Synthetic transcription factors based on the RNA-guided CRISPR-Cas9 system are used to activate specific endogenous genes in human cells. Also online, Joung and colleagues report similar developments at two other loci. Technologies for engineering synthetic transcription factors have enabled many advances in medical and scientific research. In contrast to existing methods based on engineering of DNA-binding proteins, we created a Cas9-based transactivator that is targeted to DNA sequences by guide RNA molecules. Coexpression of this transactivator and combinations of guide RNAs in human cells induced specific expression of endogenous target genes, demonstrating a simple and versatile approach for RNA-guided gene activation.

Adipose tissue is an abundant, accessible, and replenishable source of adult stem cells that can be isolated from liposuction waste tissue by collagenase digestion and differential centrifugation. These adipose-derived adult stem (ADAS) cells are multipotent, differentiating along the adipocyte, chondrocyte, myocyte, neuronal, and osteoblast lineages, and can serve in other capacities, such as providing hematopoietic support and gene transfer. ADAS cells have potential applications for the repair and regeneration of acute and chronically damaged tissues. Additionalpre-clinical safety and efficacy studies will be needed before the promise of these cells can be fully realized.

X. Zhao and co-workers develop on page 4035 a new biocompatible hydrogel system that is extremely tough and stretchable and can be 3D printed into complex structures, such as the multilayer mesh shown. Cells encapsulated in the tough and printable hydrogel maintain high viability. 3D-printed structures of the tough hydrogel can sustain high mechanical loads and deformations.