From developmental biology to tissue-engineering: printing blood vessels

Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 15, 2010).The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Dissertation advisor: Dr. Gabor Forgacs.Vita.Includes bibliographical references.Ph.D. University of Missouri--Columbia 2009.Dissertations, Academic -- University of Missouri--Columbia -- Biological sciences.Cardiovascular disease is a leading cause of death and often requires vascular reconstruction. However, the use of synthetic materials and scaffold-based approaches has shown several limitations for small-diameter blood vessel tissue-engineering, evidenced by the fact that they can elicit adverse host responses and interfere with, rather than guide, direct cellcell interaction as well as assembly and alignment of cell-produced extracellular matrix. Understanding the physical principles of biological self-assembly is thus essential for developing efficient strategies to build living tissues and organs. Here we exploit well-established liquid-like developmental processes (such as tissue fusion, envelopment or cell-sorting phenomena) to engineer scaffold-free, multilayered, small-diameter blood vessels. In particular, we show that apparent surface tensions of the three major vascular cell types (endothelial cells, smooth muscle cells and fibroblasts), determined through the exact solution of Laplace equation, guide their segregation in a multilayered fashion in vitro. Moreover, we introduce a novel rapid-prototyping technology (bioprinting) that allows for directing the self-assembly of the vascular cell types into custom-shaped tubular tissue structures, from single vascular tubes to complex hierarchical macrovascular trees. In addition to its potential for fulfilling the crucial need for small diameter vascular grafts and providing new strategies for vascularization of tissues for transplantation, this physically based approach provides a new insight into cell-patterning and structure formation and questions the paradigm of scaffold-based tissue-engineering

Experimental evaluation of apparent tissue surface tension based on the exact solution of the Laplace equation

The notion of apparent tissue surface tension offered a systematic way to interpret certain morphogenetic processes in early development. It also allowed deducing quantitative information on cellular and molecular parameters that is otherwise difficult to obtain. To accurately determine such tensions we combined novel experiments with the exact solution of the Laplace equation for the profile of a liquid drop under the employed experimental conditions and used the exact solution to evaluate data collected on tissues. Our results confirm that tissues composed of adhesive and motile cells indeed can be characterized in terms of well-defined apparent surface tension. Our experimental technique presents a way to measure liquid interfacial tensions under conditions when known methods fail.This work was supported by the National Science Foundation [FIBR-0526854]

Petit guide pratique pour la gestion des projets d'assainissement : fascicule 1 : les réseaux

L'étude et la mise en œuvre de canalisations d'assainissement doivent répondre à un nombre croissant d'exigences techniques, économiques et environnementales . Le guide apporte des recommandations essentielles pour une gestion rigoureuse des projets à même de répondre à de telles exigences. Il aborde successivement les points suivants : la prise de commande, les différentes contraintes (la loi sur l'eau, les aides au financement, les contraintes d'urbanisme, la coordination générale des réseaux, les études techniques préalables, l'hygiène et la sécurité de chantier, l'exploitation future du réseau), l'ordonnancement du projet, les dossiers techniques, la dévolution des travaux, la préparation de chantier, la qualité de mise en œuvre des remblais, la réception des travaux

Mémento pour la gestion des projets d'assainissement : fascicule 3 : les eaux pluviales

Ce fascicule aborde la gestion des eaux pluviales à deux niveaux : celui de la planification, du fait de l’importance de cette réflexion amont (fiche « enjeux d’urbanisme et d’aménagement »), et celui du projet d'aménagement, public ou privé, de type rénovation urbaine, création de lotissement, de ZAC, de zone industrielle, … Il ne traite pas le projet pluvial "isolé" du projet d'aménagement (création ou réhabilitation de collecteur, dispositif de traitement des eaux pluviales, …). Il insiste sur l’importance de prendre en compte la gestion des eaux pluviales très à l’amont du projet et en associant très tôt l’ensemble des acteurs de l’aménagement

Biofabrication: an overview of the approaches used for printing of living cells

The development of cell printing is vital for establishing biofabrication approaches as clinically relevant tools. Achieving this requires bio-inks which must not only be easily printable, but also allow controllable and reproducible printing of cells. This review outlines the general principles and current progress and compares the advantages and challenges for the most widely used biofabrication techniques for printing cells: extrusion, laser, microvalve, inkjet and tissue fragment printing. It is expected that significant advances in cell printing will result from synergistic combinations of these techniques and lead to optimised resolution, throughput and the overall complexity of printed constructs