Chapter 4 examines how countries with different scientific institutional histories and income levels have dealt with scientific uncertainty and the ethics of ‘experimental’ interventions using so-called mesenchymal ‘stem’ cells, that is cells of uncertain therapeutic character. Observing regulatory practices for clinical research and commercial interventions in the context of global competition, the chapter describes the complex intertwinement of catering for patient needs and demands, the protection of high quality scientific research, the affordability of testing methods, and the prospect of economic growth through investment into regenerative medicine in China and in higher-income countries (HICs). HICs that traditionally have had the power to define standards and conditions set by regulation, even when that power is on the wane, still enjoy considerable ‘regulatory immunity’: their reputation allows HICs to tolerate regulatory violations. In HICs, a scientific boundary is commonly asserted between established stem cell scientists and clinical providers that violate official guidelines. Scapegoating, here, is used as means to defend the reputation of the regulated collective against unauthorized, but tolerated clinical cell-applications. Examples show that the USA and the EU have used regulatory immunization to protect the reputation of stem cell communities alongside violators.