Hydrogels Could Help Repair Bones, Researchers Find

Researchers at University of Rochester have found a technique that uses stem cells to repair bones with greater efficiency.

Stem cells can be used to regenerate bone tissue. However, a major problem with these cells is that they tend to drift away from the injury site, extending the duration of treatment.

Researchers propose that using hydrogels could help keep stem cells in one place until they finish their job.  Hydrogels are polymers that attract water. They degrade once the tissue is regenerated.

According to the researchers, the technique is already used to repair cartilage and the present study shows that it can be applied to bone regrowth as well.

"Our success opens the door for many-and more complicated-types of bone repair," said Danielle Benoit,  assistant professor of Biomedical Engineering. "For example, we should now be able to pinpoint repairs within the periosteum-or outer membrane of bone material."

For the study, researchers conducted tests on animal models (in vivo) as well as in-vitro. The team first removed all living cells from the donor bone fragment to ensure that the new bone was made only by stem cells.

The stem cells used in the study were genetically altered to give florescence signals, which helped researchers track their movements.

The test bone was coated with the hydrogel containing stem cells and was then implanted into a  mouse model. Researchers wanted to know whether stem cells drifted away in the mouse's body.

Despite being in a more dynamic environment of the mouse's body, the stem cells didn't move around. The study showed that the hydrogels could trap the stem cells until the tissue was repaired. This is important because, unlike a laboratory setting, the body is much more complex and has several blood vessels.  The study shows that the hydrogels could be used in animal bodies to repair bone tissue.

"Some types of tissue repair take more time to heal than do others," said Benoit in a news release. "What we needed was a way to control how long the hydrogels remained at the site."

Additionally, researchers were also able to control the time that hydrogels took to degrade by altering a set of atoms called degradable group.

National Institutes of Health (NIH), the Orthopaedic Research and Education Foundation/Musculoskeletal Transplant Foundation and others funded the research and it is published in the journal Acta Biomaterialia.

Recently, researchers at Rice University developed a semi "smart" hydrogel that turns from liquid to solid in the body and disappears when the tissue is regenerated.