Momentum - The Magazine for Virginia Tech Mechanical Engineering Vol. 4 No. 1 Spring 2019 - Page 21

21 they have shown to be more effective than the passive delivery of injections at reaching cancer sites. NanoBEADS has produced results in both in vitro (in tumor spheroids) and in vivo (in living mice) models showing up to 100-fold improvements in the distribution and reten- tion of nanoparticles in cancerous tissues. This is a product of the five-year National Science Foundation CAREER Award of Baha- reh Behkam, associate professor of mechanical engineering. Collaborators on this interdis- ciplinary team are Rick Davis, professor of chemical engineering, and Coy Allen, assistant professor of biomedical sciences and patho- biology in the Virginia-Maryland College of Veterinary Medicine. “You can make the most amazing drugs, but if you cannot deliver it where it needs to go, it cannot be very effective,” Behkam said. “By improving the delivery, you can enhance efficacy.” This work, which combines expertise in mechanical engineering, biomedical engi- neering, chemical engineering, and veterinary medicine, was recently detailed in Advanced Science. Using salmonella for good Humans have noticed, even as far back as Ancient Egypt, that cancer went into remis- sion if the patient also contracted an infection like salmonella. Neither are ideal, but humans can treat salmonella infections more effective- ly than cancer. In modern times, Allen said the idea of treating cancer with infections traces back to the late 1800s and has evolved into immuno- therapy, in which doctors try to activate the immune system to attack cancerous cells. Of course, salmonella is harmful to humans, but a weakened version could in theory pro- vide the benefits of immunotherapy without the harmful effects of salmonella infection. The concept is similar to humans receiving a weakened flu virus in a vaccine to build immunity. Over six years ago, Behkam came up with the idea of augmenting bacterial immunother- apy to also attack cancer with conventional anti-cancer drugs. The problem was the passive delivery of anti-cancer drugs doesn’t work very well. Given her background in bio-hybrid mi- crorobotics, she wanted to use salmonella bacteria as autonomous vehicles to transport the medicine, in nanoparticle form, directly to the cancer site. The work began with Behkam’s first doctor- al student, Mahama Aziz Traore, constructing the first generation of NanoBEADS by assembling tens of polystyrene nanoparticles onto E. coli bacteria. After thoroughly study- ing the dynamics and control aspects of the NanoBEADS systems for a few years, Behkam brought Davis into the project because he had experience creating polymer nanoparticles for drug delivery. “She mentioned this radically different approach for delivering drugs and nanopar- ticles,” Davis said. “I walked away from the conversation thinking, ‘Man, if this thing could work, it would be fantastic.’” Behkam chose this particular bacterial strain, Salmonella enterica serovar Typhimurium VNP20009, because it has been thoroughly studied and successfully tested in a phase one clinical trial. “Its (salmonella’s) job as a pathogen is to penetrate through the tissue,” Behkam said. “What we thought is if bacteria are so good at moving through the tissue, how about coupling nanomedicine with the bacterium to carry that medicine much farther than it’d