Dual drug delivery collagen vehicles for modulation of skin fibrosis in vitro

Single molecule drug delivery systems have failed to yield functional therapeutic outcomes, triggering investigations into multi-molecular drug delivery vehicles. In the context of skin fibrosis, although multi-drug systems have been assessed, no system has assessed molecular combinations that directly and specifically reduce cell proliferation, collagen synthesis and transforming growth factor β 1 (TGF β 1) expression. Herein, a core–shell collagen type I hydrogel system was developed for the dual delivery of a TGF β trap, a soluble recombinant protein that inhibits TGF β signalling, and Trichostatin A (TSA), a small molecule inhibitor of histone deacetylases. The antifibrotic potential of the dual delivery system was assessed in an in vitro skin fibrosis model induced by macromolecular crowding (MMC) and TGF β 1. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and high performance liquid chromatography analyses revealed that ∼50% of the TGF β trap and ∼30% of the TSA were released from the core and shell compartments, respectively, of the hydrogel system after 10 d (longest time point assessed) in culture. As a direct consequence of this slow release, the core (TGF β trap)/shell (TSA) hydrogel system induced significantly ( p < 0.05) lower than the control group (MMC and TGF β 1) collagen type I deposition (assessed via SDS-PAGE and immunocytochemistry), α smooth muscle actin (αSMA) expression (assessed via immunocytochemistry) and cellular proliferation (assessed via DNA quantification) and viability (assessed via calcein AM and ethidium homodimer-I staining) after 10 d in culture. On the other hand, direct TSA-TGF β supplementation induced the lowest ( p < 0.05) collagen type I deposition, α SMA expression and cellular proliferation and viability after 10 d in culture. Our results illustrate the potential of core–shell collagen hydrogel systems for sustained delivery of antifibrotic molecules.