Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.3.1 (alkaline phosphatase)
 47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We analyzed the osteogenic capacity of the vascularized periosteum histologically and biochemically using a new experimental model of the vascularized tibial periosteum-hydroxyapatite composite in rats. Bone formation was observed not only on the surface but also in the pores of the hydroxyapatite at 4 weeks. The alkaline phosphatase activity increased to a peak at 2 weeks, with half this activity maintained until 8 weeks. The bone-specific bone gla protein content increased constantly as time passed. On the other hand, in the vascularized fascia-hydroxyapatite composite group (control group), no bone formation was observed histologically, alkaline phospatase activity was low, and bone gla protein content was very low. These results indicate that (1) the vascularized periosteum has the most significant osteogenic capaacity at 2 weeks, with a constant level of the activity maintained thereafter, (2) it forms new bone soon after operation, and (3) the amount of bone increases as time passes.
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PMID:Histologic and biochemical analysis of osteogenic capacity of vascularized periosteum. 859 81

Articular cartilage is both morphologically and biochemically heterogeneous. Its susceptibility to degenerative diseases such as arthritis and its limited repair capacity have made cartilage the focus of intense study; surprisingly, little is known of its development. Using a panel of specific antibodies, we have documented the temporal and spatial patterns of collagen types I, II, III, VI and X in the developing knee cartilage of the marsupial Monodelphis domestica from parturition to adulthood. Type I collagen was initially detected in the presumptive articular cartilage of the epiphyses in addition to the perichondrium. By 14 d postparturition, type I collagen was not detectable in the epiphyseal cartilage apart from insertion sites of ligaments and tendons of the joint. Similarly, type III collagen was detected at insertion sites of the major ligaments and tendons and within the perichondrium/periosteum but was never detected in the cartilage per se. Type II collagen was predictably distributed throughout the cartilage matrix and was also detected in the perichondrium. Type VI collagen was widely distributed throughout the cartilage matrix at parturition, but during development became restricted to a pericellular location particularly towards the presumptive articular cartilage, i.e. the epiphysis. Interestingly, generalised matrix immunopositivity was only retained in the hypertrophic cartilage of the secondary centre of ossification. After the formation of the secondary centre, type VI collagen became localised pericellularly in the deeper regions of the articular cartilage but was absent in the cartilage of the growth plate. Type X collagen showed a novel distribution pattern. In addition to being synthesised by hypertrophic chondrocytes, this collagen type was also expressed transiently by some cells at the presumptive articular surface. Furthermore, these surface chondrocytes also stained histochemically for alkaline phosphatase, suggesting that they were terminally differentiated. The fate of these terminally differentiated cells is unknown.
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PMID:The development of articular cartilage: I. The spatial and temporal patterns of collagen types. 918 84

The quadratojugal (QJ) is a neural crest-derived membrane bone in the maxillary region of the avian head. In vivo its periosteum undergoes both osteogenesis to form membrane bone and chondrogenesis to form secondary cartilage. This bipotential property, which also exists in some other membrane bones, is poorly understood. The present study used cell culture to investigate the differentiation potential of QJ periosteal cells. Three cell populations were enzymatically released from QJ periostea and plated at different densities. Cell density greatly affected phenotypic expression and differentiation pathways. We found two culture conditions that favored osteogenesis and chondrogenesis, respectively. In micromass culture, the periosteal cells produced a layer of osteogenic cells that expressed alkaline phosphatase (APase) and secreted bony extracellular matrix (ECM). In contrast, low-density monolayer culture elicited chondrogenesis. Cells with pericellular refractile ECM and round shape appeared at 7 to 8 days and formed colonies later. The chondrogenic phenotype of these cells was confirmed by immunolocalization of type II collagen and Alcian blue staining of ECM. This result demonstrated that a fully expressed chondrogenic phenotype can be achieved from membrane bone periosteal cells in primary monolayer culture. Chondrogenesis requires a cell density lower than confluence and cannot be initiated in confluent cultures. Among the three cell populations, those cells from the outer layer have the highest growth rate and require the lowest initial plating density (below 5 x 10(3) cells/ml) to achieve chondrogenesis. Cells from the inner layer have the slowest growth rate and chondrify at the highest initial density (below 5 x 10(4) cells/ml). Chondrocytes from all populations express distinct phenotypic markers-APase and type I collagen-from initial chondrogenesis, but are not hypertrophic morphologically. Furthermore, the fact that chondrocytes arise within the same colony as APase-positive polygonal cells suggests that chondrocytes may differentiate from precursors related to the osteogenic cell lineage. This cell culture approach mimics secondary cartilage and membrane bone formation in vivo.
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PMID:In vitro differentiation potential of the periosteal cells from a membrane bone, the quadratojugal of the embryonic chick. 895 38

