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M Riminucci

Publications and source records attributed to M Riminucci.

34 records · Page 2Linked to original sources
PubMed1998

Bone formation via cartilage models: the "borderline" chondrocyte.

Increasing evidence substantiates the view that death is not necessarily the only fate of hypertrophic chondrocytes and that, when exposed to the right microenvironment, these cells can further differentiate to osteoblast-like cells and contribute to initial bone formation. In vitro, when replated as adherent cells in the presence of ascorbic acid, hypertrophic chondrocytes resume cell proliferation, switch from the synthesis of the cartilage-characteristic type II and X collagens to the synthesis of type I collagen, and organize a mineralizing bone matrix. In vivo, expression of bone specific markers by growth plate chondrocytes occurs initially in early hypertrophic cells located at the mid-diaphysis and directly facing the osteogenic perichondrium. In bones formed via cartilage models, the first mineralized bone matrix (the earliest bony collar preceding vascular invasion and the onset of endochondral bone formation) is deposited at the outer aspect of the mid-diaphysis between rows of early hypertrophic chondrocytes and osteoblasts, which are arranged in a peculiar "vis à vis" fashion. The "vis à vis" organization of perichondrial osteogenic cells and peripheral early hypertrophic chondrocytes suggests that the latter cells are exposed -- compared to their cognate, the central hypertrophic chondrocytes -- to a specific microenvironment composed of unique matrix-originating signals and cellular cross-talks. A major role in the differentiation control of, and interaction between, hypertrophic chondrocytes and osteogenic perichondrial cells is certainly played by the Indian Hedgehog/PTHrP signalling system. We propose that all early hypertrophic chondrocytes have the inherent potential to differentiate to osteoblast-like cells and to contribute to initial bone formation, but that only chondrocytes positioned at the "borderland" between cartilage and (non-cartilage) osteogenic tissues undergo further differentiation to bone producing cells. We call these hypertrophic chondrocytes "borderline chondrocytes" to emphasize both their specific location and their dual differentiation potential. Hypertrophic chondrocytes located in different cartilage areas are exposed to an inappropriate matrix and endocrine/paracrine environment, cannot differentiate to osteoblast-like cells and therefore undergo apoptosis.

Animals↗
PubMed1998

Vis-à-vis cells and the priming of bone formation.

Bone formation throughout skeletal growth and remodeling always entails deposition of new bone onto a pre-existing mineralized surface. In contrast, the initial deposition of bone in development requires the formation, ex novo, of the first mineralized structure in a nonmineralized tissue. We investigated the cellular events associated with this initial bone formation, with specific reference to the respective role of cartilage and bone cells in bones which form via a cartilage model. The cellular architecture of initial osteogenic sites was investigated by light, confocal, and electron microscopy (EM) in the membranous ossification of fetal calvarial bones (not forming via a cartilage model) and in the membranous ossification of the bony collars of endochondral bones. Bone sialoprotein (BSP), which is expressed during early phases of bone deposition and has been proposed to be involved in the control of both mineral formation and bone cell-matrix interactions, was used as a marker of initial bone formation. We found that at all sites, BSP-producing cells (as identified by intracellular immunoreactivity) are arranged in a characteristic vis-à-vis (face to face) pattern prior to the appearance of the first mineralizing BSP-immunoreactive extracellular matrix. In perichondral osteogenesis, the vis-à-vis pattern comprises osteoblasts differentiating from the perichondrium/periosteum and early hypertrophic chondrocytes located at the lateral aspects of the rudiment. By EM, the first mineral and the first BSP-immunoreactive sites coincide temporally and spatially in the extracellular matrix at the boundary between cartilage and periosteum. We further showed that in an in vitro avian model of chondrocyte differentiation in vitro to osteoblast-like cells, early hypertrophic chondrocytes replated as adherent cells turned on the expression of high levels of BSP in conjunction with the switch to collagen type I synthesis and matrix mineralization. We propose a model for the priming of bone deposition, i.e., the formation of the first bone structure, in which the architectural layout of cells competent to deposit a mineralizing matrix (the vis-à-vis pattern) determines the polarized deposition of bone. For bones forming via a cartilage model, the priming of bone deposition involves and requires cells that differentiate from early hypertrophic chondrocytes.

Animals↗
PubMed1997

Single-colony derived strains of human marrow stromal fibroblasts form bone after transplantation in vivo.

