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Biomedical subjects

M Riminucci

Publications and source records attributed to M Riminucci.

At least 19 recordsLinked to original sources
PubMed2006

Lentiviral transduction of human postnatal skeletal (stromal, mesenchymal) stem cells: in vivo transplantation and gene silencing.

Systems for gene transfer and silencing in human skeletal stem cells (hSSCs, also stromal or mesenchymal stem cells) are important for addressing critical issues in basic hSSC and skeletal biology and for developing gene therapy strategies for treatment of skeletal diseases. Whereas recent studies have shown the efficacy of lentiviral transduction for gene transfer in hSSCs in vitro, no study has yet proven that lentivector-transduced hSSCs retain their distinctive organogenic potential in vivo, as probed by in vivo transplantation assays. Therefore, in addition to analyzing the in vitro growth and differentiation properties of hSSCs transduced with advanced-generation lentivectors, we ectopically transplanted LV-eGFP-transduced hSSCs (along with an osteoconductive carrier) in the subcutaneous tissue of immunocompromised mice. eGFP-transduced cells formed heterotopic ossicles, generating osteoblasts, osteocytes, and stromal cells in vivo, which still expressed GFP at 2 months after transplantation. eGFP-expressing cells could be recovered from the ossicles 8 weeks posttransplantation and reestablished in culture as viable and proliferating cells. Further, we investigated the possibility of silencing individual genes in hSSCs using lentivectors encoding short hairpin precursors of RNA interfering sequences under the control of the Pol-III-dependent H1 promoter. Significant long-term silencing of both lamin A/C and GFP (an endogenous gene and a transgene, respectively) was obtained with lentivectors encoding shRNAs. These data provide the basis for analysis of the effect of gene knockdown during the organogenesis of bone in the in vivo transplantation system and for further studies on the silencing of alleles carrying dominant, disease-causing mutations.

Bone Diseases↗
PubMed2005

[Bone stem cells].

Explore the source record for details and available documents.

Bone Marrow Cells↗
PubMed2003

Building bone tissue: matrices and scaffolds in physiology and biotechnology.

Deposition of bone in physiology involves timed secretion, deposition and removal of a complex array of extracellular matrix proteins which appear in a defined temporal and spatial sequence. Mineralization itself plays a role in dictating and spatially orienting the deposition of matrix. Many aspects of the physiological process are recapitulated in systems of autologous or xenogeneic transplantation of osteogenic precursor cells developed for tissue engineering or modeling. For example, deposition of bone sialoprotein, a member of the small integrin-binding ligand, N-linked glycoprotein family, represents the first step of bone formation in ectopic transplantation systems in vivo. The use of mineralized scaffolds for guiding bone tissue engineering has revealed unexpected manners in which the scaffold and cells interact with each other, so that a complex interplay of integration and disintegration of the scaffold ultimately results in efficient and desirable, although unpredictable, effects. Likewise, the manner in which biomaterial scaffolds are "resorbed" by osteoclasts in vitro and in vivo highlights more complex scenarios than predicted from knowledge of physiological bone resorption per se. Investigation of novel biomaterials for bone engineering represents an essential area for the design of tissue engineering strategies.

Biocompatible Materials↗
PubMed2003

Coexpression of bone sialoprotein (BSP) and the pivotal transcriptional regulator of osteogenesis, Cbfa1/Runx2, in malignant melanoma.

Bone sialoprotein (BSP) is a member of the SIBLINGS family, normally restricted to the skeleton, but it has been shown to be ectopically expressed in some human invasive carcinomas. BSP expression in human cancer was initially associated with the ability of BSP-expressing tumors to metastasize to bone, although the mechanism whereby BSP expression should facilitate homing of cancer cells to the bone marrow environment has remained unexplained. More recently, clinical and experimental data have converged in highlighting a potential link between BSP expression and tumor invasiveness in general. We show here that human malignant melanoma cells express BSP in vivo as a function of extent of local invasion, and that expression of BSP mRNA and protein in melanoma cells is associated with the expression of the transcriptional regulator of osteogenic cell differentiation, Cbfa1/Runx2. It has been well established that expression of Cbfa1/Runx2 in the mouse is normally restricted to bone-forming cells. In the mouse, Cbfa1/Runx2 dictates osteogenic differentiation of mesodermal cells by regulating bone-specific genes. Since it also regulates expression of at least two matrix metalloproteases implicated in tumor invasion and metastasis (collagenase 3, membrane type 1 matrix metalloproteinase), we propose that the relationship between BSP expression and an invasive behavior in human epithelial cancer cells may be rooted in a common transcriptional control exerted by Cbfa1.

