Bone substitutes are being increasingly used in surgery as over two millions bone grafting procedures are performed worldwide per year. Autografts still represent the gold standard for bone substitution, though the morbidity and the inherent limited availability are the main limitations. Allografts, i.e. banked bone, are osteoconductive and weakly osteoinductive, though there are still concerns about the residual infective risks, costs and donor availability issues. As an alternative, xenograft substitutes are cheap, but their use provided contrasting results, so far. Ceramic-based synthetic bone substitutes are alternatively based on hydroxyapatite (HA) and tricalcium phosphates, and are widely used in the clinical practice. Indeed, despite being completely resorbable and weaker than cortical bone, they have exhaustively proved to be effective. Biomimetic HAs are the evolution of traditional HA and contains ions (carbonates, Si, Sr, Fl, Mg) that mimic natural HA (biomimetic HA). Injectable cements represent another evolution, enabling mininvasive techniques. Bone morphogenetic proteins (namely BMP2 and 7) are the only bone inducing growth factors approved for human use in spine surgery and for the treatment of tibial nonunion. Demineralized bone matrix and platelet rich plasma did not prove to be effective and their use as bone substitutes remains controversial. Experimental cell-based approaches are considered the best suitable emerging strategies in several regenerative medicine application, including bone regeneration. In some cases, cells have been used as bioactive vehicles delivering osteoinductive genes locally to achieve bone regeneration. In particular, mesenchymal stem cells have been widely exploited for this purpose, being multipotent cells capable of efficient osteogenic potential. Here we intend to review and update the alternative available techniques used for bone fusion, along with some hints on the advancements achieved through the experimental research in this field.

BackgroundOsteoarthritis (OA) is a multifactorial disease characterized by destruction of the articular cartilage due to environmental, mechanical and genetic components. The genetics of OA is complex and is not completely understood. Recent works have demonstrated the importance of microRNAs (miRNAs) in cartilage function. MiRNAs are a class of small noncoding RNAs that regulate gene expression and are involved in different cellular process: apoptosis, proliferation, development, glucose and lipid metabolism. The aim of this study was to identify and characterize the expression profile of miRNAs in normal and OA chondrocytes and to determine their role in the OA.MethodsChondrocytes were moved to aggregate culture and evaluated using histological and qPCR techniques. miRNAs were isolated and analyzed using the Agilent Human miRNA Microarray.ResultsOf the 723 miRNAs analyzed, 7 miRNAs showed a statistically significant differential expression. Amongst these 7 human miRNAs, 1 was up-regulated in OA chondrocytes (hsa-miR-483-5p) and 6 were up-regulated in normal chondrocytes (hsa-miR-149*, hsa-miR-582-3p, hsa-miR-1227, hsa-miR-634, hsa-miR-576-5p and hsa-miR-641). These profiling results were validated by the detection of some selected miRNAs by qPCR. In silico analyses predicted that key molecular pathways potentially altered by the miRNAs differentially expressed in normal and OA chondrocytes include TGF-beta, Wnt, Erb and mTOR signalling; all of them implicated in the development, maintenance and destruction of articular cartilage.ConclusionsWe have identified 7 miRNAs differentially expressed in OA and normal chondrocytes. Our potential miRNA target predictions and the signalling cascades altered by the differentially expressed miRNAs supports the potential involvement of the detected miRNAs in OA pathology. Due to the importance of miRNA in mediating the translation of target mRNA into protein, the identification of these miRNAs differentially expressed in normal and OA chondrocyte micropellets could have important diagnostic and therapeutic potential. Further studies are needed to know the function of these miRNAs, including the search of their target mRNA genes, which could lead to the development of novel therapeutic strategies for the OA treatment.

The human amniotic membrane (HAM) is a highly abundant and readily available tissue. This amniotic tissue has considerable advantageous characteristics to be considered as an attractive material in the field of regenerative medicine. It has low immunogenicity, anti-inflammatory properties and their cells can be isolated without the sacrifice of human embryos. Since it is discarded post-partum it may be useful for regenerative medicine and cell therapy. Amniotic membranes have already been used extensively as biologic dressings in ophthalmic, abdominal and plastic surgery. HAM contains two cell types, from different embryological origins, which display some characteristic properties of stem cells. Human amnion epithelial cells (hAECs) are derived from the embryonic ectoderm, while human amnion mesenchymal stromal cells (hAMSCs) are derived from the embryonic mesoderm. Both populations have similar immunophenotype and multipotential for in vitro differentiation into the major mesodermal lineages, however they differ in cell yield. Therefore, HAM has been proposed as a good candidate to be used in cell therapy or regenerative medicine to treat damaged or diseased tissues.

