Granulocyte-macrophage colony stimulating factor suppresses lipopolysaccharide-induced osteoclast-like cell formation in mouse bone marrow cultures

Lipopolysaccharide (LPS) is a potent bone resorbing factor. We investigated the effect of LPS on osteoclast formation in three types of cultures. LPS inhibited osteoclast formation induced by 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], in a dose-dependent manner, in cultures of whole bone marrow cells without dexamethasone. LPS increased the amount of granulocyte-macrophage colony stimulating factor (GM-CSF) in the culture supernatant, and anti-GM-CSF antiserum almost abolished the inhibition of osteoclast formation by LPS, thereby indicating that GM-CSF generated by treatment with LPS may be responsible for the inhibition of osteoclast formation. In cultures with dexamethasone, the amount of GM-CSF was decreased to one-third of that with 1,25(OH)2D3 alone and was not changed by treatment with LPS. In this culture system, LPS enhanced osteoclast formation. In the coculture system of nonadherent bone marrow cells and a stromal cell line in the presence of 1,25(OH)2D3 and dexamethasone, where no detectable GM-CSF was present in the supernatant, LPS markedly enhanced osteoclast formation, whereas exogenously added GM-CSF (100 pg/ml) almost completely inhibited osteoclast formation. LPS stimulated pit formation on dentin slices by the osteoclast-like cells formed by in vitro culture system.

Induction of mononuclear precursor cells with osteoclastic phenotypes in a rat bone marrow culture system depleted of stromal cells

The importance of bone stromal cell involvement in osteoclast differentiation has been suggested. However, the detailed mechanism of its regulation is unclear. We investigated whether the soluble factors from osteoblastic cells influence osteoclast lineage cells in a population of rat bone marrow cells depleted of stromal cells. We show here that hematopoietic progenitor cells differentiate into mononuclear precursor cells, the preosteoclasts, that strongly express certain osteoclastic phenotypes in the absence of stromal cells. The multinucleation of the preosteoclasts occurred only in the presence of 1,25 dihydroxyvitamin D3 and stromal cells. The preosteoclasts themselves did not have dentine-resorbing activity, but they could differentiate into multinucleate osteoclast-like cells having such activity in the presence of rat primary osteoblasts. This culture system is a unique differentiation system for preosteoclast induction.

Heat-treated osteoblastic cell (ROS17/2.8)-conditioned medium induces the formation of osteoclast-like cells

To study the effects of osteoblast products on osteoclast formation, we added the conditioned medium (CM) of rat osteoblastic cell line ROS17/2.8 to rat bone marrow cultures, in which tartrate-resistant acid phosphatase (TRAP)-positive osteoclast-like multinucleate cells (MNCs) formed in the presence of 10(-8) M 1,25-dihydroxyvitamin D3 (1,25(OH)2D3). The formation of 1,25(OH)2D3-dependent TRAP-positive MNC at day 7 of culture was strongly inhibited by the > 10 kDa fraction of ROS17/2.8 cell-CM (ROSCM), but heat treated ROSCM (htROSCM) expressed marked stimulation in the formation of the MNCs. The expression of several osteoclastic phenotypes of the MNCs induced by htROSCM and 1,25(OH)2D3 was more enhanced compared with that of the MNCs induced by 1,25(OH)2D3 alone. The MNCs induced by htROSCM and 1,25(OH)2D3 were highly motile, were sensitive to calcitonin (CT), and had high bone resorbing activity. These data suggest that htROSCM promotes the osteoclast differentiation in the presence of 1,25(OH)2D3 in a rat bone marrow culture system. The stimulatory activity of TRAP-positive MNC formation in htROSCM is derived from heat-stable protein(s) that is (are) thought to be different from colony-stimulating factors (CSFs) such as macrophage-CSF (M-CSF) or granulocyte-macrophage-CSF (GM-CSF).

