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PubMed1984

Iliac bone histomorphometry in adults and children with osteogenesis imperfecta.

Histomorphometric analysis was performed on transiliac undecalcified bone biopsies taken from eight adults and four children with osteogenesis imperfecta. Double tetracycline labelling done before the biopsy allowed measurement of the calcification rate in 11 patients. The adults, as well as the children, had thin iliac cortices and considerably decreased trabecular bone volume. In addition, the calcification rate was significantly reduced. Since the thickness index of osteoid seams was low or normal in all subjects, it indicated a reduced bone formation at the cellular level. In the adults, there was no significant increase in the parameters of bone resorption or in the bone formation rates at the basic multicellular unit and the tissue levels. Thus the histomorphometric profile of iliac bone in osteogenesis imperfecta is characterised by cortical and trabecular osteoporosis with decreased activity of the individual osteoblasts. These findings would suggest the use of therapeutic agents stimulating bone formation rather than agents inhibiting bone resorption in osteogenesis imperfecta.

Adolescent↗
PubMed1997

Three modes of ossification during distraction osteogenesis in the rat.

We developed a rat model of limb lengthening to study the basic mechanism of distraction osteogenesis, using a small monolateral external fixator. In 11-week-old male rats we performed a subperiosteal osteotomy in the midshaft of the femur with distraction at 0.25 mm every 12 hours from seven days after operation. Radiological and histological examinations showed a growth zone of constant thickness in the middle of the lengthened segment, with formation of new bone at its proximal and distal ends. Osteogenic cells were arranged longitudinally along the tension vector showing the origin and the fate of individual cells in a single section. Typical endochondral bone formation was prominent in the early stage of distraction, but intramembraneous bone formation became the predominant mechanism of ossification at later stages. We also showed a third mechanism of ossification, 'transchondroid bone formation'. Chondroid bone, a tissue intermediate between bone and cartilage, was formed directly by chondrocyte-like cells, with transition from fibrous tissue to bone occurring gradually and consecutively without capillary invasion. In situ hybridisation using digoxigenin-11-UTP-labelled complementary RNAs showed that the chondroid bone cells temporarily expressed type-II collagen mRNA. They did not show the classical morphological characteristics of chondrocytes, but were assumed to be young chondrocytes undergoing further differentiation into bone-forming cells. We found at least three different modes of ossification during bone lengthening by distraction osteogenesis. We believe that this is the first report of such a rat model, and have shown the validity of in situ hybridisation techniques for the study of the cellular and molecular mechanisms involved in distraction osteogenesis.

Animals↗
PubMed1998

Bone regeneration and fracture healing. Experience with distraction osteogenesis model.

The relation between physical forces and the processes of bone regeneration and healing remains incompletely understood. Gaps in understanding of these processes stem in part from models that produce inadequate amounts of new bone for study. Bone created through the use of distraction osteogenesis provides an attractive substrate for the study of mechanical forces and their effects on bone formation because this technique produces large volumes of new bone in a controlled fashion. The optimal mechanical environment in which bone formation occurs clinically has not been fully determined. In laboratory studies, however, the mechanical environment can be manipulated, and resultant changes in bone formation can be measured. To investigate how changes in strain environment influence patterns of bone formation, a bilateral New Zealand White rabbit model of bilateral distraction osteogensis was implemented. When a stiffener was applied to the external distractor, computation analyses predicted a sevenfold to eightfold decrease in all strain measures. These reductions in gap strains appeared to induce significant decreases in bone volume fraction and mean trabecular thickness. When osteotomies were created at a 30 degrees angle to the bony axis to generate more shear within the gap tissue, changes in the distribution of gap strains and resultant new bone architecture were observed. Specific correlations between changes in tissue level strains and the pattern of bone regeneration were seen in both experiments. These results provide direct in vivo evidence that pluripotential gap tissues are sensitive to their physical surroundings. Mechanisms responsible for this sensitivity might include vascularity, stem cell supply, and scaffolding architecture. The process of bone formation in distraction osteogenesis appears to be related to bone formation processes associated with more common conditions. The distraction osteogenesis model described suggests a mechanism for bone formation that seems applicable to other more common processes associated with bone formation, including fracture healing and impaired fracture healing.

Adult↗
PubMed1982

Ocular findings in osteogenesis imperfecta congenita.

