ABSTRACT
Cardiac patches are biomaterials that can be used for transplantation and repair of damaged myocardium by combining seed cells with the ability to form cardiomyocytes and suitable scaffold materials. On the one hand, they provide temporary support to the infarcted area, and on the other hand, they repair the damaged myocardium by delivering cells or bioactive factors to integrate with the host, which have gradually become a hot research topic in recent years. This paper summarizes the structural properties of natural myocardium and reviews the recent research progress of cardiac patches, including the seed cells and scaffold materials used in patch preparation, as well as the main methods of scaffold preparation and the structure properties of various scaffolds. In addition, a comprehensive analysis of the problems faced in the clinical implementation of cardiac patches is presented. Finally, we look forward to the development of cardiac patches and point out that precisely tunable anisotropic tissue engineering scaffolds close to natural myocardial tissue will become an important direction for future research.
Subject(s)
Tissue Engineering , Tissue Scaffolds , Biocompatible Materials/therapeutic use , Myocardium , Tissue Engineering/methods , Tissue Scaffolds/chemistryABSTRACT
To evaluate the utility of ADC values and Gd-DTPA equilibrium phase MR imaging in staging hepatic fibrosis in rats. 48 rats were allocated into experimental and control groups. Experimental rats were subcutaneously injected with a mixture of CCl4. From 4th-12th weeks, MR images were obtained, which include pre-enhanced phase imaging, DWI and equilibrium phase imaging. Then the rat groups were subdivided according to the stages of fibrosis (S0, S1, S2, S3 and S4) after histopathological analysis. The original MRI data were forwarded to the workstation to obtain apparent diffusion coefficient (ADC) maps at b value of 500 s/mm(2). Pre-enhanced phase and equilibrium phase signal intensities and relative contrast enhancement index (RCEI) were measured as well. Lastly, the ADC values and RCEI of the experimental group were compared with each other and with the control group. All statistical analyses were carried out with SPSS, where P < 0.05 is considered to represent a significant difference. Hepatic ADC values are significantly different between the experimental and control groups (P = 0). There is a statistically significant difference between the experimental and control groups on RCEI (P = 0). Comparing the S1, S2, S3 and S4 groups, there is a statistically significant difference between the mild group (S1 and S2) and the severe group (S4) in terms of ADC values and RCEI (all P < 0.05). A statistically significant difference is also found between the moderate group (S3) and the severe group in ADC values. As the degree of fibrosis increases, there are a reduction in ADC values and an increase in RCEI. Comparing the groups with ADC values and enhancement index, there are statistically significant differences in sensitivity and specificity on diagnosis of hepatic fibrosis. The ADC values have the best sensitivity (93.1%) and specificity (83.3%). Quantitative ADC values and RCEI may be helpful to the staging of rat fibrosis, but their application in human is controversial.
ABSTRACT
This paper proposes a scheme for non-collocated moving actuating and sensing devices which is unitized for improving performance in distributed parameter systems. By Lyapunov stability theorem, each moving actuator/sensor agent velocity is obtained. To enhance state estimation of a spatially distributes process, two kinds of filters with consensus terms which penalize the disagreement of the estimates are considered. Both filters can result in the well-posedness of the collective dynamics of state errors and can converge to the plant state. Numerical simulations demonstrate that the effectiveness of such a moving actuator-sensor network in enhancing system performance and the consensus filters converge faster to the plant state when consensus terms are included.
