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Amniotic fluid cells (AFCs) have been proposed as a valuable source for tissue engineering and regenerative medicine. However, before clinical implementation, rigorous evaluation of this cell source in clinically relevant animal models accepted by regulatory authorities is indispensable. Today, the ovine model represents one of the most accepted preclinical animal models, in particular for cardiovascular applications. Here, we investigate the isolation and use of autologous ovine AFCs as cell source for cardiovascular tissue engineering applications. Fetal fluids were aspirated in vivo from pregnant ewes (n = 9) and from explanted uteri post mortem at different gestational ages (n = 91). Amniotic non-allantoic fluid nature was evaluated biochemically and in vivo samples were compared with post mortem reference samples. Isolated cells revealed an immunohistochemical phenotype similar to ovine bone marrow-derived mesenchymal stem cells (MSCs) and showed expression of stem cell factors described for embryonic stem cells, such as NANOG and STAT-3. Isolated ovine amniotic fluid-derived MSCs were screened for numeric chromosomal aberrations and successfully differentiated into several mesodermal phenotypes. Myofibroblastic ovine AFC lineages were then successfully used for the in vitro fabrication of small- and large-diameter tissue-engineered vascular grafts (n = 10) and cardiovascular patches (n = 34), laying the foundation for the use of this relevant pre-clinical in vivo assessment model for future amniotic fluid cell-based therapeutic applications. Copyright © 2013 John Wiley & Sons, Ltd.

Background: Chronic venous insufficiency (CVI) represents a major global health problem with increasing prevalence and morbidity. CVI is due to an incompetence of the venous valves, which causes venous reflux and distal venous hypertension. Several studies have focused on the replacement of diseased venous valves using xeno- and allogenic transplants, so far with moderate success due to immunologic and thromboembolic complications. Autologous cell-derived tissue-engineered venous valves (TEVVs) based on fully biodegradable scaffolds could overcome these limitations by providing non-immunogenic, non-thrombogenic constructs with remodeling and growth potential. Methods: Tri- and bicuspid venous valves (n=27) based on polyglycolic acid-poly-4-hydroxybutyrate composite scaffolds, integrated into self-expandable nitinol stents, were engineered from autologous ovine bone-marrow-derived mesenchymal stem cells (BM-MSCs) and endothelialized. After in vitro conditioning in a (flow) pulse duplicator system, the TEVVs were crimped (n=18) and experimentally delivered (n=7). The effects of crimping on the tissue-engineered constructs were investigated using histology, immunohistochemistry, scanning electron microscopy, grating interferometry (GI), and planar fluorescence reflectance imaging. Results: The generated TEVVs showed layered tissue formation with increasing collagen and glycosaminoglycan levels dependent on the duration of in vitro conditioning. After crimping no effects were found on the MSC level in scanning electron microscopy analysis, GI, histology, and extracellular matrix analysis. However, substantial endothelial cell loss was detected after the crimping procedure, which could be reduced by increasing the static conditioning phase. Conclusions: Autologous living small-diameter TEVVs can be successfully fabricated from ovine BM-MSCs using a (flow) pulse duplicator conditioning approach. These constructs hold the potential to overcome the limitations of currently used non-autologous replacement materials and may open new therapeutic concepts for the treatment of CVI in the future.

Kingsley Amis was a prolific writer of fiction and poetry, but alongside his literary works he wrote a considerable amount of literary criticism. The body of his non-fiction writing consists of book reviews which appeared in a wide range of periodicals: The Spectator, The New Statesman, The Observer and The Listener and two collections of essays What Became Of Jane Austin? and Other Questions and The Amis Collection. Amis, as a 'man of letters' wrote prefaces and introductions to other writers' books and edited anthologies of poetry. The subject of this dissertation is Amis's politics of writing, his views on the work and skills of the novelist, the poet and the critic. Chapter One is a discussion of Amis's criticism in the context of literary tradition in Britain. Starting from the 1950s and throughout his career as a writer, Amis opposed the tradition of Modernism and the regime of elitist literary Establishment which promoted 'highbrow' art. He also engaged in debates with British critics like F.R. Leavis, W.P. Ker, A.T. Quiller-Coach and William Empson. Opposing their approaches to literature and their style of writing. Amis offered his own style of criticism - colloquial, accessible and not requiring a profound knowledge of literary theories. Amis's politics of writing are to a great extent reflected in what he says about the art of the novel, and what constitutes 'good' or 'bad' examples of the genre. It is important how Amis relates to the writers who had dominated British literary scene in the time when he started writing, as well as it is interesting to investigate how he evaluates new movements in the novel after the war. Amis's reviews of poetry and the literary debates he engaged in focus on the same principle as the rest of his criticism, namely accessibility to the 'general reader'. Poets, whose aim was to communicate (Victorian writers) were, in his opinion, successful; whereas those who cultivated artistic detachment (Romantics and Modernists) remain in the interest of highbrow academics.