RESUMO
AIMS: Our objective was to study the vascular smooth muscle cells (VSMC) osteoblastic transdifferentiation in AGE exposed cells or those from diabetic animals, and its response to metformin treatment. METHODS: VSMC were obtained from non-diabetic rats, grown with or without AGE; while VSMC of in vivo-ex vivo studies were obtained from non-diabetic control animals (C), diabetic (D), C treated with metformin (M) and D treated with metformin (D-M). We studied the osteoblastic differentiation by evaluating alkaline phosphatase (ALP), type I collagen (Col) and mineral deposit. RESULTS: In vitro, AGE increased proliferation, migration, and osteoblastic differentiation of VSMC. Metformin cotreatment prevented the AGE induced proliferation and migration. Both AGE and metformin stimulated the expression of ALP and Col. AGE induced mineralization was prevented by metformin. VSMC from D expressed a higher production of Col and ALP. Those from D-M showed an ALP increase vs C and M, and a partial decrease vs D. Cultured in osteogenic medium, ALP, Col and mineralization increased in D vs C, remained unchanged in M, and were prevented in D-M animals. CONCLUSION: Both AGE and DM favor VSMC differentiation towards the osteogenic phenotype and this effect can be prevented by metformin.
Assuntos
Calcinose , Diabetes Mellitus , Calcificação Vascular , Ratos , Animais , Produtos Finais de Glicação Avançada/metabolismo , Músculo Liso Vascular/metabolismo , Transdiferenciação Celular , Reação de Maillard , Diabetes Mellitus/metabolismo , Células CultivadasRESUMO
Advanced glycation end products (AGE) have been demonstrated to induce the osteogenic trans-differentiation of vascular smooth muscle cells (VSMC). Strontium ranelate (SR) is an anti-osteoporotic agent that has both anti-catabolic and anabolic actions on bone tissue. However, in the last years SR has been associated with an increase of cardiovascular risk. We hypothesize that SR can increase the osteoblastic trans-differentiation of VSMC and the induction of extracellular calcifications, an effect that could be potentiated in the presence of AGE and inhibited by simultaneous administration of vitamin D. The present results of our in vitro experiments demonstrate that AGE and SR alone or in combination, stimulate L-type calcium channels, causing an increase in reactive oxygen species and activation of both ERK and NFkB, with the final effect of promoting the osteogenic shift of VSMC. Importantly, these in vitro effects of AGE and/or SR can be prevented by co-incubation with vitamin D.
Assuntos
Diferenciação Celular/efeitos dos fármacos , Produtos Finais de Glicação Avançada/farmacologia , Músculo Liso Vascular/citologia , Miócitos de Músculo Liso/citologia , Osteogênese/efeitos dos fármacos , Tiofenos/farmacologia , Vitamina D/farmacologia , Animais , Ácido Ascórbico/farmacologia , Contagem de Células , Movimento Celular/efeitos dos fármacos , Subunidade alfa 1 de Fator de Ligação ao Core/metabolismo , Masculino , Modelos Biológicos , Miócitos de Músculo Liso/efeitos dos fármacos , Miócitos de Músculo Liso/metabolismo , Nifedipino/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Ratos Sprague-Dawley , Espécies Reativas de Oxigênio/metabolismo , Sulfassalazina/farmacologia , Vitamina E/farmacologiaRESUMO
AIMS: Deleterious effects of metabolic syndrome (MS) on bone are still controversial. In this study we evaluated the effects of a fructose-induced MS, and/or an oral treatment with metformin on the osteogenic potential of bone marrow mesenchymal stromal cells (MSC), as well as on bone formation and architecture. METHODS: 32 male 8week-old Wistar rats were assigned to four groups: control (C), control plus oral metformin (CM), rats receiving 10% fructose in drinking water (FRD), and FRD plus metformin (FRDM). Samples were collected to measure blood parameters, and to perform pQCT analysis and static and dynamic histomorphometry. MSC were isolated to determine their osteogenic potential. RESULTS: Metformin improved blood parameters in FRDM rats. pQCT and static and dynamic histomorphometry showed no significant differences in trabecular and cortical bone parameters among groups. FRD reduced TRAP expression and osteocyte density in trabecular bone and metformin only normalized osteocyte density. FRD decreased the osteogenic potential of MSC and metformin administration could revert some of these parameters. CONCLUSIONS: FRD-induced MS shows reduction in MSC osteogenic potential, in osteocyte density and in TRAP activity. Oral metformin treatment was able to prevent trabecular osteocyte loss and the reduction in extracellular mineralization induced by FRD-induced MS.
