Osteoid Matrix Formation Research Articles

Growth hormone effects on healing efficacy, bone resorption and renal morphology of rats: histological and histometric study in rat calvaria

Previous reports demonstrated the utility of systemic application of growth hormone (GH) in the treatment of bone defects. Very few studies correlated bone repair efficacy with hepatic and renal side effects promoted by locally-delivered GH. The objectives of this study were to assess the bone repair properties along with hepatic and renal adverse effects promoted by local application of GH in a rat model. Thirty-two rats were randomly divided (4 groups; n = 8/group), as follows: (i) AB (autogenous bone + local application of saline solution [SS]), (ii) AB+ (autogenous bone + SS local application + SS irrigation), (iii) AB/GH+ (autogenous bone + SS local application + GH irrigation) and (iv) AB/GHL+ (autogenous bone + GH local application + GH irrigation). Critical-sized defects (diameter = 5.0 mm) were surgically created by a single operator in the calvaria of rats. Defects were filled with ground autogenous bone. Defects pertaining to AB+ and AB/GH+ received a mixture of autogenous bone and a SS-saturated (0.02 mL) collagen sponge covered with bovine cortical membrane. Defects in group AB/GHL+, were filled with the same biomaterials saturated with GH (0.02 mL). SS (0.1 mL) or GH (0.1 mL, equivalent to 0.4 IU) were applied locally on alternate days (8 weeks) in animals in groups AB, AB+ and AB/GH+ or AB/GHL+, respectively. Bone repair properties was determined in hematoxylin/eosin-stained slices using traditional histologic and histomorphometric techniques along with optical microscopy and digital image analysis. Statistical differences among groups was determined using Kruskal-Wallis and Tukey post hoc tests (α = 0.05). Histology results indicated that AB and AB+ displayed greater presence of autogenous bone as compared to AB/GH+ and AB/GHL+. Histomorphometric results indicated significantly higher osteoid matrix formation in AB and AB+ when compared to AB/GHL+ (p = 0.009). Kidneys and livers were found to have their glomeruli preserved in AB and AB+. Strong glomeruli necrosis and large areas of protein deposition were found in AB/GH+. Abnormal small-sized glomeruli were found in AB/GHL+. The utilization of autogenous bone graft associated with local application and irrigation with GH was shown to not improve the bone repair in calvarial critical-sized defects in a rat model.

Reduced graphene oxide aerogel networks with soft interfacial template for applications in bone tissue regeneration

Reduced Graphene Oxide aerogels (A-RGO), functionalized with chitosan, were found to induce and/or accelerate the mineralization of hydroxyapatite. The functionalized chitosan acts as a soft interfacial template on the surface of A-RGO assisting the growth of hydroxyapatite particles. The mineralization on these soft aerogel networks was performed by soaking the aerogels in simulated body fluid, relative to time. Polymer-induced mineralization exhibited an ordered arrangement of hydroxyapatite particles on reduced graphene oxide aerogel networks with a higher crystalline index (IC) of 1.7, which mimics the natural bone formation indicating the importance of the polymeric interfacial template. These mineralized aerogels which mimic the structure and composition of natural bone exhibit relatively higher rate of cell proliferation, osteogenic differentiation and osteoid matrix formation proving it to be a potential scaffold for bone tissue regeneration.

Delayed osteogenesis and calcification in a large true toad with a comparative survey of the timing of skeletal ossification in anurans

Postembryonic skeletogenesis in anuran amphibians has been widely studied, yet less than one percent of the extant diversity has been covered and relatively few comparative studies exist. Here we document the sequence and timing of ossification of the Common Toad Rhinella arenarum, a large true toad (Bufonidae) from South America that is a model organism for varied ongoing research. We study histological sections and cleared-and-stained specimens of an ontogenetic series ranging from early larval stages to juveniles, documenting the ossification sequence of the entire skeleton. To diminish potential environmental biases we also study the skeletogenesis of the frog Leptodactylus latinasus (Leptodactylidae) from the same pond and season. We summarize comparative data from numerous anuran species to contextualize our results in a broad phylogenetic context. Histological data shows that skeletal calcification in R. arenarum is temporally dissociated from osteoid matrix formation and occurs later than in most other anurans, which is unexpected given its generalized pond-type larva and heavily ossified adult skeleton. At the onset of metamorphosis, exoccipitals, parasphenoid, and frontoparietals are the only ossified skull elements, whereas most of the postcranium has already started ossification. This pattern is rare among anurans but is shared by other bufonids, in which it has been previously linked to rapid development. Our comparative survey, however, suggests that the delayed bufonid pattern is not related to fast-developing larvae but instead might be a distinctive feature of true toads.

