For all that the goals and future of stem cell based regenerative medicine are fairly clear, scientists are presently spending more time on the development of necessary infrastructural technologies than on first generation therapies - and quite rightly so. One problem with adult stem cells is "the doggedness with which [cells] differentiate into mature tissue the moment they're isolated from the body. This makes it nearly impossible for researchers to multiply them in the laboratory. And because adult stem cells are so rare, that makes it difficult to use them for treating disease. Now, [researchers] have discovered a way to multiply an adult stem cell 30-fold, an expansion that offers tremendous promise for treatments such as bone marrow transplants and perhaps even gene therapy."
Link: http://www.eurekalert.org/pub_releases/2006-01/wifb-ptf011706.php