Engineering the temporomandibular joint provides one of the treatment options for surgical treatment of temporomandibular joint disorders (Timothy et al., 2019). In regards to bone regeneration, temporomandibular joint tissue engineering can improve the repair of complex structures such as condyles and fossa. It accomplishes this by creating accurate anatomical and osteoinductive scaffolds. Tissue engineering scaffold materials are the foundation of tissue engineering where they provide an indispensable link within the field. However, the control of cell differentiation by scaffold materials through non-biochemical means remains an important research topic. It is well known that many cell characteristics, including self-renewal and differentiation, can be adjusted by physical stimuli (i.e., surface hardness and topography) (Cubo-Mateo & Rodríguez-Lorenzo, 2020). The surface topography of biomaterials is considered to be a key factor in regulating cell behavior and function. The latter include mechanical transduction processes, such as proliferation, migration and differentiation (Guoyou Huang et al., 2017). In previous studies, some topographic structures (e.g., wrinkles (Yang et al., 2020), grating (Dobbenga et al., 2016) and roughness (Lingjie Li et al., 2019) were used to induce the osteogenesis differentiation of cells. In the study of cell-material interaction in tissue engineering, wrinkles have received widespread attention as an indication of mechanical structure. At present, there are many substrate materials used in cell experiments. PDMS is a widely used polymer material and a commonly used elastic material in soft etching technology, which has the following characteristics. (1) Good stability, small deformation before and after curing; (2) It is a liquid before curing, which can be used for remolding of non-planar surface microstructure, and it is easy to remove after remolding; (3) The preparation process is simple, the requirements for equipment are not high, can be large-scale production, and can also be repeatedly cleaned and used; (4) It has good optical properties and can be used in a variety of optical detection systems; (5) No toxicity, and its elastic hardness can be regulated by adjusting the ratio of prepolymer and curing agent. In this study, PDMS was used to prepare experimental substrates with different microstructures, and the proliferation, morphology and osteogenic differentiation of MC3T3-E1 on PDMS substrates were observed.

The osteogenic response of cells to mechanical stimulation is co-regulated by a variety of genetic programs. These, include the Wnt/β-catenin signaling pathway (Galli, Piemontese, Lumetti, Manfredi, et al., 2012). The Wnt/β-catenin signaling pathway plays an important role in bone mass and bone cell function (Kar et al., 2020, Teufel and Hartmann, 2019; Lei Zhou et al., 2020). It participates in cell response to various stimuli (bone morphogenetic protein (Wu et al., 2018), oxygen-related stress (Y. N. Wang et al., 2021) and material surface characteristic (Wei Wang et al., 2012), etc.). Studies have shown that the specific osteogenic response of cells to mechanical stimulation can activate the Wnt/β-catenin signaling pathway (Galli, Piemontese, Lumetti, Ravanetti, et al., 2012). The micro-nano topological membrane can enable β-catenin to enter the nucleus and control the cell function (Dobbenga et al., 2016).

Previous studies have shown that autophagy plays an important role in osteoblast differentiation (Galli, Piemontese, Lumetti, Manfredi, et al., 2012). Autophagy can degrade and circulate waste in the cytoplasm by lysosomes. Both autophagy and Wnt/β-catenin signaling pathways are involved in the development and differentiation of embryos, and microtubule-associated-protein 1 light-chain-3 (LC3) can target β-catenin for autophagy degradation when cells are undernourished (Lorzadeh et al., 2021, Petherick et al., 2013). Studies by Pantovic et al. have shown that the osteogenic differentiation of human bone marrow mesenchymal stem cells (hMSCs) requires early induction of autophagy, and that genetic or pharmacological inhibition of autophagy can block the process of osteogenesis (Pantovic et al., 2013). We hypothesize that autophagy contributes significantly to the influence of micro-nanofold topology on osteogenic differentiation. Its role may be related to the Wnt/β-catenin signaling pathway.

However, the mechanism of biomimetic winkle nano/microtopography on the osteogenic differentiation of MC3T3-E1 cells has not been examined in depth. To clarify how directional topography regulates the interaction between autophagy and cell osteogenic differentiation will be an of great value in repairing temporomandibular joint bone tissue by tissue engineering. This research sought to determine whether specific topography of the PDMS surface influenced autophagy-mediated ctoplasim yes-associated protein (YAP), β-catenin and the activation of T-cell Factor/Lymphoid Enhancing Factor (TCF/LEF) transcription factors in the nucleus, as well as osteogenic differentiation of preosteoblast cells.