scholarly journals Acoustic Fabrication of Collagen–Fibronectin Composite Gels Accelerates Microtissue Formation

2020 ◽  
Vol 10 (8) ◽  
pp. 2907
Author(s):  
Emma G. Norris ◽  
Diane Dalecki ◽  
Denise C. Hocking
Keyword(s):  
Biological Activity ◽  
Collagen Fiber ◽  
Type I Collagen ◽  
Acoustic Energy ◽  
Type I ◽  
Composite Hydrogels ◽  
Composite Gels ◽  
Microfibril Assembly ◽  
Acoustic Exposure ◽  
Extracellular Matrix Interactions

Ultrasound can influence biological systems through several distinct acoustic mechanisms that can be manipulated by varying reaction conditions and acoustic exposure parameters. We recently reported a new ultrasound-based fabrication technology that exploits the ability of ultrasound to generate localized mechanical forces and thermal effects to control collagen fiber microstructure non-invasively. Exposing solutions of type I collagen to ultrasound during the period of microfibril assembly produced changes in collagen fiber structure and alignment, and increased the biological activity of the resultant collagen hydrogels. In the extracellular matrix, interactions between fibronectin and collagen fibrils influence the biological activity of both proteins. Thus, in the present study, we examined how addition of fibronectin to collagen solutions prior to ultrasound exposure affects protein organization and the biological activity of the composite hydrogels. Results indicate that ultrasound can alter the distribution of fibronectin within 3D hydrogels via thermal and non-thermal mechanisms to produce composite hydrogels that support accelerated microtissue formation. The use of acoustic energy to drive changes in protein conformation to functionalize biomaterials has much potential as a unique, non-invasive technology for tissue engineering and regenerative medicine.

scholarly journals Biologically active collagen-based scaffolds: advances in processing and characterization

2010 ◽  
Vol 368 (1917) ◽  
pp. 2123-2139 ◽  
Author(s):  
I. V. Yannas ◽  
D. S. Tzeranis ◽  
B. A. Harley ◽  
P. T. C. So
Keyword(s):  
Biological Activity ◽  
Pore Size ◽  
Type I Collagen ◽  
Biologically Active ◽  
Wound Contraction ◽  
Type I ◽  
Structural Determinants ◽  
Ligand Density ◽  
Freeze Dried ◽  
Recent Developments

A small number of type I collagen–glycosaminoglycan scaffolds (collagen–GAG scaffolds; CGSs) have unusual biological activity consisting primarily in inducing partial regeneration of organs in the adult mammal. Two of these are currently in use in a variety of clinical settings. CGSs appear to induce regeneration by blocking the adult healing response, following trauma, consisting of wound contraction and scar formation. Several structural determinants of biological activity have been identified, including ligands for binding of fibroblasts to the collagen surface, the mean pore size (which affects ligand density) and the degradation rate (which affects the duration of the wound contraction-blocking activity by the scaffold). Processing variables that affect these determinants include the kinetics of swelling of collagen fibres in acetic acid, freezing of the collagen–GAG suspension and cross-linking of the freeze-dried scaffold. Recent developments in the processing of CGSs include fabrication of scaffolds that are paucidisperse in pore size, scaffolds with gradients in physicochemical properties (and therefore biological activity) and scaffolds that incorporate a mineral component. Advances in the characterization of the pore structure of CGSs have been made using confocal and nonlinear optical microscopy (NLOM). The mechanical behaviour of CGSs, as well as the resistance to degradative enzymes, have been studied. Following seeding with cells (typically fibroblasts), contractile forces in the range 26–450 nN per cell are generated by the cells, leading to buckling of scaffold struts. Ongoing studies of cell-seeded CGSs with NLOM have shown an advantage over the use of confocal microscopy due to the ability of the former method to image the CGS surfaces without staining (which alters its surface ligands), reduced cell photodamage, reduced fluorophore photobleaching and the ability to image deeper inside the scaffold.

THE INFLUENCE OF THE ORIENTATION OF THE COLLAGEN DIPOLES ON SECOND HARMONIC GENERATION (SHG) WITH HIGH NA UNDER CRYSTALLIZED TYPE I COLLAGEN FIBER MODEL

2012 ◽  
Vol 26 (29) ◽  
pp. 1250148
Author(s):  
FEI FEI WANG ◽  
JIAN MEI LIU ◽  
XIAO YUAN DENG
Keyword(s):  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Collagen Fiber ◽  
Type I Collagen ◽  
Second Harmonic ◽  
Numerical Aperture ◽  
Orientation Angle ◽  
Type I ◽  
Dipole Orientation ◽  
First Time

