When Paula Hammond arrived on the MIT campus as a freshman in the early 1980s, she wasn’t sure she belonged there. In fact, as she told an MIT audience, she felt like “an impostor.”
MIT Institute Professor Paula Hammond, a world-renowned chemical engineer who spent most of her academic career at MIT, delivered the 2023-24 James R. Killian Jr. Professor Achievement Award. Image credit: Jake Belcher
However, this feeling did not last long, as Hammond began to find support among his fellow students and professors at MIT. “The community was really important to me, the feeling of belonging, the feeling that I belonged here, and I found people willing to embrace me and support me,” she said.
Hammond, a world-renowned chemical engineer who spent most of her academic career at MIT, made the remarks at the 2023-24 James R. Killian Jr. Professor Achievement Award conference.
Established in 1971 to honor MIT’s 10th president, James Killian, the Killian Award recognizes the extraordinary professional achievements of an MIT faculty member. Hammond was chosen for this year’s award “not only for her tremendous professional achievements and contributions, but also for her genuine warmth and humanity, her thoughtfulness and effective leadership, and her empathy and ethics,” according to the citation. price.
“Professor Hammond is a pioneer in nanotechnology research. With a program that spans basic science to translational research in medicine and energy, she has introduced new approaches for the design and development of complex drug delivery systems for cancer treatment and imaging non-invasive,” said Mary Fuller, MIT faculty chair and professor. of literature, who presented the prize. “As colleagues, we are delighted to celebrate his career today. »
In January, Hammond began serving as MIT’s vice provost for faculty. Before that, she chaired the Department of Chemical Engineering for eight years and was appointed professor at the Institute in 2021.
A versatile technique
Hammond, who grew up in Detroit, credits his parents with instilling in him a love of science. Her father was one of the few blacks with a doctorate in biochemistry at the time, while her mother earned a master’s degree in nursing from Howard University and founded the Wayne County Community School of Nursing College. “This has provided tremendous opportunities for women in the Detroit area, including women of color,” Hammond noted.
After receiving her bachelor’s degree from MIT in 1984, Hammond worked as an engineer before returning to the Institute as a graduate student and earning her doctorate in 1993. After a two-year postdoctoral fellowship at Harvard University, she returned to join the MIT faculty in 1995.
At the heart of Hammond’s research is a technique she developed to create thin films that can essentially “shrink” nanoparticles. By adjusting the chemical composition of these films, the particles can be customized to deliver drugs or nucleic acids and target specific cells in the body, including cancer cells.
To make these films, Hammond begins by layering positively charged polymers on a negatively charged surface. Next, multiple layers can be added, alternating positively and negatively charged polymers. Each of these layers may contain drugs or other useful molecules, such as DNA or RNA. Some of these films contain hundreds of layers, others just one, making them useful for a wide range of applications.
“The nice thing about the layer-by-layer process is that I can choose a group of degradable polymers that are well biocompatible, and I can alternate them with our drug materials. This means I can create thin layers containing different drugs in different places in the film,” Hammond said. “Then, when the film degrades, it can release these drugs in reverse order. This allows us to create complex multidrug films, using a simple water-based technique.
Hammond described how these layer-by-layer films can be used to promote bone growth, in an application that could help people born with congenital bone defects or those who experience traumatic injuries.
For this use, his laboratory has created films comprising layers of two proteins. One of them, BMP-2, is a protein that interacts with adult stem cells and prompts them to differentiate into bone cells, thereby generating new bone. The second is a growth factor called VEGF, which stimulates the growth of new blood vessels that help bones regenerate. These layers are applied to a very thin tissue structure that can be implanted at the injury site.
Hammond and his students designed the coating so that once implanted, it releases VEGF early, over a week or so, and continues to release BMP-2 for up to 40 days. In a study on mice, they found that this tissue scaffold stimulated the growth of new bone that was almost indistinguishable from natural bone.
Target cancer
As a member of MIT’s Koch Institute for Integrative Cancer Research, Hammond has also developed layer-by-layer coatings that can improve the performance of nanoparticles used for cancer drug delivery, such as liposomes or nanoparticles made from a polymer called PLGA.
“We have a wide range of medication carriers that we can package this way. I think of them as a gobstopper, where there are all these different layers of candy and they dissolve one at a time,” Hammond said.
Using this approach, Hammond created particles capable of delivering a punch to cancer cells. First, the particles deliver a dose of a nucleic acid such as short interfering RNA (siRNA), which can turn off a cancer gene, or a microRNA, which can turn on tumor suppressor genes. Then the particles release a chemotherapy drug such as cisplatin, to which the cells are now more vulnerable.
The particles also include a negatively charged outer “stealth layer” that prevents them from being broken down in the bloodstream before they can reach their targets. This outer layer can also be modified to help particles be taken up by cancer cells, by incorporating molecules that bind to proteins abundant in tumor cells.
In more recent work, Hammond has begun developing nanoparticles that can target ovarian cancer and help prevent the disease from recurring after chemotherapy. In about 70 percent of ovarian cancer patients, the first cycle of treatment is very effective, but the tumors come back in about 85 percent of these cases, and these new tumors are usually very resistant to drugs.
By changing the type of coating applied to drug-delivering nanoparticles, Hammond discovered that the particles can be engineered to penetrate inside tumor cells or adhere to their surfaces. Using particles that stick to cells, she designed a treatment that could help jumpstart a patient’s immune response against any recurring tumor cells.
“In ovarian cancer, very few immune cells exist in that space, and because there aren’t a lot of immune cells present, it’s very difficult to get an immune response going again,” he said. she declared. “However, if we can deliver a molecule to neighboring cells, to the few cells there, and revive them, then we might be able to do something. »
To this end, she designed nanoparticles that deliver IL-12, a cytokine that stimulates neighboring T cells to spring into action and attack tumor cells. In a study in mice, she found that this treatment induced a long-term memory T cell response that prevented ovarian cancer from recurring.
Hammond closed her talk by describing the impact the Institute has had on her throughout her career.
“It’s been a transformative experience,” she said. “I really consider this place special because it brings people together and allows us to do things together that we couldn’t do alone. And it’s the support we receive from our friends, colleagues and students that truly makes things possible.
Written by Anne Trafton
Source: Massachusetts Institute of Technology
Originally published in The European Times.
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