Osteogenesis imperfecta is a rare, inherited, connective-tissue disorder. The three main signs of this disease are multiple bone fractures, blue scleras, and deafness (osteosclerotic type). In our research, only a few reports of the morphologic studies of the eyes of patients with osteogenesis imperfecta were found. This report describes the ocular histopathologic condition of four cases of osteogenesis imperfecta congenita, with emphasis on the ultrastructural characteristics of the collagen in the cornea and sclera.

Cornea↗
PubMed1979

Osteogenesis imperfecta. A study of 160 family members.

Osteogenesis imperfecta, a genetic disease characterized by blue sclera, fragile bones, and hearing loss, was studied in 160 descendants of a single, affected individual. One hundred twenty family members in four generations were at risk of inheriting the gene for osteogenesis imperfecta. Fifty-six percent (68/120) had blue sclera, and, of this group, 66% had fragile bones, and 47% of those tested had hearing loss. The onset of hearing loss was usually in the second or third decade, and was primarily of the conductive type. The incidence of sensorineural hearing loss was only slightly less than the incidence of conductive hearing loss. To out knowledge, this is the largest reported kindred study of osteogenesis imperfecta. The genetic transmission of this disease as an autosomal dominant was confirmed.

Adolescent↗
PubMed1994

Distraction osteogenesis for reconstruction of mandibular symphyseal defects.

OBJECTIVE: We investigated the feasibility of arched trifocal distraction osteogenesis for reconstruction of mandibular symphyseal defects. DESIGN: Four adult canine subjects were used. An external apparatus was designed to allow trifocal distraction around an arc. An anterior mandibulectomy was performed between the third premolars bilaterally. The bony defect was regenerated using trifocal distraction osteogenesis at a rate of 1 mm a day bilaterally. New arced bone was produced over a period of 20 to 35 days. The apparatus functioned as an external fixator for the ensuing 6 weeks. The apparatus was then removed, the dogs were returned to their preoperative diet, and were killed after 2 weeks of observation. MAIN OUTCOME MEASURES: Grossly a smooth arc of bone was formed measuring 4.5 to 5.5 cm in length, 2.2 to 3.0 cm in height, and 1.3 to 1.5 cm in width. Histologically all specimens demonstrated direct membranous bone growth. Radiographically opaque columns were seen streaming in the direction of distraction. CONCLUSIONS: Symphyseal bony defects resulting from oncologic resection, trauma, and congenital deformities create tremendous cosmetic and functional handicaps and have remained extremely challenging to surgically reconstruct. This study demonstrates the ability to use arced trifocal distraction osteogenesis to reconstruct anterior mandibulectomy defects in a canine model. This method may provide a satisfactory solution to a difficult problem in human mandibular reconstruction.

Animals↗
PubMed1988

Osteogenesis imperfecta type I with unusual dental abnormalities.

A large kindred with dominantly inherited osteogenesis imperfecta was evaluated. Affected individuals had bone fractures, blue sclerae, and hearing loss. In addition, all had dental abnormalities distinct from those previously described in other families with this syndrome. Deciduous teeth were normal in color or blue-grey. On radiographs of an early developing deciduous dentition, pulps were larger than normal. In patients with mixed dentitions, pulp chambers of deciduous teeth were partially obliterated. Increased constriction at the junctions of the crowns and roots was found in some deciduous teeth. One patient had large pulp stones in the pulp chambers of all maxillary deciduous molars. Permanent teeth were normal in color but had oval pulp chambers with apical extensions into the coronal portions of the roots, large coronal pulp stones, narrow root canals, and thin roots. Individuals in this family who did not have osteogenesis imperfecta had normal teeth. In addition, a well circumscribed radiolucency without a sclerotic periphery, involving the apices of all permanent mandibular incisors, was found in the anterior mandible in one patient. These findings support the hypothesis that this family has yet another type I osteogenesis imperfecta "syndrome".

Adolescent↗
PubMed1994

Bone dysplasia in a child born to parents with osteogenesis imperfecta and pseudoachondroplasia.

We report on a boy born to a mother with pseudoachondroplasia and a father with osteogenesis imperfecta (Sillence type III). At birth, the boy was found to have osteogenesis imperfecta type III. Although clinical findings of pseudoachondroplasia were not manifested at the age of 8 months, roentgenographic findings showed characteristics of pseudoachondroplasia in addition to those of osteogenesis imperfecta. He died of respiratory distress at age 15 months.

