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Ayyalasomayajula V, Pierrat B, Badel P. Evaluation of a multi-scale discrete fiber model for analyzing arterial failure. J Biomech 2023; 157:111700. [PMID: 37478803 DOI: 10.1016/j.jbiomech.2023.111700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 04/18/2023] [Accepted: 06/22/2023] [Indexed: 07/23/2023]
Abstract
So far, the prevalent rupture risk quantification of aortic aneurysms does not consider information of the underlying microscopic mechanisms. Uniaxial tension tests were performed on imaged aorta samples oriented in circumferential and longitudinal directions. To account for local heterogeneity in collagen fiber architecture, SHG imaging was performed on tissues at several locations prior to mechanical testing. This enabled the quantification of micro-scale information including organization of collagen fibers using relevant probability density functions. Two different modeling approaches are presented in this study for the sake of comparison. A multi-scale mechanical model was developed using this micro-structural information with collagen fibers as main components. accounting for non-affine fiber kinematics. Simultaneously, an embedded element model that accounts for affine fiber kinematics was developed in Abaqus using the same micro-structural information. Numerical simulations emulating uniaxial tension experiments were performed on the developed models. Global mechanical response of both models agreed well with the experimental data, although leading to mismatched material properties. The models present a rudimentary yet better than before representation of structure based description of aortic-tissue failure mechanics. reinforcing the importance of structural organization of micro-scale constituents and their kinematics in determining tissue failure.
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Affiliation(s)
- Venkat Ayyalasomayajula
- Department of Structural Engineering, Norwegian University of Science and Technology, Trondheim, 7052, Norway.
| | - Baptiste Pierrat
- Mines Saint-Étienne, CIS-EMSE, F-42023 Saint-Étienne, France; INSERM, U1059, SAINBIOSE, F-42023 Saint-Étienne, France; Université de Lyon, F-69000 Lyon, France
| | - Pierre Badel
- Mines Saint-Étienne, CIS-EMSE, F-42023 Saint-Étienne, France; INSERM, U1059, SAINBIOSE, F-42023 Saint-Étienne, France; Université de Lyon, F-69000 Lyon, France
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Ayyalasomayajula V, Pierrat B, Badel P. A computational model for understanding the micro-mechanics of collagen fiber network in the tunica adventitia. Biomech Model Mechanobiol 2019; 18:1507-1528. [PMID: 31065952 PMCID: PMC6748894 DOI: 10.1007/s10237-019-01161-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 04/26/2019] [Indexed: 12/11/2022]
Abstract
Abdominal aortic aneurysm is a prevalent cardiovascular disease with high mortality rates. The mechanical response of the arterial wall relies on the organizational and structural behavior of its microstructural components, and thus, a detailed understanding of the microscopic mechanical response of the arterial wall layers at loads ranging up to rupture is necessary to improve diagnostic techniques and possibly treatments. Following the common notion that adventitia is the ultimate barrier at loads close to rupture, in the present study, a finite element model of adventitial collagen network was developed to study the mechanical state at the fiber level under uniaxial loading. Image stacks of the rabbit carotid adventitial tissue at rest and under uniaxial tension obtained using multi-photon microscopy were used in this study, as well as the force-displacement curves obtained from previously published experiments. Morphological parameters like fiber orientation distribution, waviness, and volume fraction were extracted for one sample from the confocal image stacks. An inverse random sampling approach combined with a random walk algorithm was employed to reconstruct the collagen network for numerical simulation. The model was then verified using experimental stress-stretch curves. The model shows the remarkable capacity of collagen fibers to uncrimp and reorient in the loading direction. These results further show that at high stretches, collagen network behaves in a highly non-affine manner, which was quantified for each sample. A comprehensive parameter study to understand the relationship between structural parameters and their influence on mechanical behavior is presented. Through this study, the model was used to conclude important structure-function relationships that control the mechanical response. Our results also show that at loads close to rupture, the probability of failure occurring at the fiber level is up to 2%. Uncertainties in usually employed rupture risk indicators and the stochastic nature of the event of rupture combined with limited knowledge on the microscopic determinants motivate the development of such an analysis. Moreover, this study will advance the study of coupling microscopic mechanisms to rupture of the artery as a whole.
