Surface chemistry regulates the sensitivity and tolerability of osteoblasts to various magnitudes of fluid shear stress

Abstract

Scaffolds provide a physical support for osteoblasts and act as the medium to transfer mechanical stimuli to cells. To verify our hypothesis that the surface chemistry of scaffolds regulates the perception of cells to mechanical stimuli, the sensitivity and tolerability of osteoblasts to fluid shear stress (FSS) of various magnitudes (5, 12, 20 dynes/cm ) were investigated on various surface chemistries (-OH, -CH , -NH ), and their follow-up effects on cell proliferation and differentiation were examined as well. The sensitivity was characterized by the release of adenosine triphosphate (ATP), nitric oxide (NO) and prostaglandin E (PGE ) while the tolerability was by cellular membrane integrity. The cell proliferation was characterized by S-phase cell fraction and the differentiation by ALP activity and ECM expression (fibronectin and type I collagen). As revealed, osteoblasts demonstrated higher sensitivity and lower tolerability on OH and CH surfaces, yet lower sensitivity and higher tolerability on NH surfaces. Observations on the focal adhesion formation, F-actin organization and cellular orientation before and after FSS exposure suggest that the potential mechanism lies in the differential control of F-actin organization and focal adhesion formation by surface chemistry, which further divergently mediates the sensitivity and tolerability of ROBs to FSS and the follow-up cell proliferation and differentiation. These findings are essentially valuable for design/selection of desirable surface chemistry to orchestrate with FSS stimuli, inducing appropriate cell responses and promoting bone formation. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2978-2991, 2016.

Mechanical, hormonal and metabolic influences on blood vessels, blood flow and bone

“…Shear stress stimulates the release of factors such as nitric oxide (NO) and prostaglandins (e.g., PGE 2 ) by bone-derived cells and organ cultures (Johnson et al 1996; McAllister & Frangos 1999; Zaman et al 1999; McAllister et al 2000). For example, under 12 dynes/cm 2 shear stress, the release of adenosine triphosphate (ATP), NO and PGE 2 from rat primary osteoblasts was significantly higher vs. static control conditions (Li et al 2016). These factors can modulate bone cellular activity.…”

“…We now know bone cells release a myriad of factors that modulate blood vessel function (Alam et al 1992; Delany & Canalis 1997; Ishida et al 2002; Brandi & Collin-Osdoby 2006; Li et al 2016). What is not greatly appreciated is the reciprocal relation whereby bone blood vessels release factors (e.g., insulin-like growth factor-1, endothelin-1, prostacyclin, RANKL, interleukin-11, PGE 2 , NO, ATP, ADP, AMP, adenosine, etc.)…”

Strategy for achieving standardized bone models

“…Because cells depend on specific proteins for anchorage and extracellular cues, the composition and conformation of adsorbed proteins at the material surface are key mediators of cell behavior (Bouet, Marchat, et al, ; Fourel et al, ; Streuli, ; Wilson, Clegg, Leavesley, & Pearcy, ). Material intrinsic properties and particularly surface properties (e.g., surface chemical functional groups) affect the key early event of protein adsorption and subsequent cell adhesion, growth, and differentiation (Anselme, Ponche, & Bigerelle, ; Bouet, Marchat, et al, ; Vitte, Benoliel, Pierres, & Bongrand, ), as well as their response to shear stress (Li, Luo, Huang, et al, , Li, Luo, Xie, et al, ; Li et al, ). Regarding shear stress responses, Li et al () demonstrated in 2D systems that the chemical functionalization of glass slides with terminal ‐OH, ‐CH 3 , and ‐NH 2 groups regulates primary rat osteoblast responses to fluid shear stress.…”

“…Beyond altered flow profiles (cf. Section 2), different levels of architecture defined by the manufacturing process significantly affect cell behavior (Li, Wang, Xing, Wang, & Luo, 2016;Marchat & Champion, 2017;Saiz, Zimmermann, Lee, Wegst, & Tomsia, 2013).…”

“…Because cells depend on specific proteins for anchorage and extracellular cues, the composition and conformation of adsorbed proteins at the material surface are key mediators of cell behavior Fourel et al, 2016;Streuli, 2009;Wilson, Clegg, Leavesley, & Pearcy, 2005). Material intrinsic properties and particularly surface properties (e.g., surface chemical functional groups) affect the key early event of protein adsorption and subsequent cell adhesion, growth, and differentiation (Anselme, Ponche, & Bigerelle, 2010;Vitte, Benoliel, Pierres, & Bongrand, 2004), as well as their response to shear stress Li et al, 2016). Regarding shear stress…”