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Posted: May 11, 2012
New breast implant deters cancer cells
(Nanowerk News) One in eight women in the United States will develop breast cancer. Of those, many will undergo surgery to remove the tumor and will require some kind of breast reconstruction afterward, often involving implants. Cancer is an elusive target, though, and malignant cells return for as many as one-fifth of women originally diagnosed. But a new type of implant developed by researchers at Brown University may be able to deter breast cancer cell regrowth. Made from a common federally approved polymer, the implant is the first to be modified at the nanoscale in a way that causes a reduction in the blood-vessel architecture that breast cancer tumors depend upon, while also attracting healthy cells into breast tissue.
Zhang and Webster created an implant with a "bed-of-nails" surface at the nanoscale that deters cancer cells from dwelling and thriving. This is the first such implant, say the Brown investigators, with modifications at the nanoscale that cause a reduction in the blood-vessel architecture on which breast cancer tumors depend. Equally as important, the nanoscale features on the implant's surface are hospitable to healthy cells, which means that the implant would not impede healing after surgery.
Webster and members of his lab have been modifying various implant surfaces to promote the regeneration of bone, cartilage, skin, and other cells. In this work, he and Zhang sought to reshape an implant that could be used in breast reconstruction surgery that would not only attract healthy cells but also repel any lingering breast-cancer cells. The duo created a cast on a glass plate using 23-nanometer-diameter polystyrene beads and polylactic-co-glycolic acid (PLGA), a biodegradable polymer approved by the FDA and used widely in clinical settings, such as stitches. The result is an implant whose surface was covered with adjoining, 23-nanometer-high pimples. The pair also created PLGA implant surfaces with 300-nanometer and 400-nanometer peaks for comparison.
In lab tests after one day, the 23-nanometer-peak surfaces showed a 15-percent decrease in the production of a protein (VEGF) upon which endothelial breast-cancer cells depend, compared to an implant surface with no surface modification. The 23-nanometer surface showed greater reduction in VEGF concentration when compared to the 300-nanometer and 400-nanometer-modified implants as well.
While it is unclear why the 23-nanoneter surface appears to work best at deterring breast-cancer cells, Webster thinks it may have to do something with the stiffness of malignant breast cells. When they come into contact with the bumpy surface, they are unable to fully wrap themselves around the rounded contours, depriving them of the ability to ingest the life-sustaining nutrients that permeate the surface. He likened the peak-covered surface to a bed-of-nails to cancer cells. The researchers hypothesize that even smaller surface peaks would work better at repelling cancer cells. Somewhat to their surprise, Webster and Zhang found that that the 23-nanometer semispherical surface yielded 15 percent more healthy endothelial breast cells compared to normal surface after one day of lab tests.