Quite a few. That being said, with the whole heart thing I'm kind of an atypical example. I make a point to contribute as much to research (Of my own disease and related conditions) as possible. For example, right now, there are a few kilos of my cardiac muscle growing in a lab somewhere at the University of Michigan Cardio Research unit. They harvested cells when I had my pacemaker/defibrillator replaced, then somehow converted them back into something resembling a stem cell, then re-differentiated them into different kinds of cardiac muscle. The cool part of this whole thing is that I get semi-regular reports from the lab, because part of my conditions for participating in the study was to be updated on the research as often as meaningful milestones were achieved. I'm under NDA, but it's incredibly cool stuff to read, even though some of the super jargony/technical stuff goes over my head.