Planning on medicine and/or medical research

There are some hospitals with active research programs; for example, some significant tissue engineering and polymer scaffolding research has been done through a collaboration between Bob Langer (MIT professor) and Jay Vicante, a surgeon at the Children's Hospital in Boston. Apart from the Children's Hospital, I am aware of research efforts at MCO in Ohio and the Yale-New Haven hospital in Connecticut--I would expect that hospital-based research programs aren't that unusual.
To gain employment at a research institution such as Gencorp, a bachelor's degree is sufficient provided you're content with starting as a technician. That is, provided you're interested in doing the actual lab work but don't mind if someone else is steering the research and making the major decisions. If you want to actually control projects and plan your own research, you'll probably need a more advanced degree (although a bachelor's + years of experience may also suffice). If your focus is industry (Gencorp/etc. as opposed to a hospital), a Ph.D. in biology, biochemistry, etc. would be just as good as medical school / a M.D.