Bone formation in bone marrow organ cultures

Bone tissue composed of typical bone trabeculae containing ground substance with incorporated osteogenic cells and osteoblast layer was formed in organ cultures of bone marrow obtained from adult mice. Electron microscopic properties of the bone formed in vitro were identical to those of the bone tissue in vivo. The mineralization of the bone took place only in the presence of Na-beta-glycerophosphate in the culture medium.     

Contribution of Monocyte/Macrophage Differentiation to the Stromal Layer in Human Long-Term Bone Marrow Cultures

The stroma of bone marrow is a poorly understood tissue which is believed to have important roles in haemopoietic stem cell maintenance and differentiation. We have undertaken immunohistochemical studies of bone marrow stroma in human long-term bone marrow cultures (hLTBMC) and biopsy specimens in order to characterise the cell and matrix components present. We have found two morphological variants of macrophages to be present consistently in hLTBMC stroma, adherent to a substratum of myofibroblastic cells. Large round macrophages appear to actively phagocytic and are formed in hLTBMC regardless of successful establishment of a myofibroblastic cell layer. Elongated macrophages with dendritic processes appear to be non-phagocytic and form only in the presence of a well-established layer of myofibroblasts. Although the functions of these macrophages are not yet known, they have counterparts within intact human bone marrow and their presence in hLTBMC shows some association with the haemopoietic capacity of the cultures.     

The stromal colony-forming cell (CFUf) count in the bone marrow of mice and the clonal nature of the fibroblast colonies they form

The clonal nature of FCFC-derived stromal colonies was tested by chromosomal analysis in mixed cultures of CBA and CBAT6T6 bone marrow cells depleted of macrophages and myeloid cells. Inoculation of the bone marrow cell suspensions in flasks coated with poly-l-lysine has revealed practically no stromal aggregates among the explanted cells. The coincidence of karyotypes within the stromal colonies in the mixed cultures proved that the FCFC-derived colonies were cell clones. It was shown by indirect immunofluorescence with antibodies to type 1 collagen that the mouse bone marrow FCFC-derived colonies consisted of stromal fibroblasts. The cloning efficiency of the bone marrow FCFS depends on the explantation density of cells; a stable colony-forming efficiency could be reached only in the presence of feeder cells (irradiated bone marrow). In the bone marrow cells suspensions obtained by trypsinization the amount of FCFC is markedly higher than in the suspensions of mechanically disaggregated bone marrow cells.     

In vitro study of bone marrow from leukemia patients and patients without hematologic disease

The bone-marrow of 26 patients not affected with hematological diseases and 10 patients with untreated leukemia was investigated according to Dexter in long-term cultures. Survival time and cell content of those long-term cultures started with normal bone marrow were not influenced significantly, if reinoculation was made with autologeneic or allogeneic bone marrow. Even without repeated inoculation, leukemic cells grew for a longer time in long-term cultures than normal bone marrow cells. As far as the outcome of the disease is concerned, no conclusion can be drawn from the duration of cultivating leukemic cells growth.     

Lymphohemopoiesis in culture is prevented by interaction with adherent bone marrow cells from mutant viable motheaten mice

Mice with the recessive "motheaten" (me) or "viable motheaten" (mev) mutations have severe immunologic disturbances and die at an early age. The function of hemopoietic progenitor cells and microenvironmental elements that regulate their growth and differentiation were studied in mev mice with two types of long term bone marrow cultures. Cells from bone marrow of homozygous defective mev/mev mice were non-productive under conditions that normally support replication of stem cells and production of neutrophil granulocytes. Similarly, in a different culture system, lymphocytes were produced from normal littermate, but not mev/mev bone marrow. Initial overgrowth of cells having macrophage-like characteristics occurred in both culture systems with marrow from defective mice. Co-cultures of normal and defective bone marrow cells were always non-productive. In contrast, supernatants of mev/mev bone marrow cultures did not have a detrimental effect on cultures of normal cells, implying that the suppression was cell-associated. Furthermore, there was no evidence for abnormal release of granulocyte or macrophage growth factors in mev bone marrow cultures. A small population of cells in mev/mev bone marrow cultures were morphologically similar to "stromal" cells that support lymphohemopoiesis. Certain culture strategies could be used to enrich for these. mev/mev stromal cells had affinity for normal lymphocytes; however, they did not support lymphocyte growth. The long term bone marrow cultures thus reveal an apparent imbalance in the regulatory mechanisms affected by these single gene mutations. This is manifested by preferential or aberrant growth of one type of adherent cell and a possible functional abnormality of stromal cells. mev mice could provide an ideal model for investigating cell-associated molecules that normally limit progenitor cell replication.     

