Podosome-Driven Defect Development in Lamellar Bone under the Conditions of Senile Osteoporosis Observed at the Nanometer Scale.

The degradation mechanism of human trabecular bone harvested from the central part of the femoral head of a patient with a fragility fracture of the femoral neck under conditions of senile osteoporosis was investigated by high-resolution electron microscopy. As evidenced by light microscopy, there is a disturbance of bone metabolism leading to severe and irreparable damages to the bone structure. These defects are evoked by osteoclasts and thus podosome activity.

Contribution to understand the biomineralization of bones.

Introduction: The goal is to propose a material scientific hypothesis for the atomic arrangement of calcium phosphates during the mineralization of bones.

Materials And Methods: It was reached by the analysis of bones of healthy and osteoporotic rats using analytical transmission electron microscopic methods.

Results: Electron diffraction patterns show hydroxyapatite (HAP) as dominant phase within the mineralized areas.

First evidence of octacalcium phosphate@osteocalcin nanocomplex as skeletal bone component directing collagen triple-helix nanofibril mineralization.

Tibia trabeculae and vertebrae of rats as well as human femur were investigated by high-resolution TEM at the atomic scale in order to reveal snapshots of the morphogenetic processes of local bone ultrastructure formation. By taking into account reflections of hydroxyapatite for Fourier filtering the appearance of individual alpha-chains within the triple-helix clearly shows that bone bears the feature of an intergrowth composite structure extending from the atomic to the nanoscale, thus representing a molecular composite of collagen and apatite. Careful Fourier analysis reveals that the non-collagenous protein osteocalcin is present directly combined with octacalcium phosphate.

Electric field-assisted formation of organically modified hydroxyapatite (ormoHAP) spheres in carboxymethylated gelatin gels.

Unlabelled: A biomimetic strategy was developed in order to prepare organically modified hydroxyapatite (ormoHAP) with spherical shape. The technical approach is based on electric field-assisted migration of calcium ions and phosphate ions into a hydrogel composed of carboxymethylated gelatin. The electric field as well as the carboxymethylation using glucuronic acid (GlcA) significantly accelerates the mineralization process, which makes the process feasible for lab scale production of ormoHAP spheres and probably beyond.

Octacalcium phosphate - a metastable mineral phase controls the evolution of scaffold forming proteins.

The molecular structure of collagen type 1 can be understood as the result of evolutionary selection in the process of formation of calcium phosphate based biocomposites acting as load bearing components in living organisms. The evolutionary selection fulfills the principle of 'survival of the fittest' in a particular biological environment. Disk-like post-nucleation complexes of Ca(HPO) organized in ribbon-like assemblies in the metastable octacalcium phosphate (OCP) phase, and Ca triangles in the stable HAP phase had formed the crystallographic motifs in this selection process.