Mending the gaps: ethically sensitive cells and the evolution of European stem cell policy.

The past decades witnessed the slow evolution of Europe's heterogeneous stem cell (SC) policy and substantial scientific advances in the field. Parallel to these developments, professional organizations have grown in influence. With the recently revised International Society for Stem Cell Research's Guidelines as a backdrop, we address the evolution of SC policies in 46 European countries and discuss how they fare against evolving ethical standards, societal views, and scientific advances. We identify areas of convergence, divergence, and the suitability of extant governance mechanisms to meet their stewardship roles. Europe represents a rich case study as it encompasses a wide range of policy approaches present worldwide. Comparative studies provide an opportunity to promote insight into national frameworks and to foster international harmonization.