Effects of local anesthetics associated to carriers on the modulation of inflammatory mediators, cell viability and apoptosis

Local anesthetics association to modified drug release systems have been proposed in order to prolong the anesthetic effect and reduce the toxicity. These new anesthetics formulations produced a low systemic toxicity and a longer anesthesia duration, however side effects were also observed such as local inflammation. The aim of this study was compare the effects of plain and carriers association local anesthetics formulations on the modulation of IL-6, IL1-?, IL-8, TNF-?, IL-10 and PGE2 release, their effects on cell viability and apoptosis induction in HaCaT and FGH. Cells were exposed to different concentrations of bupivacaine, lidocaine and ropivacaine in a plain formulation or associated with liposome or HP-?-CD for 6h and 24h. Cytokines and PGE2 quantification was performed by ELISA. Cell viability was measured by XTT assay and qualitatively assessed by fluorescent microscopy (LIVE/DEAD). Apoptosis induction was estimated by flow cytometry. Lidocaine in association with carriers increased cytokines release. The 100 µM liposomal formulations stimulated a significant increase in the TNF-?, IL-8 and IL-6 release by FGH cells. HP-?-CD formulations led to an increase of these mediators in the FGH cells after 24h. Lidocaine treatments induced an increase in the release of PGE2 and low effect on cell viability, where only 100 the µM plain lidocaine showed cell viability loss after 24h in HaCaT cells. Liposomal ropivacaine formulations increased the release of IL-?, TNF-? and IL-6 by FGH and IL-8 by HaCaT cells. PGE2 release was similar to lidocaine treatments. Ropivacaine formulations significantly reduced cell viability in HaCaT cells after 24h. Bupivacaine formulations showed a stronger inflammatory response than lidocaine, but with similar characteristics after carriers association. PGE2 release varied according to cell type. Bupivacaine formulations caused more cell viability loss when compared with lidocaine, being more accentuated by HP-?-CD complexation. Control and treatments showed similar results in apoptosis induction in HaCaT cells. Liposomal bupivacaine and ropivacaine formulations showed more alterations when aggregating the percentage of apoptosis and necrosis. In conclusion, cell type, local anesthetic molecule and the kind of carrier were determinants factors for cytokines and PGE2 release. Local anesthetics associated with carriers showed a higher inflammatory potential by an increased in the pro-inflammatory cytokines. The benefits of carriers association on cell viability varied with the cytotoxic potential of the local anesthetic molecule. In fact, this study produced a first reported of the effects of liposomal and HP-?-CD local anesthetics formulations on the inflammatory mediators release in HaCaT and FGH. Others aspects such as cell viability and apoptosis were also evaluated, contributing to the development and improvement of new local anesthetics formulations (AU)