Achondroplasia↗
PubMedDate not supplied

Wire-induced osteogenesis in marrow.

Although it has been reported, in observations connected to electrically stimulated bone repair, that intramedullary electrodes not attached to any electrical source can also induce osteogenesis, there has been only one systematic attempt to study this effect per se. We have extended these studies, implanting selected metal and plastic wires longitudinally into the medullary diaphyses of rat femora. Atomic absorption analysis was used for the first time in analyzing for medullary calcium. This technique and the histologic evaluation clearly indicate that osteogenesis occurs within 2 weeks after this wire implantation. Osteogenesis was not observed when the wire was immediately removed after the original trauma of wire insertion.

Animals↗
PubMed1990

Aluminum-induced neo-osteogenesis: a generalized process affecting trabecular networking in the axial skeleton.

To determine if aluminum-induced neo-osteogenesis occurs in the axial skeleton, we compared spinal bone density and vertebral histology of beagles treated with aluminum for 8 and 16 weeks to that of untreated normals. Administration of aluminum (1.25 mg/kg) did not alter serum calcium, phosphorus, or creatinine but did result in a significant elevation of vertebral bone density, measured by quantitative computed tomography, after both 8 (286.7 +/- 12.4 mg/ml) and 16 (361.7 +/- 46.5 mg/ml) weeks of treatment compared with controls (212.2 +/- 4.5 mg/ml). In accord with the increased bone density, biopsies from the spine displayed evidence of neo-osteogenesis, including the presence of woven bone, both mineralized and unmineralized, within the marrow space. The genesis of such woven bone units resulted after 16 weeks in a significant increase in trabecular bone volume, woven and lamellar (51.2 +/- 4.4 versus 32.4 +/- 1.2%; p less than 0.05), woven bone volume (9.1 +/- 3.6 versus 0 +/- 0%; p less than 0.05), and trabecular number (4.5 +/- 0.3 versus 3.5 +/- 0.2 per mm; p less than 0.05). In addition, scanning electron microscopic evaluation of the bone biopsies confirmed the existence of new trabecular plates that provided interconnections between existent units. These observations illustrate that aluminum-induced neo-osteogenesis positively influences trabecular networking in the axial skeleton. Such enhancement of bone histogenesis contrasts with the effects of other pharmacologic agents that solely alter the thickness of existing trabecular plates or rods within the vertebral spongiosa.

Aluminum↗
PubMed2003

BMP treatment of C3H10T1/2 mesenchymal stem cells induces both chondrogenesis and osteogenesis.

The molecular mechanisms by which bone morphogenetic proteins (BMPs) promote skeletal cell differentiation were investigated in the murine mesenchymal stem cell line C3H10T1/2. Both BMP-7 and BMP-2 induced C3H10T1/2 cells to undergo a sequential pattern of chondrogenic followed by osteogenic differentiation that was dependent on both the concentration and the continuous presence of BMP in the growth media. Differentiation was determined by the expression of chondrogenesis and osteogenesis associated matrix genes. Subsequent experiments using BMP-7 demonstrated that withdrawal of BMP from the growth media led to a complete loss of skeletal cell differentiation accompanied by adipogenic differentiation of these cells. Continuous treatment with BMP-7 increased the expression of Sox9, Msx 2, and c-fos during the periods of chondrogenic differentiation after which point their expression decreased. In contrast, Dlx 5 expression was induced by BMP-7 treatment and remained elevated throughout the time-course of skeletal cell differentiation. Runx2/Cbfa1 was not detected by ribonuclease protection assay (RPA) and did not appear to be induced by BMP-7. The sequential nature of differentiation of chondrocytic and osteoblastic cells and the necessity for continuous BMP treatment to maintain skeletal cell differentiation suggests that the maintenance of selective differentiation of the two skeletal cell lineages might be dependent on BMP-7-regulated expression of other morphogenetic factors. An examination of the expression of Wnt, transforming growth factor-beta (TGF-beta), and the hedgehog family of morphogens showed that Wnt 5b, Wnt 11, BMP-4, growth and differentiation factor-1 (GDF-1), Sonic hedgehog (Shh), and Indian hedgehog (Ihh) were endogenously expressed by C3H10T1/2 cells. Wnt 11, BMP-4, and GDF-1 expression were inhibited by BMP-7 treatment in a dose-dependent manner while Wnt 5b and Shh were selectively induced by BMP-7 during the period of chondrogenic differentiation. Ihh expression also showed induction by BMP-7 treatment, however, the period of maximal expression was during the later time-points, corresponding to osteogenic differentiation. An interesting phenomenon was that BMP-7 activity could be further enhanced twofold by growing the cells in a more nutrient-rich media. In summary, the murine mesenchymal stem cell line C3H10T1/2 was induced to follow an endochondral sequence of chondrogenic and osteogenic differentiation dependent on both dose and continual presence of BMP-7 and enhanced by a nutrient-rich media. Our preliminary results suggest that the induction of osteogenesis is dependent on the secondary regulation of factors that control osteogenesis through an autocrine mechanism.

