ReNeuron will be treating the first stroke patients with stem cells later this year in the UK after overcoming a string of regulatory holdups abroad. In February, the Surrey-based company received the go-ahead to start a phase 1 trial from the UK's Gene Therapy Advisory Committee (GTAC) for ReN001, a genetically engineered neural stem cell line originally derived from fetal brain tissue. ReNeuron was the first European stem cell company to go public in 2005, but at the time decided to apply for approval with the US Food and Drug Administration (FDA). The FDA, however, repeatedly delayed approval, prompting the company to apply in 2008 to the UK's Medicines and Healthcare Products Regulatory Agency and subsequently GTAC. CSO John Sinden points out that, “We decided temporarily to discontinue discussions with the FDA since we could not afford to run two phase 1 trials in stroke.” The recently approved open label dose escalation safety trial will take place at Glasgow's Southern General Hospital in 12 patients and will also evaluate potential efficacy biomarkers using structural and functional MRI. Chris Mason, who heads the Regenerative Medicine Bioprocessing Unit at University College London, says, “Given the degree of scrutiny by the regulators, the phase 1 study should not be a challenge.” Mason adds that any unwelcome surprises are more likely to crop up at later stages, due to the heterogeneity of this patient group.