(170c) Virus Microarrays for Investigating Stem Cell Behavior

The interplay of multiple genetic factors that influence the balance between pluripotency and differentiation in stem cells is highly complicated. An enabling technology that will allow for the investigation of different mixes of factors and their combinatorial effects on a cell's capacity for self-renewal will be highly valuable. To fill this technology gap, we have constructed microarrays of adeno-associated viruses (AAV) to enable stem cell biologists to study the effects of genetic circuit perturbations in stem cells or somatic cells. First, using in vitro directed evolution techniques, we have built a collection of AAV vectors that are able to transduce target cells with greater efficiency. This is an important step since delivery of genes into stem cells is remarkably inefficient. Next, viruses encapsidating overexpression or shRNA cassettes were spatially patterned onto glass slides. The genetic microarrays were seeded with the target cell type, resulting in reverse transduction, also called surface-mediated transduction. Since different combinations of over-/underexpression cassettes can be patterned in each microarray dot, stem cell biologists can investigate the combinatorial effects of different genes and shRNA on stem cell or somatic cell self-renewal states.