Human Periodontal Ligament Stem Cells Response to Titanium Implant Surface: Extracellular Matrix Deposition

SIMPLE SUMMARY: The extracellular matrix (ECM) is a fundamental component of tissues and organs, providing the structural and non-structural support that leads to the bone osseointegration. Understanding the mechanisms of ECM components modulation is essential for developing novel strategies for tissue engineering and regenerative medicine and in particular for the dental implant surface design. The release of ECM components by cells is the first step that leads to the early stage of bone formation. The present work is focused on the modulation of ECM components expression by human periodontal ligament stem cells (hPDLSCs) cultured on two different dental implant surfaces, sandblasted (CTRL) and dual acid-etched (TEST). The effects were evaluated by means of the morphological observations and protein and gene expression. The results demonstrated that the rough surface of titanium dental implant can enhance the expression of ECM molecules and osteogenic markers in hPDLSCs. The surface topography is of vital importance as it regulates cell response. It can be considered one of the main factors that influence the success of a dental implant. The influence of surface topography on osseointegration could lead to short healing times and a better quality of oral rehabilitation and patient life. ABSTRACT: The major challenge for dentistry is to provide the patient an oral rehabilitation to maintain healthy bone conditions in order to reduce the time for loading protocols. Advancement in implant surface design is necessary to favour and promote the osseointegration process. The surface features of titanium dental implant can promote a relevant influence on the morphology and differentiation ability of mesenchymal stem cells, induction of the osteoblastic genes expression and the release of extracellular matrix (ECM) components. The present study aimed at evaluating the in vitro effects of two different dental implants with titanium surfaces, TEST and CTRL, to culture the human periodontal ligament stem cells (hPDLSCs). Expression of ECM components such as Vimentin, Fibronectin, N-cadherin, Laminin, Focal Adhesion Kinase (FAK) and Integrin beta-1 (ITGB1), and the osteogenic related markers, as runt related transcription factor 2 (RUNX2) and alkaline phosphatase (ALP), were investigated. Human PDLSCs cultured on the TEST implant surface demonstrated a better cell adhesion capability as observed by Scanning Electron Microscopy (SEM) and immunofluorescence analysis. Moreover, immunofluorescence and Western blot experiments showed an over expression of Fibronectin, Laminin, N-cadherin and RUNX2 in hPDLSCs seeded on TEST implant surface. The gene expression study by RT-PCR validated the results obtained in protein assays and exhibited the expression of RUNX2, ALP, Vimentin (VIM), Fibronectin (FN1), N-cadherin (CDH2), Laminin (LAMB1), FAK and ITGB1 in hPDLSCs seeded on TEST surface compared to the CTRL dental implant surface. Understanding the mechanisms of ECM components release and its regulation are essential for developing novel strategies in tissue engineering and regenerative medicine. Our results demonstrated that the impact of treated surfaces of titanium dental implants might increase and accelerate the ECM apposition and provide the starting point to initiate the osseointegration process.