Cell-free cryopreserved arterial allografts from multiorgan donors: a new strategy to fabricate artificial blood vessels suited for peripheral vascular surgery

Critical lower limb ischemia is a severe disease. A common approach is infrainguinal bypass. Synthetic vascular prosthesis, are good conduits in high-flow low-resistance conditions but have difficulty in their performance as small diameter vessel grafts. A new approach is the use of native decellularized vascular tissues. Cell-free vessels are expected to have improved biocompatibility when compared to synthetic and are optimal natural 3D matrix templates for driving stem cell growth and tissue assembly in vivo. Decellularization of tissues represent a promising field for regenerative medicine, with the aim to develop a methodology to obtain small-diameter allografts to be used as a natural scaffold suited for in vivo cell growth and pseudo-tissue assembly, eliminating failure caused from immune response activation. Material and methods. Umbilical cord-derived mesenchymal cells isolated from human umbilical cord tissue were expanded in advanced DMEM. Immunofluorescence and molecular characterization revealed a stem cell profile. A non-enzymatic protocol, that associate hypotonic shock and low-concentration ionic detergent, was used to decellularize vessel segments. Cells were seeded cell-free scaffolds using a compound of fibrin and thrombin and incubated in DMEM, after 4 days of static culture they were placed for 2 weeks in a flow-bioreactor, mimicking the cardiovascular pulsatile flow. After dynamic culture, samples were processed for histological, biochemical and ultrastructural analysis. Discussion. Histology showed that the dynamic culture cells initiate to penetrate the extracellular matrix scaffold and to produce components of the ECM, as collagen fibres. Sirius Red staining showed layers of immature collagen type III and ultrastructural analysis revealed 30 nm thick collagen fibres, presumably corresponding to the immature collagen. These data confirm the ability of cord-derived cells to adhere and penetrate a natural decellularized tissue and to start to assembly into new tissue. This achievement makes natural 3D matrix templates prospectively valuable candidates for clinical bypass procedures

The S.T.A.B. Trial - Standardised Testing of Artificial Blood. A comparative study of various products that may be used as artificial blood for high fidelity simulation training in the critical care setting

Aim: In the current climate of medical education, there is an ever-increasing demand for and emphasis on simulation as both a teaching and training tool. The objective of our study was to compare the realism and practicality of a number of artificial blood products that could be used for high-fidelity simulation. Method: A literature and internet search was performed and 15 artificial blood products were identified from a variety of sources. One product was excluded due to its potential toxicity risks. Five observers, blinded to the products, performed two assessments on each product using an evaluation tool with 14 predefined criteria including color, consistency, clotting, and staining potential to manikin skin and clothing. Each criterion was rated using a five-point Likert scale. The products were left for 24 hours, both refrigerated and at room temperature, and then reassessed. Statistical analysis was performed to identify the most suitable products, and both inter- and intra-rater variability were examined. Results: Three products scored consistently well with all five assessors, with one product in particular scoring well in almost every criterion. This highest-rated product had a mean rating of 3.6 of 5.0 (95% posterior Interval 3.4-3.7). Inter-rater variability was minor with average ratings varying from 3.0 to 3.4 between the highest and lowest scorer. Intrarater variability was negligible with good agreement between first and second rating as per weighted kappa scores (K = 0.67). Conclusion: The most realistic and practical form of artificial blood identified was a commercial product called KD151 Flowing Blood Syrup. It was found to be not only realistic in appearance but practical in terms of storage and stain removal.

