Marrow ablation in long bones induces an increase in osteogenesis in distant skeletal sites. To test the role of marrow regeneration in this phenomenon, rat mandibular condyles were evaluated histomorphometrically during postablation healing of tibial marrow and after inhibition of healing. Ten days after removal of tibial marrow all bone formation parameters in the condylar subchondral bone were markedly elevated, indicating an enhanced osteoblastic activity. The thickness of the cartilaginous zone of calcification was also augmented. These changes were absent when postablation healing was inhibited in the tibia and after massive liver injury. Extensive periosteal injury induced only a slight increase in osteoblast activity. Except for a fall on day 7, the [methyl-3H]thymidine labeling index in the condylar cartilage and oral mucosa remained at control levels 3-18 days after ablation. These findings imply that stimulation of cell proliferation has only a secondary role in the skeletal response to marrow ablation. It is concluded that the systemic increase in osteogenesis occurs preferentially during marrow regeneration and is not a nonspecific skeletal reaction to tissue injury. Apparently, the systemic osteogenic response is mediated by circulating factors produced by the healing marrow; conceptually it is related to other instances where local repair in extraskeletal sites is accompanied by generalized alterations in respective tissues.
It has been shown in vitro that verapamil inhibits parathyroid hormone-induced bone resorption. To determine the effect of verapamil administration on bone histology in rats with chronic renal failure, male Wistar rats were divided into three groups: subtotally nephrectomized (SNX), SNX treated with verapamil, 8 mg/kg/day p.o. (SNX-V) and control (C). Thirteen weeks later, the mandibular condyle bone was studied by histomorphometry. When compared to C rats, SNX rats had active bone disease, with increased resorption parameters (resorption surface, active resorption surface, osteoclast number) and accelerated mineral appositional rate. These parameters improved with verapamil administration. When compared to C rats, SNX-V rats had decreased osteoid seam width and mineral appositional rate. Serum parathyroid hormone was similarly elevated in both uremic groups. These data suggest that verapamil administration improves active bone disease in rats with chronic renal failure and decreases bone formation.
During its osteogenic phase, post-ablation regenerating bone marrow produces bone promoting activity to osteogenic cells. In the experiments reported, activity derived from (rat) healing bone marrow conditioned medium (HBMCM) after boiling was analyzed using chromatography on heparin-Sepharose. The activity in HBMCM was shown to be divided among at least six independent activities that stimulated DNA synthesis rates is osteogenic rat osteosarcoma (ROS) cells. Three activities resolved when heparin-Sepharose was washed isocratically with phosphate buffered saline. Two of these were resistant to reduction and acidification and their effect was considerably more potent in osteogenic than non-osteogenic ROS cells. Three additional activity peaks recovered when the heparin-Sepharose column was pumped with an NaCl gradient. Two of them eluted at 0.3 and 0.65 M NaCl, affected osteogenic and non-osteogenic ROS cells to a similar extent and may be attributed to platelet-derived growth factor. A third peak, resolved at 1.2 M NaCl, implies the residual activity of acidic fibroblast growth factor that persisted after boiling of the conditioned medium. It is concluded that the activity profile of HBMCM reflects the in vivo situation where the osteogenic phase of marrow regeneration is probably regulated by multiple growth factor species.
Maple syrup urine disease is a rare inborn error of metabolism that manifests mainly by neurologic deterioration, coma, and death in early childhood. Oral manifestations described in this article were mostly gingival enlargement and rampant caries, while histopathologic findings revealed a picture compatible osteomyelitis.
The effect of laser surgery on tissues of the periodontal apparatus was studied histologically in dogs using block surface light microscopy, a novel microscopical method. With this approach, changes in the hard and soft tissue components were concomitantly demonstrated; the method enabled preservation of the in situ relationship between these components. Following laser surgery, healing in the gingiva was delayed as suggested by the presence of epithelial ulcerations and dense inflammatory infiltrate. In the enamel and cementum the application of laser resulted in crater-like defects that could be avoided only partially by insertion of a tinfoil shield into the gingival sulcus. In the vicinity of the cementoenamel junction these defects were filled with epithelium or periodontal ligament fibers; the close proximity of the hard and soft tissues at the defect sites suggested occurrence of new attachment. Enamel defects located coronal to the gingiva contained bacterial plaque. These histologic results do not demonstrate any substantial advantage of laser over conventional knife gingivectomy. Such advantage may be accomplished with the design of a special intraoral handpiece and further experiments.
