Georgia's small community of cutting-edge stem cell researchers got a boost this month when the first-ever trial testing a human embryonic stem cell therapy began at Atlanta's Shepherd Center.When it comes to stem cell research, California and Massachusetts lead the nation with hot-shot scientists and well-funded laboratories. But Georgia has its own stable of scientists working on the stem cell frontier, and the groundbreaking experiment launched on Peachtree Street could help raise the profile of Georgia's stem cell efforts.