Populations of marrow stromal fibroblasts (MSFs) can differentiate into functional osteoblasts and form bone in vivo. It is not known, however, what proportion of MSF precursor cells, colony forming units-fibroblast (CFU-Fs), have osteogenic potential. In the present study, analysis of bone formation in vivo by single-colony derived strains of human marrow stromal fibroblasts (HMSFs) has been performed for the first time. Each strain originated from an individual CFU-F and underwent four passages in vitro prior to subcutaneous implantation into immunodeficient mice within vehicles containing hydroxyapatite-tricalcium phosphate ceramic. Multicolony derived HMSF strains were also transplanted to serve as positive controls. After 8 weeks, abundant bone formation was found in the transplants of all multicolony derived HMSF strains, whereas 20 out of 34 (58.8%) single-colony derived strains from four donors formed bone. Immunostaining with antibody directed against human osteonectin and in situ hybridization for human-specific alu sequences demonstrated that cells forming new bone were of human origin and were vital for at least 45 weeks post-transplantation. Both the incidence of bone-forming colonies and the extent of bone formation by single-colony derived HMSF strains were increased by cultivation with dexamethasone and ascorbic acid phosphate. Other factors, including type of transplantation vehicle, morphology, size, and structure of the original HMSF colonies showed no obvious correlation with the incidence or extent of bone formation. Hematopoietic tissue within the newly formed bone was developed in the transplants exhibiting exuberant bone formation. These results provide evidence that individual human CFU-Fs have osteogenic potential and yet differ from each other with respect to their osteogenic capacity.

Animals↗
PubMed1997

[Cystic polyps of the stomach: review of our case series].

The Authors report their experience with gastric polyps based upon 3,384 endoscopies performed from October 1992 to August 1995. The incidence of cystic polyps with respect to the examinations performed and to the number of gastric polyps found was 0.45% and 21.3% respectively. The cases were taken into account with respect to sex, age, number of lesions, location, size and association to Gardner's syndrome. A comparison between the observed cases and a comprehensive review of the relevant Literature was performed.

Female↗
PubMed1997

Fibrous dysplasia of bone in the McCune-Albright syndrome: abnormalities in bone formation.

In addition to café-au-lait pigmentation patterns and hyperendocrinopathies, fibrous dysplasia of bone is a major finding in the McCune-Albright syndrome. Activating missense mutations of the Gs alpha gene leading to overactivity of adenylyl cyclase have been identified in patients with McCune-Albright syndrome, but the mechanism leading to the specific development of fibrous dysplasia in bone has not been elucidated. By means of specific peptide antisera and reverse transcriptase polymerase chain reaction in situ hybridization, we show that expression of Gs alpha and its mRNA is critically up-regulated during maturation of precursor osteogenic cells to normal osteoblast cells and that this pattern of expression is retained in fibrous dysplasia. A functional characterization of fibrous dysplastic tissues revealed that the fibrotic areas consist, in fact, of an excess of cells with phenotypic features of pre-osteogenic cells, whereas the lesional bone formed de novo within fibrotic areas represents the biosynthetic output of mature but abnormal osteoblasts. These cells are noted for peculiar changes in cell shape and interaction with matrix, which were mimicked in vitro by the effects of excess exogenous cAMP on human osteogenic cells. Osteoblasts involved with the de novo deposition of lesional bone in fibrous dysplasia produce a bone matrix enriched in certain anti-adhesion molecules (versican and osteonectin), and poor in the pro-adhesive molecules osteopontin and bone sialoprotein, which is in contrast to the high levels of these two proteins found in normal de novo bone. Our data indicate the need to reinterpret fibrous dysplasia of bone as a disease of cells in the osteogenic lineage, related to the effects of excess cAMP on bone cell function. They further suggest that a critical, physiological, maturation-related regulation of Gs alpha levels makes cells in the osteogenic lineage a natural target for the effects of mutations in the Gs alpha gene and may provide a clue as to why bone itself is affected in this somatic, mutation-dependent disease.

Adolescent↗
PubMed1995

The anatomy of bone sialoprotein immunoreactive sites in bone as revealed by combined ultrastructural histochemistry and immunohistochemistry.

Bone sialoprotein was immunolocalized at the EM level in thin Lowicryl K4M sections of rat bone. Because of the unconventional EM morphology of the bone matrix seen in thin demineralized acrylate sections, the pattern of immunolabeling was compared with detailed structural images of demineralized bone obtained using an en bloc treatment of tissue samples with the cationic electron 'dye,' Malachite Green (MG), which provides stabilization and retention of anionic material throughout specimen processing. A system of structures corresponding to the sites of bone sialoprotein (BSP) immunoreactivity, as seen in Lowicryl K4M this sections, could be readily identified in the MG-treated, epoxy thing sections. This system includes the cement lines, and aggregates of similar material within mineralized bone and mineralizing osteoid. The virtual identity of BSP distribution with the arrangement of the MG-visualized material indicates that a BSP-enriched, noncollagenous phase can be demonstrated using different, unrelated tissue preparation and imaging protocols for EM. Besides improving our understanding of the distribution of bone sialoprotein in bone, these data assign a previously unrecognized structural dimension to noncollagenous material in the bone matrix.