In this case the permanent successor was so radiographically indistinct due to the inflammatory process that this three-year-old Arab boy might have been classified as having congenital absence of the mandibular left first premolar, if the mass had not been sent for histological section. The clinical implications are identical.
An established experimental model of tibial bone regeneration in rats was used in order to try to provide further information on the binding site of 99mTc-MDP, which is still not clearly defined. Four groups of rats on which surgical tibial bone marrow evacuation was performed and two control groups (nonoperated animals and sham-operated animals) underwent bone scan during the different stages of marrow regeneration; they were killed immediately after, and histological examination carried out. The correlation between the scintigraphic and the histological findings suggests that 99mTc-MDP binds primarily to calcification sites in young bone trabecules.
This study examined the relationship between clinical and histomorphometric parameters in the human deciduous dentition. Clinical parameters including plaque index, gingival swelling, gingival color, tooth mobility and degree of root resorption were determined prior to the extraction of teeth. The teeth were extracted with their surrounding gingiva in order to preserve the in situ relationship between the hard and soft tissues. Histomorphometric analysis was carried out on 55 sites, using block surface light microscopy (BSLM). Apical migration of the junctional epithelium was found at 53% (29) of the sites. The gingival sulcus was shallow (0.3 +/- 0.19 mm) and coronal to the cemento-enamel junction at 84% (46) of the sites. Junctional epithelium with retepegs was present at 89% (49) of the sites, whilst an inflammatory cell infiltrate (ICI) was present at all sites examined. The ICI was located opposite to the junctional epithelium and cementum at 80% (44) of the sites. The extent of ICI correlated positively with the patients' age and was significantly increased when clinical evidence of gingival swelling or redness was present.
The osteogenic diffusion chamber culture of rodent marrow cells is a well established system. In the present study, marrow cells from children and adult human donors were incubated in diffusion chambers implanted intraperitoneally in athymic mice. After 4 or 8 weeks, the chamber content was examined by light and electron microscopy. Child-cell cultures showed osteogenic tissue consisting of a mineralizing fibrous component and cartilage. Ultrastructurally, the fibrous tissue was similar to osteoid and exhibited osteoblast-like cells and mineralizing nodules. Mineral aggregates were also found in the cartilage. These features in child-cell chambers were similar to those found in control chambers of rabbit marrow cells. Adult-cell chambers showed only unmineralized fibrous tissue. These results render previous findings in animal-cell diffusion chamber systems relevant to the understanding of bone formation in man. It is suggested that the difference between child- and adult-cell chambers reflects an age-related decline in the number of marrow osteoprogenitor cells or their potential to undergo terminal osteogenic differentiation.
It is well documented that injury to bone marrow is followed by an osteogenic phase that precedes the complete tissue regeneration. We have recently shown that postablation healing of bone marrow in rat tibiae is associated with a systemic increase in osteogenesis. It was hypothesized that a growth factor(s) with an effect on osteogenic cells is produced in the healing limb, is transferred to the blood circulation, and enhances osteogenesis systemically. To test growth factor production, healing bone marrow-conditioned medium was prepared with tissue separated from rat tibias during the osteogenic phase and assayed for enhancement of mitogenic activity in culture of osteogenic rat osteosarcoma cells (ROS 17/2). Partial purification of healing bone marrow-conditioned medium-derived growth factor(s) consisted of gel filtration on Sephadex G-25, boiling, chromatography on heparin-Sepharose, and gel filtration on Sephadex G-75. Mitogenic activity eluted in the void volume of the Sephadex G-25 column (mol wt greater than 5,000). Potent activity resolved from heparin-Sepharose with PBS, and on filtration by Sephadex G-75 this activity recovered in 3 peaks with mol wt estimates of 35,000, 19,000, and less than 10,000. The partially purified factor also showed considerable stimulatory effect on DNA synthesis in osteoblastic fetal rat calvarial cells and on in vitro elongation of fetal long bone; it had only a small effect on nonosteoblastic ROS and fetal rat calvarial cells. These data indicate that healing bone marrow produces growth factor activity with a preferential effect on osteogenic cells. It is suggested that local growth factors have a role as mediators in the sequence of events whereby bone marrow expresses its osteogenic potential. During postablation healing of bone marrow these factors may also function as systemic promoters to osteogenic cells.