In vitro hemopoiesis in human micro long-term bone marrow cultures recharged with either allogeneic, T-cell-depleted allogeneic, or syngeneic bone marrow cells

The production of granulocyte-macrophage colony-forming cells (GM-CFC) and the proliferation period in human long-term bone marrow cultures are inferior to murine cultures. There is also evidence that recharge of the cultures after establishing confluent stromal layers will not greatly improve myelopoiesis. Data in the literature indicate that PHA-responsive T lymphocytes persist for up to 5 weeks in human but not in murine long-term marrow cultures. We therefore analyzed the effects of recharging micro long-term bone marrow cultures with bone marrow cell samples depleted by T lymphocytes. Depletion was performed in a complement-mediated cytotoxicity assay by applying the monoclonal antibody CAMPATH-1. Our data show that regardless of whether T cells were removed only at recharge, at both initiation and recharge, or only at initiation, obvious enhancement could neither be achieved in the GM-CFC production nor in the proliferation period. Furthermore, no advantage was seen when using syngeneic marrow cells. We conclude that in allogeneic long-term marrow cultures hemopoiesis is not limited by immunological incompatibilities.     

Blast colony-forming cell binding from CML bone marrow, or blood, on stromal layers pretreated with G-CSF or SCF

Blast colony-forming cells (CFU-BL) represent a specific subpopulation of special primitive progenitors characterized by colony formation only in close contact with a preformed stromal layer. CFU-BL derived from bone marrow of chronic myeloid leukaemia (CML) patients have been proved to adhere poorly to bone marrow derived stromal layers suggesting that the appearance of progenitors and precursors in the circulation is due to a defective adhesion of these cells to the bone marrow microenvironment. In the present experiments the effect of short-term incubation of preformed normal bone marrow stroma on the adherence of CML derived CFU-BL was studied. For stroma cultures bone marrow cells were cultured in microplates in the presence of hydrocortisone. Cultures were used when stromal layers became confluent and no sign of haemopoiesis could be observed. CFU-BL were studied by panning plastic non-adherent mononuclear (PNAMNC) bone marrow or blood cells. 8.9 +/- 2.4 colonies/103 PNAMNC (six experiments) were formed from normal bone marrow on stromal layers and 4.8 +/- 2.1 colonies/103 PNAMNC (five experiments) from CML bone marrow. Colony formation from normal bone marrow was not increased if stromal layers were incubated with 100 ng/mL granulocyte colony-stimulating factor (G-CSF) or stem cell factor (SCF). Incubation of stroma with G-CSF or SCF, however, increased the colony formation of PNAMNC from CML bone marrow or blood significantly. These findings suggest that local concentration of haemopoietic growth factors at the time of panning may influence the attachment of CML progenitors to the stroma.     

THE DEVELOPMENT OF FIBROBLAST COLONIES IN MONOLAYER CULTURES OF GUINEA-PIG BONE MARROW AND SPLEEN CELLS

In monolayer cultures of guinea-pig bone marrow and spleen the development of discrete fibroblast colonies takes place on days 9–12. The linear increase in the number of colonies with increasing numbers of explanted cells and the distribution of male and female cells in mixed cultures support the view that fibroblast colonies are clones. The concentration of colony-forming cells in bone marrow and spleen is approximately 10^-5. Bone marrow culture (but not spleen culture) fibroblasts are capable of spontaneous bone formation in diffusion chambers. Fibroblasts from both bone marrow and spleen cultures are inducible to osteogenesis in diffusion chambers in the presence of transitional epithelium.     

