In order to track the progress of the research, the stem cells were genetically modified to include genes that give off fluorescence signals. The bone material was then coated with the hydrogels, which contained the fluorescently labeled stem cells, and implanted into the defect of the damaged mouse bone. At that point, the researchers began monitoring the repair process with longitudinal fluorescence to determine if there would be an appreciable loss of stem cells in the in vivo samples, as compared to the static, in vitro, environments. They found that there was no measurable difference between the concentrations of stem cells in the various samples, despite the fact that the in vivo sample was part of a dynamic environmentwhich included enzymes and blood flowmaking it easier for the stem cells to migrate away from the target site. That means virtually all the stem cells stayed in place to complete their work in generating new bone tissue.
"Some types of tissue repair take more time to heal than do others," said Benoit. "What we needed was a way to control how long the hydrogels remained at the site."
Benoit and her team were able to manipulate the time it took for hydrogels to dissolve by modifying groups of atomscalled degradable groupswithin the polymer molecules. By introducing different degradable groups to the polymer chains, the researchers were able to alter how long it took for the hydrogels to degrade.
Benoit believes degradable hydrogels show promise in many research areas. For example, it may be possible to initiate tissue regeneration after heart attacks without having a patient undergo difficult, invasive surgery, but a great deal of additional research is required.
|Contact: Peter Iglinski|
University of Rochester