Biology subjects

Wagermaier, W.

Publications and source records attributed to Wagermaier, W..

4 recordsLinked to original sources

bioRxiv2026

Material-driven fibronectin assembly enables low-dose BMP-2 to regenerate structurally mature bone in critical-sized load-bearing defects

Bone grafts for critical-sized load-bearing defects are usually judged by how much bone forms, and rarely by whether that bone is structurally and mechanically competent. Here, degradable ceramic monetites coated with poly(ethyl acrylate) (PEA) and functionalised with fibronectin (FN) and rhBMP-2 at 10-25 g/mL, 60-150-fold below the approved clinical concentration, are assessed across length scales. MicroCT showed that only monetites functionalised with rhBMP-2 bridged the defect, with a significant increase in new bone volume in both the monetite vicinity and the whole defect volume. In contrast, platelet-rich plasma (PRP) functionalisation significantly reduced bone formation relative to FN, showing that the identity of the adhesion cue, and not merely its presence, determines the outcome. Monetite degradation and increased interconnected porosity favoured bone ingrowth and produced a continuous interface between monetite and new bone. The multiscale analyses of quantitative polarised light microscopy, SAXS and nanoindentation show that PEA-coated monetites functionalised with FN and 25 g/mL rhBMP-2 promoted structurally and mechanically more mature bone, with a hierarchical organisation and local mechanical properties approaching those of native cortical tissue. In the bridged region this group recapitulated the preferential collagen fibre orientation of native cortical bone and reached an elastic modulus and hardness that were not statistically distinguishable from it, although mineral particles throughout the regenerated tissue remained thicker and less aligned than in cortical bone. Synchrotron microCT in an ovine model extended these findings to a clinically relevant scale, supporting the translational potential of the system. Taken together, these findings position PEA-coated monetites functionalised with FN and low-dose rhBMP-2 as a strategy for the structural and functional regeneration of large bone defects.

bioengineering↗

bioRxiv2025

Cement lines are stiffer and harder than bone but exhibit different mineral-mechanics relationships due to thicker and shorter mineral particles

The remarkable mechanical performance of bone arises from its complex hierarchical structure and from the presence of numerous internal interfaces joining the different components. Formed during bone remodeling, the cement line (CL) is a thin interface surrounding osteons. Although often neglected due to its small size, the CL has been suggested to play an important role in bone fracture toughness. However, there is an ongoing debate about its specific structure and mechanical behavior. Here, we investigate the composition-mechanics relationship at the CL and surrounding bone in human osteons using multiple methods in a correlative manner. We found that the CL is stiffer and harder than adjacent osteonal tissue. However, the CL requires more mineral than bone to attain the same stiffness and hardness. Analyzing the nanoscale properties of the mineral, we found thicker but shorter particles at the CL. Using a mechanical model, we interpreted the lower aspect ratio of the mineral particles as a less effective way to reinforce the collagen matrix. Casting our findings into a computational model, we questioned the possible protective role of the CL, which is not a soft interface as traditionally believed.

bioengineering↗

bioRxiv2022

Gradients of orientation, composition and hydration of proteins for efficient light collection by the cornea of the horseshoe crab

The lateral eyes of the horseshoe crab, Limulus polyphemus, are the largest compound eyes within recent Arthropoda. While this visual system has been extensively described before, the precise mechanism allowing vision has remained controversial. Correlating quantitative refractive index (RI) mapping and detailed structural analysis, we demonstrate how gradients of RI in the cornea result from the hierarchical organization of chitin-protein fibers, heterogeneity in protein composition and bromine doping, as well as spatial variation in water content. Combining the realistic cornea structure and measured RI gradients with full-wave optical modelling and ray-tracing approaches, we show that the light collection mechanism depends on both refraction-based graded index (GRIN) optics and total internal reflection. The optical properties of the cornea are governed by different mechanisms at different hierarchical levels, demonstrating the remarkable versatility of arthropod cuticle. One-sentence summaryStructural hierarchy and protein hydration determine the optical performance of the cornea of L. polyphemus.

biophysics↗

bioRxiv2019

Analysis of Finnish blue mussel (Mytilus edulis L.) shell: Biomineral ultrastructure, organic-rich interfacial matrix and mechanical behavior

Studying various marine biomineralized ultrastructures reveals the appearance of common architectural designs and building blocks in materials with fascinating mechanical properties that match perfectly to their biological tasks. Advanced mechanical properties of biological materials are attributed to evolutionary optimized molecular architectures and structural hierarchy. One example which has not yet been structurally investigated in great detail is the shell of Mytilus edulis L. (Finnish blue mussel) found in the archipelago of SW-Finland. Through a combination of various state-of-the-art techniques such as high-resolution electron microscopy imaging, Fourier-transformed infrared spectroscopy, powder X-ray diffraction, synchrotron wide-angle X-ray diffraction, nanoindentation and protein analysis, both the inorganic mineralized components as well as the organic-rich matrix were extensively characterized. We found very similar ultra-architecture across the shell of M. edulis L. as compared to the widely studied and closely related M. edulis. However, we also found interesting differences, for instance in the thickness and degree of orientation of the mineralized layers indicating dissimilar properties and related alterations in the biomineralization processes. Our results show that the shell of M. edulis L. has a gradient of mechanical properties, with the increase in the stiffness and the hardness from anterior to the posterior region of the shell. The shell is made from distinct and recognizable mineralized layers each varying in thickness and microstructural features. At posterior regions of the shell, moving from dorsal to ventral side, these layers are an oblique prismatic layer, a prismatic layer and a nacreous layer, in which the oblique prismatic layer is found to be the main and thickest mineralized layer of the shell. Probing the calcified rods in the oblique prismatic layer using high resolution SEM imaging revealed opening of channels with a diameters of 40-50 nm and lengths up to a micrometer extending through the rods. The chitin and protein have been found to be the main component of the organic-rich interfacial matrix as expected. Protein analysis showed two abundant proteins with sizes around 100 kD and 45 kD which likely not only regulates biomineralization and adhesion of the crystals but also governing the intrinsic-extrinsic toughening in the shell. Overall, this detailed analysis provides new structural insights into biomineralization of marine shells in general.

developmental biology↗