You are correct that stem cells are regulated by the Center for Biologics Evaluation and Research (CBER) as human cells, tissues and cellular and tissue-based products (HCT/Ps) under the authority of Section 361 of the Public Health Service (PHS) Act, and the implementing regulations in Title 21 of the Code of Federal Regulations (CFR) Part 1271 (see http://www.fda.gov/BiologicsBloodVaccines/TissueTissueProducts/RegulationofTissues/ucm150485.htm and http://www.fda.gov/BiologicsBloodVaccines/TissueTissueProducts/QuestionsaboutTissues/ucm136323.htm for more information). HCT/Ps that meet all of the criteria in 1271.10(a) are regulated solely under Section 361 of the PHS Act, and no premarket review (license application to FDA) is required. \n\nHCT/Ps that do not meet all of the criteria listed in 1271.10(a) are regulated under Section 351 of the PHS Act as drugs, devices and/or biological products, and require premarket approval. \n\nThese criteria include the intended use of the cells, and can thus be considered therapies, not just products. As Paul Richards of the FDA wrote in an email, "Cellular therapies that are minimally manipulated, intended for homologous use only, not combined with another article (with some exceptions) and are intended for autologous use or use by a first-or second-degree blood relative are examples of the type of HCT/Ps that are regulated under section 361." Thus, for the specific example you gave of using autologous bone marrow stem cells injected into the brain, this scenario would indeed require full FDA approval as it does not meet the criteria of homologous use, as you said.\n\nFurthermore, in many cases, doctors can choose to use unapproved therapies, with patient consent, under the "practice of medicine" (e.g., see http://singularityhub.com/2010/03/09/colorado-doctors-skirt-fda-jurisdiction-to-provide-human-stem-cell-therapies-video/).