Hydrogel-based microfluidic device with multiplexed 3D in vitro cell culture.

Microfluidic devices that combine an extracellular matrix environment, cells, and physiologically relevant perfusion, are advantageous as cell culture platforms. We developed a hydrogel-based, microfluidic cell culture platform by loading polyethylene glycol (PEG) hydrogel-encapsulated U87 glioblastoma cells into membrane-capped wells in polydimethyl siloxane (PDMS). The multilayer microfluidic cell culture system combines previously reported design features in a configuration that loads and biomimetically perfuses a 2D array of cell culture chambers. One dimension of the array is fed by a microfluidic concentration gradient generator (MCGG) while the orthogonal dimension provides loading channels that fill rows of cell culture chambers in a separate layer. In contrast to typical tree-like MCGG mixers, a fractional serial dilution of 1, ½, », and 0 of the initial solute concentration is achieved by tailoring the input microchannel widths. Hydrogels are efficiently and reproducibly loaded in all wells and cells are evenly distributed throughout the hydrogel, maintaining > 90% viability for up to 4 days. In a drug screening assay, diffusion of temozolomide and carmustine to hydrogel-encapsulated U87 cells from the perfusion solution is measured, and dose-response curves are generated, demonstrating utility as an in vitro mimic of the glioblastoma microenvironment.

Traumatic Left Anterior Descending Artery Dissection in a Case of Pediatric Blunt Chest Trauma.

Despite the reserve for recovery in pediatric trauma, blunt force chest trauma can cause insidious injuries that are easy to miss. Coronary artery dissection is a rare injury associated with blunt force chest trauma in the pediatric population and can present with vague or atypical symptoms. Pediatric patients can be unreliable in reporting symptoms, and providers can mistake coronary artery injuries for myocardial contusion, especially with improving laboratory tests and equivocal imaging. We report a case showing the importance of a high index of suspicion when presented with this trauma pattern in a pediatric patient.