In vitro studies investigating the effect of subcutaneous phosphatidylcholine injections in the 3T3-L1 adipocyte model: lipolysis or lipid dissolution?

BACKGROUND The demand for lipolytic injection therapies for aesthetic indications increases continuously. The substance most frequently discussed in this context is phosphatidylcholine solubilized in sodium deoxycholate, a composition known in Europe as Lipostabil (Artesan Pharma, Lüchow, Germany). The evidence for its lipolytic effect is based mainly on clinical studies that suggest a decrease in adipose tissue volume after subcutaneous injections. However, neither the actual effect nor the effective supplemental effect of Lipostabil has been clearly identified so far. The purpose of this study was to investigate the effects caused by lipolytic formulations on adipocytes using an in vitro model. METHODS 3T3-L1 adipocytes in 12-well plates were exposed to varying doses of isolated phosphatidylcholine, deoxycholate, and the combination of both (Lipostabil). Subsequently, changes in the cell membrane integrity were evaluated microscopically, and assays measuring the amount of glycerol as a biochemical lipolysis substrate (lipolysis assay) together with dimethyl thiazolyl diphenyl tetrazolium assays were performed to quantify the lipolytic effect and the cell viability. RESULTS Deoxycholate reduced cell viability significantly (p < 0.05), even at low concentrations. Neither phosphatidylcholine nor deoxycholate led to a significant (p < 0.05) induction of a lipolytic pathway. Lipostabil, the combination of deoxycholate and phosphatidylcholine, led to a significant (p < 0.05) decrease in cell viability at low doses and to a highly significant (p < 0.01) reduction at high doses. The loss in cell viability is attributable to changes in the cell membrane integrity. CONCLUSIONS These results suggest that no enzymatic lipolytic pathway is induced. The decrease in volume after Lipostabil injections is likely attributable to the detergent effect of deoxycholate.