 This study examined how the viscoelasticity of a hydrogel affects the migration and fusion of mesenchymal stem cell, MSC, spheroids. The researchers found that faster relaxing hydrogels were more conducive to cell migration and subsequent fusion than slower relaxing hydrogels. They also discovered that inhibiting two signaling pathways, rock and rack 1, prevented cell migration. Finally, they combined biophysical and biochemical cues provided by the faster relaxing hydrogels and PDGF supplementation, respectively, which resulted in a synergistic enhancement of migration and fusion. These results suggest that the viscoelasticity of a hydrogel plays an important role in tissue engineering and regenerative medicine strategies based on spheroids. This article was authored by David T. Wu, Mani Diba, Stephanie Yan and others. We are article.tv, links in the description below.