The utility of SATB2 immunohistochemical expression in distinguishing between osteosarcomas and their malignant bone tumor mimickers, such as Ewing sarcomas and chondrosarcomas

SATB2 is commonly expressed in osteosarcomas. Although apparently being a valuable diagnostic marker for differentiating between small cell osteosarcoma (SCO) and other small round cell tumors of bone, for instance Ewing sarcoma family of tumors (ESFT), it has not been tested in a large series of ESFT and chondrosarcomas so far. We studied the immunohistochemical expression of SATB2 in 42 osteosarcomas, 31 chondrosarcomas, and 371 genetically confirmed ESFT. SATB2 positivity was detected in 90.4% of osteosarcomas, 87.5% of SCO, 91.3% of osteoblastic osteosarcomas, and in all chondroblastic and parosteal osteosarcomas. The osteoblastic and SCO subtypes expressed SATB2 more intensely than other histological types. SATB2 was expressed in 46.6% of chondrosarcomas, and in 1.3% of ESFT. Sensitivity and specificity of SATB2 immunoexpression were 90.4% and 95.3%, respectively. The positive and negative predictive values in osteosarcoma diagnosis were 66.6% and 98.9%, respectively.In chondrosarcoma, SATB2 immunoexpression was more frequent and intense in high-grade chondrosarcoma (Grade III) and uncommon in chondrosarcoma grade I. SATB2 positivity was detected in 55.6% of chondrosarcomas grade II. SATB2 apparently cannot distinguish between chondroblastic osteosarcoma and high-grade chondrosarcoma. Nevertheless, SATB2 is frequently expressed in osteogenic tumors, but is rarely positive in ESFT, and with the support of CD99 expression and specific molecular studies, it is very useful for distinguishing between these two lesions. Although SATB2 immunoexpression helps to distinguish osteosarcoma from their mimickers, the identification of malignant osteoid matrix formation and the integration of clinical and radiological data remain the corner stone of osteosarcoma diagnosis and as yet no antibody has equalled the diagnostic value of this important morphologic hallmark.

Healing of tibial and calvarial bone defect using Runx-2-transfected adipose stem cells

The purpose of this study was to test the effect of Runx-2-transfected hASCs to heal the defect created on proximal tibiae and calvaria of immunosuppressed rats. Three kinds of hASCs (untransfected, pECFP-transfected ASCs or Runx-2-transfected ASCs) were cultured under osteogenic medium. Osteoblastic differentiation was measured by ALP staining on day 7 and osteoid matrix formation was observed by alizarin red staining on day 14 after osteogenic induction. Osteogenic potential in long bone defects were tested via 6 mm-sized circular defect on proximal tibiae of 9 immunosuppressed rats. Untransfected ASCs, pECFP-transfected ASCs or Runx-2-transfected ASCs embedded in fibrin scaffold were implanted in the defect (N=3 in each group). In order to assess the in vivo osteogenic capability of Runx-2-transfected ASC in intramembanous ossification, two critical size bone defects were created on parietal bone of 12 immunosuppressed rats. The defects were filled with fibrin scaffold containing pECFP-transfected ASCs, Runx-2-transfected ASCs or no cell (N=4 in each group). Runx-2 transfected ASCs showed much stronger activity of ALP and greater formation of osteoid matrix compared with untransfected ASCs or pECFP-transfected ASCs 7 and 14 after osteo-induction, respectively. When the volume of regenerated bone was compared from gross examination and radiographs after 5 weeks in the proximal tibial defect model, the defects treated with Runx-2-transfected ASCs had the greatest area of healed bone compared with other groups. In the calvarial defect model, Runx-2-transfected ASCs had significantly increased area healed with bone (p<0.05) as well as better quality of regenerated bone compared with defects which was treated with untransfected ASCs from gross and micro-CT examination 8 weeks after implantation. The implanted human cells persisted in the newly regenerated bone in defects treated with pECFP-ASCs and Runx-2-transfected ASCs. In conclusion, Runx-2-transfection significantly increased the osteogenic potential of ASCs in the in vivo orthotopic models.

