| 1. |
- Elowsson Rendin, Linda, et al.
(författare)
-
Matrisome Properties of Scaffolds Direct Fibroblasts in Idiopathic Pulmonary Fibrosis
- 2019
-
Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1422-0067. ; 20:16
-
Tidskriftsartikel (refereegranskat)abstract
- In idiopathic pulmonary fibrosis (IPF) structural properties of the extracellular matrix (ECM) are altered and influence cellular responses through cell-matrix interactions. Scaffolds (decellularized tissue) derived from subpleural healthy and IPF lungs were examined regarding biomechanical properties and ECM composition of proteins (the matrisome). Scaffolds were repopulated with healthy fibroblasts cultured under static stretch with heavy isotope amino acids (SILAC), to examine newly synthesized proteins over time. IPF scaffolds were characterized by increased tissue density, stiffness, ultimate force, and differential expressions of matrisome proteins compared to healthy scaffolds. Collagens, proteoglycans, and ECM glycoproteins were increased in IPF scaffolds, however while specific basement membrane (BM) proteins such as laminins and collagen IV were decreased, nidogen-2 was also increased. Findings were confirmed with histology, clearly showing a disorganized BM. Fibroblasts produced scaffold-specific proteins mimicking preexisting scaffold composition, where 11 out of 20 BM proteins were differentially expressed, along with increased periostin and proteoglycans production. We demonstrate how matrisome changes affect fibroblast activity using novel approaches to study temporal differences, where IPF scaffolds support a disorganized BM and upregulation of disease-associated proteins. These matrix-directed cellular responses emphasize the IPF matrisome and specifically the BM components as important factors for disease progression.
|
|
| 2. |
- Khayyeri, Hanifeh, et al.
(författare)
-
Diminishing effects of mechanical loading over time during rat Achilles tendon healing
- 2020
-
Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 15:12 December
-
Tidskriftsartikel (refereegranskat)abstract
- Mechanical loading affects tendon healing and recovery. However, our understanding about how physical loading affects recovery of viscoelastic functions, collagen production and tissue organisation is limited. The objective of this study was to investigate how different magnitudes of loading affects biomechanical and collagen properties of healing Achilles tendons over time. Achilles tendon from female Sprague Dawley rats were cut transversely and divided into two groups; normal loading (control) and reduced loading by Botox (unloading). The rats were sacrificed at 1, 2- and 4-weeks post-injury and mechanical testing (creep test and load to failure), small angle x-ray scattering (SAXS) and histological analysis were performed. The effect of unloading was primarily seen at the early time points, with inferior mechanical and collagen properties (SAXS), and reduced histological maturation of the tissue in unloaded compared to loaded tendons. However, by 4 weeks no differences remained. SAXS and histology revealed heterogeneous tissue maturation with more mature tissue at the peripheral region compared to the center of the callus. Thus, mechanical loading advances Achilles tendon biomechanical and collagen properties earlier compared to unloaded tendons, and the spatial variation in tissue maturation and collagen organization across the callus suggests important regional (mechano-) biological activities that require more investigation.
|
|
| 3. |
- Notermans, Thomas, et al.
