[1] Johns Hopkins Univ, Sch Med, Neuroregenerat Program, Inst Cell Engn,Dept Neurol, Baltimore, MD 21205 USA
[2] Univ Fribourg, Dept Med Anat, CH-1700 Fribourg, Switzerland
[3] Johns Hopkins Univ, Sch Med, Stem Cell Program, Inst Cell Engn,Dept Neurol, Baltimore, MD 21205 USA