In this paper, for the first time, we consider theoretically all the potential orientations of dipoles for second harmonic generation (SHG) under crystallized type I collagen fiber. With high numerical aperture ( NA = 14), the effect of dipole orientation angle Φ on the SHG intensity, on the maximum SHG emergence angles (θ max , φ max ) and the action of these dipole sources on the ratio of forward to backward (F/B) SHG have been studied under different cases of fibrils diameter d1 and the QPM order (m, l) in the crystallized collagen fiber, and it is found that the influential patterns of the same Φ on SHG at different fibrils diameter d1 and the QPM order (m, l) are different. The dipoles arrangement is related to the characteristic changes in biological tissue so that our work may provide a helpful theoretical tool for pathological status detecting.

scholarly journals Micromechanics of cellularized biopolymer networks

2015 ◽  
Vol 112 (37) ◽  
pp. E5117-E5122 ◽  
Author(s):  
Christopher A. R. Jones ◽  
Matthew Cibula ◽  
Jingchen Feng ◽  
Emma A. Krnacik ◽  
David H. McIntyre ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Optical Tweezers ◽  
Collagen Fiber ◽  
Type I Collagen ◽  
Qualitative Difference ◽  
Type I ◽  
Dependent Manner ◽  
Adhesion Forces ◽  
Collagen Gels ◽  
Fiber Network

Collagen gels are widely used in experiments on cell mechanics because they mimic the extracellular matrix in physiological conditions. Collagen gels are often characterized by their bulk rheology; however, variations in the collagen fiber microstructure and cell adhesion forces cause the mechanical properties to be inhomogeneous at the cellular scale. We study the mechanics of type I collagen on the scale of tens to hundreds of microns by using holographic optical tweezers to apply pN forces to microparticles embedded in the collagen fiber network. We find that in response to optical forces, particle displacements are inhomogeneous, anisotropic, and asymmetric. Gels prepared at 21 °C and 37 °C show qualitative difference in their micromechanical characteristics. We also demonstrate that contracting cells remodel the micromechanics of their surrounding extracellular matrix in a strain- and distance-dependent manner. To further understand the micromechanics of cellularized extracellular matrix, we have constructed a computational model which reproduces the main experiment findings.

Collagen-Agarose Co-Gels as a Model for Collagen-Matrix Interaction in Soft Tissue

2011 ◽  
Author(s):  
Spencer P. Lake ◽  
Sadie Doggett ◽  
Victor H. Barocas
Keyword(s):  
Collagen Fiber ◽  
Type I Collagen ◽  
Soft Tissues ◽  
Experimental System ◽  
Model System ◽  
Type I ◽  
Collagen Gels ◽  
Fiber Network ◽  
Fibrillar Material

Connective soft tissues have complex mechanical properties that are determined by their collagen fiber network and surrounding non-fibrillar material. The mechanical role of non-fibrillar material and the nature of its interaction with the collagen network remain poorly understood, in part because of the lack of a simple experimental model system to examine and quantify these properties. The development of a simple but representational experimental system will allow for greater insight into the interaction between fibers and the non-fibrillar matrix. Reconstituted Type I collagen gels are an attractive model tissue for exploring micro- and macroscale relationships between constituents (e.g., [1–2]), but standard collagen gels lack the non-fibrillar components (i.e., proteoglycan, minor collagens, etc.) present in native tissue. A recent study [3] added low quantities of agarose to collagen gels, which dramatically increased the shear storage modulus with minimal changes to the collagen fiber network. In this study, we suggest that collagen-agarose co-gels can serve as a model system to investigate the mechanical role of non-fibrillar ECM. Even though agarose is relatively compliant at low concentrations, and collagen fibers are very stiff in tension, we hypothesized that the presence of agarose in co-gels would have a pronounced effect on structural response and mechanical behavior in tensile loading. Therefore, the objective of this study was to examine the properties of collagen-agarose co-gels to understand better the nature of, and the relationships between, the collagen fiber network and non-fibrillar matrix of simplified tissue analogs.

Neotendon formation using a collagen fiber tendon prosthesis

1989 ◽  
Vol 47 ◽  
pp. 880-881
Author(s):  
Arthur J. Wasserman ◽  
Y. Pedro Kato ◽  
Don Ganim ◽  
Michael G. Dunn ◽  
Frederick H. Silver
Keyword(s):  
Collagen Fibril ◽  
Collagen Fiber ◽  
Type I Collagen ◽  
Tendon Repair ◽  
Type I ◽  
Synthetic Materials ◽  
Morphological Criteria ◽  
New Zealand White Rabbits ◽  
The Status ◽  
Fibril Diameter

Damage to tendons occurs commonly during physical activity. Tendons can be repaired using natural and synthetic materials. The purpose of a tendon prosthesis is to provide support while allowing a new tendon to form. The newly formed tendon should have morphological and mechanical properties identical to the normal tissue. Neotendon formation can be assessed ultrastructurally to compare its morphology with that of mature tendon. The extent of cell ingrowth, collagen fibril diameter, proteoglycan (PG)/collagen interactions and collagen fibril bundle formation are all morphological criteria to evaluate the status of tendon repair. The purpose of this study is to ultrastructurally evaluate the mechanism by which a reconstituted collagen fiber tow is replaced by neotendon.Collagen fibers of the tow were prepared from insoluble type I collagen derived from bovine corium and crosslinked by severe dehydration followed by treatment with cyanamide, as previously described. A tow of 250 fibers was coated with a 1% type I collagen dispersion to form a thin ribbon prosthesis. Mature New Zealand white rabbits weighing 6-7 lbs were anesthetized and the Achilles tendon was removed and replaced with a sterile collagen fiber tow. At 3 and 10 weeks postoperatively the explants were fixed for conventional TEM and SEM as previously described.

