Biology subjects

Tornifoglio, B.

Publications and source records attributed to Tornifoglio, B..

8 recordsLinked to original sources

bioRxiv2025

Low ultimate tensile strain in atherosclerotic plaques is linked to the presence of neovascularisation: insights from ex vivo uniaxial tensile testing

BackgroundNeovascularisation, the formation of new vessels within atherosclerotic plaques, has been associated with plaque progression and intraplaque haemorrhage. However, the relationship between neovascularisation and mechanical failure of plaques remains unclear. A better understanding of this link could improve rupture risk prediction beyond traditional reliance on arterial stenosis. MethodsHuman carotid plaques (n=7) from endarterectomy were sectioned into circumferential strips (n=25) and tested under uniaxial tension with digital image correlation (DIC) to determine ultimate tensile (UT) stress, UT strain, and elastic moduli. Immunohistochemistry with CD31 staining quantified neovascularisation. K-means clustering based on UT stress and strain identified mechanical phenotypes. A decision tree classifier was trained using neovascularisation percentage as the predictor. ResultsNeovascularisation showed a moderate negative correlation with UT strain (r = -0.46, p = 0.028), indicating plaques with greater neovascularisation failed at lower strains. K-means clustering identified two groups: Cluster 1 (lower UT strain) had significantly higher neovascularisation (median 2.21%) and greater initial stiffness than Cluster 2 (median 1.27%, p < 0.01). The decision tree using neovascularisation alone achieved 78.3% classification accuracy, with an area under the curve of 0.78. DIC analysis revealed rupture consistently occurred at regions of elevated local strain. ConclusionThis study demonstrates a link between neovascularisation and mechanical failure in atherosclerotic plaques. Higher neovascularisation was associated with lower UT strain, suggesting it contributes to mechanical instability. These findings support the role of neovascularisation as a marker of plaque vulnerability and encourage its integration into ultrasound-based risk assessment strategies, such as contrast-enhanced ultrasound.

bioengineering↗

bioRxiv2023

Melt electrowritten scaffold architectures to mimic vasculature mechanics and control neo-tissue orientation

Cardiovascular disease is one of the leading causes of death worldwide, commonly associated with the development of an arteriosclerotic plaque and impairment of blood flow in arteries. Current adopted grafts to bypass the stenosed vessel fail to recapitulate the unique mechanical behaviour of native vessels, particularly in the case of small diameter vessels (<6 mm), leading to graft failure. Therefore, in this study, melt-electrowriting (MEW) was adopted to produce a range of fibrous grafts to mimic the extracellular matrix (ECM) architecture of the tunica media of vessels, in an attempt to match the mechanical and biological behaviour of the native tissue. Initially, the range of collagen architectures within the native vessel was determined, and subsequently replicated using MEW (winding angles (WA) 45{degrees}, 26.5{degrees}, 18.4{degrees}, 11.3{degrees}). These scaffolds recapitulated the anisotropic, non-linear mechanical behaviour of native carotid blood vessels. Moreover, these grafts facilitated human mesenchymal stromal/stem cell (hMSC) infiltration, differentiation, and ECM deposition that was independent of WA. The bioinspired MEW fibre architecture promoted cell alignment and preferential neo-tissue orientation in a manner similar to that seen in native tissue, particularly for WA 18.4{degrees} and 11.3{degrees}, which is a mandatory requirement for long-term survival of the regenerated tissue post-scaffold degradation. Lastly, the WA 18.4{degrees} was translated to a tubular graft and was shown to mirror the mechanical behaviour of small diameter vessels within physiological strain. Taken together, this study demonstrates the capacity to use MEW to fabricate bioinspired grafts to mimic the tunica media of vessels and recapitulate vascular mechanics which could act as a framework for small diameter graft development and functional long-term tissue regeneration.

bioengineering↗

bioRxiv2022

Microstructural and mechanical insight into atherosclerotic plaques - an ex vivo DTI study to better assess plaque vulnerability