Suppression of natural killer activity in human blood and bone marrow cultures by bone marrow-adherent OKM1-positive cells

Maintenance and regulation of natural killer (NK) cell activity in human bone marrow cultures were studied using K562 leukemia cells as targets. Culture of bone marrow cells in medium supporting long-term generation of myeloid cells resulted in a rapid loss of NK activity in 1-3 days. In contrast, antibody-dependent cytotoxicity to an NK-resistant tumor was maintained for more than 7 weeks. Horse serum, a component of the myelopoietic culture medium, was found to diminish NK cytotoxicity of blood and bone marrow cultures whereas hydrocortisone supplement did not. In addition, an adherent cell is present in bone marrow which greatly inhibits NK activity. Nonadherent bone marrow cells exhibited higher cytotoxicity than unfractionated cells at all days of culture; adherent cells were not cytotoxic to K562. Purified adherent marrow cells inhibited the cytotoxic capacity of nonadherent blood or marrow mononuclear cells during coculture. Indomethacin, an inhibitor of protaglandin synthesis, augmented levels of NK activity in cultures of bone marrow cells, indicating that macrophages may be suppressing this effector function via prostaglandins. Further identification of the adherent suppressor cells came from experiments in which suppression was prevented by treatment of the adherent cells with monoclonal OKM1 antibody plus complement. This study shows that bone marrow-adherent OKM1-positive cells, presumably macrophages, negatively regulate NK activity, and it defines conditions for analysis of the generation and/or positive regulation of NK cells in human bone marrow.     

The construction of high efficiency human bone marrow tissue ex vivo

The successful ex vivo reconstruction of human bone marrow is an extraordinarily important basic scientific and clinical goal. Fundamentally, the system is the paradigm of a complex interactive tissue, in which the proliferation and regulated differentiation of one parenchymal cell type (the hematopoietic stem cell) is governed by the surrounding stromal cells. Understanding and reproducing the molecular interactions between bone marrow stromal cells and stem cells in tissue culture models is therefore the critical step in successful bone marrow tissue culture. Clinically, successful reconstruction of human bone marrow would permit the controlled production of mature blood cells for transfusion therapy, and immature bone marrow stem cells for bone marrow transplantation. In approaching the bone marrow culture system, we recognize the critical role that hematopoietic growth factors (HGFs) play in hematopoiesis. Since stromal cells in traditional human bone marrow cultures produce little HGFs, we have begun by asking whether local supplementation of hematopoietic growth factors via genetically engineered stromal cells might augment hematopoiesis in liquid cultures. The results indicate that locally produced GM-CSF and IL-3 do augment hematopoiesis for several weeks in culture. In combination with geometric and dynamic approaches to reconstructing physiological bone marrow microenvironments, we believe that this approach has promise for reconstructing human bone marrow ex vivo, thereby permitting its application to a variety of basic and clinical problems.     

Stromal cells from murine developing hemopoietic organs: comparison of colony-forming unit of fibroblasts and long-term cultures.

The adherent stromal layer in long-term marrow cultures is essential to the proliferation and differentiation of hemopoietic cells. Adhering cells are heterogeneous and morphologically not adequately characterized. Comparative morphological studies were conducted on adherent cells in short-term clonal assays and long-term cultures derived from liver and bone marrow. Liver and bone marrow at different developmental ages have different hemopoietic activities in vivo and in vitro, as tested via CFU-GM recovery in long-term cultures. Adherent cells from each organ were recovered at an age with high hemopoietic activity (fetal liver and adult bone marrow) and at an age with low hemopoietic activity (neonatal liver and bone marrow). The presence of macrophages, alkaline phosphatase, acid phosphatase, myeloperoxidase, sulfated and non-sulfated glycosaminoglycans (GAGs) and fibronectin was compared. For a given organ, CFU-f colonies showed characteristics similar to those of the confluent adherent stromal layer in long-term cultures. The presence of macrophages and GAGs (sulfated and non-sulfated) in the adherent layer were directly related to the hemopoietic activity. The amount of alkaline phosphatase-positive cells and the amount of fibronectin showed no correlation with the hemopoietic activity of the cultures.     

Interleukin 1 induces multinucleation and bone-resorbing activity of osteoclasts in the absence of osteoblasts/stromal cells

