Part 2: Making the “unproven” “proven”

The use of living, disaggregated cells in medicine involves a number of aspects that make this approach distinct from traditional pharmaceutical products. Cells are not metabolized by the liver or kidney, unlike most small-molecule drugs, but are potentially capable of distribution throughout the entire body. Cells are also highly complex and change dynamically in response to their environment and over time, making it difficult to standardize them in the same way that molecules can be engineered and mass-produced. Some type of cells may also secrete multiple bioactive molecules, such as cytokines and growth factors, as well as microvesicles, which may be released in different amounts or combinations, depending upon the cells' immediate environment or the pathophysiological state of the body into which they are introduced...