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Objectives: oxidative stress plays a major role in the onset and progression of involutional osteoporosis. However, classical antioxidants fail to restore osteoblast function. Interestingly, the bone anabolism of parathyroid hormone (pTH) has been shown to be associated with its ability to counteract oxidative stress in osteoblasts. The pTH counterpart in bone, which is the pTHrelated protein (pTHrp), displays osteogenic actions through both its n-terminal pTH-like region and the c-terminal domain. Methods: We examined and compared the antioxidant capacity of pTHrp (1-37) with the c-terminal pTHrp domain comprising the 107-111 epitope (osteostatin) in both murine osteoblastic Mc3T3-e1 cells and primary human osteoblastic cells. Results: We showed that both n- and c-terminal pTHrp peptides at 100 nM decreased reactive oxygen species production and forkhead box protein o activation following hydrogen peroxide (H2o2)-induced oxidation, which was related to decreased lipid oxidative damage and caspase-3 activation in these cells. This was associated with their ability to restore the deleterious effects of H2o2 on cell growth and alkaline phosphatase activity, as well as on the expression of various osteoblast differentiation genes. The addition of Rp-cyclic 3′,5′-hydrogen phosphorothioate adenosine triethylammonium salt (a cyclic 3',5'-adenosine monophosphate antagonist) and calphostin c (a protein kinase c inhibitor), or a pTH type 1 receptor antagonist, abrogated the effects of n-terminal pTHrp, whereas protein phosphatase 1 (an src kinase activity inhibitor), sU1498 (a vascular endothelial growth factor receptor 2 inhibitor), or an anti osteostatin antiserum, inhibited the effects of c-terminal pTHrp. Conclusion: These findings indicate that the antioxidant properties of pTHrp act through its n- and c- terminal domains and provide novel insights into the osteogenic action of pTHrp., RETICEF [FEDER “una manera de hacer Europa”], Ministerio de Economía y Competitividad. Programa Juan de la Cierva, Instituto de Salud Carlos III /Fundación para la Investigación Ósea y Metabolismo Mineral-FEIOMM, Depto. de Genética, Fisiología y Microbiología, Fac. de Ciencias Biológicas, TRUE, pub

Osteoporosis is the most common type of bone disease. Conventional treatments are based on the use of antiresorptive drugs and/or anabolic agents. However, these treatments have certain limitations, such as a lack of bioavailability or toxicity in non-specific tissues. In this regard, pleiotrophin (PTN) is a protein with potent mitogenic, angiogenic, and chemotactic activity, with implications in tissue repair. On the other hand, mesoporous silica nanoparticles (MSNs) have proven to be an effective inorganic drug-delivery system for biomedical applications. In addition, the surface anchoring of cationic polymers, such as polyethylenimine (PEI), allows for greater cell internalization, increasing treatment efficacy. In order to load and release the PTN to improve its effectiveness, MSNs were successfully internalized in MC3T3-E1 mouse pre-osteoblastic cells and human mesenchymal stem cells. PTN-loaded MSNs significantly increased the viability, mineralization, and gene expression of alkaline phosphatase and Runx2 in comparison with the PTN alone in both cell lines, evidencing its positive effect on osteogenesis and osteoblast differentiation. This proof of concept demonstrates that MSN can take up and release PTN, developing a potent osteogenic and differentiating action in vitro in the absence of an osteogenic differentiation-promoting medium, presenting itself as a possible treatment to improve bone-regeneration and osteoporosis scenarios., Universidad CEU San Pablo, European Research Council, Ministerio de Ciencia e Innovación, Depto. de Química en Ciencias Farmacéuticas, Fac. de Farmacia, TRUE, pub

