From the Labs: Biomedicine

New publications, experiments and breakthroughs in biomedicine–and what they mean.

An Anti-Cancer Implant
A polymer disc triggers an immune attack to shrink tumors

Cancer killer: A cross-¬section of a polymer matrix designed to prime the immune system against cancer.

Source: “In Situ Regulation of DC Subsets and T Cells Mediates Tumor Regression in Mice”
David J. Mooney et al.
Science Translational Medicine
1(8): 8ra19

Results: An implantable disc acts as a therapeutic vaccine against cancer, triggering the immune system to attack malignant cells. It slowed cancer growth and increased survival time in mice with melanoma tumors. The cancers completely disappeared in 20 to 50 percent of animals given two vaccinations; the success rate depended on how long the tumors had been growing.

Why it matters: This is the first vaccine to shrink tumors in rodents, rather than just slowing their growth. (A number of other therapeutic cancer vaccines are under development, but none has been approved by the U.S. Food and Drug Administration.) The vaccine appears to suppress a part of the immune system that typically neutralizes an immune response after it’s achieved its initial goal. The ability to do this might be important in stopping tumors from recurring.

Methods: Researchers impregnated a polymer scaffold with three ingredients. Cytokines, signaling molecules produced by the immune system, attract immune cells known as dendritic cells into the implant. Fragments of genetic material designed to mimic bacterial DNA alert those immune cells that a foreign invader is present. The implant also contains ground-up pieces of the patient’s tumor, which show the dendritic cells what to attack. The dendritic cells take up the tumor molecules as they move through the scaffold; then they travel to the lymph nodes, where they present the molecules to a different set of immune cells, triggering them to attack.

Next steps: Researchers will examine whether the same strategy can shrink other types of tumors. A startup called InCytu, based in Lincoln, RI, is developing the technology for human testing.

Synthetic Platelets
Nanoparticles stimulate blood clots

Source: “Intravenous Hemostat: Nanotechnology to Halt Bleeding”
Erin B. Lavik et al.
Science Translational Medicine
1(11): 11ra22

Results: Specially treated nanoparticles quickly stop bleeding by binding to blood platelets, the core of the body’s own clotting system. When injected into rodents in which an artery had been partially severed, the nanoparticles reduced bleeding time from four minutes to two.

Why it matters: Existing methods for stemming blood loss after traumatic injuries work best with open wounds or in the operating room, since they require direct access to the site of the bleeding. An injectable treatment could effectively stanch internal bleeding from wounds that existing treatments can’t reach.

Methods: Each particle contains molecules of polyethylene glycol (PEG)–a water-soluble compound that keeps the particles from sticking to each other or to blood vessels–attached to a polymer core. The PEG molecules are topped with a peptide sequence that binds to activated platelets, helping them stick together to form clots.

Next steps: Researchers plan to test the particles in larger animals, whose circulatory systems more closely approximate those of humans. They will also test them in different types of wounds, such as those that mimic the effects of blast injuries, which are particularly common among troops in Iraq and Afghanistan. The trauma that results from an explosion–for example, when someone is thrown against the ground–can shear blood vessels, causing internal bleeding.

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