Tissue engineering matrixes by emulsion templating

Foams containing poly(lactic acid) (PLA) have been prepared from the corresponding macromonomers using high internal phase emulsions (HIPEs) as templates to create the porous structure. The resulting PolyHIPE foams have been investigated by scanning electron microscopy and the influence of diluent type, either reactive (styrene or methyl methacrylate (MMA)) or unreactive (toluene), on foam morphology has been determined. The morphology was found to depend on the type of diluent: styrene resulted in cellular materials at low PLA levels but tended to give structures characteristics of phase separation at higher PLA content; MMA yielded porous cellular materials at all levels of PLA; toluene tended to give soft materials that collapsed on drying. The swelling of the foam materials in toluene, isopropyl alcohol (IPA) and water was also investigated. It was found that most of the foams swelled to a relatively low extent in all solvents, apart from that of low PLA content made with toluene. This was ascribed to a low crosslinking level and high porosity of this material. Cell and tissue growth studies on the resulting foams, as well as analogues prepared from poly(ε-caprolactone) (PCL) macromonomers, using whole chicken embryo explants, rat skin explants or individual human skin cells, indicated excellent biocompatibility of all foams over the length of each experiment (maximum length 6 days). Comparative studies indicated that cells adhered to PCL-based materials more rapidly than their PLA-containing counterparts.