(författare)
-
A numerical framework for mechano-regulated tendon healing-Simulation of early regeneration of the Achilles tendon
- 2021
-
Ingår i: PLoS Computational Biology. - : Public Library of Science (PLoS). - 1553-7358. ; 17:2, s. 1008636-1008636
-
Tidskriftsartikel (refereegranskat)abstract
- Mechano-regulation during tendon healing, i.e. the relationship between mechanical stimuli and cellular response, has received more attention recently. However, the basic mechanobiological mechanisms governing tendon healing after a rupture are still not well-understood. Literature has reported spatial and temporal variations in the healing of ruptured tendon tissue. In this study, we explored a computational modeling approach to describe tendon healing. In particular, a novel 3D mechano-regulatory framework was developed to investigate spatio-temporal evolution of collagen content and orientation, and temporal evolution of tendon stiffness during early tendon healing. Based on an extensive literature search, two possible relationships were proposed to connect levels of mechanical stimuli to collagen production. Since literature remains unclear on strain-dependent collagen production at high levels of strain, the two investigated production laws explored the presence or absence of collagen production upon non-physiologically high levels of strain (>15%). Implementation in a finite element framework, pointed to large spatial variations in strain magnitudes within the callus tissue, which resulted in predictions of distinct spatial distributions of collagen over time. The simulations showed that the magnitude of strain was highest in the tendon core along the central axis, and decreased towards the outer periphery. Consequently, decreased levels of collagen production for high levels of tensile strain were shown to accurately predict the experimentally observed delayed collagen production in the tendon core. In addition, our healing framework predicted evolution of collagen orientation towards alignment with the tendon axis and the overall predicted tendon stiffness agreed well with experimental data. In this study, we explored the capability of a numerical model to describe spatial and temporal variations in tendon healing and we identified that understanding mechano-regulated collagen production can play a key role in explaining heterogeneities observed during tendon healing.
|
|
| 4. |
- Notermans, Thomas
(författare)
-
Computational modeling of mechanobiology in intact and healing rat Achilles tendon
- 2021
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Tendons fulfill an important musculoskeletal function by enabling energy-efficient force transmission between muscles and bones. The tendon is a collagen-rich connective tissue that adapts to mechanical loading through mechanobiological processes. The tendon contains a hierarchical collagen fiber structure that displays complex mechanical behaviour by storing and dissipating energy. Current understanding of how tendon properties adapt to short and long-term mechanical loading is limited, but is key to prevent tendon disease and design optimal rehabilitation protocols after tendon rupture. Recently, an increasing amount of small animal experiments have investigated how intact and healing tendons adapt in vivo upon different mechanical loading regimens. Yet, limited numerical models have investigated tendon mechanobiology; even though existing modeling tools from other research fields are available and the amount of experimental data for validation is growing. The aim of this thesis was to investigate the mechanobiology of intact and healing tendon by utilizing and developing advanced numerical models. First, a 3D finite element framework was used to determine the constitutive viscoelastic material properties of intact healthy tendons in rats. The material properties were fitted to experimental data from rats that were subjected to two loading regimens, i.e. free cage activity (full loading) and reduced loading, for five weeks. The resulting material properties showed strong differences in both elastic and damping properties of the collagen between the rats that were subjected to full or reduced loading. Using this material model, a finite element mechanobiological healing framework for Achilles tendons was developed. The adaptive healing model investigated how principal strain and cell infiltration can govern tissue regeneration. The tendon model was stimulated with different levels of external loading, mimicking physiological and sub-physiological load levels explored in animal experiments. Model predictions of the spatio-temporal evolution of tissue distribution, collagen alignment and mechanical properties (stiffness, creep behaviour and strain levels) were validated by comparison with experimental measurements from rat Achilles tendon throughout the first four weeks of spontaneous healing after rupture. Interestingly, both strain-dependent and cell density-dependent tissue production were identified as possible explanations for decreased tissue production in the tendon core during healing. The healing framework was expanded to predict formation of different tissue types during healing. According to established tissue differentiation frameworks in bone fracture healing, different mechanobiological factors were explored to regulate the formation of different tissue types, i.e. tendon-, cartilage-, fat- and bone-like tissue. This framework is the first to reproduce experimental observations of these tissues. It provides several potential mechanisms of mechanobiological regulation of the formation of different tissue types during tendon healing. In summary, this thesis investigated mechanobiology in intact and healing tendon. An adaptive framework was developed that enabled the prediction of heterogeneous tissue distribution, organization, differentiation, and evolution of mechanical function during tendon healing. The spatial distribution of mechanical stimuli, particularly strain, but also biological stimuli such as cells and oxygen, were identified as potential mechanisms to regulate tendon healing by influencing formation of different tissue types, tissue alignment and the recovery of mechanical properties. Further development and thorough characterization of these models could expand our understanding of mechanobiological, biomechanical or biological processes in intact, diseased or healing tendons. Ultimately, these models could help designing optimal loading regimens to prevent chronic tendon disease or stimulate tendon healing after rupture.
|
|
| 5. |
- Notermans, Thomas, et al.
