Control of Oriented Extracellular Matrix Similar to Anisotropic Bone Microstructure

Abstract

Bone microstructure is dominantly composed of anisotropic extracellular matrix (ECM) in which collagen fibers and epitaxially-oriented biological apatite (BAp) crystals are preferentially aligned depending on the bone anatomical position, resulting in exerting appropriate mechanical function. The regenerative bone in bony defects is however produced without the preferential alignment of collagen fibers and the c-axis of BAp crystals, and subsequently reproduced to recover toward intact alignment. Thus, it is necessary to produce the anisotropic bone-mimetic tissue for the quick recovery of original bone tissue and the related mechanical ability in the early stage of bone regeneration. Our group is focusing on the methodology for regulating the arrangement of bone cells, the following secretion of collagen and the self-assembled mineralization by oriented BAp crystallites. Cyclic stretching in vitro to bone cells, principal-stress loading in vivo on scaffolds, step formation by slip traces on Ti single crystal, surface modification by laser induced periodic surface structure (LIPSS), anisotropic collagen substrate with the different degree of orientation, etc. can dominate bone cell arrangement and lead to the construction of the oriented ECM similar to the bone tissue architecture. This suggests that stress/strain loading, surface topography and chemical anisotropy are useful to produce bone-like microstructure in order to promote the regeneration of anisotropic bone tissue and to understand the controlling parameters for anisotropic osteogenesis induction.

Simulation of cortico-cancellous bone structure by 3D printing of bilayer calcium phosphate-based scaffolds

“…The osteoblasts alignment and spreading along the scaffold strands suggests that the newly produced bone matrix may exhibit anisotropic microstructure which in turn has its own impact on the mechanical properties [34]. In addition, the expression of collagen I, the major extracellular matrix protein, and the non-collagenous proteins, which are found in the bone and are known to be upregulated in the ostogenesis [35], indicate favourable in vitro biocompatibility of the printed scaffold and its ability to support bone tissue engineering.…”

Recent Progress in Research and Development of Metallic Structural Biomaterials with Mainly Focusing on Mechanical Biocompatibility

“…It has been recognized very recently that not only bone mineral density (BMD), but also bone orientation (biological apatite (BAp) crystal orientation) is important for the bone regeneration 70) . Figure 23 70) shows variations in the relative intensity ratio of the (002) diffraction peak to the (310) peak to evaluate the orientation degree of the BAp c-axis orientation with dif- ferent directions A, B, and C for the ulna, skull bone, and mandible 71,72) . It can be concluded from this gure that the preferential orientation of the BAp c-axis corresponds to the in vivo stress distribution and BAp c-axis tends to orient along the principal stress direction in the original bones Figure 24 70) shows degree of BAp orientation intensity ratio of (002)/(310) showing recovery of local BMD and BAp c-axis alignment in the regenerated ulna.…”