Derived from research into naturally occurring protective compounds. Most people only hear about it much later.
BPC-157
BPC-157 is a synthetic pentadecapeptide, fifteen amino acids, corresponding to a partial sequence of body protection compound, a protein identified in human gastric juice. It does not occur naturally as an isolated fragment; it is a laboratory construct derived from a larger natural protein.
The origin is gastroenterology, not sports medicine. Researchers investigating why the gastric environment tolerates conditions that would damage other tissue identified protective factors in gastric juice, and BPC-157 came out of that line of enquiry. Its later reputation in recovery contexts is downstream of work that had nothing to do with musculoskeletal injury.
A large body of rodent work exists covering gastrointestinal models, tendon and ligament healing, and vascular endpoints, much of it from Sikiric and colleagues in Zagreb. Two caveats matter when reading it: the research is heavily concentrated in a small number of affiliated groups, and controlled human trial data is essentially absent despite the volume of preclinical publication.