[Production of monoclonal antibodies against osteoclasts of rat]

In mammals, it has been difficult to collect the authentic osteoclasts on a large scale. Recently we established a culture system for forming osteoclast-like multinucleated cells (MNCs) which exhibited many characteristics of osteoclasts. MNCs instead of authentic osteoclasts were used as immunogen to establish the hybridomas which secrete monoclonal antibodies against the osteoclasts by in vitro immunization. We obtained two monoclonal antibodies, HOK 1 and HOK 2. HOK 1 showed intense immunoreactivity with MNCs, mononuclear cells and putative migratory traces of MNCs on the culture dishes, but it had weak reactivity with the stromal cells. HOK 2 also showed strong reactivity with MNCs, mononuclear cells, and the very limited area of the culture dishes just facing to one side of some MNCs. The stromal cells were faintly stained with HOK 2. In th paraffin sections of tibiae, both antibodies intensely stained osteoclasts, osteoblasts and osteocytes. The bone matrix was weakly stained by HOK 2 but not by HOK 1. The present observations indicated that HOK 1 and HOK 2 could recognize the common antigen expressed on cells both involving in the bone formation and resorption. The antigens recognized by HOK 1 and HOK 2 were shown to exist on the putative traces of motile MNCs. These antibodies would be available to investigate the mechanisms of the 'bone remodeling' as a functional marker of bone cells.

Monoclonal antibody G6K12 specific for membrane-associated differentiation marker of human stratified squamous epithelia and squamous cell carcinoma

Monoclonal antibody (G6K12) specific for differentiated keratinocytes was developed using in vitro immunization against the SCC-25 cell line. G6K12 only recognized stratified portions of cultured SCC-25 cells. Immunohistochemical examination using normal human oral mucosa showed that specific G6K12-reactivity was limited to the lower spinous-cell layers, while this antibody weakly bound to cells in basal-cell layers as well as in the upper spinous, granular and cornified-cell layers. G6K12 was also reactive to keratinocytes in most moderately- and well-differentiated SCC tissues. Immunoelectron microscopic examination further demonstrated that the G6K12-immunoreactive area was at the outer surface of the entire plasma membrane, including the microvilli of stratified SCC-25. G6K12-binding was reduced 50% by the treatment of native cells with glycoendoceramidase for 2 h. These results suggest that G6K12 recognizes a plasma membrane-anchored glycoconjugate which is specific for differentiated keratinocytes.

Recombinant LD78 protein, a member of the small cytokine family, enhances osteoclast differentiation in rat bone marrow culture system

Cytokine LD78 is a member of the small inducible protein family involved in cell growth, wound healing and inflammation. However, its exact function is not known. In this study, we demonstrated that recombinant LD78 alpha and its variant LD78 beta proteins stimulate osteoclast-like cell formation in rat bone marrow cultures in the presence of 1 alpha, 25-dihydroxyvitamin D3. This enhancing activity was independent of prostaglandin synthesis. This is the first report which describes the effect of proteins involved in the small inducible protein family on the differentiation of osteoclasts.

Demonstration of type III collagen in the dentin of mice

It has been reported that, although type III collagen is present in human dentin where there is dentinogenesis imperfecta and in reparative dentin, it is absent in normal dentin. In a preliminary study, however, we observed evidence showing that small amounts of fibers showing positive labeling for type III collagen are present in the molars of normal mice. In the present study, in order to localize type III in normal dentin, immunofluorescent and immunoelectron microscopic examinations of the molars of normal mice were carried out using affinity-purified antibodies to mouse type III and type I collagen. The fibers positive for type III collagen were much more frequently observed in the root than in the crown. These fibers ran in peritubular dentin or near that in parallel to them. The incidence of the existence of dentinal tubules associated with type III collagen-positive fibrils either in or near peritubular dentin was low. These fibrils positive for type III collagen showed a clear cross-banding. In dentinal tubules, unusual collagen aggregations, segment long-spacing-like and fibrous long-spacing-like structures which were intensively stained for type I collagen but weakly so for type III collagen were seldom observed. Type III collagen-positive fibers often extended towards the pulp beyond the odontoblast layer, suggesting that these fibers were produced, at least partly, by the pulp cells.