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Affiliation(s)
- Venkat Ayyalasomayajula
- Mines Saint-Étienne, Univ Lyon, Univ Jean Monnet, INSERM, U1059 SAINBIOSE, Centre CIS, 42023, Saint-Étienne, France.
| | - Baptiste Pierrat
- Mines Saint-Étienne, Univ Lyon, Univ Jean Monnet, INSERM, U1059 SAINBIOSE, Centre CIS, 42023, Saint-Étienne, France
| | - Pierre Badel
- Mines Saint-Étienne, Univ Lyon, Univ Jean Monnet, INSERM, U1059 SAINBIOSE, Centre CIS, 42023, Saint-Étienne, France
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Veri N, As E, Mutiah C, Seriana I, Malinda R. Protective effect of green tea on tunica adventitia and endothelial changes resulting from depot medroxy progesterone acetate. J Taibah Univ Med Sci 2019; 14:8-13. [PMID: 31435385 PMCID: PMC6694920 DOI: 10.1016/j.jtumed.2018.10.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 10/16/2018] [Accepted: 10/18/2018] [Indexed: 11/29/2022] Open
Abstract
Objective This study aimed to analyse the effects of green tea in inhibiting uterine atrophy and vascular changes due to the use of depot medroxy progesterone acetate (DMPA). Methods Twenty-five female Wistar rats aged one to two months were randomly assigned to five treatment groups: control group, DMPA-induced group, and DMPA-induced group orally treated with green tea extract (at 10.8 mg/day, 21.6 mg/day, or 43.2 mg/day). Histologic analysis of uterine and vascular tissues was performed with haematoxylin-eosin staining. Results DMPA decreased the thickness of endometrium and tunica adventitia, as well as significantly decreased endothelial cell count (p < 0.05). DMPA-induced decreases in the thickness of tunica adventitia and endothelial cell count could be significantly inhibited by green tea extract (p < 0.05). Conclusion This study concluded that DMPA triggered the depletion of uterine endometrium and vascular tunica adventitia and decreased endothelial cell count. Green tea extract at the highest dose normalized tunica adventitia and endothelial changes to the basal value.
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Affiliation(s)
- Nora Veri
- Midwifery Study Program, Ministry of Health Polytechnic of Langsa, Aceh, Special Region of Aceh, Indonesia
| | - Emilda As
- Midwifery Study Program, Ministry of Health Polytechnic of Langsa, Aceh, Special Region of Aceh, Indonesia
| | - Cut Mutiah
- Midwifery Study Program, Ministry of Health Polytechnic of Langsa, Aceh, Special Region of Aceh, Indonesia
| | - Irma Seriana
- Department of Midwifery, Polytechnic of Health-Ministry of Health, Aceh, Indonesia
| | - Risnati Malinda
- STIKES Bustanul Ulum of Langsa, Aceh, Special Region of Aceh, Indonesia
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Abstract
Besides seminal functions in angiogenesis and blood pressure regulation, microvascular pericytes possess a latent tissue regenerative potential that can be revealed in culture following transition into mesenchymal stem cells. Endowed with robust osteogenic potential, pericytes and other related perivascular cells extracted from adipose tissue represent a potent and abundant cell source for refined bone tissue engineering and improved cell therapies of fractures and other bone defects. The use of diverse bone formation assays in vivo, which include mouse muscle pocket osteogenesis and calvaria replenishment, rat and dog spine fusion, and rat non-union fracture healing, has confirmed the superiority of purified perivascular cells for skeletal (re)generation. As a surprising observation though, despite strong endogenous bone-forming potential, perivascular cells drive bone regeneration essentially indirectly, via recruitment by secreted factors of local osteo-progenitors.
