scholarly journals Degradation and erosion mechanisms of bioresorbable porous acellular vascular grafts: an in vitro investigation

2017 ◽  
Vol 14 (132) ◽  
pp. 20170102 ◽  
Author(s):  
Piyusha S. Gade ◽  
Keewon Lee ◽  
Blaise N. Pfaff ◽  
Yadong Wang ◽  
Anne M. Robertson
Keyword(s):  
Mechanical Properties ◽  
Mass Loss ◽  
Mechanistic Model ◽  
Vascular Grafts ◽  
Damage Function ◽  
Surface Erosion ◽  
Outer Diameter ◽  
In Vitro Investigation

A fundamental mechanism of in situ tissue regeneration from biodegradable synthetic acellular vascular grafts is the effective interplay between graft degradation, erosion and the production of extracellular matrix. In order to understand this crucial process of graft erosion and degradation, we conducted an in vitro investigation of grafts ( n = 4 at days 1, 4, 7, 10 each) exposed to enzymatic degradation. Herein, we provide constitutive relationships for mass loss and mechanical properties based on much-needed experimental data. Furthermore, we formulate a mathematical model to provide a physics-based framework for understanding graft erosion. A novel finding is that despite their porous nature, grafts lost mass exponentially via surface erosion demonstrating a 20% reduction in outer diameter and no significant change in apparent density. A diffusion based, concentration gradient-driven mechanistic model of mass loss through surface erosion was introduced which can be extended to an in vivo setting through the use of two degradation parameters. Furthermore, notably, mechanical properties of degrading grafts did not scale with mass loss. Thus, we introduced a damage function scaling a neo-Hookean model to describe mechanical properties of the degrading graft; a refinement to existing mass-dependent growth and remodelling (G&R) models. This framework can be used to improve accuracy of well-established G&R theories in biomechanics; tools that predict evolving structure–function relationships of neotissues and guide graft design.

IN VITRO AND IN VIVO DEGRADATION OF A TWISTED SILK FIBROIN–POLY(LACTIC-CO-GLYCOLIC ACID) FIBER COMPOSITE ROPE-LIKE SCAFFOLD AND CHANGES IN ITS MECHANICAL PROPERTIES

2016 ◽  
Vol 16 (04) ◽  
pp. 1650053
Author(s):  
WENYUAN ZHANG ◽  
YADONG YANG ◽  
KEJI ZHANG ◽  
YING LI ◽  
GUOJIAN FANG
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Tissue Engineering ◽  
Mass Loss ◽  
Silk Fibroin ◽  
Glycolic Acid ◽  
Property Loss ◽  
In Vivo Degradation

Natural silk fibroin fiber is slowly degraded, which makes it difficult to be replaced quickly by regenerating tissues of tissue engineering. We used poly(lactic-co-glycolic acid) (PLGA, lactic acid:glycolic acid [Formula: see text] 10:90) fibers to adjust the overall degradation rate of the scaffolds. This study fabricated a three-strand helical composite rope-like scaffold from silk fibroin and PLGA fibers (silk fibroin:PLGA [Formula: see text] 36:64) using a twisting method. In vitro and in vivo degradation experiments were performed over 16 weeks. Results suggest that the in vitro and in vivo degradation tendencies of the scaffold were similar, with mass loss lagging behind mechanical property loss. The speed of degradation in vivo was faster than that in vitro. Mechanical property loss of the scaffold was fast during the first three weeks, when mass loss was slow. Mass loss rate accelerated from weeks 3 to 8. The mass and mechanical properties were relatively stable from 8 to 16 weeks. After 16 weeks of degradation, the scaffold still had considerably strong mechanical properties. The scaffold showed a reasonable and suitable degradation speed with good histocompatibility for ligament tissue engineering.

Small diameter electrospun silk fibroin vascular grafts: Mechanical properties, in vitro biodegradability, and in vivo biocompatibility

2015 ◽  
Vol 54 ◽  
pp. 101-111 ◽  
Author(s):  
Valentina Catto ◽  
Silvia Farè ◽  
Irene Cattaneo ◽  
Marina Figliuzzi ◽  
Antonio Alessandrino ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Silk Fibroin ◽  
Vascular Grafts ◽  
Small Diameter

Surface Modification by Nanobiomaterials for Vascular Tissue Engineering Applications

2020 ◽  
Vol 27 (10) ◽  
pp. 1634-1646 ◽  
Author(s):  
Huey-Shan Hung ◽  
Shan-hui Hsu
Keyword(s):  
Tissue Engineering ◽  
Vascular Tissue ◽  
Thrombus Formation ◽  
Vascular Grafts ◽  
Vascular Tissue Engineering ◽  
Great Success ◽  
Natural Polymers ◽  
Vascular Biomaterials

