Cathelicidin LL-37, a protein fragment the body makes, is applied in synthetic form for long-standing leg and foot wounds; healthy adults are untested. Smaller studies pointed to faster repair, but the largest found no overall advantage; bacterial counts fell no more than with inactive cream. Risks include worsening inflammatory skin disease and, mostly in laboratory and animal work, tumour growth. No approved product exists; available material lacks pharmaceutical quality control. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Serum 25-hydroxyvitamin D | ≥32 ng/mL | Endogenous route: peptide output tracks vitamin D below this level |
| Plasma hCAP18 / LL-37 | No established target — track change from the individual's own baseline | Only direct readout of the endogenous route |
| Target wound area and granulation index | No established target — track change from the individual's own baseline | Primary efficacy readout in both wound trials |
| Aerobic wound swab culture | No established target — presence or absence of a pathogen | Safety check for wound infection |
| Full blood count with liver and kidney chemistry | Laboratory's own reference ranges | Safety check: an out-of-range result stops or changes use |
Cadence: Baseline before starting; during treatment, wound area weekly and blood safety tests monthly, with a review at 8 and 16 weeks after the last application. Endogenous route: reassessment at 1 week, 4 weeks, then every 3–6 months.