(författare)
-
Predicting the effect of reduced load level and cell infiltration on spatio-temporal Achilles tendon healing
- 2021
-
Ingår i: Journal of Biomechanics. - : Elsevier BV. - 0021-9290.
-
Tidskriftsartikel (refereegranskat)abstract
- Mechanobiology plays an important role in tendon healing. However, the relationship between mechanical loading and spatial and temporal evolution of tendon properties during healing is not well understood. This study builds on a recently presented mechanoregulatory computational framework that couples mechanobiological tendon healing to tissue production and collagen orientation. In this study, we investigated how different magnitudes of mechanical stimulation (principal strain) affect the spatio-temporal evolution of tissue production and the temporal evolution of elastic and viscoelastic mechanical parameters. Specifically, we examined the effect of cell infiltration (mimicking migration and proliferation) in the callus on the resulting tissue production by modeling production to depend on local cell density. The model predictions were carefully compared with experimental data from Achilles tendons in rats, at 1, 2 and 4 weeks of healing. In the experiments, the rat tendons had been subjected to free cage activity or reduced load levels through intramuscular botox injections. The simulations that included cell infiltration and strain-regulated collagen production predicted spatio-temporal tissue distributions and mechanical properties similarly to that observed experimentally. In addition, lack of matrix-producing cells in the tendon core during early healing may result in reduced collagen content, regardless of the daily load level. This framework is the first to computationally investigate mechanobiological mechanisms underlying spatial and temporal variations during tendon healing for various magnitudes of loading. This framework will allow further characterization of biomechanical, biological, or mechanobiological processes underlying tendon healing.
|
|
| 6. |
- Notermans, Thomas, et al.
(författare)
-
Predicting the formation of different tissue types during Achilles tendon healing using mechanoregulated and oxygen-regulated frameworks
- 2023
-
Ingår i: Biomechanics and Modeling in Mechanobiology. - : Springer Science and Business Media LLC. - 1617-7959 .- 1617-7940. ; 22:2, s. 655-667
-
Tidskriftsartikel (refereegranskat)abstract
- During Achilles tendon healing in rodents, besides the expected tendon tissue, also cartilage-, bone- and fat-like tissue features have been observed during the first twenty weeks of healing. Several studies have hypothesized that mechanical loading may play a key role in the formation of different tissue types during healing. We recently developed a computational mechanobiological framework to predict tendon tissue production, organization and mechanical properties during tendon healing. In the current study, we aimed to explore possible mechanobiological related mechanisms underlying formation of other tissue types than tendon tissue during tendon healing. To achieve this, we further developed our recent framework to predict formation of different tissue types, based on mechanobiological models established in other fields, which have earlier not been applied to study tendon healing. We explored a wide range of biophysical stimuli, i.e., principal strain, hydrostatic stress, pore pressure, octahedral shear strain, fluid flow, angiogenesis and oxygen concentration, that may promote the formation of different tissue types. The numerical framework predicted spatiotemporal formation of tendon-, cartilage-, bone- and to a lesser degree fat-like tissue throughout the first twenty weeks of healing, similar to recent experimental reports. Specific features of experimental data were captured by different biophysical stimuli. Our modeling approach showed that mechanobiology may play a role in governing the formation of different tissue types that have been experimentally observed during tendon healing. This study provides a numerical tool that can contribute to a better understanding of tendon mechanobiology during healing. Developing these tools can ultimately lead to development of better rehabilitation regimens that stimulate tendon healing and prevent unwanted formation of cartilage-, fat- and bone-like tissues.
|
|
| 7. |
- Notermans, Thomas, et al.
