A nod to Paul Knoepfler at UC Davis, who has posted a blog entry about the Geron trial for spinal cord injury. It provides a nice summary of the science behind the trial, and a reminder of why patients might be hard to recruit. He refers to Michael Martinez, a jockey who recently sustained a severe spinal cord injury, and who was rejected for participation in Geron's trial developed from human embryonic stem cells. As Knoepfler points out: