September 21, 2010

The Scientist: David Putnam

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In a journey starting from an ordinary dairy farm, Prof. David Putnam, biomedical engineering, has moved onto developing biomaterials, vaccines and drug delivery techniques for patients.

Putnam never takes “no” for an answer, he said. After a postdoctoral experience with Prof. Robert Langer at MIT, Putnam came to the university in 2002, launching into his goals.

An idea that started way back in 1996, when he was a Ph.D. student, has recently come to fruition. Putnam’s group, in collaboration with Dr. Jason Spector, a plastic surgeon at New York-Presbyterian Hospital/Weill Cornell Medical Center, has developed a new biomaterial that makes tissues stick together and aids in the post-operative healing process.

A gel, composed of polycarbonate of dihydroxyacetone (MPEG-pDHA) and polyethylene glycol, fills the dead space created by surgeries, such as cancer ablations, to prevent internal blisters and infections.

Putnam engineered the gel from substances that the body already knows how to metabolize, like DHA, a third metabolite of glucose.

Putnam explained,  “We designed a material that takes tissues and sticks them together. Tissues can heal together; the material degrades  and  is metabolized through the normal processes in the body,”

In the next step, Putnam must get companies interested in his new biomaterial.

Putnam’s research also mimics viruses to make new biomaterials for delivering nucleic acids in ways similar to the movement of drugs into cells. Nucleic acids, particularly DNA and RNA, are large and highly charged, and hence, they cannot passively diffuse through the cell membrane.

“We trick the cell in taking up this nucleic acid, thinking it’s food, just like viruses that do it automatically,” Putnam said.  “Mother nature evolved viruses over billions of years. I have only 30 years as a faculty member to be productive.”

Putnam speeds up the natural process of mutation by building libraries of biomaterial polymers. Each library contains about 5000 mutations of these polymers. Putnam is able to identify those mutations to which the cell has some response, and then he uses these mutations as a basis for another library.

Having developed the chemistry to make such libraries, “we are taking out the serendipitous ones that work and optimizing those. It’s a synthetic evolution of materials for nucleic acid delivery,” Putnam elaborated.

Putnam has also worked with Prof. Matthew DeLisa, chemical engineering, to develop vaccines.

Since making vaccines for diseases, like malaria, is difficult, Putnam related that, by just modifying the protein causing malaria a little, the body will be able to better recognize it and launch an appropriate immune response.

“We take a protein that your body doesn’t recognize very easily and make it recognized immediately. We are able to engineer bacteria to make protein that is a bad antigen and make it good,” Putnam explained.

Aside from research, Putnam is a co-founder of the start-up company, Transform Pharmaceuticals, Inc.. Last year while on his sabbatical, Putnam worked for a venture capitalist firm to develop financial experience for starting the company.

Putnam is also an excellent skier, related an anonymous student.

According to Putnam, finding good mentors and getting proper advice from smart people is crucial for success.

Original Author: Poornima Gadamsetty