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Abstract
Though the composition of the three layers constituting the blood vessel wall varies among the different types of blood vessels, and some layers may even be missing in capillaries, certain basic components, and properties are shared by all blood vessels, though each histologically distinct layer contains a unique complement of extracellular components, growth factors and cytokines, and cell types as well. The structure and composition of vessel layers informs and is informed by the function of the particular blood vessel. The adaptation of the composition and the resulting function of the extracellular matrix (ECM) to changes in circulation/blood flow and a variety of other extravascular stimuli can be characterized as remodeling spearheaded by vascular cells. There is a surprising amount of cell traffic among the three layers. It starts with endothelial cell mediated transmigration of inflammatory cells from the bloodstream into the subendothelium, and then into tissue adjoining the blood vessel. Smooth muscle cells and a variety of adventitial cells reside in tunica media and tunica externa, respectively. The latter cells are a mixture of progenitor/stem cells, fibroblasts, myofibroblasts, pericytes, macrophages, and dendritic cells and respond to endothelial injury by transdifferentiation as they travel into the two inner layers, intima and media for corrective mission in the ECM composition. This chapter addresses the role of various vascular cell types and ECM components synthesized by them in maintenance of normal structure and in their contribution to major pathological processes, such as atherosclerosis, organ fibrosis, and diabetic retinopathy.
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Affiliation(s)
- Jaroslava Halper
- College of Veterinary Medicine and AU/UGA Medical Partnership, The University of Georgia, Athens, GA, United States.
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West CC, Hardy WR, Murray IR, James AW, Corselli M, Pang S, Black C, Lobo SE, Sukhija K, Liang P, Lagishetty V, Hay DC, March KL, Ting K, Soo C, Péault B. Prospective purification of perivascular presumptive mesenchymal stem cells from human adipose tissue: process optimization and cell population metrics across a large cohort of diverse demographics. Stem Cell Res Ther 2016; 7:47. [PMID: 27029948 PMCID: PMC4815276 DOI: 10.1186/s13287-016-0302-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 07/18/2015] [Accepted: 03/01/2016] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Adipose tissue is an attractive source of mesenchymal stem cells (MSC) as it is largely dispensable and readily accessible through minimally invasive procedures such as liposuction. Until recently MSC could only be isolated in a process involving ex-vivo culture and their in-vivo identity, location and frequency remained elusive. We have documented that pericytes (CD45-, CD146+, and CD34-) and adventitial cells (CD45-, CD146-, CD34+) (collectively termed perivascular stem cells or PSC) represent native ancestors of the MSC, and can be prospectively purified using fluorescence activated cell sorting (FACS). In this study we describe an optimized protocol that aims to deliver pure, viable and consistent yields of PSC from adipose tissue. We analysed the frequency of PSC within adipose tissue, and the effect of patient and procedure based variables on this yield. METHODS Within this twin centre study we analysed the adipose tissue of n = 131 donors using flow cytometry to determine the frequency of PSC and correlate this with demographic and processing data such as age, sex, BMI and cold storage time of the tissue. RESULTS The mean number of stromal vascular fraction (SVF) cells from 100 ml of lipoaspirate was 34.4 million. Within the SVF, mean cell viability was 83 %, with 31.6 % of cells being haematopoietic (CD45+). Adventitial cells and pericytes represented 33.0 % and 8 % of SVF cells respectively. Therefore, a 200 ml lipoaspirate would theoretically yield 23.2 million viable prospectively purified PSC - sufficient for many reconstructive and regenerative applications. Minimal changes were observed in respect to age, sex and BMI suggesting universal potential application. CONCLUSIONS Adipose tissue contains two anatomically and phenotypically discreet populations of MSC precursors - adventitial cells and pericytes - together referred to as perivascular stem cells (PSC). More than 9 million PSC per 100 ml of lipoaspirate can be rapidly purified to homogeneity using flow cytometry in clinically relevant numbers potentially circumventing the need for purification and expansion by culture prior to clinical use. The number and viability of PSC are minimally affected by patient age, sex, BMI or the storage time of the tissue, but the quality and consistency of yield can be significantly influenced by procedure based variables.
