Tissue Engineering: Boston University
Pancreas, blood vessels or other organ on the fritz? She'll build you a nifty replacement.
When Tejal Desai walked into professor Mauro Ferrari's office at the University of California, Berkeley, she looked so young he mistook her for an overeager high schooler and almost threw her out. Undeterred, Desai told him she'd studied biomedical engineering as an undergrad at Brown and was seeking a challenging Ph.D. project. Ferrari assigned her a whopper: Build an implantable device that will eliminate the daily insulin injections diabetics give themselves to control blood sugar levels. Desai's colleagues warned her the task was too hard, that she'd never graduate.
But after four years of coaxing cells to grow on chemically modified silicon surfaces, Desai had it: a microscopic device that, when implanted in diabetic rats, delivered ongoing, regular doses of insulin. The device functioned like a tiny tea strainer: A hollow bit of silicon perforated with tiny holes, it was filled with pancreas cells doing what pancreas cells do naturally—produce insulin. The holes were large enough for the insulin to diffuse out, but small enough that the pancreas cells stayed inside, and the rat's immune agents—which would normally mark the cells as foreign and attack them—could not enter. "Nobody expects you to cure diabetes before you graduate," recalls Ferrari. "And then Tejal did!" (For rats, anyway.)
Desai's implant is being developed by a private company for human use, but Desai, now 31, has moved on. She has developed a speck-size layered plastic device that, when swallowed, attaches to the intestinal lining, releasing medicine. Next she plans to build better artificial blood vessels. The existing variety, mere tubes, cannot constrict or dilate as natural vessels do to control blood pressure. Desai's goal is to make artificial vessels that coax the patient's own body to grow replacements, then biodegrade, leaving the new natural vessels behind.
Desai's father, a chemical engineer whose company designs water-desalination systems, cautioned her about engineering; it can be an unexciting profession, he told her. Then, in high school, Desai heard a biomedical
engineer speak. Here was a totally new incarnation of engineering, one packed with magical promise—building artificial organs, or artificial nerves for people with spinal cord injuries. Desai had found her calling. (Her father has since relented; they occasionally talk shop, especially on the topic of nanoporous membranes.) Says Kenneth Lutchen, chair of biomedical engineering at BU, "In 10 years, some promising young student will be labeled â€the next Tejal Desai.'"
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.