GD2+ Selected Mesenchymal Stromal Cells (MSCs) Demonstrate a More Robust Proliferation and Differentiation Potential Compared to Unselected Cells.

Human mesenchymal stromal cells (MSCs) are spindle-shape, plastic-adherent cells with capacity to differentiate to bone, cartilage, and fat. MSCs express fibroblast, endothelial, and lymphocyte antigens, e.g. CD105, CD73, CD90, and CD166 which are the cornerstone of phenotypic characterization of these cells. We recently showed that MSCs are the only bone marrow cell to express GD2, a neural ganglioside. Now, for the first time we show that GD2 may serve as the single, unique, and definitive marker of marrow and adipose derived MSCs that can be used to isolate GD2+ MSCs, which possess important biologic properties justifying prospective isolation. MSCs expression of GD2 is uniformly high on freshly isolated and culture-expanded cells. Using the Miltenyi AutoMACS® device and a monoclonal antibody recognizing GD2 (clone 14.G2A) we prospectively isolated a highly enriched MSC population from bone marrow MNCs. The selected fraction was >98% pure for GD2+ cells determined by flow cytometry. Light microscopy showed that the GD2-selected cells were smaller, thinner, and more spindle-like when attached to plastic compared to unselected MSCs which spread wider along the surface of the culture flask, the so-called “fried egg” appearance. The doubling time of GD2-selected MSCs was 30 hrs compared to 90 hrs for unselected cells representing a 3-fold greater growth rate. Cell cycle analysis by flow cytometry showed ∼80% of cells were in G0/G1 and ∼20% were in S/G2/M phases of the cell cycle in both populations. With the shorter doubling time, this data indicates that GD2-selected MSCs move through the cell cycle more rapidly than unselected cells. In accordance with this finding, electron microscopy showed few organelles in the GD2-selected cells, but increase lamellar bodies indicating overall less complexity, but consistent with a greater membrane turnover rate (cell division) than unselected MSCs. Moreover, flow cytometric analysis revealed an increased expression of receptors for bFGF and EFG, known mitogenic factor receptors for MSCs, compared to unselected MSCs. In vitro differentiation of GD2-selected MSCs showed a more robust osteoid matrix formation (osteoblast) and proteoglycan formation (chondroblast) assayed by semi-quantitative Alizarin Red and Alcian blue staining, respectively. Additionally, more GD2-selected MSCs differentiated to adipocytes than among unselected cells. Surprisingly, GD2 expression persisted on the in vitro human MSC-differentiated osteoblasts, chondroblasts, and adipocytes, in contrast to human bone-derived osteoblasts, adipose tissue, and cartilage which lacked GD2 expression. We conclude thati.GD2 is a unique, stably expressed surface MSC marker which can be used to prospectively isolate MSCs from marrow,ii.GD2-selcted cells have a more robust in vitro proliferation and differentiation potential which may be valuable for cell therapy, andiii.biologically, in vitro isolated MSCs may not represent the in vivo progenitor for bone, fat, or cartilage.

