Using a Neo4j-backed ontology and data store (called SciGraph) was the subject of one the keynotes, which was presented by Dr. Melissa Haendel (from the Oregon Health & Science University) and titled 'Envisioning a world where everyone helps solve disease'. Slides of the talk itself are available
here. The SciGraph code is
here and is well worth a visit. The proceedings for 2015 should be out fairly soon (the previous years' proceedings are all available too).