Interaction between polyethylene films and bromhexine HCl in solid dosage form. V. Effect of packaging materials on the sorption of bromhexine HCl

A prevention method of the sorption of bromhexine HCl to plastic materials used in packaging was investigated. Four kinds of plastic packaging materials were used: Polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP) and polyacrylonitrile (PAN). Three polyethylenes having different densities were used. No effect of PE density on the sorption of bromhexine HCl from granules was observed. The effects of different kinds of plastics on the sorption of bromhexine HCl from solution and granules were studied. The sorption of bromhexine HCl to PAN, which had a high relative dielectric constant, was the most depressed among the four plastics. The sorption of meclizine HCl to PAN from the solution was also lowest, the same as bromhexine HCl.

Primary and secondary culture of rat ameloblasts in serum-free medium

Enamel is the hardest tissue in vertebrates. Ameloblasts are derived from epithelial cells and are responsible for enamel formation. They secrete enamel matrix components in which amelogenins are the major proteins, the biochemical properties of which are well known. However, little is known about the characteristics of ameloblasts themselves or about the functions of amelogenins. In this study, we developed a novel primary and secondary culture system for ameloblasts using a monoclonal antibody which recognized amelogenin (En3). The cell layer on dentine removed from rat mandibular incisors was isolated and cultured in low calcium, serum-free medium. Primary culture was performed on collagen-coated culture plates and typically, two types of cells appeared. One major type changed morphology after the addition of a high concentration of calcium to the medium. Expression of amelogenin was shown as cytoplasmic particles in these cells using En3. In the secondary culture, expression of amelogenins was also observed. In this system, the cells grew and maintained the expression of amelogenin for about 3 weeks.

Demonstration of amelogenin in the enamel-free cusps of rat molar tooth germs: immunofluorescent and immunoelectron microscopic studies

The enamel-free cusps of 1-4 day-old rat mandibular first molars were investigated using the monoclonal antibody En3 against rat amelogenin at light and electron microscopic levels in order to clarify whether the enamel-free cusp is virtually devoid of enamel. At 1 day after birth, there were presecretory ameloblast-like cells (PALCs), which were short and were not polarized, at the cusp tips. They were close to the outer enamel epithelium. Hematoxylin positive enamel matrix was not distinctly observed in the enamel-free cusp by light microscopy, but almost continuous immunofluorescence for amelogenin was detected at the interface between PALCs and dentin. The penetration of immunopositive material toward the dental pulp was also observed in the enamel-free cusp. At 4 day after birth, both in the frontal section and in the horizontal section, almost continuous immunofluorescence was recognized at the interface between PALCs and dentin in the enamel-free cusp. The penetration of amelogenin toward the dental pulp was not seen in the enamel-free cusp. By immunoelectron microscopy, immunolabelling was recognized in the Golgi apparatus of PALCs, in a layer of amorphous material at the interface between PALCs and dentin, and in stippled material-like substance in the intercellular space between PALCs. Although no basement membrane was observed beneath PALCs, they did not have Tomes' processes. These investigations suggest that PALCs in the enamel-free cusp differentiate into the secretory cells and that they can synthesize and secrete the amorphous material containing amelogenin at the interface between PALCs and dentin. The penetration of amelogenin toward the dental pulp might play a role in the interaction between PALCs and odontoblasts in the enamel-free cusp and/or the initiation of mineralization of predentin.

Interaction between polyethylene films and bromhexine HCl in solid dosage form. IV. Prevention of the sorption by addition of magnesium aluminum silicate

The effects of magnesium aluminum silicate (MAS) addition on the sorption of bromhexine HCl to polyethylene film in tablets were studied. The addition of MAS prevented the sorption of bromhexine HCl to polyethylene film. In order to investigate the mechanism, the interaction between bromhexine HCl and MAS was studied by the powder X-ray diffraction method. It was observed that bromhexine HCl was preferentially adsorbed to the surface of MAS rather than to polyethylene film. The adsorption was accelerated at high temperature and reduced pressure conditions. The sorption of bromhexine base and bromhexine HCl to packaging material were compared using tablet dosage forms. The sorption of bromhexine base to polyethylene film was greater than that of bromhexine HCl.

