Mesenchymal Condensations (IMAGE) University of Pennsylvania School of Medicine Caption Mesenchymal condensations, the engineered stem cells used in the researchers' process to kick off rapid bone development in bone defects. Credit Joel Boerckel Usage Restrictions Credit as specified. 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.