Two methods of collecting osteoblast-like cells from newborn rat calvaria were tested, either placing individual glass fragments or tipping dense glass beads onto the endocranial surface of periosteum-free bone. Inoculated at high density, cells collected by using these two methods form large mineralized plates after three weeks of culture. The main purpose of our investigation was to analyze the progressive formation of this mineralized structure and to localize alkaline phosphatase activity. At the beginning of the culture, flattened cells gathered into multilayers and synthesized collagen fibers. Cells in the upper layer became rapidly cuboidal in shape and continued to secrete collagen at their basal pole, whereas other cells became progressively embedded in the extracellular matrix. The upper cells featured ultrastructural characters of osteoblasts, whereas the embedded cells resembled osteocytes. After two weeks, the matrix began to mineralize: crystals appeared on collagen fibers, on matrix vesicles, and on cell debris. During the first days of the culture, the alkaline phosphatase activity was localized on the plasma membranes and on the collagen fibers. Thereafter, only the upper cells and collagen fibers that were juxtaposed to these cells showed alkaline phosphatase activity. In addition, the presence of mineralized matrix prevented the reaction product from being visualized on collagen fibers. The ultrastructural analysis reveals large mineralized plates with a structure resembling that of bone in vivo. This culture appears to be an appropriate model to study bone formation and regulation.
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PMID:Ultrastructure and cytochemical detection of alkaline phosphatase in long-term cultures of osteoblast-like cells from rat calvaria. 905 74

Timing and pattern of expression of alkaline phosphatase was examined during early differentiation of the 1st arch skeleton in inbred C57BL/6 mice. Embryos were recovered between 10 and 18 d of gestation and staged using a detailed staging table of craniofacial development prior to histochemical examination. Expression of alkaline phosphatase is initiated at stage 20.2 in the plasma membrane of mesenchymal cells in the distal region of the first arch. Expression is strongest in osteoid (unmineralised bone matrix) and presumptive periosteum at stage 21.32. Mineralisation begins at stage E23. Expression is present in the mineralised bone matrix. Secondary cartilages form in the condylar and angular processes by stage M24. The cartilaginous cells and surrounding cells in the processes are all alkaline phosphatase-positive and surrounded by the common periosteum, suggesting that progenitor cells of the processes, dentary ramus and secondary cartilages all originate from a common pool. Nonhypertrophied chondrocytes of Meckel's cartilage express alkaline phosphatase at stage M23. Expression in these chondrocytes is preceded by the expression in their adjacent perichondrium. This is true of chondrocytes in all other cranial cartilages examined. 3-D reconstruction of expression in Meckel's cartilage also revealed that the chondrocytes of Meckel's cartilage which express alkaline phosphatase and the matrix of which undergoes mineralisation are those surrounded by the alkaline phosphatase-positive dentary ramus. By stage 25, coincident with mineralisation in the distal section of Meckel's cartilage, most chondrocytes are strongly positive. The perichondria of malleus and incus cartilages express alkaline phosphatase at stage M24. Nonhypertrophied chondrocytes along these perichondria also express alkaline phosphatase. Superficial and deep cells in the dental laminae of incisor and 1st molar teeth become alkaline phosphatase-positive at the bud stage, stages 21.16 and 21.32, respectively. Dental papillae are negative until stage M24 when alkaline phosphatase expression begins in the dental papillae and follicles of the incisor teeth and the dental follicles of the 1st molar teeth. The dental papillae of the 1st molar teeth express alkaline phosphatase at stage 25. Expression in the dental papillae and follicles appears to coincide with cellular differentiation of follicle from papilla. The presumptive squamosal, ectotympanic and gonial membrane bones, lingual oral epithelial cells connected to the dental laminae of the incisor teeth, hair follicle papillae and sheath and surrounding dermis all express alkaline phosphatase in a stage-specific manner.
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PMID:Stage-specific expression patterns of alkaline phosphatase during development of the first arch skeleton in inbred C57BL/6 mouse embryos. 906 47

