Low-Molecular-Weight Salmon Collagen Peptides Promote Extracellular Matrix Gene (ECM) Expression in BJ Fibroblasts

Salmon skin, a high-volume by-product of seafood processing, offers a circular-bioeconomy route to sustainable, value-added ingredients. This study aimed to generate low-molecular-weight collagen peptides (LMWCPs) from salmon skin using a stepwise enzymatic process and to evaluate their safety and pro-extracellular-matrix (ECM) activity in human BJ fibroblasts. LMWCPs were produced by sequential hydrolysis (alcalase/papain, then collagenase) and characterized as low-molecular-weight peptide preparations with a mean dispersed particle diameter of approximately 117 nm. LMWCPs display negatively charged peptide dispersions with a mass centered around ~1 kDa. Cytocompatibility (MTT) showed no toxicity up to 1.5 mg/mL over 48 h. Gene expression by reverse transcription–quantitative polymerase chain reaction (RT-qPCR) revealed a robust, dose-dependent ECM response: collagen type I alpha 1 chain (COL1A1) increased by approximately 7-fold, with additional rises of 5–6-fold in versican (VCAN) levels and modest increases in elastin (ELN) and transforming growth factor-β (TGF-β). These findings provide an exploratory process-to-phenotype link between the two-step hydrolysis process, physicochemical characteristics of the resulting LMWCPs, and changes in ECM-related gene expression in BJ fibroblasts. Overall, this study demonstrates that salmon skin LMWCPs were cytocompatible within the tested concentration range and modulated several ECM-related genes, providing a preliminary basis for future protein-level, functional, and translational evaluation.