Experiment and simulation
The stomach is a central organ of vertebrates and its extreme deformations place special demands on the stomach tissue and especially on the active smooth muscle. Although a variety of dysfunctions and associated tissue changes are known, mechanical studies are scarce compared to other organs. Thus, the main objective of this project is to establish and validate an electro-chemo-mechanical model of the stomach based on experimental studies in the porcine stomach.
Four steps are planned for the creation and validation of the stomach model, which show a close interconnection between experiment and modeling. Here, the experiments are performed on domestic pigs, since the structure and contraction behavior of the stomach are very similar in humans and pigs. An essential prerequisite for the model development is the method development (I) for the acquisition of the 3D deformation as well as the measurement of the excitation propagation on the stomach surface. Based on the optical method for 3D deformation measurement of skeletal muscle developed by the applicants, a method for determining stomach geometry under water will be developed. Furthermore, surface electrodes will be developed to measure the propagation of the action potential on the stomach surface. In a first experimental step, targeted studies on tissue strips (II) will be performed. In order to detect regional differences in the gastric structure, the preparations will be taken from the gastric wall at defined positions to determine the layer-specific architecture as well as the active and passive material properties. These data will be used in an intermediate step for the development and associated parameter identification of the electro-chemo-mechanical model. Through active and passive investigations on whole stomachs (III), gastric capacity, pressure-volume dependencies, 3D deformation as well as the propagation of the action potential on the gastric surface will be determined. In a final step, the additional input data from the experiments on the whole stomach will be used for model development and validation (IV).
The developed stomach model represents a replacement and complementary method to animal experiments and, based on the similarity of the human and porcine bladder, to human studies. Thus, in the future it can contribute to the reduction of animal experiments as well as to a better understanding of stomach function. In perspective (continuation phase), the model will be used for predictions of various functional effects of tissue changes (e.g. due to chronic disease conditions). For this purpose, morphological and mechanical changes of the diseased tissue will be recorded experimentally and transferred to the model.
Literature:
- Papenkort, S., Borsdorf, M., Böl, M., Siebert, T., 2023. A geometry model of the porcine stomach featuring mucosa and muscle layer thicknesses. J Mech Behav Biomed Mater 142, 105801.[link]
- Klemm, L., Seydewitz, R., Siebert, T., Böl, M., 2023. Three-dimensional multi-field modelling of gastric arrhythmias and their effects on antral contractions. doi: 10.1016 Comput Biol Med 153, 106488.[link]
- Borsdorf, M., Böl, M., Siebert, T., 2021. Influence of layer separation on the determination of stomach smooth muscle properties. Pflugers Arch. Eur J Physiol 473, 911–920(2021).doi:10.1007/s00424-021-02568-5 [link]
- Bauer, M., Morales Orcajo, E., Klemm, L., Seydewitz, R., Fiebach, V., Siebert, T., Böl, M., 2020. Biomechanical and microstructural characterisation of the porcine stomach wall: Location- and layer-dependent investigations. Acta Biomater. [link]
- Klemm L., Seydewitz R., Borsdorf M., Siebert T., Böl M. (2020). On a coupled electro-chemomechanical model of gastric smooth muscle contraction, Acta Biomater,doi:10.1016/j.actbio.2020.04.007109, 163-181.[Link]
- Tomalka, A., Borsdorf, M., Bol, M., & Siebert, T. (2017). Porcine Stomach Smooth Muscle Force Depends on History-Effects. Front Physiol, 8, 802. doi:10.3389/fphys.2017.00802 [link]
