Micro-CT measurements showed no significant differences in bone regeneration between the two stem cell groups. However, combining the two types of stem cells produced significantly higher bone volume and strength compared to scaffolds without cellular augmentation.
Although stem cell delivery significantly enhanced bone growth and biomechanical properties, it was not able to consistently repair the injury. Eight weeks after the treatment, new bone bridged the gaps in four of nine defects treated with scaffolds seeded with adult stem cells, one of nine defects treated with scaffolds seeded with fetal stem cells, and none of the defects treated with the scaffold alone.
"We thought that the functional regeneration of the bone defects may have been limited by stem cells migrating away from the injury site, so we decided to investigate the fate and distribution of the delivered cells," said Guldberg.
To do this, Guldberg labeled stem cells with fluorescent quantum dots -- nanometer-scale particles that emit light when excited by near-infrared radiation -- to track the distribution of stem cells after delivery on the scaffolds and completed the same experiments as previously described.
Throughout the entire study, the researchers observed significant fluorescence at the stem cell scaffold sites. However, beginning seven to 10 days after treatment, signals appeared at the scaffold-only sites. Additional analysis with immunostaining revealed that the quantum dots present at the scaffold-only sites were contained in inflammatory cells called macrophages that had taken up quantum dots released from dead stem cells.
"While our overall study shows that stem cell therapy has a lot of promise for treating massive bone defects, this experiment shows
|Contact: Abby Vogel|
Georgia Institute of Technology Research News