller blood vessels.

Having clearer images of blood vessels would allow surgeons to have a more complete understanding of the blockage they are dealing with before they operate. Hopefully, in the future use of this device will prevent heart attacks and save many people’s lives.

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Sponges Save a Soldier

Aug. 22, 2014

By Medical Discovery News

Since the wars in Afghanistan and Iraq began in 2001 and 2004 respectively, over 1 million people have died in the combat. By the end of 2013, 5,829 of those were American soldiers. In 76 percent of potentially survivable battlefield wounds, the leading cause of death was hemorrhage. But more soldiers may make it home thanks to a new invention called XStat. It uses a light, pocket-sized injector to send 92 sponges into a wound, stopping arterial bleeding in 15 seconds.

Currently, caring for a wounded soldier on the battlefield is limited to what combat medics carry with them. Controlling hemorrhage is the first priority when treating a wounded soldier and can involve tourniquets or field dressings, Hemcon, Quickclot, and Fibrin bandages. Hemcon dressings are treated with chitosan, a naturally occurring biocompatible compound from shrimp shells that strongly adheres to blood and reduces blood clotting times. Quickclot gauze and pads are coated with a naturally occurring mineral, kaolin, which initiates the body’s natural coagulation to reduce clotting times. Fibrin bandages contain fibrin and thrombin, two key factors in the normal clotting process that cause rapid blood clotting once in contact with the wound. 

However, these products are not ideal for deep-penetrating wounds, which require packing gauze into the wound and applying pressure. If that does not work the first time, the process is repeated. This is an agonizing ordeal for the wounded person and bleeding can begin again once the pressure is taken off. This keeps the medic from being able to treat anyone else because he or she has to keep applying pressure to the wound to stop the bleeding. 

Medics have long been packing open wounds with combat gauze with mixed results and even the new treated gauzes, though much better, still are not ideal. The XStat system uses disk-shaped injectable sponges made of special sterile cellulose and coated with chitosan in a syringe-like injector. The sponges expand from three millimeters thick to 50 when they come in contact with blood, which not only speeds up clotting but also puts pressure on the blood vessels to slow bleeding. The sponges expand into tube shapes that clump together once they are saturated with blood and can be easily removed later. The sponges are also labeled with an X symbol that can be seen by X-Ray to ensure that they are all removed.

One injection of XStat is the equivalent of five rolls of combat gauze. It is smaller, faster, and less painful. All the medic has to do is inject the sponges close to the wound and bleeding is stopped within seconds. This invention is likely to help save many soldiers’ lives. RevMedx, the makers of XStat, are developing a smaller version of the device to inject sponges into narrower wounds like those from shrapnel, handguns, or knives. They are also creating a bandage with embedded sponges and a dressing with an inflatable bladder that would maintain pressure on wounds. Such devices would not just save lives on the battlefield but in everyday emergencies to stop hemorrhages and would be a welcome addition for emergency medical technicians to use.

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