Treatment of cardiovascular disease has achieved great success using artificial implants, particularly synthetic-polymer made grafts. However, thrombus formation and restenosis are the current clinical problems need to be conquered. New biomaterials, modifying the surface of synthetic vascular grafts, have been created to improve long-term patency for the better hemocompatibility. The vascular biomaterials can be fabricated from synthetic or natural polymers for vascular tissue engineering. Stem cells can be seeded by different techniques into tissue-engineered vascular grafts in vitro and implanted in vivo to repair the vascular tissues. To overcome the thrombogenesis and promote the endothelialization effect, vascular biomaterials employing nanotopography are more bio-mimic to the native tissue made and have been engineered by various approaches such as prepared as a simple surface coating on the vascular biomaterials. It has now become an important and interesting field to find novel approaches to better endothelization of vascular biomaterials. In this article, we focus to review the techniques with better potential improving endothelization and summarize for vascular biomaterial application. This review article will enable the development of biomaterials with a high degree of originality, innovative research on novel techniques for surface fabrication for vascular biomaterials application.

scholarly journals The impact of indole-3-lactic acid on immature intestinal innate immunity and development: a transcriptomic analysis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Wuyang Huang ◽  
Ky Young Cho ◽  
Di Meng ◽  
W. Allan Walker
Keyword(s):  
Lactic Acid ◽  
Mechanistic Model ◽  
Transcriptomic Analysis ◽  
Dependent Manner ◽  
Protective Effects ◽  
Very Preterm Infants ◽  
Anti Inflammatory ◽  
The Impact

AbstractAn excessive intestinal inflammatory response may have a role in the pathogenesis of necrotizing enterocolitis (NEC) in very preterm infants. Indole-3-lactic acid (ILA) of breastmilk tryptophan was identified as the anti-inflammatory metabolite involved in probiotic conditioned media from Bifidobacteria longum subsp infantis. This study aimed to explore the molecular endocytic pathways involved in the protective ILA effect against inflammation. H4 cells, Caco-2 cells, C57BL/6 pup and adult mice were used to compare the anti-inflammatory mechanisms between immature and mature enterocytes in vitro and in vivo. The results show that ILA has pleiotropic protective effects on immature enterocytes including anti-inflammatory, anti-viral, and developmental regulatory potentials in a region-dependent and an age-dependent manner. Quantitative transcriptomic analysis revealed a new mechanistic model in which STAT1 pathways play an important role in IL-1β-induced inflammation and ILA has a regulatory effect on STAT1 pathways. These studies were validated by real-time RT-qPCR and STAT1 inhibitor experiments. Different protective reactions of ILA between immature and mature enterocytes indicated that ILA’s effects are developmentally regulated. These findings may be helpful in preventing NEC for premature infants.

scholarly journals Injectable non-leaching tissue-mimetic bottlebrush elastomers as an advanced platform for reconstructive surgery

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Erfan Dashtimoghadam ◽  
Farahnaz Fahimipour ◽  
Andrew N. Keith ◽  
Foad Vashahi ◽  
Pavel Popryadukhin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Reconstructive Surgery ◽  
Biomedical Applications ◽  
The Body ◽  
Surrounding Tissue ◽  
Curing Time ◽  
Materials Used ◽  
Significant Health

AbstractCurrent materials used in biomedical devices do not match tissue’s mechanical properties and leach various chemicals into the body. These deficiencies pose significant health risks that are further exacerbated by invasive implantation procedures. Herein, we leverage the brush-like polymer architecture to design and administer minimally invasive injectable elastomers that cure in vivo into leachable-free implants with mechanical properties matching the surrounding tissue. This strategy allows tuning curing time from minutes to hours, which empowers a broad range of biomedical applications from rapid wound sealing to time-intensive reconstructive surgery. These injectable elastomers support in vitro cell proliferation, while also demonstrating in vivo implant integrity with a mild inflammatory response and minimal fibrotic encapsulation.

scholarly journals Zn-Containing Membranes for Guided Bone Regeneration in Dentistry

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1797
Author(s):  
Manuel Toledano ◽  
Marta Vallecillo-Rivas ◽  
María T. Osorio ◽  
Esther Muñoz-Soto ◽  
Manuel Toledano-Osorio ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Bone Regeneration ◽  
Bone Healing ◽  
Bone Repair ◽  
Complex Modulus ◽  
Bacterial Colonization ◽  
Guided Bone Regeneration ◽  
M2 Macrophage