Assuntos
Osso e Ossos/efeitos dos fármacos , Células-Tronco Mesenquimais/efeitos dos fármacos , Síndrome Metabólica/tratamento farmacológico , Metformina/uso terapêutico , Osteogênese/efeitos dos fármacos , Adipócitos/efeitos dos fármacos , Adipócitos/fisiologia , Animais , Densidade Óssea/efeitos dos fármacos , Osso e Ossos/fisiologia , Diferenciação Celular/efeitos dos fármacos , Células Cultivadas , Frutose , Masculino , Células-Tronco Mesenquimais/fisiologia , Síndrome Metabólica/induzido quimicamente , Síndrome Metabólica/fisiopatologia , Metformina/farmacologia , Ratos , Ratos WistarRESUMO
Natural and synthetic cross-linked polymers allow the improvement of cytocompatibility and mechanical properties of the individual polymers. In osteochondral lesions of big size it will be required the use of scaffolds to repair the lesion. In this work a borax cross-linked scaffold based on fumarate-vinyl acetate copolymer and chitosan directed to osteochondrondral tissue engineering is developed. The cross-linked scaffolds and physical blends of the polymers are analyzed in based on their morphology, glass transition temperature, and mechanical properties. In addition, the stability, degradation behavior, and the swelling kinetics are studied. The results demonstrate that the borax cross-linked scaffold exhibits hydrogel behavior with appropriated mechanical properties for bone and cartilage tissue regeneration. Bone marrow progenitor cells and primary chondrocytes are used to demonstrate its osteo- and chondrogenic properties, respectively, assessing the osteo- and chondroblastic growth and maturation, without evident signs of cytotoxicity as it is evaluated in an in vitro system.
Assuntos
Quitosana/química , Condrogênese , Fumaratos/química , Osteogênese , Polímeros/química , Engenharia Tecidual , Alicerces Teciduais , Animais , Biomarcadores/metabolismo , Células Cultivadas , Expressão Gênica , Ratos , Ratos Sprague-Dawley , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Bisphosphonates such as alendronate are antiosteoporotic drugs that inhibit the activity of bone-resorbing osteoclasts and secondarily promote osteoblastic function. Diabetes increases bone-matrix-associated advanced glycation end products (AGEs) that impair bone marrow progenitor cell (BMPC) osteogenic potential and decrease bone quality. Here we investigated the in vitro effect of alendronate and/or AGEs on the osteoblastogenic, adipogenic, and chondrogenic potential of BMPC isolated from nondiabetic untreated rats. We also evaluated the in vivo effect of alendronate (administered orally to rats with insulin-deficient Diabetes) on long-bone microarchitecture and BMPC multilineage potential. In vitro, the osteogenesis (Runx2, alkaline phosphatase, type 1 collagen, and mineralization) and chondrogenesis (glycosaminoglycan production) of BMPC were both decreased by AGEs, while coincubation with alendronate prevented these effects. The adipogenesis of BMPC (PPARγ, intracellular triglycerides, and lipase) was increased by AGEs, and this was prevented by coincubation with alendronate. In vivo, experimental Diabetes (a) decreased femoral trabecular bone area, osteocyte density, and osteoclastic TRAP activity; (b) increased bone marrow adiposity; and (c) deregulated BMPC phenotypic potential (increasing adipogenesis and decreasing osteogenesis and chondrogenesis). Orally administered alendronate prevented all these Diabetes-induced effects on bone. Thus, alendronate could improve bone alterations in diabetic rats by preventing the antiosteogenic, antichondrogenic, and proadipocytic effects of AGEs on BMPC.