Animals↗
PubMed1994

Oral nodular fasciitis. A case report.

A rare case of nodular fasciitis arising in the buccinator muscle sheath in a 76-year-old patient is reported. Nodular fasciitis is a benign proliferation of fibroblasts, often mistaken for a sarcoma because of its rapid growth, rich cellularity and high mitotic activity. Although the cause of nodular fasciitis is unknown, it is likely that the fibroblastic proliferation is due to local injury or an inflammatory process.

Aged↗
PubMed1994

Giemsa as a fluorescent stain for mineralized bone.

We present evidence for a previously unrecognized differential staining effect of Giemsa solution in fluorescence microscopy. The effect consists of selective fluorescent staining of mineralized bone (and elastic fibers) in tissue sections and, like the classical Romanowsky effect, is based on the differential binding of Eosin Y to tissue structures in the presence of Azur II and Methylene Blue. This effect opens the way to new applications of the Giemsa solution in fluorescence microscopy and in confocal fluorescence microscopy.

Animals↗
PubMed1994

In vitro production of plasminogen activator by human granulosa cells.

Plasminogen activator (PA) production by granulosa cells has been demonstrated in several species. In the human ovary, tissue-type PA and urokinase-type PA antigens have been found in the follicular fluids, but neither PA activity nor mRNA for both enzymes was found in granulosa cells of preovulatory follicles. All of these studies were performed on granulosa cells collected from follicles immediately before ovulation, when the cells were already in the luteal phase. In the attempt to better characterize the PA/plasminogen system in the human ovary, we examined PA and PA inhibitor (PAI) production in cultures of granulosa cells obtained from normally cycling untreated women at different stages of the cycle. In addition, we analyzed granulosa-luteal cells obtained from hormonally stimulated women undergoing gamete intrafallopian tube transfer, as a model of late phase follicular development. Zymographic analysis as well as immunoprecipitation with specific antisera revealed that granulosa cells from follicles at early phases of antral stages secreted high levels of PA of the urokinase type in the medium. No free tissue-type PA activity was found in any of the examined samples. On the contrary, free PAI was undetectable in medium obtained from granulosa cell cultures, and it was abundant in granulosa-luteal cell cultures, where it was found in two forms. These data show that in the human ovary as in that of the rat, PAs and PAIs are tightly time regulated. The timing of PA production in human granulosa cells suggests a role for PA activity at early stages of follicular maturation.

Adult↗
PubMed1993

Bone sialoprotein (BSP) secretion and osteoblast differentiation: relationship to bromodeoxyuridine incorporation, alkaline phosphatase, and matrix deposition.

We defined two distinct maturational compartments (proliferative and secretory) of osteogenic cells in vivo on the basis of ALP activity, BrdU incorporation, cell shape, and BSP production. BSP immunoreactivity was found to mark cells in the secretory but not in the proliferative compartment. We established the phenotypic similarity of primitive marrow stromal cells with proliferating perichondral cells (fibroblast-like, ALP+, BrdU+, BSP-). This suggests the potential functional equivalence of the two cell types as committed non-secretory osteogenic cells and points to the duality of osteogenic cell compartments as a generalized feature of bone formation. We further showed that although BSP secretion is a hallmark of the onset of osteogenesis, BSP antigenicity is lost both in osteoid and in a large proportion of mature osteoblasts during subsequent phases of bone deposition. This suggests that bone formation may not be a uniform event, as bone cells actually deposit antigenically, and likely biochemically, distinct matrices at specific times.

Alkaline Phosphatase↗
PubMed1993

Localization of bone sialoprotein (BSP) to Golgi and post-Golgi secretory structures in osteoblasts and to discrete sites in early bone matrix.

Bone sialoprotein (BSP), a bone matrix-enriched glycoprotein containing the Arg-Gly-Asp (RGD) motif and endowed with cell binding properties, was localized in osteoblasts and early bone matrix of developing rat bone at the ultrastructural level. Preliminary light microscopic observations indicated that intracellular labelling was restricted to a paranuclear dot corresponding to the "negative Golgi image" of classical histology. The same pattern was observed whether antisera against the fully glycosylated protein or a peptide antiserum to a stretch of amino acids in human BSP sequence were employed. At the EM level, we obtained labeling over the Golgi area of osteoblasts but not over the rER. The labeling was concentrated over distensions of the trans Golgi and over pro-secretory granules. In the matrix, BSP was distributed in a non-random manner. The label was concentrated over spherical aggregates of finely fibrillar material corresponding to the sites of early mineral deposition (so-called "mineralization nodules"). Such BSP-positive foci were seen both close to and away from the cell surface. The predominant association of BSP with Golgi and post-Golgi secretory structures and its absence from rER, as well as the reproducibility of the same pattern of localization with different antisera, might indicate a slow transit of the protein through the Golgi, not necessarily associated with protein glycosylation.

