An hypothesis on the role of cellular colloid osmotic pressure in determining behavior of cells in vitro including anchorage dependency and maintenance of the differentiated state

Review-progress in concept and practice of growing anchorage-dependent mammalian cells in three dimension

Tissue culture has played a major role in the rapid advances made in medical science in the past 50 yr. The full potential of the technique, however, is limited by the fact that growth of cells is usually restricted to a monolayer accompanied by major decreases in many of their tissue-specific functions. This has been shown to be due, in large part, to the inadequate oxygenation of cells growing in tissue culture dishes. Studies that show that the high charge density and rigidity of the plastic and glass surfaces used for culture are also major factors limiting growth of cells to a monolayer, are reviewed. A new culture system has been developed in which cells are grown on substrata made using perfluorocarbons (PFCs) coated with collagen type 1 and other adhesive factors. Perfluorocarbons have a much higher solubility for oxygen than water and have been used as oxygen delivery systems to protect cells from hypoxia. These new PFC-based substrata can provide both the optimal level of oxygen cells need to maintain differentiated functions and the flexible and weaker type of adhesion that allows cells to round up, interact with each other, and when provided with adequate nutritional support, to grow in three dimension.

The effect of alginate and hyaluronate on the viability and function of immunoisolated neonatal rat islets

Recent observations suggest that the extracellular matrix plays a role as regards the viability and morphological integrity in long-term culture of Langerhans islets. For the present study we encapsulated neonatal rat islets without extracellular matrix (WEM), with alginate solution (AL) and with hyaluronate solution (HY) into cuprophane hollow fibers. Function was tested after week 1 and 5. The insulin release of WEM encapsulated islets decreased significantly during the culture period. In contrast to this, AL and HY embedded islets had stable secretion values throughout the whole cultivation. Histological examination confirmed that viability of HY and of AL embedded islets differed significantly from that of WEM encapsulated islets. Furthermore, HY seems to be a more advantageous environment to immunoisolated islets than AL. Both the insulin secretion values and the viability of HY embedded islets were higher than of AL embedded islets. We conclude that an extracellular matrix is important for immunoisolated islets, to maintain their function and morphological integrity and that HY is especially suitable for this application.

A theory of carcinogenesis based on an analysis of the effects of carcinogens

Carcinogenic stimuli appear to act on target cells (and their daughters) by one or more of three mechanisms. The first is by oxidation of membrane component molecules on the extracellular surfaces of their plasma membranes. The second is by chronic and continuous impingement of electrons on the extracellular surfaces of their plasma membranes and the third is by relocation of predominantly basic molecules to the cytoplasmic surfaces of their plasma membranes. This latter effect in turn causes electrostatic attraction of image charged acidic molecules to the extracellular surfaces to balance the transmembrane charge of the target cells. Each of the above mechanisms results in a condition of increased electronegativity of the extracellular surfaces of plasma membranes of the target cells and their daughters. A theory of transformation is advanced based on the above related modes of action and it is used to explain some previously unexplainable properties of tumors.