Background. The interests in mesenchymal stem cells (MSCs) and their application in cell therapy have resulted in a better understanding of the basic biology of these cells. Recently hypoxia has been indicated as crucial for complete chondrogenesis. We aimed at analyzing bone marrow MSCs (BM-MSCs) differentiation capacity under normoxic and severe hypoxic culture conditions. Methods. MSCs were characterized by flow cytometry and differentiated towards adipocytes, osteoblasts, and chondrocytes under normoxic or severe hypoxic conditions. The differentiations were confirmed comparing each treated point with a control point made of cells grown in DMEM and fetal bovine serum (FBS). Results. BM-MSCs from the donors displayed only few phenotypical differences in surface antigens expressions. Analyzing marker genes expression levels of the treated cells compared to their control point for each lineage showed a good differentiation in normoxic conditions and the absence of this differentiation capacity in severe hypoxic cultures. Conclusions. In our experimental conditions, severe hypoxia affects the in vitro differentiation potential of BM-MSCs. Adipogenic, osteogenic, and chondrogenic differentiations are absent in severe hypoxic conditions. Our work underlines that severe hypoxia slows cell differentiation by means of molecular mechanisms since a decrease in the expression of adipocyte-, osteoblast-, and chondrocyte-specific genes was observed.

Adipose tissue represents a hot topic in regenerative medicine because of the tissue source abundance, the relatively easy retrieval, and the inherent biological properties of mesenchymal stem cells residing in its stroma. Adipose-derived mesenchymal stem cells (ASCs) are indeed multipotent somatic stem cells exhibiting growth kinetics and plasticity, proved to induce efficient tissue regeneration in several biomedical applications. A defined consensus for their isolation, classification, and characterization has been very recently achieved. In particular, bone tissue reconstruction and regeneration based on ASCs has emerged as a promising approach to restore structure and function of bone compromised by injury or disease. ASCs have been used in combination with osteoinductive biomaterial and/or osteogenic molecules, in either static or dynamic culture systems, to improve bone regeneration in several animal models. To date, few clinical trials on ASC-based bone reconstruction have been concluded and proved effective. The aim of this review is to dissect the state of the art on ASC use in bone regenerative applications in the attempt to provide a comprehensive coverage of the topics, from the basic laboratory to recent clinical applications.

Fibroblast growth factors (FGFs) 15/19 and 21 belong to the FGF endocrine subfamily. They present the intriguing characteristic to be transcribed and secreted in certain tissues and to act as hormones. The insulin-mimetic properties of FGF21 and the regulatory role of FGF15/19 in bile acid and glucose homeostasis endorse these hormones as druggable targets in metabolic disorders. Here, we present details on discoveries, identification, transcriptional regulation, and mechanism of actions of FGF15/19 and FGF21 with a critical perspective view on their putative role as metabolic integrators in the liver. (HEPATOLOGY 2012;56:2404-2411 T he fibroblast growth factors (FGFs) family comprises 22 members classified, by gene-locus analyses and mechanisms of action, into seven subfamilies and recognized as crucial modulators of cell proliferation, differentiation, embryonic development, and organogenesis 1,2 (Fig. 1). Eighteen members are secreted proteins, whereas four FGFs are intracellular signaling proteins. Most of the 18 secreted FGFs bind and activate cell-surface tyrosine kinase FGF receptors (FGFRs) by a high-affinity interaction with heparan sulfate glycosaminoglycans (HSGAGs). Unlike the canonic FGFs that act as autocrine and paracrine factors, three members, namely, FGF15, FGF19, and FGF23 (also known as the FGF19 subfamily), display extremely low affinity to HSGAGs, thus functioning as endocrine hormones and exerting metabolic actions distant from the tissues from which they are secreted. FGF19 subfamily members require single-pass transmembrane glycoproteins, named klotho proteins (aklotho and b-klotho), to bind FGFRs and activate FGF-signaling pathways. Recently, the FGF19 subfamily has received great attention because its members coordinately govern bile acid (BA) and glucose metabolism and modulate vitamin D and phosphate homeostasis. 3,4 In this review, we focus on the metabolic activities of FGF15/19 and 21, placing emphasis on the liver as a major target tissue. FGF15/19Identification. Initially described as a direct target of the chimeric oncoprotein, E2A-PBX1, in the brain, 5 FGF15 has been the first FGF19 subfamily member to be identified. Although the FGF15 gene shares only 51% amino-acid identity with its human ortholog, FGF19, 6,7 FGF15 and FGF19 messenger RNA (mRNA) expression patterns are similar (mostly small intestine, fetal cartilage, skin, retina, and gallbladder) 8,9 and, as ileum-derived postprandial hormones, govern similarly both BA and glucose metabolism. 10Expression Regulation and Mechanism of Action. Earlier studies in primary human hepatocytes

No abstract

The aim of this pilot study was to analyze the effects of glucosamine (GlcN) and its N-acetyl-phenylalanine derivative (NAPA) in Vitamin A model of osteoarthritis (OA) in rabbits. GlcN or NAPA or saline solution was intra-articularly administered in rabbit OA knees. Histological analysis revealed that treatment with GlcN or NAPA was associated with more homogeneous chondrocyte cellularity, absence of fissures and fragmentation and more intense staining of the matrix with Alcian Blue compared to the articular surfaces of the knees treated with saline solution. Comparative in vitro study performed on rabbit primary chondrocytes revealed that GlcN and NAPA were also able to counteract the IL-1beta-upregulation of genes coding for metalloproteases and inflammatory cytokines. Our preliminary in vivo and in vitro studies suggest that GlcN and NAPA could play a disease-modifying protective role in OA by an anti-catabolic effect and an anti-inflammatory activity on chondrocytes.