Cell Line, Tumor↗
PubMed2003

Osteoclastogenesis in fibrous dysplasia of bone: in situ and in vitro analysis of IL-6 expression.

Fibrous dysplasia of bone (FD) is caused by somatic mutations of the GNAS1 gene, which lead to constitutive activation of adenylyl cyclase and overproduction of cAMP in osteogenic cells. Previous in vitro studies using nonclonal, heterogeneous strains of FD-derived cells suggested that IL-6 might play a critical role in promoting excess osteoclastogenesis in FD. In this study, we investigated IL-6 expression in FD in situ and its relationship to the actual patterns of osteoclastogenesis within the abnormal tissue. We found that osteoclastogenesis is not spatially restricted to bone surfaces in FD but occurs to a large extent ectopicly in the fibrous tissue, where stromal cells diffusely express IL-6 mRNA and exhibit a characteristic cell morphology. We also observed specific expression of IL-6 mRNA in a proportion of osteoclasts, suggesting that an autocrine/paracrine loop may contribute to osteoclastogenesis in vivo in FD, as in some other bone diseases, including Paget's disease. We also generated homogeneous, clonally derived strains of wild-type and GNAS1-mutated stromal cells from the same individual, parent FD lesions. In this way, we could show that mutated stromal cells produce IL-6 at a basal magnitude and rate that are significantly higher than in the cognate wild-type cells. Conversely, wild-type cells respond to db-cAMP with a severalfold increase in magnitude and rate of IL-6 production, whereas mutant strains remain essentially unresponsive. Our data establish a direct link between GNAS1 mutations in stromal cells and IL-6 production but also define the complexity of the role of IL-6 in regulating osteoclastogenesis in FD in vivo. Here, patterns of osteoclastogenesis and bone resorption reflect not only the cell-autonomous effects of GNAS1 mutations in osteogenic cells (including IL-6 production) but also the local and systemic context to which non-osteogenic cells, local proportions of wild-type vs mutated cells, and systemic hormones contribute.

Adult↗
PubMed2002

An R201H activating mutation of the GNAS1 (Gsalpha) gene in a corticotroph pituitary adenoma.

In the pituitary gland, activating mutations of the GNAS1 (Gsalpha) gene at Gln227 have been identified in adrenocorticotrophin secreting, growth hormone secreting, and prolactin secreting adenomas. To date, mutations at the codon encoding R201, typically underlying the McCune-Albright syndrome and isolated fibrous dysplasia of bone, have been demonstrated only in growth hormone secreting pituitary adenomas. In this study, a polymerase chain reaction amplified target sequence in exon 8 of the GNAS1 gene was sequenced, identifying the first R201 mutation seen in an isolated basophilic adenoma which generated Cushing's disease in a child. This case adds Cushing's disease to the range of human diseases caused by R201 mutations of the GNAS1 gene.

Adenoma, Basophil↗
PubMed2001

Gnathodiaphyseal dysplasia: a syndrome of fibro-osseous lesions of jawbones, bone fragility, and long bone bowing.

We report an unusual generalized skeletal syndrome characterized by fibro-osseous lesions of the jawbones with a prominent psammomatoid body component, bone fragility, and bowing/sclerosis of tubular bones. The case fits with the emerging profile of a distinct syndrome with similarities to previously reported cases, some with an autosomal dominant inheritance and others sporadic. We suggest that the syndrome be named gnathodiaphyseal dysplasia. The patient had been diagnosed previously with polyostotic fibrous dysplasia (PFD) elsewhere, but further clinical evaluation, histopathological study, and mutation analysis excluded this diagnosis. In addition to providing a novel observation of an as yet poorly characterized syndrome, the case illustrates the need for stringent diagnostic criteria for FD. The jaw lesions showed fibro-osseous features with the histopathological characteristics of cemento-ossifying fibroma, psammomatoid variant. This case emphasizes that the boundaries between genuine GNAS1 mutation-positive FD and other fibro-osseous lesions occurring in the jawbones should be kept sharply defined, contrary to a prevailing tendency in the literature. A detailed pathological study revealed previously unreported features of cemento-ossifying fibroma, including the participation of myofibroblasts and the occurrence of psammomatoid bodies and aberrant mineralization, within the walls of blood vessels. Transplantation of stromal cells grown from the lesion into immunocompromised mice resulted in a close mimicry of the native lesion, including the sporadic formation of psammomatoid bodies, suggesting an intrinsic abnormality of bone-forming cells.

Animals↗
PubMed2001

Bone marrow stromal stem cells: nature, biology, and potential applications.

