Search Results by Classification Category

Results for entries tagged with "Tissue-Based Assays"

Histological Bone Morphometry

Traditional 2D bone morphometric analyses utilize hard-tissue histological sectioning and evaluation of bone cores (human or animal) stained with Toluidine Blue and embedded in PMMA.

Large field-of-view Analysis of Fracture Callus Healing

In order to assess the extent of healing following non-union fracture in response to various therapies (PTH, bisphosphonates, etc), the callus sites of histologically stained (i.e. Safranin-O/FAST Green) and sectioned long bones can be digitized using a high resolution, large field-of-view microscope and subsequently evaluated for thickness, area, and tissue composition (fibrous, bone, cartilagenous tissue content) in a quati.

Gene Therapy R&D

Genetic transfection of cell types to elucidate pathways involved in specific pathologies requires ongoing assessment of transfection efficiencly to ensure that modification was successful and subsequent assays performed are valid.

Bright Field Immuno-Staining

Non-fluorescent, immuno-staining of histological tissue for specific antigens generally involves enzymatic subtrates that oxidize compounds such as diaminobenzidine (DAB) to precipitate a brown chromogenic product. Unfortunately, "brown" color is composed of a mixture of hues not easily segmented or characterized from background.

Shock-Induced Electroporation

Internal defibrillation shock while often necessary can permanently damage the heart via disruption of cell membranes (electroporation). To study the spatial extent of cell death and tissue damage of such a shock, a coil shock electrode was inserted into the right ventricle of Langendorff-perfused rabbit heart.

Osseointegration of Bone Scaffolds in a Canine Defect Model

The canine femoral multi-defect model enables evaluation of bone in-growth within 4 separate defects placed > 1.5 cm apart in the proximal femur. For this model, animals are euthanized 4 weeks following implantation and bone scaffolds inserted into the surgically created cylindrical defects (1.0 cm diameter, 1.5 cm deep) are explanted and imaged using micro-computed tomography (CT).

Micro-Computed Tomography (CT) Evaluation of Cartilage Profile using the Contrast Agent Conray

Evaluation of articular cartilage defects or delamination in small animal models for assessment of repair or response to pharmaceuticals requires both high spatial and density resolution. Unfortunately while small animal MRI systems will allow visualization cartilage, resolution is poor. While micro-computed tomography will provide the necessary resolution (as high as 1 um), soft tissue interfaces like cartilage do not attenuate well and thus are not generally visible or extremely noisy at best.

Retinal Vascularization in Small Animal Models

A number of ophthalmic pathologies can be studied in small animals (rats and mice) to assess progression of disease following drug or gene therapy. This approach calls for the perfusion of retinal vasculature with a fluorescent dye, animal sacrifice, and "flat-mounting" of the explanted retina onto a slide (four radial incisions).

Tube Formation Analysis

Endothelial cells (EC), when provided with a 3D extracellular matrix substrate and appropriately supplemented growth media, will self-organize into a network of capillary-like "tubes." This in-vitro, "tube formation" assay, is commonly used to assess ability of compounds to stimulate or inhibit angiogenesis.

Automated Histological Analysis of Cartilage Defects

Sports-related injuries can produce large focal defects in articular joint cartilage that often lead to delamination of surrounding healthy cartilage and eventual degeneration of the joint. To study this process in an animal model, a pendulum was swung onto the medial condyles of a rabbit femur. After a predefined length of time, the rabbit was sacrificed and the impact region was explanted, sectioned, and stained with Safranin-O.

Automated Histological Analysis of Osseointegration

The structure and chemical composition of bone scaffolds or implants will impact their ability to promote bone in-growth and consequently dictate stability of the implant. Small animal models are often utilized for evaluation of bone in-growth in candidate scaffolds. Scaffolds are generally implanted into proximal sites of long bones for a fixed period of time.

In-vivo Histological Bone Growth Assay

Traditional methods of in-vivo bone growth evaluation in small animal models utilize longitudinal micro-CT imaging. Unfortunately, live animal imaging requires low radiation dose protocols that limit spatial resolution to ~20 um which is inadequate for small animals (particularly adults) whose bone growth rates are on the order of a few um/day.

Cell/Vessel Proximity Assay

Since tumor survival is strongly dependent on vascularization, there are number of anticancer drugs that specifically target vessel growth. A subset of these drugs bind to growth factors (i.e. VEGF) and prevent them from binding to receptors that initiate angiogenesis cascades.

Adipocyte Characterization

Morphometric analysis of fat cells or adipocytes within specific organs enables quantitative assessment of various pathologies or compounds that affect metabolic pathways. Unfortunately, most labs will perform such analysis with multiple observers manually delineating each adipocyte in a given field-of-view.

TEM Collagen Fibril Morphometry

Transmission electron microscopy (TEM) is a valuable imaging tool for nanometer scale assessment of extracellular matrix organization and localization/morphology of subcellular structures. As an example, collagen fibrils in a genetically modified animal model were imaged using TEM for evaluation of collagen morphology and spacing/packing.