Développement de milieux de culture permettant un transport et un transfert d'oxygène accru dans des systèmes de culture cellulaire tridimensionnels

Abstract

Oxygen is an essential nutrient for proper cell growth, although it is also often the limiting element. This is especially true when one wishes to grow and differentiate large masses of cells or tissues. Growth of large tissue mass creates hypoxic zones, where seeded cells eventually die because of improper oxygen accessibility due to non-existing or remote blood microvessels. This problem arises since oxygen has a poor solubility in aqueous culture media and because the oxygen molecules do not reach the cells in the center of cell aggregates. In order to palliate to this problem, two different types of oxygen carriers were considered and developed: 1) Perfluorocarbon-based emulsions (PFC), and 2) Liposomes encapsulating hemoglobin (LEH). In this work, PFC/EYP emulsions were prepared and their physico-chemical properties were evaluated using dynamic light scattering (DLS) and electron microscopy (TEM, SEM). Cytotoxicity assays were performed to test their cytocompatibility and these tests revealed important and irreversible cytotoxicity. For this reason, further studies on these types of carriers were suspended. PEGylated liposomes encapsulating hemoglobin were also prepared and characterized for size-distribution and temperature effect, using DLS and electron microscopy. Although exposure of LEH to cells in monolayers demonstrated some toxicity, 3-D cultures of endothelial cells did not. LEHs preparations were then loaded with oxygen and their transport and transfer capacities were analyzed. The outcome of this project demonstrated the ability of liposomes-encapsulating hemoglobin to transport and deliver efficiently oxygen, as well as the promotion of cell proliferation and the decrease of cellular hypoxia in a three-dimensional culture environment.