Mesenchymal Stem Cells (MSCs) possessing the capacity to differentiate into various cell types such as osteoblasts, chondrocytes, myoblasts, and adipocytes have been previously isolated from the marrow and periosteum of human, murine, lapine, and avian species. This study documents the existence of similar multipotential stem cells in canine marrow. The cells were isolated from marrow aspirates using a modification of techniques previously established for human MSCs (hMSCs), and found to possess similar growth and morphological characteristics, as well as osteochondrogenic potential in vivo and in vitro. On the basis of these results, the multipotential cells that were isolated and culture expanded are considered to be canine MSCs (cMSCs). The occurrence of cMSCs in the marrow was determined to be one per 2.5 x 10(4) nucleated cells. After enrichment of the cMSCs by centrifugation on a Percoll cushion, the cells were cultivated in selected lots of serum. Like the hMSCs, cMSCs grew as colonies in primary culture and on replating, grew as a monolayer culture with very uniform spindle morphology. The population doubling time for these cMSCs was approximately 2 days. The morphology and the growth kinetics of the cMSCs were retained following repeated passaging. The osteogenic phenotype could be induced in the cMSC cultures by the addition of a synthetic glucocorticoid, dexamethasone. In these osteogenic cultures, alkaline phosphatase activity was elevated up to 10-fold, and mineralized matrix production was evident. When cMSCs were loaded onto porous ceramics and implanted in autologous canine or athymic murine hosts, copious amounts of bone and cartilage were formed in the pores of the implants. The MSC-mediated osteogenesis obtained by the implantation of the various MSC-loaded matrix combinations is the first evidence of osteogenesis in a canine model by implantation of culture expanded autologous stem cells. The identification and isolation of cMSCs now makes it feasible to pursue preclinical models of bone and cartilage regeneration in canine hosts.
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PMID:Culture expanded canine mesenchymal stem cells possess osteochondrogenic potential in vivo and in vitro. 914 44

A major problem in developmental bone biology is the inability to clearly identify early progenitor cells of the osteogenic and related lineages. Identification of these cells is important for the study of their normal development and for determination of potential changes in skeletal diseases. The objective of the present study was to obtain specific markers for early progenitor cells. Monoclonal antibodies were raised against human marrow stromal fibroblastic cell cultures, known to be rich in progenitors for the stromal lineages. Antibodies were selected initially by their reactivity with these marrow cultures and their immunohistochemical localization in human fetal tissues, in progenitor cell regions adjacent to osteoblastic cells. Antibody HOP-26 was strongly reactive with cells in marrow stromal colonies at early stages of differentiation, before the induction of alkaline phosphatase activity, and decreased dramatically after the cells reached confluence. In sections of human fetal limb, binding of HOP-26 was restricted to cells in close proximity to the developing bone, in periosteum, and between the developing bone trabeculae. In adult trabecular bone tissue, HOP-26 was reactive with occasional cells present within the marrow spaces with osteoblasts, adipocytes, and fibrous tissue unreactive. No antibody binding was detected in sections of skin, muscle, appendix, brain, tonsil, or liposarcoma, or cultured SaOS II, MG63, or skin cells. In primary cell suspensions, HOP-26 was unreactive with blood cells but strongly reactive with 0.59 +/- 0.27% of nucleated marrow cells. The antigen associated with these cells was detectable both intracellularly and on the cell surface, and by using immunopanning, HOP-26 selected the marrow stromal fibroblastic colony-forming units (CFU-F). HOP-26 provides the means to identify osteogenic progenitor cells directly and with high specificity. The present studies demonstrate the value of this antibody in providing enriched populations of progenitor cells for experimental studies of osteogenic differentiation and in histopathology.
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PMID:Identification and enrichment of human osteoprogenitor cells by using differentiation stage-specific monoclonal antibodies. 921 1

