All-trans retinoic acid release from biodegradable polyester microcapsules

Tissue engineering strategies frequently include a scaffold, living cells and bioactive substances to promote cell growth and guide cell differentiation. The encapsulation in carriers enables protects the bioactivity of those substances upon implantation, avoids being transported by the body fluids and also allows controlling the re- lease rate. Encapsulation materials are preferably biodegradable polymers. In this work, all-trans retinoic acid (atRA) was used as a model bioactive agent; since it was shown that atRA enhances the expression of osteocalcin, a specific osteogenic marker.

atRA was encapsulated into polyester microcapsules by a water/ oil/water double emulsion/solvent evaporation technique. The polyesters used in this study are poly(butylene succinate) (PBS), poly(butylene succinate-co-adipate) (PBSA) and poly(butylene terephthalate-co-adipate) (PBTA). The kinetics of atRA release was studied in phosphate buffered saline solution of pH 7.4 at 378C under orbital shaking.