Epoxy-Tiglianes Modulate Dermal Fibroblast-Myofibroblast Wound Healing Responses and Reduce Scarring

Objectives: Unlike oral mucosal wounds, dermal wounds are characterised by prominent scar formation. Excessive scarring (fibrosis) occurs due to aberrant wound healing or insult, during situations such as keloid/hypertrophic scarring, burns or trauma. Such situations pose significant challenges to Healthcare Services; confounded by acceptance that existing therapies are clinically unsatisfactory. The epoxy-tiglianes, EBC-46 and EBC-211, occur within seeds of the Fontain’s Blushwood Tree, indigenous to Queensland’s tropical rainforest. EBC-46 is currently being developed by QBiotics, as an anti-cancer drug. In clinical studies, EBC-46 stimulates exceptional dermal wound healing responses following tumour destruction, including minimal scarring. As TGF-β₁-driven, fibroblast-myofibroblast differentiation is pivotal to dermal scarring, fibroblasts and myofibroblasts represent viable targets for the anti-scarring properties of epoxy-tiglianes. Therefore, this study examined epoxy-tigliane effects on dermal fibroblast proliferation, migration and TGF-β₁-driven, myofibroblast differentiation.
Methods: Human dermal fibroblasts were cultured with EBC-46 or EBC-211 (0-100µg/ml). Fibroblast proliferation and cell cycle analysis were analysed by MTT assay and Draq5/FACS. Migration was assessed by in vitro scratch wounds and Time-Lapse Microscopy. TGF-β₁-driven, fibroblast-myofibroblast differentiation was examined by the detection of α-smooth muscle actin (α-SMA) expression and stress fibres, by ICC and QRT-PCR.
Results: Both EBC-46 and EBC-211 induced significant fibroblast cytotoxicity at 100µg/ml and retarded proliferation at 0.001-10µg/ml, but no significant effects on fibroblast migration were evident. Although EBC-46 had no effects on α-SMA expression, stress fibres and myofibroblast formation at 0.001-0.01µg/ml or 1-10µg/ml, EBC-46 significantly inhibited α-SMA expression and fibre formation at 0.1µg/ml, with cells retaining normal fibroblastic morphologies. EBC-211 induced similar inhibitory effects at 10µg/ml.
Conclusions: These findings suggest that epoxy-tiglianes attenuate fibroblast proliferation and TGF-β₁-driven myofibroblast differentiation, explaining their enhanced anti-scarring responses in treated skin. Such findings highlight the potential of epoxy-tiglianes as novel therapeutics for excessive dermal scarring.