The progenitors for cells of bone, cartilage, fat, and muscle are thought to be derived from mesenchymal stem cells but despite extensive study of stromal cell differentiation, neither mesenchymal stem cells or the more committed, tissue-specific progenitors have been well-characterized. In this study we used flow cytometry to isolate from fetal rat periosteum a population of small, slowly cycling cells with low cytoplasmic granularity (S cells) that display stem cell characteristics. On plating, S cells exhibited a 90% higher labeling index with [3H]-thymidine compared to unsorted cells and when grown in culture generated cartilage, adipocyte, and smooth muscle phenotypes, in addition to bone. Only the S-cell population showed extensive self-renewal of cells with osteogenic potential. Electron microscopy showed that S cells have high nuclear:cytoplasmic ratios with large condensed nuclei and a paucity of cytoplasmic organelles. Freshly sorted suspensions of immunocytochemically stained S cells did not express differentiation-associated markers such as type I, II, and III collagens, alkaline phosphatase, or osteopontin. However, after attachment, S cells became immunopositive for collagens I, II, III, osteopontin, and also for the cell surface receptor CD44, which mediates cell attachment to hyaluronan and osteopontin. These studies show that viable osteogenic precursor cells with the stem cell characteristics of self-renewal, high proliferative capacity, and multipotentiality can be enriched from heterogeneous stromal cell populations with simple flow cytometric methods. These cells may be useful for regeneration of stromal tissues.
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PMID:Characterization of stromal progenitor cells enriched by flow cytometry. 934 31

In human periosteum-derived osteoblastic cells (SaM-1) and human osteosarcoma-derived cells (SaOS-2, HOS, MG-63), the mRNA expressions of calcitonin gene-related peptide receptor (CGRP-R), substance P receptor (SP-R), neuropeptide Y receptor (NPY-R), beta-adrenergic receptors (beta1-R, beta2-R, beta3-R), vasoactive intestinal polypeptide type 1 and type 2 receptors (VIP-1R, VIP-2R) and pituitary adenylate cyclase activating polypeptide receptor (PACAP-R) were examined by reverse transcription-polymerase chain reaction (RT-PCR). According to the magnitude of the mRNA expression of alkaline phosphatase (ALP), the relative state of commitment of these osteoblastic cell lines to the osteoblast lineage was SaM-1 > SaOS-2 > HOS > MG-63. CGRP-R, NPY-R, VIP-1R and beta2-R, but not SP-R, VIP-2R, PACAP-R, beta1-R and beta3-R, were expressed in osteoblasts as well as osteosarcoma cells. Expression of these receptors seems to be a common feature in osteoblastic cells, but the magnitude of expression was not dependent upon the relative state of commitment of the osteoblastic cells to the osteoblast lineage. In addition, VIP mRNA was not expressed in osteoblastic cells, suggesting the absence of an autocrine system of VIP in osteoblasts. These observations suggest that these neuropeptides and norepinephrine are involved in local regulation of human bone metabolism.
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PMID:Expression of mRNAs for neuropeptide receptors and beta-adrenergic receptors in human osteoblasts and human osteogenic sarcoma cells. 935 Aug 48

Other than its known effects on the cardiovascular system, angiotensin II (Ang II) stimulates cell growth in several cell types. In this study, we examined whether it also might affect bone cell metabolism. Ang II stimulated DNA and collagen synthesis and decreased alkaline phosphatase (AP) activity in bone cell populations derived from the periosteum of fetal rat calvariae. Similar effects of Ang II were observed on human adult bone cells obtained by collagenase digestion from trabecular bone. Clonal cell analysis, autoradiographic studies, and receptor subtype analysis suggested the presence of specific Ang II receptor subtype 1 (AT1) binding sites on AP+ osteoblastic precursor cells. Ang II had no direct effects on osteoblastic cells with a mature phenotype, but paracrine effects of Ang II on mature osteoblasts could be observed upon coculture with Ang II-responsive bone cell populations. Because Ang II is known to be locally generated by endothelial cells, Ang II might play an important role in coordinating capillary cell growth and osteoblastic bone formation during bone remodeling.
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PMID:Effects of angiotensin II on bone cells in vitro. 949 84


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