Bone marrow stromal cells are progenitors of skeletal tissue components such as bone, cartilage, the hematopoiesis-supporting stroma, and adipocytes. In addition, they may be experimentally induced to undergo unorthodox differentiation, possibly forming neural and myogenic cells. As such, they represent an important paradigm of post-natal nonhematopoietic stem cells, and an easy source for potential therapeutic use. Along with an overview of the basics of their biology, we discuss here their potential nature as components of the vascular wall, and the prospects for their use in local and systemic transplantation and gene therapy.

Animals↗
PubMed2001

Achondrogenesis type IB: agenesis of cartilage interterritorial matrix as the link between gene defect and pathological skeletal phenotype.

Achondrogenesis type IB is a lethal osteochondrodysplasia caused by mutations in the diastrophic dysplasia sulfate transporter gene. How these mutations lead to the skeletal phenotype is not known. Histology of plastic-embedded skeletal fetal achondrogenesis type IB samples suggested that interterritorial epiphyseal cartilage matrix was selectively missing. Cartilage was organized in "chondrons" separated by cleft spaces; chondrocyte seriation, longitudinal septa, and, in turn, mineralized cartilaginous septa were absent. Agenesis of interterritorial matrix as the key histologic change was confirmed by immunohistology using specific markers of territorial and interterritorial matrix. Biglycan-enriched territorial matrix was preserved; decorin-enriched interterritorial areas were absent, although immunostaining was observed within chondrocytes. Thus, in achondrogenesis type IB: (1) a complex derangement in cartilage matrix assembly lies downstream of the deficient sulfate transporter activity; (2) the severely impaired decorin deposition participates in the changes in matrix organization with lack of development of normal interterritorial matrix; and (3) this change determines the lack of the necessary structural substrate for proper endochondral bone formation and explains the severe skeletal phenotype.

Adult↗
PubMed2001

[Stem cells in medicine].

We witness an unprecedented explosion of knowledge and interest in the field of stem cells and stem cell-dependent organ systems. The notion of stem cell has expanded to encompass cells with different properties but all amenable to ex vivo manipulation. We have learned that not only rapidly self-renewing tissues, but also unsuspected systems such as the central nervous system are associated with post-natal progenitor cells. The bone marrow seems to represent an important cross-road of many different progenitors, and perhaps the easiest source of diverse progenitors to be used for therapeutic purposes in a large spectrum of diseases. While some applicative uses of post-natal progenitor cells are either already in use, or soon to be routinely implemented, much larger perspectives are linked to the design of appropriate strategies for cell delivery and stable cell transduction. Meanwhile, major gains in understanding of the biology of different diseases are implied by the very recognition that many diseases are indeed stem cell diseases.

Bone Marrow↗
PubMed2000

Mutations of the GNAS1 gene, stromal cell dysfunction, and osteomalacic changes in non-McCune-Albright fibrous dysplasia of bone.

Activating missense mutations of the GNAS1 gene, encoding the alpha subunit of the stimulatory G protein (Gs), have been identified in patients with the McCune-Albright syndrome (MAS; characterized by polyostotic fibrous dysplasia, café au lait skin pigmentation, and endocrine disorders). Because fibrous dysplasia (FD) of bone also commonly occurs outside of the context of typical MAS, we asked whether the same mutations could be identified routinely in non-MAS FD lesions. We analyzed a series of 8 randomly obtained, consecutive cases of non-MAS FD and identified R201 mutations in the GNAS1 gene in all of them by sequencing cDNA generated by amplification of genomic DNA using a standard primer set and by using a novel, highly sensitive method that uses a protein nucleic acid (PNA) primer to block amplification of the normal allele. Histologic findings were not distinguishable from those observed in MAS-related FD and included subtle changes in cell shape and collagen texture putatively ascribed to excess endogenous cyclic adenosine monophosphate (cAMP). Osteomalacic changes (unmineralized osteoid) were prominent in lesional FD bone. In an in vivo transplantation assay, stromal cells isolated from FD failed to recapitulate a normal ossicle; instead, they generated a miniature replica of fibrous dysplasia. These data provide evidence that occurrence of GNAS1 mutations, previously noted in individual cases of FD, is a common and perhaps constant finding in non-MAS FD. These findings support the view that FD, MAS, and nonskeletal isolated endocrine lesions associated with GNAS1 mutations represent a spectrum of phenotypic expressions (likely reflecting different patterns of somatic mosaicism) of the same basic disorder. We conclude that mechanisms underlying the development of the FD lesions, and hopefully mechanism-targeted therapeutic approaches to be developed, must also be the same in MAS and non-MAS FD.

Adolescent↗
PubMed1999

The histopathology of fibrous dysplasia of bone in patients with activating mutations of the Gs alpha gene: site-specific patterns and recurrent histological hallmarks.

