ABSTRACT
Background: Failure to close the abdominal wall after intestinal transplantation (ITx) or multivisceral Tx remains a surgical challenge. An attractive method is the use of nonvascularized rectus fascia (NVRF) in which both layers of the donor abdominal rectus fascia are used as an inlay patch without vascular anastomosis. How this graft integrates over time remains unknown. The study aims to provide a multilevel analysis of the neovascularization and integration process of the NVRF. Methods: Three NVRF-Tx were performed after ITx. Clinical, radiological, histological, and immunological data were analyzed to get insights into the neovascularization and integration process of the NVRF. Moreover, cryogenic contrast-enhanced microfocus computed tomography (microCT) analysis was used for detailed reconstruction of the vasculature in and around the NVRF (3-dimensional histology). Results: Two men (31- and 51-y-old) and 1 woman (49-y-old) underwent 2 multivisceral Tx and 1 combined liver-ITx, respectively. A CT scan showed contrast enhancement around the fascia graft at 5 days post-Tx. At 6 weeks, newly formed blood vessels were visualized around the graft with Doppler ultrasound. Biopsies at 2 weeks post-Tx revealed inflammation around the NVRF and early fibrosis. At 6 months, classical 2-dimensional histological analysis of a biopsy confirmed integration of the fascia graft with strong fibrotic reaction without signs of rejection. A cryogenic contrast-enhanced microCT scan of the same biopsy revealed the presence of microvasculature, enveloping and penetrating the donor fascia. Conclusions: We showed clinical, histological, and microCT evidence of the neovascularization and integration process of the NVRF after Tx.
ABSTRACT
The kidney's microstructure, which comprises a highly convoluted tubular and vascular network, can only be partially revealed using classical 2D histology. Considering that the kidney's microstructure is closely related to its function and is often affected by pathologies, there is a need for powerful and high-resolution 3D imaging techniques to visualize the microstructure. Here, we present how cryogenic contrast-enhanced microCT (cryo-CECT) allowed 3D visualization of glomeruli, tubuli, and vasculature. By comparing different contrast-enhancing staining agents and freezing protocols, we found that the preferred sample preparation protocol was the combination of staining with 1:2 hafnium(IV)-substituted Wells-Dawson polyoxometalate and freezing by submersion in isopentane at -78°C. This optimized protocol showed to be highly sensitive, allowing to detect small pathology-induced microstructural changes in a mouse model of mild trauma-related acute kidney injury after thorax trauma and hemorrhagic shock. In summary, we demonstrated that cryo-CECT is an effective 3D histopathological tool that allows to enhance our understanding of kidney tissue microstructure and their related function.
ABSTRACT
HYPOTHESIS: Characterizing the microstructure of an ice/surface interface and its effect on the icephobic behavior of surfaces remains a significant challenge. Introducing X-ray Computed Tomography (XCT) can provide unprecedented insights into the internal (porosity) and interfacial structures, i.e. wetting regime, between (super)hydrophobic surfaces and ice by visualizing these optically inaccessible regions. EXPERIMENTS: Frozen droplets with controlled volume were deposited on top of metallic and polymeric substrates with different levels of wettability. Different modes of XCT (3D and 4D) were utilized to obtain information on the internal and interfacial structure of the ice/surface system. The results were supplemented by conventional surface analysis techniques, including optical profilometry and contact angle measurements. FINDINGS: Using XCT on ice/surface systems, the 3D and 4D (imaging with temporal resolution) structural information can be visualized. From these datasets, qualitative and quantitative results were obtained, not only for characterizing the interface but also for analyzing the entire droplet/surface system, e.g., measurement of porosity size, shape, and location. These results highlight the potential of XCT in the characterization of both droplets and substrates and proves that the technique can aid to develop hydrophobic surfaces for use as icephobic materials.
ABSTRACT
Biological tissues comprise a spatially complex structure, composition and organization at the microscale, named the microstructure. Given the close structure-function relationships in tissues, structural characterization is essential to fully understand the functioning of healthy and pathological tissues, as well as the impact of possible treatments. Here, we present a nondestructive imaging approach to perform quantitative 3D histo(patho)logy of biological tissues, termed Cryogenic Contrast-Enhanced MicroCT (cryo-CECT). By combining sample staining, using an X-ray contrast-enhancing staining agent, with freezing the sample at the optimal freezing rate, cryo-CECT enables 3D visualization and structural analysis of individual tissue constituents, such as muscle and collagen fibers. We applied cryo-CECT on murine hearts subjected to pressure overload following transverse aortic constriction surgery. Cryo-CECT allowed to analyze, in an unprecedented manner, the orientation and diameter of the individual muscle fibers in the entire heart, as well as the 3D localization of fibrotic regions within the myocardial layers. We foresee further applications of cryo-CECT in the optimization of tissue/food preservation and donor banking, showing that cryo-CECT also has clinical and industrial potential.
