A laboratory-made platelet growth protein. No human hair-count trials of this ingredient alone exist; the hair case is mouse and stem-cell culture. Wound-repair data are strong; hair-density benefit when used alone is theoretical. Known tumors at the site are a reason not to use it. The safety file is large for topical wounds, thin for repeated scalp injection. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Hair density (trichoscopy, hairs/cm²) | No established target; track change from the individual's own mapped-site baseline | Primary hair-regrowth endpoint |
| Hair shaft diameter (μm) | No established target; track change from own baseline | Miniaturization versus thickening |
| Vellus-to-terminal ratio | Shift toward terminal versus that person's baseline | Marks real follicle recovery rather than persistent vellus hair |
| Daily shed count (collected hairs) | Fall versus that person's pre-treatment average | Early shedding signal |
| Application-site skin exam | Intact skin without new papules, ulcers, or suspected tumors | Catches irritation and lesions |
Cadence: Matched photos and trichoscopy at about 12 weeks, 24 weeks, then every 6–12 months if use continues; lesion check at each in-office visit