Abstract
ObjectivesTopographic cues can modulate morphology and differentiation of mesenchymal stem cells. This study aimed to determine how topographic cues of a novel bilayered poly (lactic‐co‐glycolic acid) (PLGA) scaffold affect osteogenic/odontogenic differentiation of dental pulp stem cells (DPSCs).MethodsThe surface morphology of the scaffolds was visualized by scanning electron microscope, and the surface roughness was measured by profilometry. DPSCs were cultured on each side of the scaffolds. Cell morphology, expression of Yes‐associated protein (YAP) and osteogenic/odontogenic differentiation were analysed by immunohistochemistry, real‐time polymerase chain reaction, and Alizarin Red S staining. In addition, cytochalasin D (CytoD), an F‐actin disruptor, was used to examine the effects of F‐actin on intracellular YAP localisation. Verteporfin, a YAP transcriptional inhibitor, was used to explore the effects of YAP signalling on osteogenic/odontogenic differentiation of DPSCs.ResultsThe closed side of our scaffold showed smaller pores and less roughness than the open side. On the closed side, DPSCs exhibited enhanced F‐actin stress fibre alignment, larger spreading area, more elongated appearance, predominant nuclear YAP localization and spontaneous osteogenic differentiation. Inhibition of F‐actin alignments was correlated with nuclear YAP exclusion of DPSCs. Verteporfin restricted YAP localisation to the cytoplasm, down‐regulated expression of early osteogenic/odontogenic markers and inhibited mineralization of DPSCs cultures.ConclusionsThe surface topographic cues changed F‐actin alignment and morphology of DPSCs, which in turn regulated YAP signalling to control osteogenic/odontogenic differentiation.
Highlights
The topography, microgeometry and mechanical properties, such as stiffness, roughness and extracellular forces, play significant roles in how scaffolds may regulate stem cells behaviour.[1,2,3,4] Biophysical properties of the scaffolds affect cell adhesion, migration, prolifer‐ ation and differentiation.[5]
Differentiation of human mesenchymal stem cells (MSCs) into chon‐ drocytes and osteoblasts is associated with structural changes of F‐actin networks.[11,12]
MSCs on both planar and porous surfaces seemed to be more rounded when compared to their parallel orientation on ridged or grooved surface.[2]
Summary
The topography, microgeometry and mechanical properties, such as stiffness, roughness and extracellular forces, play significant roles in how scaffolds may regulate stem cells behaviour.[1,2,3,4] Biophysical properties of the scaffolds affect cell adhesion, migration, prolifer‐ ation and differentiation.[5]. Studies have shown that using PRP adjunct to blood clot promotes root lengthen‐ ing and thickening.[22] Other materials, such as dentin matrix and pep‐ tide hydrogel (PuramatrixTM), have been tested in animal models and shown to have a certain level of regenerative potential.[23] In ad‐ dition, growth factors, such as TGFβ1, SDF‐1 and BMP, have been incorporated into scaffolds to promote stem cell differentiation and tissue regeneration.[24] all these new scaffold materials sup‐ port three‐dimensional cell cultures, their homogenous nature limits their capability to provide spatial control over cell activities, fail to provide the different zone for pulp (centre area) and dentin (pe‐ ripheral area) regeneration.[25]. The purpose of this study was to test our hypothesis that the open and closed sides of our scaffold provide different topographic cues, which change the cytoskeleton arrangement and target the YAP signalling pathway, leading to the spontaneous differentiation of DPSCs into osteoblasts/odontoblasts on the closed side
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