Animals↗
PubMed1993

Cranial osteogenesis in Monodelphis domestica (Didelphidae) and Macropus eugenii (Macropodidae).

The pattern of onset and general rate of cranial ossification are compared in two marsupials, Monodelphis domestica (Didelphidae) and Macropus eugenii (Macropodidae). In both species a similar suite of bones is present at birth, specifically those surrounding the oral cavity and the exoccipital, and in both postnatal events follow a similar course. The facial skeleton matures more rapidly than the neurocranium, which is characterized by an extended period of ossification. Most dermal bones begin ossification before most endochondral bones. Endochondral bones of the neurocranium are particularly extended in both the period of onset of ossification and the rate of ossification. These data confirm suggestions that morphology at birth is conservative in marsupials and we hypothesize that the pattern of cranial osteogenesis is related to two distinct demands. Bones that are accelerated in marsupials are correlated with a number of functional adaptations including head movements during migration, attachment to the teat, and suckling. However, the very slow osteogenesis of the neurocranium is probably correlated with the very extended period of neurogenesis. Marsupials appear to be derived relative to both monotreme and placental mammals in the precocious ossification of the bones surrounding the oral cavity, but share with monotremes an extended period of neurocranial osteogenesis.

Animals↗
PubMed1983

Electrical osteogenesis by low direct current.

A constant direct current cathode was employed in the medullary canal of the rabbit tibia to investigate electrical osteogenesis at low current levels. Currents of 0.015 or 0.075 microA were delivered to the bone and the biological response was compared with contralateral controls receiving 20 microA. This investigation was performed to determine if electrical osteogenesis occurs at current levels below the previously studied range of 1-100 microA with stainless steel electrodes. New bone formed by 0.015 microA cathodes was statistically comparable with that found around inactive cathodes from an earlier pertinent study. The osteogenic response to 0.075 microA cathodes was significantly elevated above that to inactive ones, thus substantiating electrical osteogenesis for currents below 1 microA. However, it is evident that this does not demonstrate a further stimulatory range but that currents near 0.075 microA probably approach the lower significant limit for electrically induced bone growth with stainless steel electrodes.

Animals↗
PubMed1989

Heterotopic osteogenesis in porous ceramics induced by marrow cells.

When untreated porous calcium phosphate ceramics were transplanted into subcutaneous (s.c.) or intramuscular (i.m.) sites, fibrovascular tissue grew in the pore region without evidence of bone formation. However, when these same ceramics were combined with syngeneic marrow cells, osteogenesis was observed inside the pore region of the implanted ceramic. The osteogenesis began on the surface of the pore region at approximately 3 weeks postimplantation by a process of intramembranous bone formation, with the de novo bone tissue observed directly interfacing with the ceramic surface. Infrequently, small isolated areas showed cartilage formation with no noticeable endochondral ossification. At 4 weeks postimplantation of the ceramic with marrow cells, the osteogenesis in the ceramic accompanied an observed increase in compressive strength, rigidity, and energy absorption of the ceramic. These results suggest that a combination of porous ceramics and marrow cells may be useful for clinical problems requiring osseous reconstruction.

Animals↗
PubMed1997

Rat model of distraction osteogenesis.