Barrier membranes are employed in guided bone regeneration (GBR) to facilitate bone in-growth. A bioactive and biomimetic Zn-doped membrane with the ability to participate in bone healing and regeneration is necessary. The aim of the present study is to state the effect of doping the membranes for GBR with zinc compounds in the improvement of bone regeneration. A literature search was conducted using electronic databases, such as PubMed, MEDLINE, DIMDI, Embase, Scopus and Web of Science. A narrative exploratory review was undertaken, focusing on the antibacterial effects, physicochemical and biological properties of Zn-loaded membranes. Bioactivity, bone formation and cytotoxicity were analyzed. Microstructure and mechanical properties of these membranes were also determined. Zn-doped membranes have inhibited in vivo and in vitro bacterial colonization. Zn-alloy and Zn-doped membranes attained good biocompatibility and were found to be non-toxic to cells. The Zn-doped matrices showed feasible mechanical properties, such as flexibility, strength, complex modulus and tan delta. Zn incorporation in polymeric membranes provided the highest regenerative efficiency for bone healing in experimental animals, potentiating osteogenesis, angiogenesis, biological activity and a balanced remodeling. Zn-loaded membranes doped with SiO2 nanoparticles have performed as bioactive modulators provoking an M2 macrophage increase and are a potential biomaterial for promoting bone repair. Zn-doped membranes have promoted pro-healing phenotypes.

scholarly journals Fibronectin Adsorption on Electrospun Synthetic Vascular Grafts Attracts Endothelial Progenitor Cells and Promotes Endothelialization in Dynamic In Vitro Culture

Cells ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 778 ◽  
Author(s):  
Ruben Daum ◽  
Dmitri Visser ◽  
Constanze Wild ◽  
Larysa Kutuzova ◽  
Maria Schneider ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cell Activation ◽  
Vascular Endothelial Cells ◽  
Endothelial Progenitor ◽  
Advanced Therapy Medicinal Product ◽  
Endothelial Colony Forming Cells ◽  
Advanced Therapy ◽  
Custom Made

Appropriate mechanical properties and fast endothelialization of synthetic grafts are key to ensure long-term functionality of implants. We used a newly developed biostable polyurethane elastomer (TPCU) to engineer electrospun vascular scaffolds with promising mechanical properties (E-modulus: 4.8 ± 0.6 MPa, burst pressure: 3326 ± 78 mmHg), which were biofunctionalized with fibronectin (FN) and decorin (DCN). Neither uncoated nor biofunctionalized TPCU scaffolds induced major adverse immune responses except for minor signs of polymorph nuclear cell activation. The in vivo endothelial progenitor cell homing potential of the biofunctionalized scaffolds was simulated in vitro by attracting endothelial colony-forming cells (ECFCs). Although DCN coating did attract ECFCs in combination with FN (FN + DCN), DCN-coated TPCU scaffolds showed a cell-repellent effect in the absence of FN. In a tissue-engineering approach, the electrospun and biofunctionalized tubular grafts were cultured with primary-isolated vascular endothelial cells in a custom-made bioreactor under dynamic conditions with the aim to engineer an advanced therapy medicinal product. Both FN and FN + DCN functionalization supported the formation of a confluent and functional endothelial layer.

scholarly journals Review: Tissue Engineering of Small-Diameter Vascular Grafts and Their In Vivo Evaluation in Large Animals and Humans

Cells ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 713
Author(s):  
Shu Fang ◽  
Ditte Gry Ellman ◽  
Ditte Caroline Andersen
Keyword(s):  
Animal Models ◽  
Vascular Grafts ◽  
Small Diameter ◽  
Large Animal ◽  
Large Animal Models ◽  
Graft Outcome ◽  
Limited Success ◽  
Large Animals