Non-invasive microstructural characterisation has the potential to determine the stability, or lack thereof, of atherosclerotic plaques and ultimately aid in better assessing plaques risk to rupture. If linked with mechanical characterisation using a clinically relevant imaging technique, mechanically sensitive rupture risk indicators could be possible. This study aims to provide this link - between a clinically relevant imaging technique and mechanical characterisation within human atherosclerotic plaques. Ex vivo diffusion tensor imaging, mechanical testing, and histological analysis were carried out on human carotid atherosclerotic plaques. DTI-derived tractography was found to yield significant mechanical insight into the mechanical properties of more stable and more vulnerable microstructures. Coupled with insights from digital image correlation and histology, specific failure characteristics of different microstructural arrangements furthered this finding. More circumferentially uniform microstructures failed at higher stresses and strains when compared to samples which had multiple microstructures, like those seen in a plaque cap. The novel findings in this study motivate diagnostic measures which use non-invasive characterisation of the underlying microstructure of plaques to determine their vulnerability to rupture. Statements and DeclarationsThe authors have no competing interests or declarations to declare. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=133 SRC="FIGDIR/small/508689v1_ufig1.gif" ALT="Figure 1"> View larger version (61K): org.highwire.dtl.DTLVardef@15174d8org.highwire.dtl.DTLVardef@ce3db1org.highwire.dtl.DTLVardef@344257org.highwire.dtl.DTLVardef@ef8f19_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2022

Exploring DTI-derived metrics to non-invasively track recellularisation in vascular tissue engineering

Despite significant growth in the field of tissue engineering over the past decades, non-invasive, non-destructive methods to characterise recellularisation of grafts are lacking. Here, we investigate a non-invasive magnetic resonance imaging technique, diffusion tensor imaging (DTI), within acellular and recellularised vascular grafts. Using two decellularised porcine carotid grafts, smooth muscle cells were cultured dynamically for two weeks with terminal time points at day 3, 7, and 14. Grafts were fixed at each time point and investigated by DTI in an ex vivo set up. Semi-quantitative histology was carried out to investigate collagen, elastin, and cell density changes over time. DTI-derived metrics, namely the fractional anisotropy, mean diffusivity and tractography, not only were significantly different between day 3 and day 7 grafts, but also distinguished between acellular and recellularised grafts. Specifically, within the wet decellularised grafts, increasing fractional anisotropy was strongly correlated to increasing cell density. The results from this study show, for the first time, DTIs place in the field of tissue engineering, offering non-invasive, non-destructive insight into graft recellularisation.

bioengineering↗

bioRxiv2022

Phosphotungstic acid (PTA) preferentially binds to collagen-rich regions of porcine carotid arteries and human atherosclerotic plaques using 3D micro-computed tomography (CE-μCT)

Background and aimsAtherosclerotic plaque rupture in the carotid artery can cause small emboli to travel to cerebral arteries, causing blockages and preventing blood flow leading to stroke. Contrast enhanced micro computed tomography (CECT) using a novel stain, phosphotungstic acid (PTA) can provide insights into the microstructure of the vessel wall and atherosclerotic plaque, and hence their likelihood to rupture. Furthermore, it has been suggested that collagen content and orientation can be related to mechanical integrity. This study aims to build on existing literature and establish a robust and reproducible staining and imaging technique to non-destructively quantify the collagen content within arteries and plaques as an alternative to routine histology. MethodsPorcine carotid arteries and human atherosclerotic plaques were stained with a concentration of 1% PTA staining solution and imaged using MicroCT to establish the in-situ architecture of the tissue and measure collagen content. A histological assessment of the collagen content was also performed from picrosirius red (PSR) staining. ResultsPTA stained arterial samples highlight the reproducibility of the PTA staining and MicroCT imaging technique used with a quantitative analysis showing a positive correlation between the collagen content measured from CECT and histology. Furthermore, collagen-rich areas can be clearly visualised in both the vessel wall and atherosclerotic plaque. 3D reconstruction was also performed showing that different layers of the vessel wall and various atherosclerotic plaque components can be differentiated using Hounsfield Unit (HU) values. ConclusionsThe work presented here is unique as it offers a quantitative method of segmenting the vessel wall into its individual components and non-destructively quantifying the collagen content withing these tissues, whilst also delivering a visual representation of the fibrous structure using a single contrast agent. Graphical Abstract O_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY C_FIG_DISPLAY

bioengineering↗

bioRxiv2022

A short-term decellularisation technique for porcine carotid arteries that conveys a structural stimulus to cells

