Genome-wide transcriptional responses of osteoblasts to different titanium surface topographies

Keiji Komatsu; Takanori Matsuura; Toshikatsu Suzumura; Takahiro Ogawa

doi:10.1016/j.mtbio.2023.100852

Genome-wide transcriptional responses of osteoblasts to different titanium surface topographies

Mater Today Bio. 2023 Nov 4:23:100852. doi: 10.1016/j.mtbio.2023.100852. eCollection 2023 Dec.

Authors

Keiji Komatsu^{1

2}, Takanori Matsuura¹, Toshikatsu Suzumura¹, Takahiro Ogawa¹

Affiliations

¹ Weintraub Center for Reconstructive Biotechnology and the Division of Regenerative and Reconstructive Sciences, UCLA School of Dentistry, Los Angeles, CA, 90095, USA.
² Department of Lifetime Oral Health Care Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, 113-8549, Japan.

Abstract

This is the first genome-wide transcriptional profiling study using RNA-sequencing to investigate osteoblast responses to different titanium surface topographies, specifically between machined, smooth and acid-etched, microrough surfaces. Rat femoral osteoblasts were cultured on machine-smooth and acid-etched microrough titanium disks. The culture system was validated through a series of assays confirming reduced osteoblast attachment, slower proliferation, and faster differentiation on microrough surfaces. RNA-sequencing analysis of osteoblasts at an early stage of culture revealed that gene expression was highly correlated (r = 0.975) between the two topographies, but 1.38 % genes were upregulated and 0.37 % were downregulated on microrough surfaces. Upregulated transcripts were enriched for immune system, plasma membrane, response to external stimulus, and positive regulation to stimulus processes. Structural mapping confirmed microrough surface-promoted gene sharing and networking in signaling pathways and immune system/responses. Target-specific pathway analysis revealed that Rho family G-protein signaling pathways and actin genes, responsible for the formation of stress fibers, cytoplasmic projections, and focal adhesion, were upregulated on microrough surfaces without upregulation of core genes triggered by cell-to-cell interactions. Furthermore, disulfide-linked or -targeted extracellular matrix (ECM) or membranous glycoproteins such as laminin, fibronectin, CD36, and thrombospondin were highly expressed on microrough surfaces. Finally, proliferating cell nuclear antigen (PCNA) and cyclin D1, whose co-expression reduces cell proliferation, were upregulated on microrough surfaces. Thus, osteoblasts on microrough surfaces were characterized by upregulation of genes related to a wide range of functions associated with the immune system, stress/stimulus responses, proliferation control, skeletal and cytoplasmic signaling, ECM-integrin receptor interactions, and ECM-membranous glycoprotein interactions, furthering our knowledge of the surface-dependent expression of osteoblastic biomarkers on titanium.

Keywords: Dental implant; Osseointegration; Osteoblast differentiation; Titanium surface topography; Transcriptional profile.