Interleukin-1 (IL-1) is one of the most potent bone-resorbing factors involved in bone loss associated with inflammation. We previously reported that IL-1 prolonged the survival of multinucleated osteoclast-like cells (OCLs) formed in cocultures of murine osteoblasts/stromal cells and bone marrow cells via the prevention of spontaneously occurring apoptosis. It was reported that macrophage colony-stimulating factor (M-CSF/CSF-1) prolongs the survival of OCLs without the help of osteoblasts/stromal cells. The present study was conducted to determine whether IL-1 also directly induces the multinucleation and activation of OCLs. Mononuclear osteoclast-like cells (prefusion osteoclasts; pOCs) were purified using the "disintegrin" echistatin from cocultures of murine osteoblastic cells (MB 1.8 cells) and bone marrow cells. Both IL-1 and M-CSF prolonged the survival and induced the multinucleation of pOCs through their respective receptors. However, actin ring formation (a functional marker of osteoclasts) by multinucleated cells was observed in the pOC cultures treated with IL-1, but not those treated with M-CSF. We previously reported that enriched multinucleated OCLs as well as pOCs placed on bone/dentine slices formed few resorption pits, but their pit-forming activity was greatly increased by the addition of osteoblasts/stromal cells. Here, pit-forming activity of both pOCs and enriched OCLs placed on dentine slices was induced by adding IL-1, even in the absence of osteoblasts/stromal cells. M-CSF failed to induce pit-forming activity in pOC and enriched OCL cultures. These results indicate that IL-1 induces the multinucleation and bone-resorbing activity of osteoclasts even in the absence of osteoblasts/stromal cells.     

Interleukin-3 induces proliferation but not lymphokine activated killer activity from human and murine mononuclear cells

Recombinant IL-3 (rIL-3) is a potent colony stimulating factor capable of stimulating early hematopoietic pluripotential progenitor cells and of supporting the differentiation of multiple cells. IL-3 has also been shown to have effects on mature, differentiated circulating cells including eosinophils and T cells. We evaluated the role of exogenous rIL-3 in the generation of cells with LAK activity from murine splenocytes and human bone marrow, spleen, unseparated PBMC and purified null cell preparations. rIL-3 was unable to generate lytic activity from any of these populations by itself and appeared to decrease LAK activity in bone marrow cultures containing high dose IL-2, (bone marrow derived cells (n = 3) with LAK activity for fresh tumor, mean lytic units(LU) 94.6 +/- 63.5 vs 32.8 +/- 44.8 for IL-2 and IL-2 plus IL-3 cultures, respectively p2 less than 0.05). Unlike previous reports testing murine cells, IL-3 priming and subsequent culture in IL-2 of human unseparated bone marrow cells or human or murine splenocytes, failed to generate long-term cultures with lytic activity. IL-3 did, however, induce a dose dependent stimulation of bone marrow and null cell preparations (mean null cell stimulation (3H Thymidine incorporation) with IL-3, 436 +/- 168 cpm vs 9802 +/- 9799 cpm, for 0 vs 10(3) units of IL-3, respectively n = 4, p2 less than 0.05). Furthermore, in bone marrow, unseparated PBMC and null cell cultures, the addition of rIL-3 generated characteristic large blastic appearing cells with prominent basophilic granules.(ABSTRACT TRUNCATED AT 250 WORDS)     

Corticosteroid-resistant bone marrow-derived B lymphocyte progenitor for long term in vitro cultures

A long-term in vitro culture system derived from murine bone marrow cells can successfully support the growth of B cell precursors, pre-B cells, and IgM-expressing B cells. Intermediates in the B cell developmental pathway are known to have differential sensitivities to the toxic effects of corticosteroids. We demonstrate here that long term B lineage cultures can be established with the corticosteroid-resistant cell population from bone marrow. Kinetics for the establishment and growth of cultures derived from corticosteroid-treated marrow are similar to those observed with control cultures. Cells obtained from both sets of cultures have similar morphologies and ranges of phenotypic markers. These results indicate that the cell responsible for the outgrowth of the long term B lineage cultures is corticosteroid resistant and is likely to be earlier in the B lymphocyte lineage than steroid-sensitive pre-B cells.     

Increased bone mass is a part of the generalized lymphoproliferative disorder phenotype in the mouse

We investigated the bone phenotype of mice with generalized lymphoproliferative disorder (gld) due to a defect in the Fas ligand-mediated apoptotic pathway. C57BL/6-gld mice had greater whole body bone mineral density and greater trabecular bone volume than their wild-type controls. gld mice lost 5-fold less trabecular bone and had less osteoclasts on bone surfaces after ovariectomy-induced bone resorption. They also formed more bone in a model of osteogenic regeneration after bone marrow ablation, had less osteoclasts on bone surfaces and less apoptotic osteoblasts. gld and wild-type mice had similar numbers of osteoclasts in bone marrow cultures, but marrow stromal fibroblasts from gld mice formed more alkaline phosphatase-positive colonies. Bone diaphyseal shafts and bone marrow stromal fibroblasts produced more osteoprotegerin mRNA and protein than wild-type mice. These findings provide evidence that the disturbance of the bone system is a part of generalized lymphoproliferative syndrome and indicates the possible role of osteoprotegerin as a regulatory link between the bone and immune system.     

