Interpenetrating network hydrogels for studying the role of matrix viscoelasticity in 3D osteocyte morphogenesis
Open access
Date
2024-02-21Type
- Journal Article
ETH Bibliography
yes
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Abstract
During bone formation, osteoblasts are embedded in a collagen-rich osteoid tissue and differentiate into an extensive 3D osteocyte network throughout the mineralizing matrix. However, how these cells dynamically remodel the matrix and undergo 3D morphogenesis remains poorly understood. Although previous reports investigated the impact of matrix stiffness in osteocyte morphogenesis, the role of matrix viscoelasticity is often overlooked. Here, we report a viscoelastic alginate–collagen interpenetrating network (IPN) hydrogel for 3D culture of murine osteocyte-like IDG-SW3 cells. The IPN hydrogels consist of an ionically crosslinked alginate network to tune stress relaxation as well as a permissive collagen network to promote cell adhesion and matrix remodeling. Two IPN hydrogels were developed with comparable stiffnesses (4.4–4.7 kPa) but varying stress relaxation times (t_1/2, 1.5 s and 14.4 s). IDG-SW3 cells were pre-differentiated in 2D under osteogenic conditions for 14 days to drive osteoblast-to-osteocyte transition. Cellular mechanosensitivity to fluid shear stress (2 Pa) was confirmed by live-cell calcium imaging. After embedding in the IPN hydrogels, cells remained highly viable following 7 days of 3D culture. After 24 h, osteocytes in the fast-relaxing hydrogels showed the largest cell area and long dendritic processes. However, a significantly larger increase of some osteogenic markers (ALP, Dmp1, hydroxyapatite) as well as intercellular connections via gap junctions were observed in slow-relaxing hydrogels on day 14. Our results imply that fast-relaxing IPN hydrogels promote early cell spreading, whereas slow relaxation favors osteogenic differentiation. These findings may advance the development of 3D in vivo-like osteocyte models to better understand bone mechanobiology. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000654801Publication status
publishedExternal links
Journal / series
Biomaterials ScienceVolume
Pages / Article No.
Publisher
Royal Society of ChemistryOrganisational unit
03565 - Müller, Ralph / Müller, Ralph
Funding
188522 - Subtractive 3D Micro-Printing of Functional Osteocyte Networks as An In Vitro Model for Bone Organoids (SNF)
190345 - Mini-Bone-on-a-Chip: Microfluidic Engineering of 3D Osteocyte Networks in Void-forming Hydrogels (SNF)
206501 - Human Organoid-on-Chip: A Novel Experimental Tool to Replace Animal Models of Rare Bone Disease (SNF)
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ETH Bibliography
yes
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