In many cases, treatment for stenotic atherosclerotic lesions requires the use of bypass grafts to divert blood flow around the diseased vessel sections. Autologous vessels are considered the "gold standard" for bypass conduits; however, the shortage of healthy autologous vessels has resulted in an increasing focus on optimising synthetic, biological and/or tissue engineered vascular bypass grafts. While many of the previously published methods have been shown to fall short of producing an ideal TEVG, this report presents a decellularisation process that produces an acellular vascular graft that is efficient, cost effective, and could be readily automated. The resulting graft can be used "off the shelf", has preserved arterial structure and mechanical properties, and conforms to decellularisation criteria regarding the sufficient removal of cellular and genetic components. Additionally, the graft does not require any priming, supports molecular transport, can withstand supraphysiological pressures, and can support cell attachment and growth under physiological strain conditions whilst providing structural cues for cell adhesion and growth. Impact statementVascular disease remains the leading cause of mortality worldwide. In the absence of suitable autologous vessels, there currently exists a clear clinical need for off the shelf vascular grafts that can successfully bypass diseased arteries. This paper outlines a short-term method for obtaining such a graft. The technique used involves decellularising porcine carotid arteries whilst preserving arterial structure and mechanical properties and is compliant with the international standard for implantable vascular prostheses: EN ISO 7198:2017. Additionally, this protocol is cost and time effective, and produces reproducible "ready to use" acellular grafts that support molecular transport, can withstand supraphysiological pressures, and can support cell attachment and growth with controlled structural cues under physiological strain conditions.

bioengineering↗

bioRxiv2021

Quantitative susceptibility mapping of carotid arterial tissue ex vivo: assessing sensitivity to vessel microstructural composition

PurposeTo characterise microstructural contributions to the magnetic susceptibility of carotid arteries. MethodArterial vessels were scanned using high resolution quantitative susceptibility mapping (QSM) at 7T. Models of vessel degradation were generated using ex vivo porcine carotid arteries that were subjected to several different enzymatic digestion treatments that selectively removed microstructural components (smooth muscle cells, collagen and elastin). Magnetic susceptibilities measured in these tissue models were compared to those in untreated (native) porcine arteries. Magnetic susceptibility measured in native porcine carotid arteries was further compared to the susceptibility of cadaveric human carotid arteries to investigate their similarity. ResultsThe magnetic susceptibility of native porcine vessels was diamagnetic ([X]native = -0.1820ppm), with higher susceptibilities in all models of vessel degradation ([X]elastin degraded = -0.0163ppm; [X]collagen degraded = -0.1158ppm; [X]decellularised = -0.1379ppm; [X]fixed native = -0.2199ppm). Magnetic susceptibility was significantly higher in collagen degraded compared to native porcine vessels (Tukey-Kramer, p<0.01) and between elastin degraded and all other models (including native, Tukey-Kramer, p<0.001). The susceptibility of fixed healthy human arterial tissue was diamagnetic and no significant difference was found between fixed human and fixed porcine arterial tissue susceptibilities (ANOVA, p>0.05). ConclusionsMagnetic susceptibility measured using QSM is sensitive to the microstructural composition of arterial vessels - most notably to collagen. The similarity of human and porcine arterial tissue susceptibility values provides a solid basis for translational studies. As vessel microstructure becomes disrupted during the onset and progression of carotid atherosclerosis, QSM has the potential to provide a sensitive and specific marker of vessel disease.

bioengineering↗

bioRxiv2020

Diffusion tensor imaging and arterial tissue: establishing the influence of arterial tissue microstructure on fractional anisotropy, mean diffusivity and tractography

In this study we investigated the potential of diffusion tensor imaging (DTI) for providing insight into microstructural changes in arterial tissue by exploring the influence that cell, collagen and elastin content have on fractional anisotropy (FA), mean diffusivity (MD) and tractography. Five ex vivo porcine carotid artery models (n = 6 vessels each) - native, fixed native, collagen degraded, elastin degraded and decellularised - were developed to selectively remove components of arterial microstructure. Intact vessels were imaged at 7 T using a DTI protocol with b = 0 and 800 s/mm2 and 10 isotopically distributed directions. FA and MD values were evaluated in the medial layer of vessels and compared across tissue models. FA values measured in native and fixed native vessels were significantly higher (p<0.0001) than those in the elastin degraded and decellularised arteries. Collagen degraded vessels had a significantly higher (p<0.01) FA than elastin degraded and decellularised vessels. Native and fixed vessels had significantly lower (p<0.0001) MD values than elastin degraded, while the MD in decellularised arteries was significantly higher than that in both native (p<0.01) and fixed (p<0.005) tissue. Significantly lower (p<0.005) MD was measured in collagen degraded compared with the elastin degraded model. Tractography results yielded similar helically arranged tracts for native and collagen degraded vessels, whilst elastin degraded and decellularised vessels showed no consistent tracts. FA, MD and tractography were found to be highly sensitive to changes in the microstructural composition of arterial tissue, with cell content being a dominant source of the measured anisotropy in the vessel wall.

bioengineering↗