The hydrogel is designed for stability over its long-term use as a scaffold for cells to take root and proliferate. But it's also designed for its own timely destruction.
"I came up with the idea a few years ago, but it's finally all come together," said Watson, who is pursuing both a Rice doctorate and a medical degree in a joint program with nearby Baylor College of Medicine. "These chemical crosslinks are attached by phosphate ester bonds, which can be degraded by catalysts in particular, alkaline phosphatase -- that are naturally produced by bone tissue.
"The catalysts are naturally present in your body at all times, in low levels. But in areas of newly formed bone, they actually get to much higher levels," he said. "So what we get is a semismart material for bone-tissue engineering. As new bone is formed, the gel should degrade more quickly in that area to allow even more space for bone to form."
The fine balancing act took a lot of expertise from his colleagues and co-authors, including Paul Engel, chair of Rice's Department of Chemistry, and F. Kurtis Kasper, a senior faculty fellow in bioengineering. "It looks like we may have just decided to try something and found that, hey, it worked! But that wasn't the case," said Watson, describing the months and years it took to refine the hydrogel. Engel's help with the sophisticated chemistry was especially valuable, he said.
Watson expects that the material degradation can be tuned to match various bone growth rates.
"Optimizing the degradation kinetics is nontrivial and may be better suited for a biotech company," he said. "We focus more on the performance of the hydrogels and the underlying molecular mechanisms"
|Contact: David Ruth|