Assuntos
Alendronato/administração & dosagem , Células da Medula Óssea/citologia , Diferenciação Celular/efeitos dos fármacos , Diabetes Mellitus Experimental/tratamento farmacológico , Adipogenia/efeitos dos fármacos , Animais , Células da Medula Óssea/efeitos dos fármacos , Células da Medula Óssea/metabolismo , Regeneração Óssea/efeitos dos fármacos , Condrogênese/efeitos dos fármacos , Diabetes Mellitus Experimental/patologia , Produtos Finais de Glicação Avançada/administração & dosagem , Produtos Finais de Glicação Avançada/metabolismo , Humanos , Osteogênese/efeitos dos fármacos , RatosRESUMO
Patients with long-term type 1 and type 2 diabetes mellitus (DM) can develop skeletal complications or "diabetic osteopathy". These include osteopenia, osteoporosis and an increased incidence of low-stress fractures. In this context, it is important to evaluate whether current anti-diabetic treatments can secondarily affect bone metabolism. Adenosine monophosphate-activated protein kinase (AMPK) modulates multiple metabolic pathways and acts as a sensor of the cellular energy status; recent evidence suggests a critical role for AMPK in bone homeostasis. In addition, AMPK activation is believed to mediate most clinical effects of the insulin-sensitizer metformin. Over the past decade, several research groups have investigated the effects of metformin on bone, providing a considerable body of pre-clinical (in vitro, ex vivo and in vivo) as well as clinical evidence for an anabolic action of metformin on bone. However, two caveats should be kept in mind when considering metformin treatment for a patient with type 2 DM at risk for diabetic osteopathy. In the first place, metformin should probably not be considered an anti-osteoporotic drug; it is an insulin sensitizer with proven macrovascular benefits that can secondarily improve bone metabolism in the context of DM. Secondly, we are still awaiting the results of randomized placebo-controlled studies in humans that evaluate the effects of metformin on bone metabolism as a primary endpoint.
RESUMO
La diabetes mellitus (DM) crónica se asocia con reducción en el contenido mineral óseo (osteopenia y osteoporosis). El objetivo de este trabajo fue evaluar la acción del ranelato de estroncio (RaSr) administrado por vía oral a animales control y diabéticos, sobre el potencial osteogénico de células progenitoras de médula ósea (CPMO). Dieciséis ratas Wistar macho jóvenes se dividieron en dos grupos: controles (C) y diabéticas (D) con destrucción parcial de células b-pancreáticas mediante inyecciones intraperitoneales consecutivas de nicotinamida y estreptozotocina. Siete días después de la inyección, cada grupo se subdividió: sin tratamiento, o tratadas oralmente con RaSr (625 mg/kg/día) durante seis semanas, luego de lo cual los animales fueron sacrificados. Las CPMO se obtuvieron de ratas de los cuatro grupos, por lavados del canal diafisario medular (húmero o fémur o ambos) y cultivo hasta confluencia en DMEM-10% FBS. La proliferación celular se evaluó mediante el ensayo de MTT. Luego las CPMO se replaquearon e incubaron en un medio osteogénico durante 14 días (fosfatasa alcalina [FAL] y colágeno tipo 1) o 21 días (mineralización). Las CPMO del grupo C+RaSr mostraron un aumento significativo versus control en la proliferación (133%) y en la diferenciación osteogénica (colágeno 143%, FAL 168%, mineralización 117%). La DM (grupo D) disminuyó significativamente la proliferación y diferenciación osteoblástica de las CPMO. El tratamiento con RaSr (grupo D+RaSr) previno completamente estos efectos antiosteogénicos de la DM. Así, en nuestro modelo experimental in vivo, la DM disminuye el potencial osteogénico de CPMO, efecto que puede ser prevenido por un tratamiento oral con RaSr. (AU)
