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DFG Collaborative Research Centre 1444

This Collaborative Research Centre aims to unravel the basic mechanisms that differentiate between success and failure in regeneration of musculoskeletal tissue using bone healing as a role model.

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Subproject 7 - Principal Investgators

Dr. Paul Zaslansky

CRC 1444 Subproject 7

The role and the development of internal tissue tension in normal versus compromised healing bone

Mechanical stress in biological tissues is used as a communicative signal that prompts cells to discriminate and explore the geometric and mechanical properties of their environment. Internal stress in bones significantly increases the resistance of the material to mechanical overload. However, stress is also generated by modulating osmotic gradients, locally controlling the molecular composition of the extracellular matrix and regulating pH and salt concentration. We are using X-ray diffraction, in situ collagen visualisation and NanoCT strategies to unravel the principles of pre-stress restoration in bone healing to improve the macroscopic understanding of mechanical stress and strain within the fracture zone. In parallel, we aim to deepen the understanding of how internal stress is generated in bone tissue. To do this, we are investigating the hypothesis that cells coordinate and use large polymer molecules (collagen, glycosaminoglycans, etc.) to induce and express internal stress conditions in the extracellular matrix surrounding them.

Most important results

In-situ measurement of residual internal stress due to radiation damage

Energy Supply & Consumption | Force Transmission & Sensing

Radioactive radiation destroys the collagen mineral bond. This also changes the residual stress. However, we can also use this radiation damage directly to determine it and compare it in different bone types.

Residual internal stress in normal healing bones

Energy Supply & Consumption | Force Transmission & Sensing

Taking bone healing as an example, we measure the internal stress in bone tissue by measuring the lattice spacing with the help of mineral particles using synchrotron radiation diffraction, which act as stress sensors. It turns out that the values are strongly site-dependent and thus also depend on the age and condition of the bone tissue.

Residual internal stress in impaired healing bone

Energy Supply & Consumption | Force Transmission & Sensing

Bones from older mice exhibit lower internal stresses, resulting in greater fragility of the mineralized tissue. At the same time, the increased immune experience of the mice leads to a delay in healing, allowing more stages of bone healing to be studied.

In collaboration with subproject P01

Model for the deformation of mineralised collagen fibres

Energy Supply & Consumption | Force Transmission & Sensing

We update published models of deformation and fracture of mineralized collagen fibers with the observed internal stresses.

Mineralisation in the early stage of bone healing

Energy Supply & Consumption | Force Transmission & Sensing

The methods used in this project are based on the measurement of mineralized tissue. Here we investigate how mineral particles and collagen staggering behave in the early stages of bone healing. In the future, these results can then also be compared to those of various influences.

In collaboration with subproject P01

Osmotic pressure sensors for cell cultures

Energy Supply & Consumption | Force Transmission & Sensing

With FRET liposomes we can determine spatial and temporal osmotic gradients in systems with osteoblasts.

Polarisation microscopy

Energy Supply & Consumption | Force Transmission & Sensing

With the help of polarization microscopy, not only the alignment of collagen fibers but also the internal stress due to delay can be shown. This is because drying bone samples reduces the compressive stress on the mineral, which affects the optical retardation of the bones and can be measured by us.

In collaboration with subproject P09

Laminography simplifies 3D measurements of bone samples compared to tomography

Energy Supply & Consumption | Force Transmission & Sensing

Compared to synchrotron-based computer tomography, laminography allows bone samples to be mounted more easily and thus examined.


Dr. Victoria Schemenz (Postdoc)

Residual strain in healing bone

Efe Cuma Yavuzsoy (Doctoral Researcher)

The effect of osmotic pressure on tissue growth






Founded by the DFG (Project Number: 427826188)
Funding Period 2021-2024