To coincide with the release of the new sci-fi thriller Splice, in which scientists Adrien Brody and Sarah Polley create a dangerous half-human hybrid via genetic manipulation, Alex Fitch talks to director Vincenzo Natali about the film and the other three movies he’s collaborated on with actor David Hewlett – Cypher, Nothing, the cult classic Cube – and his forthcoming adaptation of William Gibson’s novel Neuromancer.