Stem Cell Therapy for Knee Pain—What Exactly Are We Injecting, and Why?

Abstract

Few developments in orthopaedic surgery have been accompanied by as much hype as the use of “stem cells.” While the potential benefits of allogenic tissue-specific cells, stem cells, and progenitor cells are commonly discussed1, and many clinical trials seem to be underway2, few cell preparations have made their way through formal regulatory review and into orthopaedic practice. It is difficult to clearly define the rules for the clinical evaluation of cell products within the regulatory environment, especially in the United States. Focusing just on cell preparations potentially available for cartilage repair, based on draft guidelines from the FDA (U.S. Food and Drug Administration) and the 361 exemption for Human Cells, Tissues, and Cellular and Tissue-Based Products (HCT/Ps)3, the processing of minimally manipulated cells of structural tissues must preserve the original relevant characteristics of the tissue relative to reconstruction, repair, or replacement; must be intended for homologous use only (e.g., use of musculoskeletal cells for musculoskeletal restoration); and may not be combined with another article (e.g., scaffold or carrier). The preparation may not have …