Ingredient or product comparison
Head-to-Head Research Model Comparisons
In vitro fibroblast collagen synthesis: Primary HDF, passage 4–8, serum-free medium (to avoid growth factor confounds), 72h treatment. Endpoints: procollagen type I C-peptide ELISA (PIP ELISA, Takara) as quantitative collagen synthesis marker, COL1A1 qPCR (2^-
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- In vitro fibroblast collagen synthesis: Primary HDF, passage 4–8, serum-free medium (to avoid growth factor confounds), 72h treatment. Endpoints: procollagen type I C-peptide ELISA (PIP ELISA, Takara) as quantitative collagen synthesis marker, COL1A1 qPCR (2^-ΔΔCt, GAPDH/HPRT reference), total soluble collagen Sircol assay, MMP-1 ELISA (collagenase activity), and TIMP-1 ELISA. GHK-Cu (0.1–100 ng/ml) vs Pro-Hyp (10–1000 µM) vs combination factorial — dose-response with EC50 determination for each endpoint.
- UV-aged fibroblast model: HDFs exposed to cumulative UVA/UVB (4×100 mJ/cm² UVA + 20 mJ/cm² UVB, 3 sessions over 2 weeks) produce a photoaged phenotype: reduced COL1A1/III, elevated MMP-1/3, increased SA-β-gal senescence, reduced proliferation, and increased p16/p21. GHK-Cu (anti-senescent, NRF2-driven antioxidant, anti-MMP-1) vs collagen peptides (pro-proliferative via Pro-Hyp-PDGFR) address different features of the photoaged phenotype — GHK-Cu is mechanistically better positioned for the senescence/antioxidant component, Pro-Hyp for proliferative restoration.
- In vivo: Hairless mouse photoageing model (SKH-1): Chronic narrowband UVB irradiation (3×/week, 12 weeks) in hairless mice produces dermal collagen loss, wrinkling, and inflammatory infiltration. GHK-Cu topical (1–3%) vs oral collagen peptide (500–2000 mg/kg/day via gavage) comparison at week 12: skin replica wrinkle scoring (PRIMOS profilometry, Ra roughness, wrinkle depth), dermal collagen I IHC, Masson trichrome collagen area fraction, hydroxyproline content, MMP-1/3 dermal IHC, and fibroblast density (PDGFR-β IHC). This parallel-group design enables genuine head-to-head comparison while controlling administration route differences.