Heterogeneous distribution of the precursor of type I and type III collagen and fibronectin in the rough endoplasmic reticulum of palatal mesenchymal cells of the mouse embryo cultured in ascorbate-depleted medium

In order to examine the intracellular distribution of precursors of type I and type III collagen and fibronectin in the palatal mesenchymal (MEPM) cells of the mouse embryo cultured under ascorbate-deficient conditions, immuno-electron-microscopic studies were carried out by use of affinity purified antibodies for these proteins. MEPM cells were obtained from the palatal shelves of 14-day-old mouse fetuses and cultured for 3-7 days in medium, either with or without 50 ng/dish/day ascorbic acid. Results obtained were as follows: (1) Although the rough endoplasmic reticulum (rER) of MEPM cells cultured for 5 days in ascorbate-supplemented medium was flattened, that in cells cultured in ascorbate-deficient medium had a distended or vesicular appearance. (2) Vesicular or distended rER showed heterogeneous staining for both type I and type III collagen, namely, some parts of rER showed positive staining for both types of collagen, while others showed negative staining. (3) Both type I and type III collagen showed codistribution in the same vesicular rER. (4) Vesicular rER showed negative or very faint labelling for fibronectin. These results may suggest regional differences in the function of rER.

12-O-tetradecanoylphorbol-13-acetate inhibits osteoclast-like cell differentiation in rat bone marrow cultures by inducing macrophage polykaryons

The tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) at 10(-9) M stimulated the formation of osteoclast-like multinucleated cells (MNCs) in the presence of 1 alpha,25-dihydroxyvitamin D3 in rat bone marrow cultures. However, at 10(-7) M, it clearly inhibited 1 alpha,25-dihydroxyvitamin D3-dependent osteoclast-like MNC formation at 6 days of culture. In cultures treated with 10(-7) M TPA, numerous MNCs that lack the marker enzyme tartrate-resistant acid phosphatase (TRAP) were formed. These TRAP-negative MNCs had neither receptors for calcitonin nor dentine-resorbing activity. The reactivity of the cells against antirat macrophage antibodies was completely different from that of authentic osteoclasts. These data suggest that TRAP-negative MNCs formed in the presence of 10(-7) M TPA are macrophage polykaryons. Time-course studies showed that 10(-7) M TPA stimulated osteoclast-like MNC formation at 4 days of culture, but these osteoclast-like MNCs were converted to TRAP-negative MNCs. Furthermore, 1-(5-isoquinolinyl-sulfonyl)2-methylpiperazine (H-7), a protein kinase-C inhibitor, inhibited osteoclast-like MNC formation in a dose-dependent fashion. These results suggest that activation of protein kinase-C may play a role in osteoclast differentiation.

Trypsinized osteoclast-like multinucleated cells formed in rat bone marrow cultures efficiently form resorption lacunae on dentine

Rat bone marrow cultures containing 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25(OH)2D3] formed multinucleated cells (MNCs) that had many characteristics of osteoclasts. These MNCs, which have a tartrate-resistant acid phosphatase (TRAP) activity, could be classified into two morphological types: one type had smooth cellular margins (smooth-margined MNCs) and the other type had irregular spike-like margins (stellate MNCs). When bone marrow cells depleted of authentic osteoclasts were seeded and cultured on dentine slices, only low numbers of resorption lacunae could be detected. However, when preformed MNCs were detached by trypsinization and replated on dentine slices, numerous resorption lacunae were observed by scanning electron microscopy on these slices. Formation of lacunae occurred reproducibly during the five to ten days of culture. We also examined the effect of retinoic acid on TRAP-positive MNC formation in this bone marrow culture system. Although RA inhibited total TRAP-positive MNC formation, it increased the ratio of stellate MNCs to smooth-margined MNC, suggesting that RA may have the ability to regulate the formation of active osteoclasts.

