More Like this

1. The impact of extracellular matrix proteins on bovine fibro‐adipogenic progenitor cell adhesion, proliferation, and differentiation in vitro

   https://doi.org/10.14814/phy2.70283  

   Gish, Perri; Stewart, Madison; Khuu, Brandon; Meyer, Nathaniel; Vahmani, Payam; Smith, Lucas (May 2025, Physiological Reports)

   Abstract Fibro‐adipogenic progenitor cells (FAPs) are mesenchymal stem cells that produce extracellular matrix (ECM) and intramuscular adipocytes in skeletal muscle. While FAPs have demonstrated responsiveness to their physical environment, there is limited knowledge of how the ECM substrate of FAPs impacts their differentiation, particularly in livestock animals. We hypothesized that the ECM substrate FAPs are cultured on will differentially impact their adherence, proliferation, and differentiation. Through an initial screen of 9 ECM proteins and their combinations, significant variation of bovine FAP attachment and differentiation across coatings was observed. The ECM substrates fibronectin, collagen 6, vitronectin, and a combination of fibronectin and collagen 6 were selected for further testing. Notably, fibronectin increased cell proliferation and attachment rates, without impairing FAP adipogenic or fibrogenic differentiation compared to the other coatings. Benefits of fibronectin were maintained at lower concentrations and when combined with less favorable coatings such as collagen 6. When assessed for their adipogenic potential on each coating at different substrate stiffnesses, lipid accumulation decreased with increasing substrate stiffness, while cell attachment increased on stiffer substrates. Overall, these results demonstrate the high responsiveness of FAPs to their ECM substrate, along with highlighting fibronectin as a preferred substrate for in vitro experiments with bovine FAPs. 

   more » « less
2. Endothelial glycocalyx sensitivity to chemical and mechanical sub-endothelial substrate properties

   https://doi.org/10.3389/fbioe.2023.1250348  

   Hamrangsekachaee, Mohammad; Wen, Ke; Yazdani, Narges; Willits, Rebecca K; Bencherif, Sidi A; Ebong, Eno E (October 2023, Frontiers in Bioengineering and Biotechnology)

   Glycocalyx (GCX) is a carbohydrate-rich structure that coats the surface of endothelial cells (ECs) and lines the blood vessel lumen. Mechanical perturbations in the vascular environment, such as blood vessel stiffness, can be transduced and sent to ECs through mechanosensors such as GCX. Adverse stiffness alters GCX-mediated mechanotransduction and leads to EC dysfunction and eventually atherosclerotic cardiovascular diseases. To understand GCX-regulated mechanotransduction events, anin vitromodel emulatingin vivovessel conditions is needed. To this end, we investigated the impact of matrix chemical and mechanical properties on GCX expression via fabricating a tunable non-swelling matrix based on the collagen-derived polypeptide, gelatin. To study the effect of matrix composition, we conducted a comparative analysis of GCX expression using different concentrations (60–25,000 μg/mL) of gelatin and gelatin methacrylate (GelMA) in comparison to fibronectin (60 μg/mL), a standard coating material for GCX-related studies. Using immunocytochemistry analysis, we showed for the first time that different substrate compositions and concentrations altered the overall GCX expression on human umbilical vein ECs (HUVECs). Subsequently, GelMA hydrogels were fabricated with stiffnesses of 2.5 and 5 kPa, representing healthy vessel tissues, and 10 kPa, corresponding to diseased vessel tissues. Immunocytochemistry analysis showed that on hydrogels with different levels of stiffness, the GCX expression in HUVECs remained unchanged, while its major polysaccharide components exhibited dysregulation in distinct patterns. For example, there was a significant decrease in heparan sulfate expression on pathological substrates (10 kPa), while sialic acid expression increased with increased matrix stiffness. This study suggests the specific mechanisms through which GCX may influence ECs in modulating barrier function, immune cell adhesion, and mechanotransduction function under distinct chemical and mechanical conditions of both healthy and diseased substrates. 

   more » « less
3. Age-Related Collagen Remodeling Occurs in the Absence of Hypertension in Aortas of NOS3 Heterozygous Mice

   Du, Liya; Azar, Dara; Eliadorani, Dorsa; Shazly, Tarek; Lessner, Susan M. (June 2020, Summer Biomechanics, Bioengineering, and Biotransport Conference (SB3C))