(författare)
-
Tendon mechanobiology in small animal experiments during post-transection healing
- 2021
-
Ingår i: European Cells and Materials. - Switzerland : AO Research Institute Davos. - 1473-2262. ; 42, s. 375-391
-
Tidskriftsartikel (refereegranskat)abstract
- Ruptures to tendons are common and costly, and no clinical consensus exists on the appropriate treatment and rehabilitation regimen to promote their healing as well as full recovery of functionality. Although mechanobiology is known to play an important role in tendon regeneration, the understanding of how mechano-regulated processes affect tendon healing needs further clarification. Many small-animal studies, particularly in rats and mice, have characterized the progression of healing in terms of geometrical, structural, compositional, mechanical, and cellular properties. Some of the properties are also studied under different mechanical loading regimens. The focus of this review is to summarize and generalize the information in the literature regarding spatial and temporal differentiation of tendon properties during rodent tendon healing following full-tendon transection, as well as how this is affected by altered in vivo loading regimens.
|
|
| 8. |
- Notermans, Thomas, et al.
(författare)
-
Understanding how reduced loading affects Achilles tendon mechanical properties using a fibre-reinforced poro-visco-hyper-elastic model
- 2019
-
Ingår i: Journal of the Mechanical Behavior of Biomedical Materials. - : Elsevier BV. - 1751-6161. ; 96, s. 301-309
-
Tidskriftsartikel (refereegranskat)abstract
- Understanding tendon mechanobiology is important for gaining insight into the development of tendon pathology and subsequent repair processes. The aim of this study was to investigate how experimentally observed mechanobiological adaptation of rat Achilles tendons translate to changes in constitutive mechanical properties and biomechanical behavior. In addition, we assessed the ability of the model to simulate tendon creep and stress-relaxation. A three dimensional finite element framework of rat Achilles tendon was implemented with a fibre-reinforced poro-visco-hyper-elastic constitutive model. Stress-relaxation and creep data from Achilles tendons of Sprague Dawley rats that had been subjected to both daily loading and a period of reduced loading were used to determine the constitutive properties of the tendons. Our results showed that the constitutive model captures creep and stress-relaxation data from rat Achilles tendons for both loaded and unloaded tendons with good accuracy (normalized root mean square error between model and experimental data were 0.010–0.027). Only when the model parameters were fitted to data from both mechanical tests simultaneously, were we able to also capture similar increase in elastic energy (increased stiffness)and decreased viscoelasticity in response to unloading, as was reported experimentally. Our study is the first to show that experimentally observed mechanobiological changes in tendon biomechanics, such as stiffness and viscoelasticity, can be designated to mechanical quantities in a constitutive model. Further investigation in this direction has potential to discriminate tissue components responsible for specific biomechanical response, and enable targeted treatment strategies for tendon health.
|
|
| 9. |
- Pierantoni, Maria, et al.
(författare)
-
Spatiotemporal and microstructural characterization of heterotopic ossification in healing rat Achilles tendons
- 2023
-
Ingår i: FASEB Journal. - : WILEY. - 0892-6638 .- 1530-6860. ; 37:6
-
Forskningsöversikt (refereegranskat)abstract
- Achilles tendon rupture is a common debilitating medical condition. The healing process is slow and can be affected by heterotopic ossification (HO), which occurs when pathologic bone-like tissue is deposited instead of the soft collagenous tendon tissue. Little is known about the temporal and spatial progression of HO during Achilles tendon healing. In this study we characterize HO deposition, microstructure, and location at different stages of healing in a rat model. We use phase contrast-enhanced synchrotron microtomography, a state-of-the-art technique that allows 3D imaging at high-resolution of soft biological tissues without invasive or time-consuming sample preparation. The results increase our understanding of HO deposition, from the early inflammatory phase of tendon healing, by showing that the deposition is initiated as early as one week after injury in the distal stump and mostly growing on preinjury HO deposits. Later, more deposits form first in the stumps and then all over the tendon callus, merging into large, calcified structures, which occupy up to 10% of the tendon volume. The HOs were characterized by a looser connective trabecular-like structure and a proteoglycan-rich matrix containing chondrocyte-like cells with lacunae. The study shows the potential of 3D imaging at high-resolution by phase-contrast tomography to better understand ossification in healing tendons.
|
|
