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Due to the lack of regeneration capacity of Articular cartilage and very limited therapies available, it is necessary to design a construct which can mimic hydrogel behavior in articular cartilage. Gelatin and sulphated polysaccharide blends are used for that purpose of this study. Swelling behavior of these hydrogel is observed in both deionized water and phosphate buffer salin (PBS). For mechanical...
In this work, we will report on the design and validation of a Laminar Optical Tomography systems developed at RPI to image tissue-engineered constructs. The systems characteristics and image reconstruction methods will be presented and discussed. In silico and in vitro validation of the imaging platform based on phantom studies mimicking the optical properties of various bio-tissues will demonstrate...
The Computational Imaging and Biomechanics Lab(CIBL) at Drexel University has been continuously researching the mechanical properties of soft tissues, specifically tendon and heart valves. Our current effort is on a new testing device scaled down for individual fascicles also known as the mesostructure-scale. This paper presents preliminary results of that system capturing the properties of electrospun...
We present the solution of the nonlinear inverse elasticity problem, wherein we image the linear and nonlinear hyperelastic properties of soft tissues in-vivo. For this, we solve a constrained optimization problem iteratively. The discrepancy between measured and predicted displacement fields is minimized in the objective function in the presence of regularization. The predicted displacement fields...
Introduction: Advanced Normalization Tools (ANTs) is an image registration program that has been validated for analysis of several tissues, but not previously applied to the disc. The objectives of this study were to optimize ANTs for disc image registration and to validate ANTs strain measurements by comparison with Vic2D, a commercially available software previously applied to quantify disc strain,...
The objective of this study is to induce chondrogensis in primary bovine mesenchymal stem cells (MSCs), and determine the effects of insulin-like growth factor 1 (IGF-1) delivery on the resulting chondrocyte population. Chondrogenesis was initiated by TGF-β3 delivery over 8 days, and IGF-1 was delivered from days 9 through 13. Gene expression of chondrogenic markers (sox9, type II collagen, and aggrecan)...
Low-speed, rear end motor vehicle collisions may cause small but significant medial meniscal tears that have been previously unexplained in published literature. The medial meniscus can be torn when a compressive load is applied to the leg in the flexed position and is then twisted. Rear end collisions occurring at low speeds may produce loading patterns to the legs of the occupants that are capable...
We have developed a scaffold-free, cell-based, single fiber approach toward tissue engineered tendon. This method provides a culture system in which key aspects of embryonic tenogenesis may be replicated, such as high initial cell density, cell-cell adhesion, and dynamic mechanical cues. Through the application of embryonic development inspired growth factors and mechanical stimulation, we ultimately...
Over the past decade there has been a significant increase in the number of Traumatic Brain Injury (TBI) cases among armed forces due to blast. Finite Element (FE) models of brain injury are essential to study brain injury mechanisms. The available FE models are based on the material properties that have been determined from experiments at strain rates below 100 s-1. In this study a novel experimental...
Currently biopsy is considered the gold standard for diagnosis of prostate cancer in humans, although it samples only 19mm3 volume of prostate, corresponding to 0.95% of a 50cm3 prostate gland for a regular 12-core biopsy procedure. The aim of this study was to increase the sampling volume by incorporating electrical impedance spectroscopy (EIS) into the standard biopsy needle. Electrical impedance...
The curvature of the cardiac geometry has a major impact on regional wall stress, but most computational models lack detailed curvature representations. A surface with continuous second-order derivatives is required to model continuous curvatures. The goal of this research was to develop a mouse epicardial geometry model with quantitative surface curvatures.
This study investigates the combinations of loading which cause injury to knee joint ligaments. A 3D model of a knee, including bones, cartilage, menisci and ligament bundles was created from magnetic resonance images (MRI). Material properties for bone, cartilage, meniscus and ligament were all determined based on previous published work. The model incorporates a novel approach for accounting for...
The cellular contribution to increased aortic stiffness associated with hypertension and aging is not fully understood. To study this potential role, a reconstituted aortic tissue model (vascular smooth muscle cells (VSMCs) in a collagen matrix) was developed. VSMCs isolated from thoracic aortic samples of 5-week and 18-week old male spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto...
Cells cultured within a 3D environment acquire phenotypes and respond to stimuli analogous to in vivo development. This approach can be applied to the study of tumorigenesis in vitro. In this study, collagen I hydrogels were engineered as a platform for in vitro solid tumor development. Cell seeding density, scaffold thickness, and matrix stiffness were varied to characterize the development of a...
In the present paper, a novel tactile sensor is proposed for use in minimally invasive surgery to provide surgeons with tactile information. The sensing element of the sensor relies on a piezoresistive material. The proposed sensor measures contact force as well as the relative hardness of soft contact objects. A prototype of the sensor has been built, calibrated, and tested. Experimental test results...
Electrospun and fibers hydrogels are two focal points of research within the biomaterials community. The electrospinning process allows for fabrication of nanoscale, aligned topography and has been shown to direct cellular migration and outgrowth. Hydrogels exhibit benefits over traditional, rigid scaffolds in that they are injectable and can be tailored to mimic the mechanical properties of the surrounding...
Biphasic contact of soft tissues is fundamental to understanding the biomechanical behavior of human diarthrodial joints. In this paper, a finite element formulation is developed for 2D axisymmetric contact of biphasic tissues. Augmented Lagrange method is used to enforce the continuity of contact traction and fluid pressure across the contact interface, and implemented in COMSOL Multiphysics. The...
It has been 60 years since the first knee implant surgery was performed yet questions concerning which material and implant design is most effective for specific populations still remain unanswered. There is a need for a faster, cost effective solution to test implants for their efficacy under physiological conditions. The primary objective of this project is to establish a workable design space for...
PCL foams were fabricated and tested mechanically and observed via scanning electron microscopy for use in future studies to elucidate the interactions between tissue engineered scaffolds and host tissue following implantation.
Quantification of viscoelastic properties of soft fibrous protein gels and tissue biopsies is vital to the study of disease progression and wound healing, among other research areas. The aim of this work is to establish a method of testing irregularly-shaped and anisotropic biological samples. This method has been tested with samples that have G' in the range of 10-500 Pa and sizes of approximately...
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