Involvement of 3D osteoblast migration and bone apatite during in vitro early osteocytogenesis

Abstract

The transition from osteoblast to osteocyte is described to occur through passive entrapment mechanism (self-buried, or embedded by neighboring cells). Here, we provide evidence of a new pathway where osteoblasts are "more" active than generally assumed. We demonstrate that osteoblasts possess the ability to migrate and differentiate into early osteocytes inside dense collagen matrices. This step involves MMP-13 simultaneously with IBSP and DMP1 expression. We also show that osteoblast migration is enhanced by the presence of apatite bone mineral. To reach this conclusion, we used an in vitro hybrid model based on both the structural characteristics of the osteoid tissue (including its density, texture and three-dimensional order), and the use of bone-like apatite. This finding highlights the mutual dynamic influence of osteoblast cell and bone extra cellular matrix. Such interactivity extends the role of physicochemical effects in bone morphogenesis complementing the widely studied molecular signals. This result represents a conceptual advancement in the fundamental understanding of bone formation.

High Mineralization Capacity of IDG-SW3 Cells in 3D Collagen Hydrogel for Bone Healing in Estrogen-Deficient Mice

“…Thus, we used type I collagen and matrigel fusion gel. In contract with the pure type I collagen hydrogel, although it mimics the composition and the structure of native osteoid tissue, it is not favorable to cellular process extension and is more suitable for studying the spatially polarized process of osteocytogenesis in vitro ( Robin et al, 2016 ). Of note, there are many other collagen-free 3D gels utilized in osteocyte culture systems, including calcium phosphate particles ( Boukhechba et al, 2009 ), commercialized 3D polystyrene scaffolds ( Spatz et al, 2015 ), and nanofiber-enabled layer-by-layer cell assembly ( Yang et al, 2009 ), to mimic the structural complexity of osteoid, in which the osteocytes are completely embedded in the 3D matrix environment.…”

Self‐Assembled Collagen Microparticles by Aerosol as a Versatile Platform for Injectable Anisotropic Materials

“…Mechanical properties of these biomaterials allow their use without requiring any additive, rendering their application non‐toxic. Besides, mimicking the 3D ECM organization could promote a more physiological response of mesenchymal stem cells (MSCs); such behavior was demonstrated in particular for osteoblasts and fibroblasts . This shows the interest of working at higher collagen concentrations …”

Alkali Treatment of Anodized Titanium Alloys Affects Cytocompatibility

“…The anodized and chemically-treated surface in the NaOH solution enhances the formation of apatite, and this mechanism has been addressed in several publications and serves for the assessment of the surface bioactivity [30][31][32]. In vivo, the apatite layer does not occur on the surface, and the osteoblast cells are mainly responsible for matrix production and tissue mineralization [33,34]. The adhesion of the osteoblast-like Saos-2 cells to the reference and modified titanium alloy samples was investigated after 24 h of culture.…”