Aluminum-related osteomalacia has been a topic of major interest for some time. Patients on dialysis who are affected exhibit reduced parathyroid function and osteomalacia associated with high levels of aluminum in the extracellular fluid and tissues. In bone, aluminum is found in the interface between mineralized and nonmineralized osteoid. In the present study we attempted treatment of the aluminum-related bone disease with DFO, a potent chelating agent. A thyroparathyroidectomized patient on hemodialysis with proven osteomalacia and aluminum deposits in bone received DFO 3 times/week for 1 year. Consequently, there was a marked improvement in his skeletal status, both clinically and histologically. This was associated with aluminum deposits within the mineralized component of bone as well as elevated parathyroid function measured in blood and bone. These findings suggest that calcification may occur despite the presence of aluminum in the mineralizing front. The main beneficial effect of DFO could be relief of the inhibitory action of aluminum on parathyroid cells and osteoblasts.
Mechanical load influences the remodelling of skeletal tissues. In the mandibular condyle, occlusal alterations and the consequent mechanical stimulus induce changes in chondrocytes and cartilage mineralization. In the present study we quantified in the mandibular condyle the effect of occlusal interference on remodelling of the subchondral bone. Computerized histomorphometry after 5-21-day exposure to the influence of a unilateral occlusal splint revealed an increased rate of trabecular remodelling, consisting of enhancement in osteoblast and osteoclast numbers and activities. The bone formation parameters reached their high values on Days 5 or 9 and remained stable thereafter. Bone resorption showed a gradual increase throughout the experimental period. These results further characterize the temporomandibular joint reaction to occlusal alterations. It is suggested that the present increase in bone turnover together with the known enhancement in chondrogenesis are part of a process of functional adaptation in response to mechanical stimulus.
Cells of the dental papilla are capable of odontoblastic, fibroblastic, and endothelial differentiation and formation of dentin and the dental pulp. In the present study dental papilla cells, obtained from human tooth buds (HDP cells), were cultured in vitro through 3 to 7 passages. After exposure to prostaglandin E2 there was a marked decrease in intracellular cyclic AMP (cAMP) levels as compared to hormone-free controls. Parathyroid hormone and calcitonin had stimulatory effects with 1 and 2 log increases in cAMP, respectively. The HDP cells showed moderate activity of alkaline phosphatase, 1 log higher than that of hamster kidney fibroblasts (BHK 13) and 1 log lower than that of osteoblastic osteosarcoma cells (ROS 17/2). When cultured for 4 or 8 wk in diffusion chambers (DC) implanted in athymic mice, many of the HDP cells underwent odontoblastic morphodifferentiation with very long, single processes extending into the matrix. This matrix contained banded and unbanded collagen fibers. Neither light nor electron microscopy of the DC content revealed mineral deposits. These results suggest that HDP cells have an intrinsic potential for partial odontoblastic differentiation; inductive signals like those originating from odontogenic epithelium are probably essential for the completion of hard tissue formation.
Two boys aged six and four with the syndrome of hereditary resistance to 1,25-dihydroxyvitamin D3 with rickets alopecia and growth retardation are presented. After unsuccessful therapeutic trials with pharmacologic doses of vitamin D or its active metabolites, the patients were treated by long-term intracaval infusions of calcium through an implantable catheter. A total of 0.5 to 0.9 g of elemental calcium was infused daily for 18 months and the serum calcium concentration was maintained at 9 to 10 mg/dl. Bone pain subsided within one week of treatment. Serum phosphorus, immunoreactive parathyroid hormone, and 1,25-dihydroxyvitamin D concentrations and alkaline phosphatase activity were normalized within four to nine months. Radiographs of the knees and hands revealed progressive healing of rickets with complete resolution after one year of treatment. The patients gained 12 cm and 8 cm per year in height as compared with 3 cm and 2 cm, respectively, in the previous year. A transilial bone biopsy obtained from one patient prior to treatment revealed severe osteomalacia associated with osteitis fibrosa. A follow-up biopsy examined after 12 months of therapy showed almost complete healing of osteomalacia and normal mineralization. These observations indicate the following: (1) Long-term intracaval calcium infusions are an effective mode of therapy for these patients, and (2) When adequate serum calcium and phosphorus concentrations are maintained, healing of rickets and normal growth rate could be achieved even in the absence of a normal 1,25-dihydroxyvitamin D3 receptor-effector system.
