Diffusion chamber (DC) culturing of haemopoietic cells: a reliable assay system for regulators of proliferation?

If i.p. DC culturing of haemopoietic cells shall serve as a reliable assay for systemic and/or local peritoneal regulators of proliferation, cell growth must not be restricted by the diffusion capacity through the chamber membranes. Diffusion was assessed by measuring uptake in DC or 51Cr-EDTA of 3H-thymidine, given intravenously to mouse hosts or to chambers incubated in vitro. Fractional incorporation of 3H-thymidine, numbers of mouse spleen colony-forming stem cells, agar colony-forming progenitors (of granulocytes and macrophages), and total cell numbers were taken to reflect cell growth. Changing the diffusion capacity did not lead to marked changes in cell growth; and vice versa, culturing cells under host or chamber conditions that increased cell growth was not associated with an appreciably increased diffusion capacity. Diffusion was increased by replacing Acropor with Millipore DC or by repeatedly cleaning the DC during the culture period. Cell growth was increased by using irradiated rather than normal host mice, and Nucleopore rather than Millipore DC in irradiated mice. Increasing the oxygen delivery to the cultured cells by using polycythaemic and hyperoxic hosts did not enhance cell growth either.