(IMAGE) Helmholtz Association Caption This is a scanning electron microscopy of stem cells (yellow / green) in a scaffold structure (blue) serving as a basis for the artificial bone marrow. Credit Photo: C. Lee-Thedieck/KIT Usage Restrictions None 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.