Musculoskeletal manifestations of scurvy

Scurvy occurs in individuals who eat inadequate amounts of fresh fruit or vegetables, often because of dietary imbalances related to advanced age or homelessness. Asthenia, vascular purpura, bleeding, and gum abnormalities are the main symptoms. In 80% of cases, the manifestations of scurvy include musculoskeletal symptoms consisting of arthralgia, myalgia, hemarthrosis, and muscular hematomas. Vitamin C depletion is responsible for structural collagen alterations, defective osteoid matrix formation, and increased bone resorption. Imaging studies may show osteolysis, joint space loss, osteonecrosis, osteopenia, and/or periosteal proliferation. Trabecular and cortical osteoporosis is common. Children experience severe lower limb pain related to subperiosteal bleeding. Laboratory tests show nonspecific abnormalities including anemia and low levels of cholesterol and albumin. The finding of a serum ascorbic acid level lower than 2.5 mg/l confirms the diagnosis. Vitamin C supplementation ensures prompt resolution of the symptoms.

Manifestations rhumatologiques du scorbut

Scurvy occurs in individuals who eat inadequate amounts of fresh fruit or vegetables, often because of dietary imbalances related to advanced age or homelessness. Asthenia, vascular purpura, bleeding, and gum abnormalities are the main symptoms. In 80% of cases, the manifestations of scurvy include musculoskeletal symptoms consisting of arthralgia, myalgia, hemarthrosis, and muscular hematomas. Vitamin C depletion is responsible for structural collagen alterations, defective osteoid matrix formation, and increased bone resorption. Imaging studies may show osteolysis, joint space loss, osteonecrosis, osteopenia, and/or periosteal proliferation. Trabecular and cortical osteoporosis is common. Children experience severe lower limb pain related to subperiosteal bleeding. Laboratory tests show nonspecific abnormalities including anemia and low levels of cholesterol and albumin. The finding of a serum ascorbic acid level lower than 2.5 mg/l confirms the diagnosis. Vitamin C supplementation ensures prompt resolution of the symptoms.

The many faces of osteosarcoma.

Osteosarcoma is the most common primary malignant tumor of bone in adolescents and young adults. It accounts for approximately 15% of all primary bone tumors confirmed at biopsy. There are numerous types of primary osteosarcoma, including intramedullary (high grade, telangiectatic, low grade, small cell, osteosarcomatosis, and gnathic), surface (intracortical, parosteal, periosteal, and high-grade surface), and extraskeletal. Osteosarcoma may also occur as a secondary lesion in association with underlying benign conditions. The identification of osteoid matrix formation and aggressive characteristics usually allows prospective radiologic diagnosis of osteosarcoma. As with all bone tumors, differential diagnosis is best assessed with radiographs, whereas staging is performed with computed tomography or magnetic resonance imaging. Understanding and recognition of the variable appearances of the different varieties of osteosarcoma allow improved patient assessment and are vital for optimal clinical management including diagnosis, biopsy, staging, treatment, and follow-up.

Roentgenographic manifestations of osseous changes in the jaws

1. 1. Bone tissue, under physiologic conditions, is the result of an interplay of two mechanisms: (a) bone formation and (b) bone resorption. 2. 2. Bone formation actually occurs in two phases: (a) the formation of an osteoid matrix and (b) matrix mineralization. 3. 3. Bone resorption is an all-or-none phenomenon characterized by removal of both the organic and the inorganic components of bone. 4. 4. Pathologic bone tissue is the result of a disturbance in either bone formation or bone resorption. 5. 5. Roentgenolucent shadows are due to (a) decreased osteoid matrix formation, (b) decreased mineralization of the osteoid frame, or (3) increased bone resorption. 6. 6. Osteoporosis may be defined as a roengenolucent shadow due to a decrease in osteoid matrix formation. 7. 7. Osteomalacia is defined as a roentgenolucent shadow, the result of an interference with physiologic mineralization. 8. 8. Osteitis fibrosa is defined as a roentgenolucent shadow caused by an increase in bone resorption. 9. 9. Roentgenopaque shadows, referred to as osteosclerosis, are caused by an increase in the formation of osteoid matrix or a decrease in bone resorption. 10. 10. Many disorders are characterized by a basic process of increased bone resorption with superimposed secondary and compensatory bone formation. 11. 11. Roentgenolucent, roentgenopaque, and roentgenolucent-roentgenopaque shadows may be part of generalized skeletal disease, confined to a single bone, or restricted to only a small portion of one bone.