Production of a Novel, Self-Assembled, Collagenous Matrix Mimicking the Hierarchical Structure of Native Aligned Connective Tissue

1995 ◽  
Vol 414 ◽  
Author(s):  
G. D. Pins ◽  
D. L. Christiansen ◽  
R. Patel ◽  
F. H. Silver
Keyword(s):  
Self Assembly ◽  
Collagen Fiber ◽  
Type I Collagen ◽  
Tensile Tests ◽  
Fiber Formation ◽  
Morphological Properties ◽  
Uniaxial Tensile ◽  
Type I ◽  
Native Collagen

AbstractThe primary goal of the biomaterials scientist and tissue engineer is to create a biocompatible implant which mimics the mechanical and morphological properties of the tissue being replaced. In vitro experimentation has documented the propensity of soluble type I collagen to self-assemble and form microscopic collagen fibrils with periodic banding analogous to native collagen fiber. Our laboratory has further investigated in vitro self-assembly by incorporating several of the “natural” processes into a multi-step fiber formation procedure which generates macroscopic collagen fiber from its molecular constituents. Results of uniaxial tensile tests and ultrastructural analyses indicate that these coextruded and stretched collagen fibers have mechanical properties and fibrillar substructure comparable to that observed in native collagen fiber.

scholarly journals Second harmonic generation light quantifies the ratio of type III to total (I + III) collagen in a bundle of collagen fiber

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shukei Sugita ◽  
Takuya Suzumura ◽  
Akinobu Nakamura ◽  
Shinya Tsukiji ◽  
Yoshihiro Ujihara ◽  
...  
Keyword(s):  
Light Intensity ◽  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Fiber Bundle ◽  
Collagen Fiber ◽  
Type I Collagen ◽  
Second Harmonic ◽  
Type I ◽  
Type Iii ◽  
The Relationship

AbstractThe ratio of type III to type I collagen is important for properly maintaining functions of organs and cells. We propose a method to quantify the ratio of type III to total (type I + III) collagen (λIII) in a given collagen fiber bundle using second harmonic generation (SHG) light. First, the relationship between SHG light intensity and the λIII of collagen gels was examined, and the slope (k1) and SHG light intensity at 0% type III collagen (k2) were determined. Second, the SHG light intensity of a 100% type I collagen fiber bundle and its diameter (D) were measured, and the slope (k3) of the relationship was determined. The λIII in a collagen fiber bundle was estimated from these constants (k1-3) and SHG light intensity. We applied this method to collagen fiber bundles isolated from the media and adventitia of porcine thoracic aortas, and obtained λIII = 84.7% ± 13.8% and λIII = 17.5% ± 15.2%, respectively. These values concurred with those obtained with a typical quantification method using sodium dodecyl sulfate–polyacrylamide gel electrophoresis. The findings demonstrated that the method proposed is useful to quantify the ratio of type III to total collagen in a collagen fiber bundle.

Cartilage proteoglycan aggregate and fibronectin can modulate the expression of type X collagen by embryonic chick chondrocytes cultured in collagen gels

1988 ◽  
Vol 8 (2) ◽  
pp. 163-171 ◽  
Author(s):  
J. Terrig Thomas ◽  
Michael E. Grant
Keyword(s):  
Type I Collagen ◽  
Normal Serum ◽  
Type I ◽  
Collagen Gels ◽  
Type X Collagen ◽  
Caudal Region ◽  
Composite Gels ◽  
Cartilage Proteoglycan ◽  
Extracellular Matrix Components ◽  
Stimulation Of

Chick embryo sternal chondrocytes from the caudal and cephalic regions were cultured within type I collagen gels and type I collagen/proteoglycan aggregate composite gels in normal serum. Caudal region chondrocytes were also cultured within type I collagen gels in the presence of fibronectindepleted serum. There was a marked stimulation of type X collagen synthesis by the caudal region chondrocytes after 9 days in the presence of fibronectin-depleted serum and after 14 days in the presence of proteoglycan aggregate. These results provide evidence for the ability of chondrocytes from a zone of permanent cartilage to synthesise type X collagen and for the involvement of extracellular matrix components in the control of type X collagen gene expression.

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