By offering unproven therapies, a Texas biotechnology firm has sparked a bitter debate about how stem cells should be regulated. Ann McFarlane is losing faith. In the first half of 2012, the Houston resident received four infusions of adult stem cells grown from her own fat. McFarlane has multiple sclerosis (MS), and had heard that others with the inflammatory disease had experienced improvements in mobility and balance after treatment. The infusions — which have cost her about US$32,000 so far — didn't help, but she knew that there were no guarantees. It is McFarlane's experience with Celltex Therapeutics, the company...