Kam Leong to Lead Duke Initiative Aimed at Nanomedicine

Kam Leong, a national leader in drug and gene delivery at Johns Hopkins University, has joined the department of biomedical engineering at Duke University’s Pratt School of Engineering, where he will serve as director of the school’s Bioengineering Initiative.

Leong said he plans to focus on the emerging field of "nanotherapeutics," the application of devices on the scale of nanometers -– one billionth of a meter -- for treating disease via drug, gene and immunization therapies. He said he will also lead a research effort to develop nanostructures for tissue engineering and regenerative medicine.

The collaborative endeavor will draw on the expertise of those at Duke’s Pratt School, particularly in the areas of biophotonics (applications of light to medicine), materials sciences and tissue engineering, Leong said. The initiative also will aim to complement and capitalize on related efforts now underway at Duke University Medical Center, he said. Leong holds a joint appointment in the medical center’s department of surgery.

"Nanoscience and nanoengineering are leading to revolutionary advances in the understanding and control of the fundamental building blocks of physical systems," Leong said. "Convergence of these disciplines with biomedical sciences has in turn led to considerable progress, including advances in nanoscale biosensors, nanoparticles with multiple imaging and therapeutic functions, and nanosystems capable of detecting and manipulating single molecules. This is a fertile area where discoveries and inventions will continue to materialize.

"There is a lot of room for innovative science that could have a significant impact on health care," Leong added. "Such investigation is inherently highly interdisciplinary and will require close collaborations. Duke is an ideal place for this as it is already very collaborative."

Originally from Macau, Leong completed his undergraduate work at the University of California, Santa Barbara, and received his Ph.D. in chemical engineering from the University of Pennsylvania. He became involved with the emerging drug delivery field at the Massachusetts Institute of Technology as a postdoctoral fellow before joining the faculty at Johns Hopkins, where he was professor of biomedical engineering and orthopedic surgery. Leong was Director of the Biomaterials Program and technical advisor to the Institute of Materials Research and Engineering in Singapore from 1998 until 2004, and also directs the Tissue and Therapeutics Engineering Lab of the Division of Johns Hopkins in Singapore. He has now authored 152 peer-reviewed journal articles and holds 27 patents.

"Kam Leong is one of the leaders in the areas of drug and gene delivery and bionanotechnology" said George Truskey, chair of Pratt’s Department of Biomedical Engineering. "His research is very interdisciplinary, and he has been effective at translating basic research into clinically relevant advances. We are extremely excited that he is here, and look forward to his continued innovative research."

Leong’s early research efforts led to the development of so-called polyanhydrides, biodegradable polymers designed for biomedical applications, including controlled drug delivery for brain tumor chemotherapy. His Johns Hopkins group later designed and synthesized a second class of biodegradable polymers, the poly(phosphoester)s, which Guilford Pharmaceuticals licensed and tested for potential use in ovarian cancer treatment.

Research now underway in Leong’s lab has turned to the use of poly(phosphoester)s for gene therapy. Gene therapy generally employs viruses to deliver therapeutic bits of DNA into cells, but such methods are not without problems, Leong said.

"The use of viral carriers to deliver foreign genes is efficient, but long-term safety is always a concern," he said. "Increasing attention has shifted to non-viral methods of gene delivery."

Leong’s team was the first to show in an animal vaccination model that a non-viral delivery agent taken orally can generate a therapeutic effect. These oral gene delivery systems were licensed to Aarmedis Corp. and are undergoing further development for the treatment of hemophilia and diabetes, he said.
"We believe these studies will pave the way toward realizing the ultimate goal of gene therapy, that of applying a gene as a ‘drug’," Leong said.

Leong’s group also studies the use of poly(phosphoester)s and other natural biopolymers as scaffolds for tissue engineering, particularly the growth and differentiation of stem cells. The fibrous nanostructures are coated with growth factors that encourage the infiltration and growth of progenitor cells at sites of injury, he explained. His team found that polymer fibers embedded with neural growth factors could promote sciatic nerve re-growth in rats.

"We’ve begun to demonstrate how electrospun fibers could be used in regenerative medicine, and we think there will be many other therapeutic applications," Leong said.
Many questions remain, however. "While studies in cell culture and in animals have shown promise, there is a lot of work to be done to get to the therapeutic level," Leong said.

The research initiative Leong plans to build at Duke will address many of the outstanding questions in non-viral gene therapy and regenerative medicine by incorporating Pratt School’s strengths -- including optical imaging, ultrasound, sensors, drug and gene delivery and tissue engineering -- into his research program. The ultimate goal: to bring nanomedicine to patients, he said.