[Effects of EGF and retinoic acid on differentiation of squamous cell carcinoma cells]

Using monoclonal antibody, G6K12, a novel differentiation marker of keratinocyte, we examined the effect of EGF and retinoic acid on the differentiation of SCC-25, a cell line established from human squamous cell carcinoma. EGF inhibited the expression of cell-surface differentiation marker in low cell-density, but not in high cell-density. Retinoic acid (more than 10(-8) M) inhibited the expression of the antigens. The terminal differentiation of SCC-25 cells occurred at the condition of high cell density. These results obtained demonstrate that EGF and retinoic acid inhibit the terminal differentiation of SCC-25 cells, and that the cell density is the important factor for the commitment of the terminal differentiation.

Immunohistochemical demonstration of amelogenin penetration toward the dental pulp in the early stages of ameloblast development in rat molar tooth germs

In order to examine the synthesis and secretion of enamel protein by ameloblasts in their early stages of development, immunohistochemical localization was carried out at light and electron microscopic levels using a monoclonal antibody produced in a preliminary experiment. Materials used were tooth germs of mandibular first molars of rats at 0-5 days after birth. Immunoblot analysis after two-dimensional electrophoresis revealed that antigen molecules recognized by the monoclonal antibody were amelogenins of 26-28 kDa (pI, 6.6-7.0). An immunohistochemical examination using this monoclonal antibody demonstrated that the presecretory ameloblasts in their early stages of differentiation both synthesized amelogenin and secreted through a classical merocrine secretory pathway. In some presecretory ameloblasts as well as ameloblasts we observed the distended cisternae of rough endoplasmic reticulum (rER) which demonstrated heterogenous immunolabelling. The immunolabellings were also detected in the predentin as well as the intercellular spaces of odontoblasts and dental pulp cells which indicated penetration of amelogenin from the presecretory ameloblast layer to the dental pulp. The presence of coated pits at the plasma membrane of odontoblasts in close proximity to enamel protein along with the immunolabelling of lysosomes of the odontoblasts suggests the phagocytosis of the enamel protein into the odontoblasts. These observations suggest the possibility that the penetration of enamel protein toward the dental pulp and odontoblasts plays a role in the interaction between ameloblasts and odontoblasts.

[Interaction between polyethylene films and brombexine HCl in solid dosage form. II. Effects of moisture property on the sorption of the drug]

The interaction between bromhexine HCl and polyethylene containers was studied in solutions and in tablet packaging systems. Various bromhexine HCl aqueous solutions of different pHs were stored in polyethylene containers at 25 degrees C. The remaining amount of bromhexine HCl was determined by high performance liquid chromatography. It was observed that the transition of bromhexine HCl to polyethylene was inhibited by the addition of some surfactants into the solution, and by lowering the solution pH. In the solid dosage forms, influences of the additives were also studied. It was observed that the decrease of the content of bromhexine HCl in the solid dosage form was inhibited by the addition of acids (citric acid, tartaric acid) and surfactant (sodium dodecyl sulfate) and accelerated by the addition of sodium bicarbonate, similarly to those in solutions. The results indicated that the transition to polyethylene films was influenced by the molecular state of bromhexine HCl.

[A case of empyema after plastic ball plombage cured by air-plombage method]