Prior studies of distraction osteogenesis in dog and rabbit models have shown predominantly intramembranous bone formation. Other models of fracture healing normally display mixtures of both endochondral and intramembranous bone formation. We have established a rat model of tibial lengthening that reliably reproduces the pattern of zonal osteogenesis previously observed in dog and rabbit models. A distraction rate of 0.25 mm twice a day with a 0-day latency period produced intramembranous bone with zones of progressive mineralization from collagen. With this protocol, rats bridged the distraction gap with a 25% increase in the tibial bone length. After 20 days of distraction and 50 days of consolidation, the three-point bending stiffness, as a percentage of the contralateral control, reached a level equivalent to that measured in the canine model for a 15% lengthening (28-day distraction and 84-day consolidation). Radiodensitometric analysis of the regenerate bones measured 97% of the unaffected contralateral tibial densities, and mineral analyses demonstrated that calcium and phosphorus levels in the regenerate bone reached 78% of contralateral tibial levels by day 70. We concluded that a rat model of distraction osteogenesis will be useful for a wide range of studies involving rapid intramembranous bone formation.

Animals↗
PubMed2001

Physical shock wave mediates membrane hyperpolarization and Ras activation for osteogenesis in human bone marrow stromal cells.

Physical shock wave (SW) has shown effectiveness on promotion of bone growth. We have recently demonstrated that SW could promote bone marrow stromal cell differentiation toward osteoprogenitor associated with induction of TGF-beta1. We have further demonstrated that SW-induced membrane hyperpolarization and Ras activation acted an early signal for the osteogenesis in human bone marrow stromal cells. An optimal dose of SW treatment at 0.16 mJ/mm(2) for 500 impulses induced a rapid membrane hyperpolarization in 5 min, activation of Ras in 30 min, and cell proliferation in 2 days. The SW-promoted cell growth was related to osteogenesis as demonstrated by increase of bone alkaline phosphatase activity in 6 days and osteocalcin mRNA expression in 12 days. In support that SW-induced Ras activation mediated osteogenesis of human bone marrow stromal cells, we further demonstrated that transfection of bone marrow stromal cells with a dominant negative Ras mutant (Asn-17 ras(H)) abrogated the SW enhancement of osteogenic transcription factor (CBFA1) activation, osteocalcin mRNA expression, and bone nodule formations. These results suggest that physical SW promotes bone marrow stromal cell differentiation toward osteogenic lineage via membrane hyperpolarization, followed by Ras activation and specific osteogenic transcription factor CBFA1 expression. A link between physical SW and biomembrane perturbation-mediated Ras activation may highlight how noninvasive physical agents could be used to promote fracture healing and to rescue patients with osteoporosis and osteopenic disorders in the future.

Bone Marrow Cells↗
PubMed2002

Leukaemia inhibitory factor (lif) is expressed in hypertrophic chondrocytes and vascular sprouts during osteogenesis.

Avascular cartilage is replaced by highly vascularized bone tissue during endochondral ossification, a process involving capillary invasion of calcified hypertrophic cartilage in association with apoptosis of hypertrophic chondrocytes, degradation of cartilage matrix and deposition of bone matrix. All of these events are closely controlled, especially by cytokines and growth factors. Leukaemia inhibitory factor (LIF), a member of the gp130 cytokine family, is involved in osteoarticular tissue metabolism and might participate in osteogenesis. Immunohistochemical staining showed that LIF is expressed in hypertrophic chondrocytes and vascular sprouts of cartilage and bone during rat and human osteogenesis. LIF is also present in osteoblasts but not in osteoclasts. Observations in a rat endochondral ossification model were confirmed by studies of human cartilage biopsies from foetuses with osteogenesis imperfecta. LIF was never detected in adult articular chondrocytes and bone-marrow mesenchymal cells. These results and other data in the literature suggest that LIF is involved in the delicate balance between the rate of formation of calcified cartilage and its vascularization for bone development.

Animals↗
PubMed1989

A histochemical localization on Maclura pomifera lectin during osteogenesis.

Mandibular condyles of 4-week-old Wistar strain rats and mandibles of ICR strain mice from 14 days gestation stage to 2 days postnatal stage were used to investigate the localization of Maclura pomifera lectin (MPA) during two modes of osteogenesis. During endochondral ossification of the mandibular condyle, MPA was only localized at the peripheral regions of calcified cartilage after the destruction of chondrocyte lacunae. Bone extracellular matrix (ECM) was not reacted with MPA. In intramembranous ossification of mice mandibles, MPA was stained intensively in the early bone ECM. The intensity of the MPA reaction decreased during bone development. In both cases of osteogenesis, chondroclasts and osteoclasts showed the strong affinity to MPA. These results indicated that the time- and position-specific changes within ECM proceeded during osteogenesis and that MPA was the useful probe to detect chondroclasts and osteoclasts.

Animals↗