Chronic diabetes mellitus (DM) is associated with a reduction in bone mineral content (osteopenia and osteoporosis). The object of this study was to evaluate the in vivo effect of he anti-osteoporotic drug strontium ranelate (SrRa) administered orally to control and diabetic animals, on the osteogenic potential of bone marrow progenitor cells (BMPC). Sixteen young male Wistar rats were divided into two groups: control (C) and diabetic with partial beta-cell destruction via consecutive intra-peritoneal injections of nicotinamide and streptozotocin (D). Seven days postinjection, each group was sub-divided: without treatment, or oral treatment with SrRa (625 mg/kg/day) for six weeks, after which the animals were euthanised (groups C, C+SrRa, D, D+SrRa). BMPC were obtained from rats of all four groups by flushing of the diaphysary canal (humerus and/or femur). Adherent cells were then cultured until confluence in DMEM10% FBS. Cell proliferation was evaluated with the MTT mitogenic bioassay. BMPC were replated and incubated in an osteogenic medium for 14 days (determination of alkaline phosphatase [ALP] and type-1 collagen) or 21 days (evaluation of mineralisation). BMPC from C+SrRa rats showed a significant increase versus control in proliferation (133%) and in osteogenic differentiation (collagen 143%, ALP 168%, mineralisation 117%). Induction of diabetes (group D) significantly decreased the proliferation and osteoblastic differentiation of BMPC. Treatment of diabetic animals with SrRa (group D+SrRa) completely prevented these anti-osteogenic effects of Diabetes. Thus, in our experimental in vivo model, Diabetes decreases the osteogenic potential of BMPC, an effect that can be prevented by oral treatment with strontium ranelate. (AU)
Assuntos
Animais , Masculino , Ratos , Osteoblastos/efeitos dos fármacos , Tiofenos/farmacologia , Células da Medula Óssea/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Diabetes Mellitus Experimental/tratamento farmacológico , Osteoporose/fisiopatologia , Tiofenos/administração & dosagem , Ratos Wistar , Modelos Animais de DoençasRESUMO
OBJECTIVE: The aims of this study were: first, to evaluate the possible effects of a fructose rich diet (FRD)-induced metabolic syndrome (MS) on different aspects of long bone histomorphometry in young male rats; second, to investigate the effects of this diet on bone tissue regeneration; and third, to correlate these morphometric alterations with changes in the osteogenic/adipogenic potential and expression of specific transcription factors, of marrow stromal cells (MSC) isolated from rats with fructose-induced MS. MATERIALS/METHODS: MS was induced in rats by treatment with a FRD for 28 days. Halfway through treatment, a parietal wound was made and bone healing was evaluated 14 days later. After treatments, histomorphometric analysis was performed in dissected femoral and parietal bones. MSC were isolated from the femora of control or fructose-treated rats and differentiated either to osteoblasts (evaluated by type 1 collagen, Alkaline phosphatase and extracellular nodule mineralization) or to adipocytes (evaluated by intracellular triglyceride accumulation). Expression of Runx2 and PPARγ was assessed by Western blot. RESULTS: Fructose-induced MS induced deleterious effects on femoral metaphysis microarchitecture and impaired bone regeneration. Fructose treatment decreased the osteogenic potential of MSC and Runx2 expression. In addition, it increased the adipogenic commitment of MSC and PPARγ expression. CONCLUSIONS: Fructose-induced MS is associated with deleterious effects on bone microarchitecture and with a decrease in bone repair. These alterations could be due to a deviation in the adipogenic/osteogenic commitment of MSC, probably by modulation of the Runx2/PPARγ ratio.
