Traditionally, such DNA insertions have been carried out using viruses that have a natural ability to penetrate the cell and insert segments of DNA into the nucleus. But these viruses can sometimes have dangerous side effects, and have been responsible for deaths in some early gene-therapy trials.
Were working on polymers that could deliver DNA as efficiently as viruses, that could put a DNA strand wherever you want, without the safety problems of viruses, Langer says. In addition, they could be cheaper and easier to manufacture.
So far, the problem has been that such synthetic vectors have been far less efficient in carrying out the delivery. But in early tests conducted by Jordan Green and Dan Anderson in Langers lab, some polymers have been as effective at delivering the DNA strands to their target as the viruses, but with 100 times less toxicity.
Such new polymers, Langer says, might eventually lead to new treatments for some kinds of cancer. And they may also enable the delivery of small interfering RNA segments (siRNAs), whose discovery led to a Nobel Prize in 2006. These may be used to combat a variety of diseases.
Anderson, Langer and graduate student Michael Goldberg have also been working on the design of chemicals similar to lipids in the body, called lipidoids that could be used to deliver drugs including siRNA to specific tissues in the body and release them in a controlled way. Already more than 50 promising compounds have been found and are undergoing tests. That work is going quite well, Langer says.
Tissue engineering is another important area of ongoing research, Langer says. One key project is growing replacements for damaged tissues such as the neurons damaged by spinal cord injuries that lead to paralysis. Using a neuronal sc
|Contact: Elizabeth Thomson|
Massachusetts Institute of Technology