Editor's Spotlight/Take 5: Adipose-derived Mesenchymal Stem Cells Are Phenotypically Superior for Regeneration in the Setting of Osteonecrosis of the Femoral Head.

S ome treatments carry so much intuitive appeal that we cannot help but feel cheated when they do not work. No doubt every reader of this has, at one time or another, been drawn to an intervention that seems like it should have been a bigger hit than it was. Perhaps—even worse—the intervention should have been a winner but instead harmed patients. Using critical reading skills and adopting new treatments only when high-quality research supports the concepts behind them can keep us from betting on too many of these wrong horses. Then there are those treatments that seem to evolve before our eyes. Mesenchymal stem cells (MSCs) come to mind here. Certainly we crave a biological approach driven by a plentiful source of cells that possess a nearlimitless potential to regenerate and differentiate into kinds of tissue that don’t heal well, such as cartilage and tendon. Yet as intuitively sensible as this approach seems, a two-decadeplus history of inquiry into the topic [6] has delivered little, if any, clinical impact. But the search continues, and in new ways. Since 2014, Clinical Orthopaedics and Related Research has published two promising papers in human subjects from one group; one of these pointed towards potential future avenues involving amplifying the native MSC response to meniscal injury [3], and the other used synovially derived MSCs to repair articular-cartilage defects in the knee [4]. The latter study, an uncommonly well-designed (if small) clinical series, showed exciting results in terms of histology, MRI appearance, knee scores, and even second-look arthroscopy in a few patients. One of the most interesting elements of that group’s work was the source of stem cells they used: They chose synovial MSCs [4], rather than the more commonly used bone-marrow-derived MSCs [5]. Researchers harvest MSCs from a variety of places—from bone marrow and synovium, as noted already, but also from muscle, umbilical blood vessels, dental pulp, and fat, among other inauspicious-sounding sites [7]—with each source of cells having its advantages and Note from the Editor-In-Chief: In ‘‘Editor’s Spotlight,’’ one of our editors provides brief commentary on a paper we believe is especially important and worthy of general interest. Following the explanation of our choice, we present ‘‘Take Five,’’ in which the editor goes behind the discovery with a oneon-one interview with an author of the article featured in ‘‘Editor’s Spotlight.’’ The authors certify that they, or any members of their immediate family, have no commercial associations (eg, consultancies, stock ownership, equity interest, patent/ licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research editors and board members are on file with the publication and can be viewed on request. The opinions expressed are those of the writers, and do not reflect the opinion or policy of CORR or The Association of Bone and Joint Surgeons. This comment refers to the article available at: 10.1007/s11999-015-4385-8. S. S. Leopold MD (&) Clinical Orthopaedics and Related Research, 1600 Spruce Street, Philadelphia, PA 19013, USA e-mail: sleopold@clinorthop.org Editor’s Spotlight/Take 5 Published online: 9 July 2015 The Association of Bone and Joint Surgeons1 2015