Visualization of microvessels by angiography using inverse-Compton scattering X-rays in animal models

Monitoring cardiovascular disease severity using near-infrared mechanoluminescent materials as a built-in indicator

Artificial vascular grafts (AVGs) are widely used to treat cardiovascular diseases (CVDs). But none of the reported AVGs can also monitor the CVD severity. Because CVDs affect the blood pressure, we proposed to employ a force-sensing material that emits near-infrared (NIR) light upon force loading, a NIR mechanoluminescent (ML) material (CaZnOS:Nd³⁺), as an indicator in AVGs to tackle this challenge. Specifically, we used a polydimethylsiloxane AVG modified with this ML material, termed ML-AVG, to achieve the rapid and convenient monitoring of two CVD models (vascular occlusion and hypertension) in real time. The NIR ML material showed good blood and tissue compatibility without causing an inflammatory response. By implanting the ML-AVGs into the common carotid artery (CCA) of rats, we observed the NIR ML signals emitted from the AVGs by a thermal camera, a NIR spectrometer, and a NIR camera. The NIR ML signal was linearly correlated with the degree of vascular opening (in the vascular occlusion model) or the degree of hypertension (in the hypertension model). Our work suggests that NIR ML materials can monitor the severity of diseases with force or pressure as biomarkers.

Accurate and continuous ultrasonography evaluation of small diameter vascular prostheses in vivo

There is a large clinical requirement for novel vascular grafts; however, the development of novel vascular grafts has not been extremely successful to date. The most successful method for the continuous evaluation of vascular grafts in vivo remains unclear. Therefore, an optimal successive, non-invasive imaging modality is necessary for the study of vascular transplantation. In the present study, a common rabbit model of carotid artery defect was utilized. The patency and hemodynamic characteristics of implanted grafts was examined following surgery by color Doppler ultrasound in three modes, including B-mode, color flow map and pulse-Doppler examination. The results revealed that ultrasound had sufficient spatial resolution to generate clear images of the carotid artery of rabbits with or without the implanted grafts. Color Doppler ultrasound may be applied to evaluate and differentiate the patent, stenosis and occlusion of carotid arteries in rabbits with different vascular grafts implanted. Furthermore, color Doppler ultrasound is an optimal imaging modality for continuous evaluation in vivo. It is also possible for some quantitative analyses to be performed, including measuring the diameter of vascular lumens and the flow velocity of the region of interest. The present study suggests vascular ultrasound as the optimum choice for continuous surveillance of vascular prostheses in vivo, which may provide valuable information about the grafts in order to greatly shorten the experimental period.

Altered blood flow in cerebral perforating arteries of rat models of diabetes: A synchrotron radiation microangiographic study toward clinical evaluation of white matter hyperintensities

AIM

As altered blood flow in the cerebral perforating arteries (PA) might be related to development of cerebral white matter hyperintensities, we examined whether the hemodynamic relationship of the PA and middle cerebral artery (MCA) is altered in rat models of diabetes, compared with normal rats and a rat model of sinoatrial denervation (blood pressure fluctuation model).

METHODS

We used microangiography with monochromatic synchrotron radiation to measure the diameters of the PA and MCA at 4.5 μm resolution in five groups of rats: (i) Long-Evans Tokushima Otsuka (LETO); (ii) Otsuka Long-Evans Tokushima Fatty (a model of type 2 diabetes with obesity); (iii) LETO with sinoaortic denervation (LETO + SAD); (iv) F344; and (v) F344 + streptozotocin (a model of type 1 diabetes).

RESULTS

Compared with LETO, Otsuka Long-Evans Tokushima Fatty rats showed a significant reduction in the diameter of both PA and MCA, though the PA/MCA diameter ratio was unchanged. In contrast, compared with LETO, LETO + SAD rats showed an increased MCA diameter, and the PA/MCA diameter ratio was decreased. Compared with F344 rats, the MCA diameter was increased in F344 + streptozotocin rats, and the PA/MCA diameter ratio was decreased. Scatter diagrams showed that the diameters of the PA and MCA were essentially independent of each other in the two types of diabetic models.

CONCLUSION

PA were consistently visualized at high resolution by means of microangiography using synchrotron radiation. The present results show that rat diabetic models exhibit changes in PA diameter and PA/MCA diameter ratio, which might be related to the development of diabetes-associated cerebral white matter hyperintensities.