Agent 3 (image) Rice University Caption An X-ray image of unlabeled mesenchymal stem cells in test tubes shows the dramatic difference between those tagged with nanotubes that don't include bismuth (left) and those that do (right). The technique developed at Rice University shows promise for tracking live stem cells in the body. Credit Eladio Rivera/Rice University Usage Restrictions None Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.