Conventionally, thoracoplasty has been conducted for empyema space after removal of plastic ball for empyema cases after plastic ball plombage. We applied air-plombage method for empyema as a new operative technique. The patient was a 56-year-old man who had had 37 plastic balls implanted for the treatment of pulmonary tuberculosis 39 years ago. In April 1988 he was admitted to our department complaining bloody sputum and high fever. Roentogenographic findings revealed residual middle lobe with normal size and plastic balls some with niveau. From these findings, the case was diagnosed as partial empyema after plastic ball plombage. In June 1988 air-plombage method was performed. At 5 months after operation, reinflation of the residual pulmonary lobe was seen accompanying improvement of pulmonary functions; FVC increased from 1780 ml to 1910 ml and blood gas PaO2 from 75.0 mmHg to 88.3 mmHg. Blood loss during operation was about 2,000 ml, which was smaller than the conventionally experienced amount of blood loss. Because of residual right middle lobe, pulmonary decortication was impossible and significant reinflation of the collapsed pulmonary lobe could not be expected. We selected air-plombage method rather than thoracoplasty as postoperative worsening of pulmonary functions was anticipated by the latter. Postoperative improvement of pulmonary functions could be explained by reinflation of the residual lobe due to removal of plastic balls and the capsule. When conventional thoracoplasty is carried out to obtain satisfying closure of the empyema cavity, pulmonary functions are always deteriorated, while air-plombage method is followed by slight improvement of pulmonary functions.(ABSTRACT TRUNCATED AT 250 WORDS)

[Interaction between polyethylene films and bromhexine HCl in solid dosage forms. I. Effects of moisture contents in the solid dosage forms on the sorption of the drug]

The decrease of bromhexine HCl contents in granules and tablets was determined when the preparations were stored in polyethylene film package. Effects of temperature, contact area with film, excipients and moisture contents in the preparation on the remaining amount of bromhexin HCl were studied in order to investigate the interaction mechanism between bromhexine HCl and polyethylene film. It was observed that the decrease of bromhexine HCl was due to the sorption to the polyethylene film. The results indicated that the moisture contents of the dosage forms determined the rate of sorption predominantly, and that removal of adsorbed water from dosage forms was effective to prevent bromhexine HCl content decrease.

[Production of monoclonal antibodies against tooth germs of hamster or rat by in vitro immunization]

The in vitro immunization procedure for the production of monoclonal antibodies has several advantages over the in vivo procedure; e.g. it requires a much smaller amount of immunogen and only a few days are required for immunization. However, no in vitro immunization procedure for the production of monoclonal antibodies against tooth germs has been reported. By means of in vitro immunization, we tried to produce monoclonal antibodies against the components of tooth germs which would be useful for immunohistochemical investigation of the development of tooth germs. Spleen cells of mice were immunized with a homogenate of molar tooth germs from hamsters or rats. The hybridomas produced were screened by immunohistochemical examination of paraffin sections of tooth germs. We obtained five monoclonal antibodies reacting with the dental tissues; ameloblasts, odontoblasts, enamel, dentin, predentin, and dental sac. One of them reacted specifically with only ameloblasts and one with ameloblasts and enamel, but the others are not specific for individual dental tissues. The results demonstrate that in vitro immunization is a satisfactory method for producing monoclonal antibodies useful for immunohistochemical investigation of tooth germs.

Development of a monoclonal antibody to osteoclasts formed in vitro which recognizes mononuclear osteoclast precursors in the marrow

Osteoclast precursors have not been well characterized because there are no known markers that can detect them. We have used osteoclast-like cells formed in vitro to develop a panel of specific antibodies that react with mature osteoclasts, osteoclast precursors, and other cells in the osteoclast lineage. Monoclonal antibody Kn22 reacted strongly with osteoclast-like multinucleated cells formed in long term marrow cultures and reacted very strongly with freshly isolated bone-derived baboon osteoclasts. Using immune cell panning, Kn22 enriched precursors for osteoclasts. The majority of multinucleated cells (71%) formed from fresh marrow mononuclear cells adherent to Kn22 strongly reacted with a monoclonal antibody that recognizes mature osteoclasts (23c6) and responded appropriately to calcitonin. In contrast, only 23% of multinucleated cells formed from marrow mononuclear cells that were not bound by Kn22 formed osteoclast-like cells. The majority (77%) of these multinucleated cells did not strongly react with the osteoclast-specific monoclonal antibody 23c6 or respond to calcitonin. Thus, we have developed a panel of monoclonal antibodies that recognize cells in the osteoclast lineage. One of these antibodies, Kn22, is unique in that it identifies an osteoclast precursor. The 50K antigen detected by Kn22 appears to be a membrane protein present on osteoclast precursors and osteoclasts that has not been previously identified.

