Big help in small packages
Tuesday 19 July 2011
UCSF bioengineer Tejal Desai builds medical implants – with parts as tiny as human cells – that may be used to treat diabetes, kidney failure and other diseases.
As a Santa Barbara high school student, Tejal Desai got a kick out of making things work. Her father was a chemical engineer, and she thought she knew what engineering was all about.
So, she was startled when a bioengineer visited her class and told the students about research to develop artificial organs and implants.
“I was very excited. I had always thought that engineering was about building bridges and mechanical devices. I didn’t know you could use it to help people.”
The class visit was part of a national program to encourage girls to pursue engineering careers. The revelation about artificial organs started Desai on two paths. She not only became a bioengineer, but also an outspoken advocate for young women entering science and engineering fields.
“Because I was so influenced by that program myself, I’ve always had an interest in mentoring girls of various backgrounds who are interested in science and engineering careers," she said. "I hope that if you can encourage them and make them enthusiastic, it will help them continue. It’s something I believe in.”
As a bioengineering undergraduate at Brown University, Desai also studied sociology and political science, and after college, she played an active – even activist – role in urging her alma mater to assure that female students and faculty had full opportunity to pursue the sciences and engineering. She ended up writing a 100-page document outlining admission policy changes that would encourage more student and faculty diversity in these fields.
Her other path has led her to develop new ways to make implantable medical devices so small that their individual parts are the size of human cells. Such minuscule implants can overcome the limitations of conventional therapy to treat diabetes, kidney failure and other debilitating diseases.
The new tiny-focused technology ironically goes by a very long name: biomedical micro-electro-mechanical systems (bio MEMS). "Micro" refers to sizes that are thousandths of a millimeter, the size of a human cell. The technology now increasingly focuses on still smaller, "nano" scales – millionths of a millimeter.
Desai directs the Laboratory of Therapeutic and Micro and Nanotechnology at UCSF. Her lab has gained national attention for devising and demonstrating the feasibility of an implantable artificial pancreas to treat type 1 diabetes. People with type 1 diabetes cannot maintain healthy blood sugar levels because their immune systems attack and destroy their precious insulin-producing “beta cells” in the pancreas.
Even with frequent self-monitoring and injections of insulin, the blood sugar levels of those with type 1 diabetes spike and plummet, degrading the body’s crucial ability to regulate many metabolic functions. Though self-treatment is fairly effective in the short-run, type 1 diabetes, if left untreated, can ultimately lead to cardiac complications, poor circulation that threatens limbs, and generally, a shorter life span.
Desai conceived of a kind of micro/nano-scale cage, to protect beta cells in the body. The cage, or biocapsule, contains “nanopores” large enough to allow the vital beta cells to secrete insulin, but small enough to prevent the immune system’s molecular soldiers from entering and destroying the beta cells. The device could be implanted near the abdominal wall, or anywhere in the body where the cells are exposed to the body’s sugar levels.
Unlike self-administered insulin shots, an implantable device maintains and protects the body’s natural insulin control and allows normal regulation of the body’s metabolism. It is a cure.
The micro-parts are made of materials accepted by they body’s immune system, and are fabricated using the techniques developed by California’s microelectronics industry. Desai’s lab has already demonstrated in animals that the artificial pancreas device works as intended.
She expects that this technology could be of use for many other chronic, cell-based diseases, such as Parkinson’s, Alzheimer’s, hormone deficiencies – anywhere the body is unable to produce something it needs naturally, she said.
Desai earned her doctorate in the UC Berkeley and UCSF Graduate Program in Bioengineering – a collaboration between the two UC campuses that draws on Berkeley’s nationally recognized engineering expertise and UCSF’s equally recognized clinical research and treatment programs.
“We’ve always felt that we could be better together than either of us apart, and now it’s one of the highest ranked programs in bioengineering in the country,” she said.
Desai is an active member in two other productive collaborations – UCSF’s bioengineering and therapeutic sciences department, and the California Institute for Quantitative Biosciences, or QB3, which links UC Berkeley, UCSF and UC Santa Cruz scientists with counterparts in the biomedical and biotech industries. The network meets one of Desai’s major goals: Speeding the advance of university discoveries into clinical trials and the real world of patient care.
“The goal of all of this is to help people,” she says.
(See more about Desai’s research and UCSF’s “What’s Next in Science” series.)
Teaming with industry
Desai’s insulin delivery research is only one of several potential therapies her team is working on. Some projects receive partial funding from companies eager to translate life-saving innovations into treatments and products. One promising effort aims to deliver drugs directly to the intestines to treat disorders such as colitis and irritable bowel syndrome.
Desai’s team is creating a kind of microscopic “band aid” so small that hundreds of them can be placed in a normal-sized pill. Each strip is as wide as a human hair. Once ingested, these strips will travel to the small intestine, stick to the intestinal wall and deliver medicine. They contain nano-scale drug reservoirs, as well as projections that create a textured surface that can stick to the body’s cells.
Because of the extraordinarily small scale, the projections mechanically interact with intestinal wall cells, and deliver drugs into openings between the cells. There they remain for at least several hours, providing much-needed medication before they are sloughed off.
Desai’s lab is supported in this research by a company called Zcube srl through a sponsored research agreement aimed to help speed such novel treatments into medical practice. Such collaborations are central to QB3, one of four such institutes throughout the UC system, founded 10 years ago to foster research alliances among different UC campuses and with industry.
Some of Desai’s former students have launched a startup company called Nano Precision Medical that is developing devices such as an implantable drug-delivery pump to treat hepatitis C and other chronic diseases. (See video.) The company is starting its life in the QB3 “garage” on the Berkeley campus. It is one of two QB3 startup incubators – the other is at UCSF’s Mission Bay campus – to support the very early stages of promising new biomedical and biotech innovations.
Photo by Elisabeth Fall