Identification of novel antigens in blood vessels in rectovaginal endometriosis

To identify specific markers of rectovaginal endometriotic nodule vasculature, highly enriched preparations of vascular endothelial cells and pericytes were obtained from endometriotic nodules and control endometrial and myometrial tissue by laser capture microdissection (LCM), and gene expression profiles were screened by microarray analysis. Of the 18 400 transcripts on the arrays, 734 were significantly overexpressed in vessels from fibromuscular tissue and 923 in vessels from stromal tissue of endometriotic nodules, compared with vessels dissected from control tissues. The most frequently expressed transcripts included known endothelial cell-associated genes, as well as transcripts with little or no previous association with vascular cells. The higher expression in blood vessels was further corroborated by immunohistochemical staining of six potential markers, five of which showed strong expression in pericytes. The most promising marker was matrix Gla protein, which was found to be present in both glandular epithelial cells and vascular endothelial cells of endometriotic lesions, although it was barely expressed at all in normal endometrium. LCM, combined with microarray analysis, constitutes a powerful tool for mapping the transcriptome of vascular cells. After immunohistochemical validation, markers of vascular endothelial and perivascular cells from endometriotic nodules could be identified, which may provide targets to improve early diagnosis or to selectively deliver therapeutic agents.

In vivo velocity vector imaging and time-resolved strain rate measurements in the wall of blood vessels using MRI

In this paper, we present a new approach for velocity vector imaging and time-resolved measurements of strain rates in the wall of human arteries using MRI and we prove its feasibility on two examples: in vitro on a phantom and in vivo on the carotid artery of a human subject. Results point out the promising potential of this approach for investigating the mechanics of arterial tissues in vivo.

Interstitial cells of blood vessels

Blood vessels are made up of several distinct cell types. Although it was originally thought that the tunica media of blood vessels was composed of a homogeneous population of fully differentiated smooth muscle cells, more recent data suggest the existence of multiple smooth muscle cell subpopulations in the vascular wall. One of the cell types contributing to this heterogeneity is the novel, irregularly shaped, noncontractile cell with thin processes, termed interstitial cell, found in the tunica media of both veins and arteries. While the principal role of interstitial cells in veins seems to be pacemaking, the role of arterial interstitial cells is less clear. This review summarises the knowledge of the functional and structural properties of vascular interstitial cells accumulated so far, offers hypotheses on their physiological role, and proposes directions for future research.

Increased levels of advanced glycation endproducts in the lenses and blood vessels of cigarette smokers.

BACKGROUND: Advanced glycation endproducts (AGEs) arise from the spontaneous reaction of reducing sugars with the amino groups of macromolecules. AGEs accumulate in tissue as a consequence of diabetes and aging and have been causally implicated in the pathogenesis of several of the end-organ complications of diabetes and aging, including cataract, atherosclerosis, and renal insufficiency. It has been recently proposed that components in mainstream cigarette smoke can react with plasma and extracellular matrix proteins to form covalent adducts with many of the properties of AGEs. We wished to ascertain whether AGEs or immunochemically related molecules are present at higher levels in the tissues of smokers.

MATERIALS AND METHODS: Lens and coronary artery specimens from nondiabetic smokers and nondiabetic nonsmokers were examined by immunohistochemistry, immunoelectron microscopy, and ELISA employing several distinct anti-AGE antibodies. In addition, lenticular extracts were tested for AGE-associated fluorescence by fluorescence spectroscopy.

RESULTS: Immunoreactive AGEs were present at significantly higher levels in the lenses and lenticular extracts of nondiabetic smokers (p < 0.003). Anti-AGE immunogold staining was diffusely distributed throughout lens fiber cells. AGE-associated fluorescence was significantly increased in the lenticular extracts of nondiabetic smokers (p = 0.005). AGE-immunoreactivity was significantly elevated in coronary arteries from nondiabetic smokers compared with nondiabetic nonsmokers (p = 0.015).

CONCLUSIONS: AGEs or immunochemically related molecules are present at higher levels in the tissues of smokers than in nonsmokers, irrespective of diabetes. In view of previous reports implicating AGEs in a causal association with numerous pathologies, these findings have significant ramifications for understanding the etiopathology of diseases associated with smoking, the single greatest preventable cause of morbidity and mortality in the United States.