Cytotoxicity of local anesthetics on rabbit adipose-derived mesenchymal stem cells during early chondrogenic differentiation

Local anesthetics (LAs) are commonly used to provide peri-operative pain control in the peripheral joints. In the field of regenerative medicine, adipose-derived mesenchymal stem cells (ADMSCs) are gaining attention as a cellular source for repair and regeneration in degenerative diseases. However, previous studies have demonstrated that the commonly used drugs lidocaine, ropivacaine, bupivacaine and mepivacaine may be toxic to human chondrocytes, which has raised concerns over whether they exert similar negative effects on ADMSCs during early chondrogenic differentiation. In the present in vitro study, the cytotoxicity of different LAs to ADMSCs was determined during early chondrogenic differentiation. At concentrations similar to those after physiological dilution once injected into the degenerative tissues, LAs (1% lidocaine, 0.5% bupivacaine, 0.5% ropivacaine or 2% mepivacaine) and PBS (control group) were incubated with rabbit ADMSCs (rADMSCs) for 60 min. Following further culture for 3 or 7 days, the cell viability, apoptosis and morphological alterations of chondrogenic differentiation were measured by determining the mitochondrial activity, by flow cytometric analysis, Safranine Fast Green double staining and reverse transcription-quantitative polymerase chain reaction of chondrogenesis-associated genes. The results indicated that the mitochondrial activity in rADMSC was decreased and the apoptotic rate was increased, following treatment with LAs (P<0.05). Lidocaine (1%) was less cytotoxic to rADMSCs during early chondrogenesis compared with other LAs. The expression levels of chondrogenesis-associated markers, including collagen I, collagen III and sex-determining region Y box 9 were all decreased at day 3 following exposure to LAs compared with the control group (P<0.05). The expression levels of these chondrogenesis-associated genes began to increase on day 7 following exposure but remained lower compared with the control group (P<0.05). Of note, 2% mepivacaine and 1% lidocaine exhibited a less pronounced negative effect on chondrogenesis-associated gene expression compared with other LAs. Therefore, the present study concluded that LAs are cytotoxic to rADMSCs during early chondrogenesis. Attention should be paid to the different types of LA selected in conjunction with ADMSC injection therapy.