https://www.seas.upenn.edu/%7Edischer/pdfs/Cell_on_Gel-CELLpaper.pdf

Matrix elasticity directs stem cell lineage specification.

Gold, enigmatically represented by the target-like design of its ancient alchemical symbol, has been considered a mystical material of great value for centuries. Nanoscale particles of gold now command a great deal of attention for biomedical applications. Depending on their size, shape, degree of aggregation, and local environment, gold nanoparticles can appear red, blue, or other colors. These visible colors reflect the underlying coherent oscillations of conduction-band electrons (“plasmons”) upon irradiation with light of appropriate wavelengths. These plasmons underlie the intense absorption and elastic scattering of light, which in turn forms the basis for many biological sensing and imaging applications of gold nanoparticles. The brilliant elastic light-scattering properties of gold nanoparticles are sufficient to detect individual nanoparticles in a visible light microscope with ∼102 nm spatial resolution. Despite the great excitement about the potential uses of gold nanoparticles for medical diag...

Gold nanoparticles in biology: beyond toxicity to cellular imaging

Mechanical properties of the adventitia are largely determined by the organization of collagen fibers. Measurements on the waviness and orientation of collagen, particularly at the zero-stress state, are necessary to relate the structural organization of collagen to the mechanical response of the adventitia. Using the fluorescence collagen marker CNA38-OG488 and confocal laser scanning microscopy, we imaged collagen fibers in the adventitia of rabbit common carotid arteries ex vivo. The arteries were cut open along their longitudinal axes to get the zero-stress state. We used semi-manual and automatic techniques to measure parameters related to the waviness and orientation of fibers. Our results showed that the straightness parameter (defined as the ratio between the distances of endpoints of a fiber to its length) was distributed with a beta distribution (mean value 0.72, variance 0.028) and did not depend on the mean angle orientation of fibers. Local angular density distributions revealed four axially symmetric families of fibers with mean directions of 0°, 90°, 43° and −43°, with respect to the axial direction of the artery, and corresponding circular standard deviations of 40°, 47°, 37° and 37°. The distribution of local orientations was shifted to the circumferential direction when measured in arteries at the zero-load state (intact), as compared to arteries at the zero-stress state (cut-open). Information on collagen fiber waviness and orientation, such as obtained in this study, could be used to develop structural models of the adventitia, providing better means for analyzing and understanding the mechanical properties of vascular wall.

/pdf/experimental-investigation-of-collagen-waviness-and-35sv8tu15v.pdf

Experimental investigation of collagen waviness and orientation in the arterial adventitia using confocal laser scanning microscopy.

Fibroblast biology in three-dimensional collagen matrices.

The use of bone grafts is the standard to treat skeletal fractures, or to replace and regenerate lost bone, as demonstrated by the large number of bone graft procedures performed worldwide. The most common of these is the autograft, however, its use can lead to complications such as pain, infection, scarring, blood loss, and donor-site morbidity. The alternative is allografts, but they lack the osteoactive capacity of autografts and carry the risk of carrying infectious agents or immune rejection. Other approaches, such as the bone graft substitutes, have focused on improving the efficacy of bone grafts or other scaffolds by incorporating bone progenitor cells and growth factors to stimulate cells. An ideal bone graft or scaffold should be made of biomaterials that imitate the structure and properties of natural bone ECM, include osteoprogenitor cells and provide all the necessary environmental cues found in natural bone. However, creating living tissue constructs that are structurally, functionally and mechanically comparable to the natural bone has been a challenge so far. This focus of this review is on the evolution of these scaffolds as bone graft substitutes in the process of recreating the bone tissue microenvironment, including biochemical and biophysical cues.

Scaffold Design for Bone Regeneration

The human femoral artery can bleed dangerously following the removal of a catheter during cardiac catheterization. In this study, a modified technique of needle insertion, simply inserting the needle bevel-down instead of the standard bevel-up approach, was tested as a means to reduce bleeding after catheter removal. Large bore needle punctures were made in surgically exposed arteries of anesthetized pigs using either a standard technique (45 degree approach, bevel up) or a modified technique (25 degree approach, bevel down). For half the punctures, topical phenylephrine solution (1 mg/ml) was applied to the adventitia of the artery to cause constriction. Median bleeding rates were reduced from 81 to less than 1 ml/min/100 mmHg intraluminal pressure by the modified technique with application of phenylephrine. In most cases zero bleeding, that is self-sealing, of the arteries occurred. It is postulated that a flap-valve of tissue created by the modified technique produced this set-sealing behavior. Sophisticated modeling studies are needed to fully understand this new phenomenon.

Self-sealing, large bore arterial punctures: a counterintuitive new phenomenon.

A stent (42) for use in a stent graft comprising a strut region comprising at least two struts (46,48), the struts having at least one radius of curvature; a bend connecting the at least two struts and forming an eyelet region (54), where the strut region and the eyelet region are electropolished and the eyelet region is locally polished; and an eyelet (54) positioned in the eyelet region, having at least one radius of curvature greater than zero is provided. A method of manufacturing the same also is disclosed.

Stent and method of making a stent

Various stent structures are provided with improved axial and torsional flexibility. One type of stent structure includes multiple segmented stent structures connected to each other by biodegradable interconnectors. A delivery system adapted to delivery the multiple segmented stents is also described. Another type of stent structure includes biodegradable connectors that are incorporated into a framework of non-biodegradable interconnecting members that form the support structure of the stent. The biodegradable connectors in both stent structures degrade or are absorbed after the stent is deployed. Stabilizing elements may be provided to the stent structures to supplement the stiffness of the stent with stability during loading and deployment.

Stents with connectors and stabilizing biodegradable elements

PROBLEM TO BE SOLVED: To improve a system for inserting an endoluminal prosthesis like a stent graft.SOLUTION: An insertion system may include the stent graft, a locking member and one or more diameter reduction member(s). The stent graft may include a tubular graft including lateral parts that are each disposed to be faced, connected using a tangent line and extended in the first and second longitudinal directions. When the locking member is in a locking position, the locking member restricts a surface of the graft with respect to a cannula. The first diameter reduction member is slidably connected to a first portion of the graft that is arranged approximate the tangent line, and is slidably connected to a second portion of the graft that is circumferentially separate from the tangent line. When the first diameter reduction member is in a restricted position, the second portion of the graft is drawn toward the first portion of the graft, and a proximal portion has a diameter reduction structure with at least two lobes.

System for inserting shape-adaptive prosthesis, and method for arranging the system

RR23. Multicenter International Experience With Endovascular Treatment of Ascending Aortic Pathology in High-Risk Patients With a Specifically Designed Ascending Aortic Stent Graft

Blayne A. Roeder

Papers

Self-sealing, large bore arterial punctures: a counterintuitive new phenomenon.

Stent and method of making a stent

Stents with connectors and stabilizing biodegradable elements

System for inserting shape-adaptive prosthesis, and method for arranging the system

RR23. Multicenter International Experience With Endovascular Treatment of Ascending Aortic Pathology in High-Risk Patients With a Specifically Designed Ascending Aortic Stent Graft