Critical association concentration assembly

A method for growing mammalian cells in culture into a three-dimensional, tubular matrix, said method comprising the steps of:

• (a) placing a tubular core centrally inside a tubular limiting membrane to form an inside chamber, wherein the limiting membrane restricts diffusion of macromolecules from the inside chamber, but allows diffusion of culture medium into the inside chamber;
• (b) introducing the cells into the inside chamber;
• (c) placing the tubular limiting membrane and tubular core inside a culture medium holder to form an outside chamber;
• and
• (d) supplying culture medium to the outside chamber;
• so that the macromolecules secreted by the growing cells are restricted by the tubular limiting membrane, while the culture medium may traverse the tubular limiting membrane from the outer chamber to the inner chamber;
• and
• (e) maintaining the culture medium holder and cells under conditions conducive to the growth of the cells;
• until the cells have formed a tubular three-dimensional cellular and extracellular matrix inside the tubular limiting membrane that differs substantially from the pattern of cells that would form in an otherwise similar holder under otherwise similar conditions, but lacking the limiting membrane.

An apparatus for growing cells in culture to maintain macromolecules secreted by the cells in close proximity to the cells, said apparatus comprising:

• (a) a culture medium holder;
• and
• (b) a limiting membrane adapted to be placed into said culture medium holder to divide said culture medium holder into a first chamber with growing cells and culture medium and a second chamber with additional culture medium;
• wherein said limiting membrane restricts diffusion of macromolecules out of the first chamber but allows the diffusion of the culture medium.

An apparatus for growing mammalian cells in culture into a three-dimensional, tubular matrix, said apparatus comprising:

• (a) a culture medium holder;
• (b) a tubular core centrally located inside said culture medium holder;
• and
• (c) a tubular limiting membrane placed around said tubular core to divide said cell culture medium holder into an inside chamber for holding the cells and culture medium, and an outside chamber with culture medium but without a substantial number of the cells;
• wherein said tubular limiting membrane restricts diffusion of macromolecules from said inside chamber.