Osteoclast-like cells formed in long-term human bone marrow cultures express a similar surface phenotype as authentic osteoclasts

Long-term cultures of human bone marrow form multinucleated cells (MNC) with many functional characteristics of osteoclasts including: expression of tartrate-resistant acid phosphatase, appropriate responses to osteotropic hormones, calcitonin-induced contraction and formation of resorption lacunae on calcified matrices. However, it is unclear if these cells express similar surface antigens as expressed by authentic osteoclasts, since they form on plastic surfaces in the absence of bone. Bone may be required to complete the differentiation process for osteoclasts. Therefore, we have examined the surface phenotype of MNC and compared it with that of osteoclasts freshly isolated from bone, to determine if MNC express similar surface antigens, and if MNC express antigens which identify their cellular origin. Similar to bone-derived osteoclasts, MNC formed in long-term human bone marrow culture expressed osteoclast-specific antigens (detected by monoclonal antibodies 13c2 and 23c6) and did not express Fc receptors, T cell specific antigens, most myeloid antigens or mature macrophage antigens. In contrast to authentic osteoclasts, MNC reacted with a monoclonal antibody (Mol) which identifies an antigen present on myeloblasts, monocytes, granulocytes, and null cells from human peripheral blood and bone marrow. MNC also reacted with the monoclonal antibody My11, which is present on CFU-GM, the granulocyte-macrophage colony-forming cell, the probable precursor for MNC. These data demonstrate that MNC formed in long-term human marrow cultures express a similar surface phenotype to osteoclasts. This phenotype is different from that expressed by macrophage polykaryons. In addition, MNC also expressed monocyte-related antigens (My11, Mol), suggesting that are derived from or related to the monocytic lineage.

Osteoclast-like cells form in long-term human bone marrow but not in peripheral blood cultures

Transplantation studies have suggested that peripheral blood mononuclear cells contain precursors for osteoclasts. Thus we tested the capacity of peripheral blood monocytes to form osteoclasts in long-term culture. We have reported previously that mononuclear cells from feline, baboon, and human marrow form osteoclast-like cells in long term cultures. Further, the formation of these cells is increased in response to bone resorption stimulatory agents such as PTH, interleukin 1, and transforming growth factor alpha. We now report that these cells show characteristic cytoplasmic contraction with calcitonin and form resorption lacunae when cultured on sperm whale dentine. Thus, these bone marrow-derived multinucleated cells fulfill the functional criteria for osteoclasts. Although cultured peripheral blood monocytes can be induced to form multinucleated cells with 1,25-dihydroxyvitamin D3, these cells did not show similar responses to the osteotropic factors as multinucleated cells formed in the bone marrow cultures multinucleated cells. These results indicate that osteoclasts or cells closely related to osteoclasts form in long-term human bone marrow cultures. In contrast, few mononuclear cells in the peripheral blood appear capable of forming osteoclasts under the culture conditions used in these experiments.

Immunocytochemical demonstration of simultaneous synthesis of types I, III and V collagen and fibronectin in mouse embryonic palatal mesenchymal cells in vitro

An immunocytochemical study was made on the palatal mesenchymal cells obtained from mouse embryos during palatal development with special reference to synthesis of types of collagen and fibronectin in vitro. Most cells showed positive staining with antibodies against the four proteins examined. The staining for type I collagen was most intense among the four proteins and was distributed perinuclearly. The staining for type III collagen was quite similar as that for type I collagen but less intense, whereas that for type V collagen was weak and its staining pattern was different from those for types I and III collagen in that the surface of the plasma membrane, in addition to the perinuclear cytoplasm, showed weak staining for type V collagen. Antibodies to fibronectin showed perinuclear and extracellular fibrous staining. These data suggest that palatal mesenchymal cells synthesize types I, III, and V collagen and fibronectin simultaneously.