Title: A tunable synthetic osteoid to support 3D osteocyte-like cell culture

Abstract: Bone formation and remodeling depend on dynamic biochemical and biomechanical signaling from the collagen-rich osteoid that precedes mineralization, yet the role of osteoid nonlinear mechanics in regulating osteocyte-like network formation remains poorly understood. Synthetic strain-stiffening hydrogels offer a unique synthetic platform to isolate the impact of hydrogel pore structure, viscoelasticity, and nonlinear elastic behavior on cell-matrix interactions. In this work, a bottlebrush (BB) polymer hydrogel was synthesized with comparable stiffness (~70 Pa) to a collagen type 1 hydrogel (Col1). Both scaffolds exhibited strain-stiffening behavior within the biological relevant stress regime, but only the Col1 system exhibited viscoelastic behavior – stress-relaxation. Human bone marrow-derived mesenchymal stem/stromal cells (hMSCs) were encapsulated within both hydrogel platforms and cultured for 28 days in growth (GM) or osteogenic media (OM) to examine network formation and functional connectivity using live cell fluorescence recovery after photobleaching. hMSCs cultured in BB networks and OM showed upregulation of early osteocyte markers compared to Col1. We find that strain-stiffening materials with minimal stress-relaxation promote osteocyte-like cell differentiation with functional connectivity, establishing osteoid-mimetic BB hydrogels as a promising matrix to study human osteocytogenesis and osteocyte mechanotransduction in vitro. BB polymer-based materials hold great potential to recapitulate biologically relevant biomechanical and biochemical signals for in vitro cell culture, for tissue and disease modeling in the future.

Lab Website

Join Zoom Meeting
https://uwmadison.zoom.us/j/91814162149?pwd=AYgwgbFNekOLHyQrj7wUCkxem9b2Yw.1 

Meeting ID: 918 1416 2149
Passcode: 970506