Cell Printing in Complex Hydrogel Scaffolds.

Advancements in the microfabrication of soft materials have enabled the creation of increasingly sophisticated functional synthetic tissue structures for a myriad of tissue engineering applications. A challenge facing the field is mimicking the complex microarchitecture necessary to recapitulate proper morphology and function of many endogenous tissue constructs. This paper describes the creation of PEGDA hydrogel microenvironments (microgels) that maintain a high level of viability at single cell patterning scales and can be integrated into composite scaffolds with tunable modulus.

Context-Dependent Requirements for FimH and Other Canonical Virulence Factors in Gut Colonization by Extraintestinal Pathogenic Escherichia coli.

Extraintestinal pathogenic (ExPEC) acts as a commensal within the mammalian gut but can induce pathology upon dissemination to other host environments such as the urinary tract and bloodstream. ExPEC genomes are likely shaped by evolutionary forces encountered within the gut, where the bacteria spend much of their time, provoking the question of how their extraintestinal virulence traits arose. The principle of coincidental evolution, in which a gene that evolved in one niche happens to be advantageous in another, has been used to argue that ExPEC virulence factors originated in response to selective pressures within the gut ecosystem.