Mesenchymal Stem Cells (IMAGE) University of Pennsylvania Caption This image shows fluorescently labeled mesenchymal stem cells (MSC) in a hyaluronic acid hydrogel. MSCs are a kind of adult stem cell found in bone marrow that is capable of turning into bone, fat or cartilage cells. The Penn team has been particularly interested in deducing the microenvironmental signals that tell these cells which way to differentiate. Credit Megan Farrell Usage Restrictions with credit. License Licensed content 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.