Hematopoiesis on cellulose-ester membranes (CEM). VI. Histochemical evaluation of stromal-CEM interactions after stromal enrichment

Histochemical procedures were used to elucidate differences in the distribution of glycosaminoglycans (GAGs) and glycoproteins (GPs) in tubes made of cellulose-ester membrane (CEM) in six weeks and 12 months following intraperitoneal (i.p.) implantation. After six weeks, CEM tubes coated on their inner surfaces with bone marrow (BM), bone homogenate (BH), or regenerating medullary mesenchyme (M) contained a highly vascularized loose connective tissue and scattered hematopoietic elements. Numerous mononuclear cells were seen at the stromal-CEM interface and infiltrating the CEM. At the site of infiltration, there were accumulations of GPs and nonsulfated acidic GAGs. The remainder of the CEM contained limited amounts of sulfated and nonsulfated GAGs. By 12 months, both coated and uncoated CEMs were saturated with sulfated and nonsulfated acidic GAGs. However, only coated CEM tubes contained trilineal hematopoiesis surrounded by a shell of bone that was incorporated into the structure of the CEM. Exterior to the bone, the CEM was infiltrated with GPs, some of which were acidic and nonsulfated, possibly sialoglycoproteins. No bone or glycoproteins infiltrated the uncoated CEMs. The stroma supporting trilineal hematopoiesis contained GPs and nonsulfated acidic GAGs, but not sulfated acidic GAGs. However, both sulfated and nonsulfated GAGs were found in the fibrous connective tissue filling the lumens of uncoated CEMs. While CEM tubes accumulate peritoneal GAGs that may be conducive for the retention, differentiation, and proliferation of osteogenic and other stromal cells provided by coatings of BM, BH, or M, it is these cells that produce the bone and glycoproteins that appear to contribute to a microenvironment conducive to trilineal hematopoiesis. However, the relative roles of these substances in this process remain to be elucidated.