Pre-CFU-f: young-type stromal stem cells in murine bone marrow following administration of DNA inhibitors

Occurrence of young-type stromal stem cells (defined here as "pre-CFU-f") in murine bone marrow is reported in this study. Two consecutive intraperitoneal (i.p.) cytosine arabinoside (ara-C) injections were administered to C57B1 mice (2 X 200 mg/kg at 6-h intervals). Two days later the bone marrow was collected and assayed for colony-forming units-fibroblastoid (defined here as "CFU-f"). In additional experiments, ara-C-treated marrow was exposed in vitro to hydroxyurea (HU; "hydroxyurea killing test"), prior to plating, to establish the cycling state of stromal stem cells. In separate cultures of ara-C-treated marrow, replating of adherent cells was carried out up to quaternary sub-cultures. The results indicate ara-C-treated marrow produces approximately 20% "huge" fibroblastoid colonies (approximately 5 mm diameter versus 0.5-2 mm normal size); most stromal stem cells producing huge colonies are cycling cells; and adherent cells from primary ara-C-treated marrow cultures replated to secondary cultures produce adherent layers with double the number of cells than in the control secondary cultures. We conclude that the ara-C-treated murine bone marrow contains certain young-type cycling stromal stem cells which we refer to as pre-CFU-f. These stem cells produce huge fibroblastoid colonies in culture, indicating that they probably go through more cell cycles than CFU-f during the culture period. Alternatively, pre-CFU-f may have a higher self-replicative capacity than CFU-f.     

Origin of stromal bone marrow mechanocytes according to the results of typing them by isoantigens and chromosomal markers]

The bone marrow of radiochimaeras and heterotopic bone marrow transplants were used to study the origin of precursors of the fibroblasts growing in the monolayer cultures of hemopoietic tissue. In the bone marrow explants of the (C57BL/6 X CBA) F1 mice, in which the CBA bone marrow was transplanted following the lethal irradiation, the fibroblasts grown in the colonies were of recipient origin judging by isoantigens in the reaction of indirect immunofluorescence with the anti-C57BL/6-serum. At the same time in the bone marrow explants from heterotopic transplants (CBA leads to CBA X C57BL/6) the fibroblasts grown in colonies were of donor origin. The cultures of hemopoietic cells of the bone marrow of females heterotopically transplanted in the singenic male (guinea pigs Huston) contained only fibroblasts which were of donor origin judging by sex chromosomes in the metaphase plates of dividing cells. Hence, the bone marrow precursors of fibroblasts do not depend histogenetically on hemopoietic cells and are not replaced at the expense of repopulating cells of the second partner.     

The production of factors regulating the proliferation of haemopoietic spleen colony-forming cells by bone marrow macrophages

Media conditioned by normal murine bone marrow cells contain an inhibitor of haemopoietic spleen colony-forming cell proliferation that is concentrated in a nominal 50-100K fraction. Media conditioned by regenerating marrow cells contain a proliferation-stimulatory activity that is concentrated in a nominal 30-50K fraction. Cell separation experiments demonstrated that the activities are produced by adherent, phagocytic, radioresistant, Thy 1.2- Fc+, F4/80+ cells. Cultured macrophages, obtained from long-term marrow cultures or derived from progenitor cells in methyl cellulose cultures are also capable of producing inhibitory and stimulatory activities. The results are consistent with macrophages being an important source of stem cell proliferation regulators in the bone marrow.     

Effects of Murine Erythroleukemia Inducers on Mouse Erythroid Colony Formation in Culture

The effect of various agents which are known to increase the differentiation of Friend erythroleukemia cells was investigated in cultures of mouse bone marrow cells. N, N-dimethylacetamide (5 and 15 mM) and acetamide (60 mM) significantly increased the number of erythroid colonies observed. Tetramethylurea, dimethylformamide, pyridine N-oxide, and butyric acid were ineffective. Dimethylsulfoxide at a concentration of 1% significantly increased colony number in cultures of marrow cells obtained from male mice, but had no effect in cultures of female bone marrow cells.