Polydimethylsiloxane (silicone) implants were subcutaneously placed in the back of diabetic and normal rats. After three months the rats were killed and the fibrous capsule around the implants was histologically and biochemically examined. A significant quantitative difference (p less than 0.001) was found in the thickness of the capsules, which were two to three times thicker in the diabetic animals. The biochemistry showed an increase of neutral salt-soluble collagen in the diabetic group; electrophoresis revealed only type I collagen in the diabetic and type I and III in the normal rats. From this experimental trial it seems that diabetes mellitus is another factor in formation of a thick capsule around silicone implants.
The potential of clonal rat osteosarcoma (ROS) cell lines to form mineralized matrices was assessed in diffusion chambers in vivo. Diffusion chambers were inoculated with osteoblastic (ROS 17/2 and its subclone ROS 17/2.8) and non-osteoblastic (ROS 24/1) clonal lines and implanted either intraperitoneally into athymic mice or subcutaneously into syngeneic ACI rats. Control chamber cultures of rabbit marrow or spleen cells were also incubated in athymic mice. Light and electron microscopy of chambers with ROS 17/2 and ROS 17/2.8 cells revealed production of mineralized matrices typical of osteosarcoma and characterized by abundance of collagen fibrils and associated mineralizing nodules. ROS 24/1 cells produced similar collagenous matrices, but these were devoid of mineral. The present experiments, carried out independently in two different laboratories, demonstrate the potential of ROS cells to produce a mineralized matrix. This corroborates previous studies on other osteoblastic features of these cell lines.
Chondromyxoid fibroma is a benign skeletal tumor which rarely affects the jaws. Only 10 cases have been found in the literature, all of them located in the mandible. In the present articles, 2 additional cases are described, one of them being the first reported case located in the maxilla. Up-to-date clinical and pathological data of 2 reported cases and a review of the literature are presented.
Thirty-four femoral necks from human cadavers were measured by techniques assessing bone density and bone mineral density, and by the Singh index. These methods are based on photon interaction with biological components and can be applied noninvasively for clinical evaluation of changes in skeletal status. Trabecular bone volume, mineralized bone volume, and relative osteoid volume were evaluated histomorphometrically using undecalcified histologic sections obtained from the same samples. The trabecular and mineralized bone volumes showed significant correlations with the bone density and mineral density. These results enhance the validity of recently developed photon-interaction techniques for evaluating bone properties.
Rabbit marrow cells inoculated into diffusion chambers (10(7) cells/chamber) were implanted intraperitoneally into athymic mouse hosts and cultured in vivo for 20 days. A connective tissue consisting of bone, cartilage and fibrous tissues is formed by the stromal fibroblastic cells of marrow within the chambers. Cell kinetics and tissue differentiation have been studied using histomorphometric and biochemical analyses. Haemopoietic cell numbers decrease to less than 0.05% of the initial inoculum during the 20-day period. At 3 days an average of 15 stromal fibroblastic cells only are identifiable within the chambers. After 3 days there is a high rate of stromal cell proliferation with a doubling time of 14.5 h during the period from 3 to 8 days and an increase in the total stromal cell population by more than six orders of magnitude from 3 to 20 days. Thirteen to fourteen population doublings occur before expression of the first observable differentiation parameter, alkaline phosphatase activity. The data demonstrate that the mixture of connective tissues formed within the chamber is generated by a small number of cells with high capacity for proliferation and differentiation. This is consistent with the current hypothesis that stromal stem cells are present in bone marrow.
The authors report the case of a 15-year-old female who presented with a history of vague but constant pain about the medial aspect of her right knee. X-ray established the presence of an expanding lesion in the medial tibial plateau. Computerized axial tomography (CT) and magnetic resonance imaging (MRI) were used in the evaluation of the lesion. The authors compare the preoperative CT and MRI findings with the microscopic histopathology of the amputation specimen and note that the CT scan underestimated the extent of the microscopic tumor boundaries, whereas MRI showed altered activity beyond these boundaries.