To prevent fibrous encapsulation of implants, measures are taken to suppress inflammatory reactions around them. Sustained anti-inflammatory drug release from the scaffolds can potentially be a way to reduce inflammation around these implants. Alginate-crosslinked chitosan is often used to make biocompatible tissue engineered scaffolds. However, there is a lack of quantitative studies on the drug delivery properties of alginate-crosslinked chitosan scaffolds. For this study, chitosan, crosslinked with different concentrations of alginate, was made into porous scaffolds. Infrared and thermal gravimetric analyses showed polyelectrolyte complex formation between chitosan and alginate units. The alginate-crosslinked chitosan scaffolds were more hydrophilic, showed less swelling, had lower pentoxifylline (PTX) release efficacies, were more favorable for initial cell attachment, and were mechanically stronger and more resistant to enzymatic degradation when compared to non-crosslinked chitosan scaffolds. The differences became more significant as the concentrations of chitosan and alginate increased. Furthermore, in vitro tests showed that when PTX was slowly released from the scaffolds, it became more effective in suppressing the production of TNF-alpha and IL-6 by stimulated macrophage cells.

No abstract

Controlled release carriers are often made into microspheres or tablets. Systematic and quantitative characterization of porous tissue engineered scaffolds as release carriers have not been done. Chitosan and chitosan crosslinked with various concentrations of genipin were made into porous tissue engineered scaffolds. Their thermal and enzymatic stabilities, hydrophobicities, porous structures, swelling and release properties, and compressional moduli were measured. The effects of scaffolds loaded with pentoxifylline (PTX) in suppressing inflammatory reactions in vitro were quantified.Fourier Transform Infrared spectra showed new bond formation after crosslinking chitosan with genipin. As genipin increased from 0.01% to 0.1%, the crosslinked chitosan scaffolds swelled 0.5% to 1.8% less, had 1.9-5% decrease in PTX release efficiencies, became less wettable, were less favorable for initial cell attachment, had 4-20% increase in Young's modulus and were more resistant to enzymatic degradation. In vitro tests showed that when PTX was released more slowly from crosslinked scaffolds, PTX became more effective in suppressing macrophage cells from releasing IL-6 and TNF-α.