ASE: Contrast-enhanced ultrasound can be used to track stem cells
Contrast-enhanced ultrasound might be used to track the fate of stem cells after their administration, according to study results presented at the 2008 American Society of Echocardiography (ASE) meeting held in Toronto this week.

While newer techniques to repair damaged heart muscle and blood vessels using stem cells are currently being tested, the best method to track these cells after their delivery is still unknown, according to the presenters. However, the researchers believe results from their study could help direct strategies to reverse damage to the heart muscle or circulation system by tracking incorporation of stem cells to specific parts of the heart and its blood vessels. 

By using contrast enhanced ultrasound imaging, Michael A. Kuliszewski, MD, from St. Michael's Hospital in Toronto, and colleagues said physicians can ‘see’ where stems cells go, and how they interact with a patient’s heart and circulation, thereby helping to determine which strategies to direct cells to the specific areas of the heart and circulatory system are the most effective.

“This research ultimately could make it possible for doctors to use contrast-enhanced ultrasound to accurately track stem cells as they move through the heart and circulation and may someday help doctors ‘place’ them where they are most needed,” said study author Howard Leong-Poi, MD.  “Contrast-enhanced ultrasound technology may eventually play an important role in the stem cell revolution in treating heart and vascular disease.”

Researchers used specially developed ultrasound contrast microbubble agents that can be targeted to unique cell surface markers on genetically engineered stem cells, known as endothelial progenitor cells, which were implanted into nine recipient rats. 

The rats randomly received either intravenous targeted microbubbles, or control microbubbles, during ultrasound imaging. The visualized ultrasound signal enhancement was significantly higher after injection of targeted microbubbles, compared to the non-targeted contrast agent.

The study concluded that targeted microbubbles exhibit specific binding to engineered stem cells and can be visually detected by their enhancement on contrast-enhanced ultrasound imaging.