An Evaluation of Different 3D Cultivation Models on Expression Profiles of Human Periodontal Ligament Fibroblasts with Compressive Strain

Abstract

The effects of compressive strain during orthodontic treatment on gene expression profiles of periodontal ligament fibroblasts (PDLFs) have mostly been studied in 2D cell culture. However, cells behave differently in many aspects in 3D culture. Therefore, the effect of pressure application on PDLFs in different 3D structures was investigated. PDLFs were either conventionally seeded or embedded into different 3D structures (spheroids, Mebiol® gel, 3D scaffolds) and exposed to compressive force or incubated without pressure. For one 3D scaffold (POR), we also tested the effect of different compressive forces and application times. Expression of an angiogenic gene (VEGF), a gene involved in extracellular matrix synthesis (COL1A2), inflammatory genes (IL6, PTGS2), and genes involved in bone remodelling (OPG, RANKL) were investigated by RT–qPCR. Depending on the used 3D cell culture model, we detected different effects of compressive strain on expression profiles of PDLFs. COL1A2 was downregulated in all investigated 3D culture models. Angiogenetic and proinflammatory genes were regulated differentially between models. In 3D scaffolds, regulation of bone-remodelling genes upon compressive force was contrary to that observed in 3D gels. 3D cell culture models provide better approximations to in vivo physiology, compared with conventional 2D models. However, it is crucial which 3D structures are used, as these showed diverse effects on the expression profiles of PDLFs during mechanical strain.

Dentoalveolar anomalies and modern views on the mechanisms of local stress-modeling effect of orthodontic appliances on the periodontal tissues (a literature review)

“…In turn, this has an impact on how genes involved in cell adhesion, proliferation, differentiation, and death are expressed. Additionally, by applying direct mechanical stimulation to extracellular matrix proteins, cells can transfer the stress created in the actin cytoskeleton, affecting the three-dimensional organization of the extracellular matrix and its remodeling [26,27].…”

“…Stretching deformations in the periodontal ligament and alveolar bone have the ability to stimulate the activation of osteogenic gene expression with the differentiation of osteogenic progenitor cells into mature osteoblasts that deposit osteoid, which subsequently undergoes mineralization. It has been established that bone formation caused by tensile stress is not associated with osteoblast proliferation, but with an increase in the rate of differentiation and maturation of osteoblast progenitor cells [27,31].…”

“…There is a progressive decrease in the tensile strength of collagen bundles as a result of the release of matrix metalloproteinases and other catabolic agents that disrupt the cross-links and molecular integrity of the extracellular matrix. Accordingly, the hydrodynamic damping effect of the periodontal ligament decreases, and the elasticity of the bone increases [27,33,34].…”

“…Cells in the periodontal ligament respond differently to tensile and compressive deformations, mediating predominantly catabolic tissue changes in areas of compression and predominantly anabolic activity in areas under tension. This coordinated ligament remodeling is important for orthodontic tooth movement [27].…”

Impact of PIEZO1‐channel on inflammation and osteoclastogenesis mediated via periodontal ligament fibroblasts during mechanical loading

“…Pressure was applied through sterile zirconia plates (2 g/cm 2 ) for further 48 h [23]. This experiment was repeated two times in biological triplicates ( n = 6).…”