Assuntos
Adipócitos/metabolismo , Células da Medula Óssea/metabolismo , Osso e Ossos/metabolismo , Frutose/administração & dosagem , Frutose/farmacologia , Síndrome Metabólica/metabolismo , Osteoblastos/metabolismo , Edulcorantes/administração & dosagem , Edulcorantes/farmacologia , Fosfatase Alcalina/metabolismo , Animais , Western Blotting , Células da Medula Óssea/efeitos dos fármacos , Regeneração Óssea , Osso e Ossos/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Colágeno Tipo I/metabolismo , Subunidade alfa 1 de Fator de Ligação ao Core/metabolismo , Dieta , Fêmur/metabolismo , Frutose/metabolismo , Masculino , Síndrome Metabólica/patologia , Osteogênese/efeitos dos fármacos , PPAR gama/metabolismo , Ratos , Ratos Sprague-Dawley , Edulcorantes/metabolismo , Fatores de Tempo , Triglicerídeos/metabolismoRESUMO
AIMS: Diabetes mellitus is associated with metabolic bone disease and increased low-impact fractures. The insulin-sensitizer metformin possesses in vitro, in vivo and ex vivo osteogenic effects, although this has not been adequately studied in the context of diabetes. We evaluated the effect of insulin-deficient diabetes and/or metformin on bone microarchitecture, on osteogenic potential of bone marrow progenitor cells (BMPC) and possible mechanisms involved. METHODS: Partially insulin-deficient diabetes was induced in rats by nicotinamide/streptozotocin-injection, with or without oral metformin treatment. Femoral metaphysis micro-architecture, ex vivo osteogenic potential of BMPC, and BMPC expression of Runx-2, PPARγ and receptor for advanced glycation endproducts (RAGE) were investigated. RESULTS: Histomorphometric analysis of diabetic femoral metaphysis demonstrated a slight decrease in trabecular area and a significant reduction in osteocyte density, growth plate height and TRAP (tartrate-resistant acid phosphatase) activity in the primary spongiosa. BMPC obtained from diabetic animals showed a reduction in Runx-2/PPARγ ratio and in their osteogenic potential, and an increase in RAGE expression. Metformin treatment prevented the diabetes-induced alterations in bone micro-architecture and BMPC osteogenic potential. CONCLUSION: Partially insulin-deficient diabetes induces deleterious effects on long-bone micro-architecture that are associated with a decrease in BMPC osteogenic potential, which could be mediated by a decrease in their Runx-2/PPARγ ratio and up-regulation of RAGE. These diabetes-induced alterations can be totally or partially prevented by oral administration of metformin.
Assuntos
Células da Medula Óssea/citologia , Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Experimental/patologia , Insulina/deficiência , Metformina/uso terapêutico , Células-Tronco/citologia , Animais , Células da Medula Óssea/efeitos dos fármacos , Masculino , Osteogênese/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Células-Tronco/efeitos dos fármacosRESUMO
Accumulation of advanced glycation endproducts (AGEs) in bone tissue occurs in ageing and in Diabetes mellitus, and is partly responsible for the increased risk of low-stress bone fractures observed in these conditions. In this study we evaluated whether the anti-osteoporotic agent strontium ranelate can prevent the deleterious effects of AGEs on bone cells, and possible mechanisms of action involved. Using mouse MC3T3E1 osteoblastic cells in culture we evaluated the effects of 0.1mM strontium ranelate and/or 100 µg/ml AGEs-modified bovine serum albumin (AGEs-BSA) on cell proliferation, osteogenic differentiation and pro-inflammatory cytokine production. We found that AGEs-BSA alone decreased osteoblastic proliferation and differentiation (P<0.01) while increasing IL-1ß and TNFα production (P<0.01). On its own, strontium ranelate induced opposite effects: an increase in osteoblast proliferation and differentiation (P<0.01) and a decrease in cytokine secretion (P<0.01). Additionally, strontium ranelate prevented the inhibitory and pro-inflammatory actions of AGEs-BSA on osteoblastic cells (P<0.01). These effects of strontium ranelate were blocked by co-incubation with either the MAPK inhibitor PD98059, or the calcium channel blocker nifedipine. We also evaluated by Western blotting the activation status of ERK (a MAPK) and b-catenin. Activation of both signaling pathways was decreased by AGEs treatment, and this inhibitory effect was prevented if AGEs were co-incubated with strontium ranelate (P<0.01). On its own, strontium ranelate increased both pERK and activated b-catenin levels. In conclusion, this study demonstrates that strontium ranelate can prevent the deleterious in vitro actions of AGEs on osteoblastic cells in culture by mechanisms that involve calcium channel, MAPK and b-catenin activation.