Gs alpha mutations and histopathology have been analysed in a series of 13 patients with fibrous dysplasia (FD) of bone, including 12 patients with the McCune-Albright syndrome (MAS) and one patient with monostotic FD. Activating mutations (either R201C or R201H) of the gene encoding the alpha subunit of the stimulatory G protein, Gs, were detected in all cases, including the case of monostotic FD, using a variety of techniques [reverse transcription-polymerase chain reaction (RT-PCR) with allele-specific primers, allele-specific oligonucleotide hybridization, and DNA sequencing]. A spectrum of bone lesions associated with such mutations was identified and it was possible to recognize three primary, but distinct, histological patterns, defined here as Chinese writing type, sclerotic/Pagetoid type, and sclerotic/hypercellular type, which are characteristically associated with the axial/appendicular skeleton, cranial bones, or gnathic bones, respectively. Features of FD histopathology were characterized by confocal fluorescence microscopy, which allowed the definition of osteogenic cell shape changes and 'Sharpey fibre bone' as common denominators of all histological subtypes. Defining characteristics of the different subtypes, two of which diverge from standard descriptions of FD and have never been characterized before, were dependent on the amount and structure of bone tissue within the FD lesion. These data emphasize the non-random (site-specific) variability of FD histopathology in patients carrying activating mutations of the Gs alpha gene and provide additional evidence for the occurrence of Gs alpha mutations in cases of FD other than typical MAS.

Adolescent↗
PubMed1999

Multipotential cells in the bone marrow stroma: regulation in the context of organ physiology.

Multipotential (osteogenic, adipogenic, chondrogenic, and myelosupportive) cells associated with the bone marrow stroma are revealed by in vitro or in vivo differentiation assays. If considered in the context of development, growth, and adaptive changes of bone as an organ, the hierarchical organization, histophysiology, and biological significance of the so-called "stromal system" appear distinct from those predicted from the commonly used analogy with the hematopoietic system, with which the stromal system and its putative "stem" cell are usually compared. The plasticity of differentiated phenotypes and the emergence of individual lineages in a defined temporal succession throughout development and postnatal life reflect the role of the multipotential cells in the stromal system in tissue adaptation and growth, rather than in cell consumption and replacement. This makes the stromal system and its progenitors an interesting paradigm of the biology of an individual cell's flexibility in complex organisms.

Bone Marrow Cells↗
PubMed1998

Reproduction of human fibrous dysplasia of bone in immunocompromised mice by transplanted mosaics of normal and Gsalpha-mutated skeletal progenitor cells.

We have isolated progenitor cells from the stromal system of the fibrous dysplastic marrow of patients with McCune-Albright Syndrome. Analysis of the Gsalpha gene from individual colonies provided direct evidence for the presence of two different genotypes within single fibrous dysplastic lesions: marrow stromal cells containing two normal Gsalpha alleles, and those containing one normal allele and an allele with an activating mutation. Transplantation of clonal populations of normal cells into the subcutis of immunocompromised mice resulted in normal ossicle formation. In contrast, transplantation of clonal populations of mutant cells always led to the loss of transplanted cells from the transplantation site and no ossicle formation. However, transplantation of a mixture of normal and mutant cells reproduced an abnormal ectopic ossicle recapitulating human fibrous dysplasia and providing an in vivo cellular model of this disease. These results provide experimental evidence for the necessity of both normal and mutant cells in the development of McCune-Albright Syndrome fibrous dysplastic lesions in bone.

Animals↗
PubMed1998

Disseminated growth of murine plasmacytoma: similarities to multiple myeloma.

Murine plasma cell tumors share a number of common features with human multiple myeloma, suggesting their possible use as a model for this disease. However, one major difference between the two is the peritoneal localization of murine tumors as opposed to bone marrow residence of malignant plasma cells in early stages of multiple myeloma. We have thus examined the ability of murine plasmacytoma to produce disseminated growth similar to that seen in myeloma or other lymphoid neoplasias. Of four murine cell lines evaluated, all were demonstrated to effect highly metastatic disease involving multiple organs, although variation was observed between lines. A temporal analysis was accordingly performed with the S107 line to assess the pattern of cellular localization. Both light microscopy and PCR analysis revealed that engraftment of plasma cells occurs first in the bone marrow, followed by dissemination to other sites including the spleen, lung, and liver. Cells passaged in vivo through the bone marrow display an entirely different metastatic pattern with no homing preference to bone marrow or any other organ, suggesting the occurrence of a phenotypic change. Microscopic osteolytic lesions were observed adjacent to plasma cell tumor masses in the bone marrow, indicating early stages of bone disease. These findings demonstrate previously unrecognized similarities between the murine and human diseases and suggest the use of this in vivo model for experimental approaches to the treatment of human disease.

Animals↗