Incorporation of simvastatin in PLLA membranes for guided bone regeneration: effect of thermal treatment on simvastatin release

Electrospun membranes based on biodegradable polymers are promising materials to be used for guided bone regeneration (GBR) therapy. The incorporation of osteostimulatory compounds can improve the biofunctionality of those membranes, making them active players in bone regeneration. Simvastatin has been shown to promote osteogenic differentiation both in vitro and in vivo. However, in most of these systems, the drug was quickly released, not matching the pace of bone regeneration. The aim of this study was to develop poly(l-lactic acid) (PLLA) membranes containing simvastatin (SV) that have a prolonged drug release rate, compatible with GBR applications. To this end, SV was mixed with PLLA and electrospun. The membranes were subjected to a thermal treatment in order to increase the crystallinity of PLLA. Morphological, structural and chemical properties of the electrospun membranes were characterized. The effect of the thermal treatment on the release profile of SV was evaluated by near physiological release experiments at 37 °C. The osteostimulatory potential was determined by in vitro culture of the membranes with rat bone marrow stromal cells (rBMSCs). The results confirmed that the thermal treatment led to an increase in polymer crystallinity and a more sustained release of SV. In vitro assays demonstrate cellular proliferation over time for all the membranes and a significant increase in osteogenic differentiation for the membranes containing SV subjected to thermal treatment.