Erythropoietic response of bone marrow cells cultivated in diffusion chambers

Decalcified tooth matrix powder induces new bone formation and hematopoietic microenvironment in the mouse

Implants of bone and tooth matrix powder were placed subcutaneously (s.c.) on intraperitoneal (i.p.) Mitex or Polyvic membranes. Implants were removed for histology after 1-24 weeks. Macrophages, fibroblasts, and vascular sinusoids infiltrated around bone and tooth matrix particles after one week. In the s.c. tooth matrix implants, a few sites of cartilage formation and ossification developed at two weeks, and by three weeks granulocytopoiesis and megakaryocytopoiesis developed adjacent to new bone; erythropoiesis was not observed. In s.c. bone matrix implants and in the i.p. artificial membranes coated with bone or tooth matrix powder, ossification or hematopoiesis was not observed. Small numbers of CFU-s, CFU-nm, BFU-e, and CFU-e appeared 10-20 days after s.c. implantation of tooth matrix; none were detected in s.c. bone matrix implants.

Hematopoiesis on cellulose ester membranes (CEM). IV. Effect of variation in membrane composition and pore size

Artificial membranes composed of mixed cellulose nitrate and acetate esters (MCEM), polytetrafluoroethylene (Mitex), cellulose acetate (Celotate), polyvinylchloride (Polyvic), polycarbonate (Nuclepore), or linear polyethylene with pore sizes ranging from 0.45 mu to 70 mu were coated on their inner surfaces with a paste of bone marrow, diaphyseal bone, or cells proliferating in vitro on the inner surfaces of curetted femurs obtained from syngeneic mice. Squares of these membranes were folded into thirds, stapled to form an open-ended, tube-like structure, and implanted i.p. into mice. At intervals of 6-12 months, the membranes were removed and studied histologically. Control membranes not coated with any substance were also studied. Trilineal hematopoiesis, bone formation, sinusoidal structures, fat cells, and hemosiderin-laden macrophages were found with all three coatings in the tubes formed from the MCEM or Mitex membranes. The Celotate and Polyvic membranes coated with bone cells and the Polyvic membranes coated with marrow also developed trilineal hematopoiesis and new bone tissue. The remaining membranes essentially had only fibrous tissue, except for rare foci of hematopoiesis which developed on an occasional 30 mu (but not 70 mu) pore size linear polyethylene membrane. The results of these studies suggest that hematopoiesis and bone cell formation on these artificial membranes is closely linked, and that there may be some interaction between membrane constituents and the cells destined to form the hematopoietic support layer in the fostering of hematopoiesis. Whether this interaction is stimulatory or inhibitory was not defined by these studies.