Resveratrol protects primary cilia integrity of human mesenchymal stem cells from cigarette smoke to improve osteogenic differentiation in vitro
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Several studies have explored the negative effects of cigarette smoke on bone healing; however, the complex pathogenesis still remains unclear. One crucial and primary factor determining effective fracture repair is the recruitment and differentiation of mesenchymal stem cells (MSCs) into bone-forming cells. Recently, primary cilia, microtubule-based sensory organelles, have been shown to be critical in lineage commitment and differentiation of MSCs. Our present study indicates that exposure to cigarette smoke extract (CSE 0.1–10%) impaired osteogenic differentiation of human mesenchymal stem cell line (SCP-1) and interestingly, also affected primary cilia distribution and integrity in these cells during the differentiation. Furthermore, significant amounts of free radicals generated by CSE could be causative of primary cilia loss since treatment with 0.01% of hydrogen peroxide, a prime free radical in CSE, destroyed primary cilia in these cells. The debilitated differentiation of CSE-exposed SCP-1 cells also correlated with the significantly reduced expression of transcription factor and target genes of primary cilia-specific hedgehog signalling, a key player in osteogenic differentiation. As a treatment strategy, co-incubation of the CSE-exposed SCP-1 cells with the antioxidant resveratrol (1 µM) had a protective effect as it significantly reduced free radical production, protected the primary cilia and enhanced osteogenic differentiation. The current study shows for the first time that cigarette smoke affects primary cilia in human MSCs during osteogenic differentiation and treatment with resveratrol could reverse the effects and enhance differentiation, thus opening up potential therapeutic alternatives to treat fracture healing in smokers, in particularly, when delayed fracture healing is assumed.
KeywordsCigarette smoke Primary cilia SCP-1 cells Reactive oxygen species Hedgehog signalling Bone regeneration
We would like to thank all the authors who contributed to the study. Conceived and designed the experiments: VS AKN SE RA. Performed the experiments: RA VS JS. Analysed the data: RA VS JS. Wrote the paper: VS RA. Revised critically the manuscript and gave important intellectual input: AKN SE GT JS DH AS CA. All authors have given final approval of the version to be published. We would like to thank Hanna Scheffler for her technical assistance. The study was partially funded by Fortüne Juniorantrag (Nr. 2420-0-0) Universitätsklinikum Tübingen and Elsbeth Bonhoff stiftung. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
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Conflict of interest
The authors declare that they have no conflict of interest.
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