Hematopoiesis on cellulose ester membranes (CEM). II. Enrichment of the hematopoietic microenvironment by the addition of selected cellular elements.

Cellulose ester membranes (CEM) were folded into a trilaminar open-ended tube which was implanted into the peritoneal cavity of mice. CEM rapidly acquired a stromal core with many features of marrow such as fat, fibroblasts, an abundant sinusoidal microcirculation and monocyte-macrophage-like cells. CEM took up 59iron, 99technetium sulfur colloid and produced CSF in in vitro culture but their microenvironment supported only granulopoiesis. CEM were coated on their interior surfaces with bone marrow or regenerating medullary cavity mesenchyme or bone but the stromal cores supported only granulopoiesis after 3 weeks to 3 months of implantation. CEM coated with spleen and implanted into mice developed trilineal hematopoiesis within 6 weeks with abundant erythropoiesis and megakaryocytopoiesis in addition to granulopoiesis. These CEM differed from splenic tissue in that only scattered lymphoid tissue was present. CEM coated with bone marrow and bone developed trilineal hematopoiesis but only after3--6 months of peritoneal implantation. CEM coated with regenerating medullary cavity mesenchyme failed to develop trilineal hematopoiesis. Cyclophosphamide injection did not enhance hematopoiesis. These experiments indicate that splenic, marrow and bone tissue contain stromal elements capable of being transferred onto CEM which then develop a microenvironment capable of supporting trilineal hematopoiesis.