How physical environment influences stem cell development

Scientists around the world are involved in studying, describing and even manipulating the development of stem cells on their path into becoming specialized cells, such as heart, muscle, brain or any other tissue. This research has tremendous implications for the future utilization of stem cells as a new tool of medical treatment.

In an article published in Nature Physics, Dr. Assaf Zemel of the Institute of Dental Sciences at the Hebrew University and his fellow researchers, Prof. Samuel Safran from the Weizmann Institute of Science, Dr. Florian Rehfeldt from Gottingen University in Germany, and Dr. Andre Brown and Prof. Dennis Discher from the University of Pennsylvania, tell how they have developed a theoretical model and carried out experiments on stem cells to propose a mechanism for the recently discovered sensitivity of stem cell differentiation to the rigidity of their surroundings.

They described the physical changes that take place in stem cells that are layered on supporting foundations of differing rigidities. They showed that on a supporting matrix whose rigidity mimics that of muscle tissue, the cells become elongated and filled with aligned muscle-like fibers. The authors explain how this situation is fundamentally different from the case where the supporting substance is made either softer (to mimic brain tissue) or harder (to mimic bone tissue), in which case the cells adopt more symmetric structures and differentiate into brain and bone cells, respectively.

These findings shed new light on our understanding of the mechanisms that govern the differentiation of stem cells and may have important implications for the design of artificial tissues and the development of novel therapeutic strategies, says Dr. Zemel.