   The endothelium, composed of a single layer of endothelial cells, is the innermost lining of vessels, acting as the interface between blood and the arterial wall. “Endothelial dysfunction” is defined as reduction or loss of bioavailability of endothelial-derived nitric oxide (NO), a condition that precedes or accompanies several cardiovascular pathologies associated with aging, such as atherosclerosis. [1] [2] NO plays an important role in regulating vascular tone and maintaining vascular homeostasis as a vasodilator. Thus, we hypothesize that decreased NO production may induce collagen fiber reorientation and increased collagen production, to shift load from smooth muscle cells to the extracellular matrix, eventually leading to vascular remodeling. The aim of this project is to study the impact of NO deficiency on hemodynamic parameters, collagen content, and collagen fiber orientation during age-related vascular remodeling using a mouse model. 

   more » « less
4. Collagen Fibril Abnormalities in Human and Mice Abdominal Aortic Aneurysm

   Jones, B.; Tonniges, J. R.; Debsk, A.i; Albert, B.; Yeung, D. A.; Gadde, N.; Mahajan, A.; Sharma, N.; Calomeni, E. P.; Go, M.; et al (August 2020, Biomedical Engineering Society 2020 Annual Meeting)

   null (Ed.)

   Introduction: Vascular diseases like abdominal aortic aneurysms (AAA) are characterized by a drastic remodeling of the vessel wall, accompanied with changes in the elastin and collagen content. At the macromolecular level, the elastin fibers in AAA have been reported to undergo significant structural alterations. While the undulations (waviness) of the collagen fibers is also reduced in AAA, very little is understood about changes in the collagen fibril at the sub-fiber level in AAA as well as in other vascular pathologies. Materials and Methods: In this study we investigated structural changes in collagen fibrils in human AAA tissue extracted at the time of vascular surgery and in aorta extracted from angiotensin II (AngII) infused ApoE−/− mouse model of AAA. Collagen fibril structure was examined using transmission electron microscopy and atomic force microscopy. Images were analyzed to ascertain length and depth of D-periodicity, fibril diameter and fibril curvature. Tissues were also stained using collagen hybridizing peptide (CHP) and analyzed using fluorescent microscopy and second harmonic generation (SHG) microscopy to locate regions of healthy and degraded collagen. Results: Abnormal collagen fibrils with compromised D-periodic banding were observed in the excised human tissue and in remodeled regions of AAA in AngII infused mice (Figure 1). These abnormal fibrils were characterized by statistically significant reduction in depths of D-periods and an increased curvature of collagen fibrils. These features were more pronounced in human AAA as compared to murine samples. Additionally, regions of abnormal collagen were located within the remodeled areas of AAA tissue and were distinct from healthy collagen regions as ascertained using CHP staining and SHG (Figure 1). Thoracic aorta from Ang II-infused mice, abdominal aorta from saline-infused mice, and abdominal aorta from non-AAA human controls did not contain abnormal collagen fibrils. Conclusions: The structural alterations in abnormal collagen fibrils appear similar to those reported for collagen fibrils subjected to mechanical overload or chronic inflammation in other tissues. Detection of abnormal collagen could be utilized to better understand the functional properties of the underlying extracellular matrix in vascular as well as other pathologies. 

   more » « less
5. 3D collagen architecture regulates cell adhesion through degradability, thereby controlling metabolic and oxidative stress

   https://doi.org/10.1093/intbio/zyz019  

   Velez, Daniel O; Ranamukhaarachchi, Sural K; Kumar, Aditya; Modi, Rishi N; Lim, Esther W; Engler, Adam J; Metallo, Christian M; Fraley, Stephanie I (June 2019, Integrative Biology)

   Abstract The collagen-rich tumor microenvironment plays a critical role in directing the migration behavior of cancer cells. 3D collagen architectures with small pores have been shown to confine cells and induce aggressive collective migration, irrespective of matrix stiffness and density. However, it remains unclear how cells sense collagen architecture and transduce this information to initiate collective migration. Here, we tune collagen architecture and analyze its effect on four core cell-ECM interactions: cytoskeletal polymerization, adhesion, contractility, and matrix degradation. From this comprehensive analysis, we deduce that matrix architecture initially modulates cancer cell adhesion strength, and that this results from architecture-induced changes to matrix degradability. That is, architectures with smaller pores are less degradable, and degradability is required for cancer cell adhesion to 3D fibrilar collagen. The biochemical consequences of this 3D low-attachment state are similar to those induced by suspension culture, including metabolic and oxidative stress. One distinction from suspension culture is the induction of collagen catabolism that occurs in 3D low-attachment conditions. Cells also upregulate Snail1 and Notch signaling in response to 3D low-attachment, which suggests a mechanism for the emergence of collective behaviors. 

   more » « less