4 research outputs found
An Arthroscopic Device to Assess Articular Cartilage Defects and Treatment with a Hydrogel
The hydraulic resistance R across osteochondral tissue, especially articular cartilage, decreases with degeneration and erosion. Clinically useful measures to quantify and diagnose the extent of cartilage degeneration and efficacy of repair strategies, especially with regard to pressure maintenance, are still developing. The hypothesis of this study was that hydraulic resistance provides a quantitative measure of osteochondral tissue that could be used to evaluate the state of cartilage damage and repair. The aims were to (1) develop a device to measure R in an arthroscopic setting, (2) determine whether the device could detect differences in R for cartilage, an osteochondral defect, and cartilage treated using a hydrogel ex vivo, and (3) determine how quickly such differences could be discerned. The apparent hydraulic resistance of defect samples was ~35% less than intact cartilage controls, while the resistance of hydrogel-filled groups was not statistically different than controls, suggesting some restoration of fluid pressurization in the defect region by the hydrogel. Differences in hydraulic resistance between control and defect groups were apparent after 4 s. The results indicate that the measurement of R is feasible for rapid and quantitative functional assessment of the extent of osteochondral defects and repair. The arthroscopic compatibility of the device demonstrates the potential for this measurement to be made in a clinical setting
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Effects of materials on electrophysiology when interfaced with whole heart and cardiomyocytes
Myocardial infarction (MI) is occlusion of the heart coronary artery. The resulting breakdown of extracellular matrix and adverse remodeling of the myocardium lead to heart failure. Cell and material transplantation therapies have been investigated to help in regeneration and improve heart function. Some cell types like skeletal myoblasts show increased risk for arrhythmias compared to saline injections, but arrhythmia inducibility of materials has not been studied. To assess the safety of injectable materials, programmed electrical stimulation (PES) was used with a rat MI model. This involves burst and extra- stimulation of the heart with rapid pulses alone or preceded by pulses of lower frequency. We found similar arrhythmia inducibility in myocardial matrix, Polyethylene Glycol, and PBS injections. Arrhythmogenicity of materials being similar to that of PBS indicates that use of materials is safe. The materials were injected largely into the infarct region (already a conduction block), which may be a reason for the low occurrence of arrhythmias. Since materials can be injected with cells, a study of electrophysiological effects of the biomaterial on cardiomyocytes (CM) is necessary, and was done with optical mapping (OM) of monolayers. OM uses a voltage sensitive dye that, when the monolayer is stimulated, fluoresces and is recorded to measure action potential duration (APD) and conduction velocity (CV). This showed significantly lower CV and APD at 20% repolarization in cells cultured on myocardial matrix versus collagen. Reduced APD indicates increased maturity of the CM, while lower CV suggests reduced connexin gap junctions and current channel
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Effects of materials on electrophysiology when interfaced with whole heart and cardiomyocytes
Myocardial infarction (MI) is occlusion of the heart coronary artery. The resulting breakdown of extracellular matrix and adverse remodeling of the myocardium lead to heart failure. Cell and material transplantation therapies have been investigated to help in regeneration and improve heart function. Some cell types like skeletal myoblasts show increased risk for arrhythmias compared to saline injections, but arrhythmia inducibility of materials has not been studied. To assess the safety of injectable materials, programmed electrical stimulation (PES) was used with a rat MI model. This involves burst and extra- stimulation of the heart with rapid pulses alone or preceded by pulses of lower frequency. We found similar arrhythmia inducibility in myocardial matrix, Polyethylene Glycol, and PBS injections. Arrhythmogenicity of materials being similar to that of PBS indicates that use of materials is safe. The materials were injected largely into the infarct region (already a conduction block), which may be a reason for the low occurrence of arrhythmias. Since materials can be injected with cells, a study of electrophysiological effects of the biomaterial on cardiomyocytes (CM) is necessary, and was done with optical mapping (OM) of monolayers. OM uses a voltage sensitive dye that, when the monolayer is stimulated, fluoresces and is recorded to measure action potential duration (APD) and conduction velocity (CV). This showed significantly lower CV and APD at 20% repolarization in cells cultured on myocardial matrix versus collagen. Reduced APD indicates increased maturity of the CM, while lower CV suggests reduced connexin gap junctions and current channel