Amino Acid Sequence↗
PubMed1992

Freeze-drying of bone tissue: immunocytochemistry and enzyme histochemistry on paraffin embedded and low-temperature resin embedded specimens.

A simple protocol of tissue preparation was sought, which would enable marker enzymes of bone cells and extracellular matrix antigens to be localized in the same tissue section with high optical resolution. For this purpose, snap-frozen samples of rat fetal skeletal tissues were dried in a FDU 010 freeze-drying unit (Balzers) for 8-12 h at -50 to -40 degrees C and 0.02 bar. Freeze-dried tissues were either vacuum-infiltrated at 45 degrees C and embedded undemineralized in Paraplast, or vacuum-infiltrated overnight at 4 degrees C and embedded undemineralized in glycol methacrylate. These procedures enabled enzyme cytochemistry for alkaline phosphatase and tartrate-resistant acid phosphatase, and immunocytochemical staining for collagen types I, III, and laminin to be performed on the same sections. No pretreatment of the sections was necessary to reveal collagen antigenicity. This study reveals the possibility of complementing immunocytochemical studies of extracellular matrix with enzyme cytochemistry and, above all, with the excellent tissue preservation and high resolution afforded by plastic embedding.

Animals↗
PubMed1991

In vitro production of estradiol by ovarian granulosa cells in a case of McCune-Albright syndrome.

A 14-year-old girl presented with classic McCune-Albright syndrome. She underwent the ablation of several cysts during a laparotomy performed on the basis of persistent and intense pelvic pain and recurrent episodes of menometrorrhagia not responsive to pharmacologic therapy. Granulosa cells obtained from an isolated follicle and a cyst were cultured and estradiol (E2) secreted in the culture medium measured. Granulosa cells, obtained from the follicle, produced much higher levels of estradiol compared to those of cells coming both from follicles of equivalent size and preovulatory follicles of normal patients. Secretion of E2 by granulosa cells from the cyst was comparable to that of normal preovulatory follicles. We conclude that in this patient, ovaries are hyperfunctioning in terms of E2 production. This high production of estradiol and the fact that several cysts were found in the ovaries can justify the high levels of estradiol found in the serum of this patient at the moment of the operation.

Adolescent↗
PubMed1984

Early programming of maturation competence in mouse oogenesis.

Growing mouse oocytes incompetent to mature were freed of attached granulosa cells at different stages of growth, and cultured in vitro in the presence of fibroblast monolayers and/or their products. In these culture conditions, although growth was arrested, isolated oocytes survived in vitro for several days, and finally resumed meiosis spontaneously, progressing up to metaphase I. The culture time length needed for in vitro acquisition of the capacity to mature was inversely related to the initial oocyte size at the time of isolation from granulosa cells, and closely corresponded to developmental timing of acquisition of such ability in vivo. We conclude that the acquisition of mouse oocyte competence to mature follows a definite time program, which is independent of the presence of granulosa cells and of heterologous cell contacts, at least within the developmental stages studied.

Animals↗
PubMedDate not supplied

Malignant stromal tumor consistent with fibrosarcoma arising from Meckel's diverticulum. Clinicopathological study of an incidentally discovered tumor and review of the literature.

The authors report a case of a Meckel's diverticulum mesenchymal tumor incidentally discovered in a 69-year-old woman undergoing laparotomy for an ovarian cyst. Histological examination of the tumor revealed a fasciculated proliferation of spindle cells that proved to be immunoreactive to vimentin only; pleomorphism was mild, necrosis extensive and mitotic count high. Because these features were consistent with those of fibrosarcoma, the tumor was classified in the category of gastrointestinal stromal tumors; more specifically, it was considered malignant for the presence of spread beyond the primary site in the form of peritoneal nodules and for the high mitotic count. We have been able to find only one previously reported case of mesenchymal malignant tumor of Meckel's diverticulum classified as fibrosarcoma among the 199 malignant tumors described in the literature. Based on this personal experience and on the review of the literature concerning malignant tumors of Meckel's diverticulum, we discuss both the rarity of these tumors and the importance of removing Meckel's diverticulum every time it is found during laparotomy.

Aged↗