To date, a wide range of materials, from synthetic to natural or a mixture of these, has been explored, modified, and examined as small-diameter tissue-engineered vascular grafts (SD-TEVGs) for tissue regeneration either in vitro or in vivo. However, very limited success has been achieved due to mechanical failure, thrombogenicity or intimal hyperplasia, and improvements of the SD-TEVG design are thus required. Here, in vivo studies investigating novel and relative long (10 times of the inner diameter) SD-TEVGs in large animal models and humans are identified and discussed, with emphasis on graft outcome based on model- and graft-related conditions. Only a few types of synthetic polymer-based SD-TEVGs have been evaluated in large-animal models and reflect limited success. However, some polymers, such as polycaprolactone (PCL), show favorable biocompatibility and potential to be further modified and improved in the form of hybrid grafts. Natural polymer- and cell-secreted extracellular matrix (ECM)-based SD-TEVGs tested in large animals still fail due to a weak strength or thrombogenicity. Similarly, native ECM-based SD-TEVGs and in-vitro-developed hybrid SD-TEVGs that contain xenogeneic molecules or matrix seem related to a harmful graft outcome. In contrast, allogeneic native ECM-based SD-TEVGs, in-vitro-developed hybrid SD-TEVGs with allogeneic banked human cells or isolated autologous stem cells, and in-body tissue architecture (IBTA)-based SD-TEVGs seem to be promising for the future, since they are suitable in dimension, mechanical strength, biocompatibility, and availability.

In Vitro and In Vivo Degradation, Mechanical Properties, and Histocompatibility of Weft-Knitted Silk Mesh-Like Grafts

2022 ◽  
Vol 12 (2) ◽  
pp. 411-416
Author(s):  
Liang Tang ◽  
Si-Yu Zhao ◽  
Ya-Dong Yang ◽  
Geng Yang ◽  
Wen-Yuan Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Simulated Body Fluid ◽  
Body Fluid ◽  
Degradation Rate ◽  
Maximum Load ◽  
Artificial Ligament ◽  
In Vivo Degradation

To investigate the degradation, mechanical properties, and histocompatibility of weft-knitted silk mesh-like grafts, we carried out the In Vitro and In Vivo silk grafts degradation assay. The In Vitro degradation experiment was performed by immersing the silk grafts in simulated body fluid for 1 year, and the results showed that the degradation rate of the silk mesh-like grafts was very slow, and there were few changes in the mechanical properties and quality of the silk mesh-like graft. In Vivo degradation assay was taken by implantation of the silk mesh-like grafts into the subcutaneous muscles of rabbits. At 3, 6, and 12 months postoperation, the rate of mass loss was 19.36%, 31.84%, and 58.77%, respectively, and the maximum load was 63.85%, 34.63%, and 10.76%, respectively of that prior to degradation. The results showed that the degradation rate of the silk graft and the loss of mechanical properties In Vivo were faster than the results obtained in the In Vitro experiments. In addition, there were no significant differences in secretion of serum IL-6 and TNF-α between the experimental and normal rabbits (P >0.05), suggesting no obvious inflammatory reaction. The findings suggest that the weft-knitted silk mesh-like grafts have good mechanical properties, histocompatibility, and In Vivo degradation rate, and therefore represent a candidate material for artificial ligament

Effects of Cyclic Stress on the Mechanical Properties of Cultured Collagen Fascicles from the Rabbit Patellar Tendon

2003 ◽  
Vol 125 (6) ◽  
pp. 893-901 ◽  
Author(s):  
Ei Yamamoto ◽  
Susumu Tokura ◽  
Kozaburo Hayashi
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Patellar Tendon ◽  
Control Level ◽  
Quadratic Function ◽  
Peak Stress ◽  
Cyclic Stress ◽  
Original Strength

Effects of cyclic stress on the mechanical properties of collagen fascicles were studied by in vitro tissue culture experiments. Collagen fascicles (approximately 300 μm in diameter) obtained from the rabbit patellar tendon were applied cyclic load at 4 Hz for one hour per day during culture period for one or two weeks, and then their mechanical properties were determined using a micro-tensile tester. There was a statistically significant correlation between tensile strength and applied peak stress in the range of 0 to 5 MPa, and the relation was expressed by a quadratic function. The maximum strength (19.4 MPa) was obtained at the applied peak stress of 1.8 MPa. The tensile strength of fascicles were within a range of control values, if they were cultured under peak stresses between 1.1 and 2.6 MPa. Similar results were also observed in the tangent modulus, which was maintained at control level under applied peak stresses between 0.9 and 2.8 MPa. The stress of 0.9 to 1.1 MPa is equivalent to approximately 40% of the in vivo peak stress which is developed in the intact rabbit patellar tendon by running, whereas that of 2.6 to 2.8 MPa corresponds to approximately 120% of the in vivo peak stress. Therefore, the fascicles cultured under applied peak stresses of lower than 40% and higher than 120% of the in vivo peak stress do not keep the original strength and modulus. These results indicate that the mechanical properties of cultured collagen fascicles strongly depend upon the magnitude of the stress applied during culture, which are similar to our previous results observed in stress-shielded and overstressed patellar tendons in vivo.

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