There's a great TED talk by a guy who talks about this in extensive detail. Not sure what his specialty is, but I remember him saying that the first person who will live to be 1000 years old has probably already been born. Can't remember his name, but he's tall and skinny and has a long beard.

EDIT: Quick Google search... his name is Aubrey de Grey

https://www.ted.com/talks/aubrey_de_grey_a_roadmap_to_end_aging?language=en