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Affiliation(s)
- C. C. West
- British Heart Foundation Centre for Vascular Regeneration & Medical Research Council Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, UK
- Department of Plastic and Reconstructive Surgery, St Johns Hospital, Howden Road West, Livingston, UK
| | - W. R. Hardy
- Orthopaedic Hospital Department of Orthopaedic Surgery and the Orthopaedic Hospital Research Center, University of California, Los Angeles, CA USA
| | - I. R. Murray
- British Heart Foundation Centre for Vascular Regeneration & Medical Research Council Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, UK
| | - A. W. James
- Orthopaedic Hospital Department of Orthopaedic Surgery and the Orthopaedic Hospital Research Center, University of California, Los Angeles, CA USA
| | - M. Corselli
- Orthopaedic Hospital Department of Orthopaedic Surgery and the Orthopaedic Hospital Research Center, University of California, Los Angeles, CA USA
- BD Biosciences, San Diego, CA USA
| | - S. Pang
- Orthopaedic Hospital Department of Orthopaedic Surgery and the Orthopaedic Hospital Research Center, University of California, Los Angeles, CA USA
| | - C. Black
- Orthopaedic Hospital Department of Orthopaedic Surgery and the Orthopaedic Hospital Research Center, University of California, Los Angeles, CA USA
- Bone and Joint Research Group, Institute of Developmental Sciences, University of Southampton, Southampton, UK
| | - S. E. Lobo
- Orthopaedic Hospital Department of Orthopaedic Surgery and the Orthopaedic Hospital Research Center, University of California, Los Angeles, CA USA
- Department of Surgery, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil
| | - K. Sukhija
- Orthopaedic Hospital Department of Orthopaedic Surgery and the Orthopaedic Hospital Research Center, University of California, Los Angeles, CA USA
- Department of Emergency Medicine, Kaweah Delta Health Care District, Visalia, CA USA
| | - P. Liang
- Orthopaedic Hospital Department of Orthopaedic Surgery and the Orthopaedic Hospital Research Center, University of California, Los Angeles, CA USA
- Department of Urology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA USA
| | - V. Lagishetty
- Orthopaedic Hospital Department of Orthopaedic Surgery and the Orthopaedic Hospital Research Center, University of California, Los Angeles, CA USA
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA USA
| | - D. C. Hay
- British Heart Foundation Centre for Vascular Regeneration & Medical Research Council Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, UK
| | - K. L. March
- Indiana Center for Vascular Biology and Medicine, Krannert Institute of Cardiology, and Vascular and Cardiac Center for Adult Stem Cell Research, Indiana University, Bloomington, IN USA
| | - K. Ting
- Orthopaedic Hospital Department of Orthopaedic Surgery and the Orthopaedic Hospital Research Center, University of California, Los Angeles, CA USA
- Division of Growth and Development and Section of Orthodontics, School of Dentistry, University of California, Los Angeles, CA 90095 USA
| | - C. Soo
- Orthopaedic Hospital Department of Orthopaedic Surgery and the Orthopaedic Hospital Research Center, University of California, Los Angeles, CA USA
- Division of Plastic and Reconstructive Surgery, Department of Surgery and the Orthopaedic Hospital Research Center, University of California, Los Angeles, CA 90095 USA
- Department of Orthopaedic Surgery and the Orthopaedic Hospital Research Center, University of California, Los Angeles, CA 90095 USA
| | - B. Péault
- British Heart Foundation Centre for Vascular Regeneration & Medical Research Council Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, UK
- Orthopaedic Hospital Department of Orthopaedic Surgery and the Orthopaedic Hospital Research Center, University of California, Los Angeles, CA USA
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