Chondrocytes in osteoarthritic (OA) cartilage acquire a hypertrophic-like phenotype, where Hedgehog (Hh) signaling is pivotal. Hh overexpression causes OA-like cartilage lesions, whereas its downregulation prevents articular destruction in mouse models. Mutations in EVC and EVC2 genes disrupt Hh signaling, and are responsible for the Ellis-van Creveld syndrome skeletal dysplasia. Since Ellis-van Creveld syndrome protein (Evc) deletion is expected to hamper Hh target gene expression we hypothesized that it would also prevent OA progression avoiding chondrocyte hypertrophy. Our aim was to study Evc as a new therapeutic target in OA, and whether Evc deletion restrains chondrocyte hypertrophy and prevents joint damage in an Evc tamoxifen induced knockout (EvccKO) model of OA. For this purpose, OA was induced by surgical knee destabilization in wild-type (WT) and EvccKO adult mice, and healthy WT mice were used as controls (n = 10 knees/group). Hypertrophic markers and Hh genes were measured by qRT-PCR, and metalloproteinases (MMP) levels assessed by western blot. Human OA chondrocytes and cartilage samples were obtained from patients undergoing knee joint replacement surgery. Cyclopamine (CPA) was used for Hh pharmacological inhibition and IL-1 beta as an inflammatory insult. Our results showed that tamoxifen induced inactivation of Evc inhibited Hh overexpression and partially prevented chondrocyte hypertrophy during OA, although it did not ameliorate cartilage damage in DMM-EvccKO mice. Hh pathway inhibition did not modify the expression of proinflammatory mediators induced by IL-1 beta in human OA chondrocytes in culture. We found that hypertrophic—IHH—and inflammatory—COX-2—markers co-localized in OA cartilage samples. We concluded that tamoxifen induced inactivation of Evc partially prevented chondrocyte hypertrophy in DMM-EvccKO mice, but it did not ameliorate cartilage damage. Overall, our results suggest that chondrocyte hypertrophy per se is not a pathogenic ev

Oxidative damage is an important contributor to the morphological and functional changes in osteoporotic bone. Aging increases the levels of reactive oxygen species (ROS) that cause oxidative stress and induce osteoblast apoptosis. ROS modify several signaling responses, including mitogen-activated protein kinase (MAPK) activation, related to cell survival. Both parathyroid hormone (PTH) and its bone counterpart, PTH-related protein (PTHrP), can regulate MAPK activation by modulating MAPK phosphatase-1 (MKP1). Thus, we hypothesized that PTHrP might protect osteoblasts from ROS-induced apoptosis by targeting MKP1. In osteoblastic MC3T3-E1 and MG-63 cells, H2 O2 triggered p38, JNK, ERK and p66Shc phosphorylation, and cell apoptosis. Meanwhile, PTHrP (1-37) rapidly but transiently increased ERK and Akt phosphorylation without affecting p38, JNK, or p66Shc activation. H2 O2 -induced p38 and ERK phosphorylation and apoptosis were both decreased by pre-treatment with specific kinase inhibitors or PTHrP (1-37) in both osteoblastic cell types. These dephosphorylating and prosurvival actions of PTHrP (1-37) were prevented by a phosphatase inhibitor cocktail, the phosphatase MKP1 inhibitor sanguinarine or a MKP1 siRNA. PTHrP (1-37) promptly enhanced MKP1 protein and gene expression and MKP1-dependent catalase activity in osteoblastic cells. Furthermore, exposure to PTHrP (1-37) adsorbed in an implanted hydroxyapatite-based ceramic into a tibial defect in aging rats increased MKP1 and catalase gene expression in the healing bone area. Our findings demonstrate that PTHrP counteracts the pro-apoptotic actions of ROS by a mechanism dependent on MKP1-induced dephosphorylation of MAPKs in osteoblasts., Ministerio de Ciencia e Innovación (MICINN)- Juan de la Cierva (España), Instituto deSalud Carlos III, (España), Depto. de Genética, Fisiología y Microbiología, Fac. de Ciencias Biológicas, TRUE, pub

RESEARCHER ID M-3378-2014 (María Vallet Regí) ORCID 0000-0002-6104-4889 (María Vallet Regí) RESEARCHER ID N-4501-2014 (Sandra Sánchez Salcedo) ORCID 0000-0002-1889-2057 (Sandra Sánchez Salcedo) RESEARCHER ID B-5081-2017 (Daniel Lozano Borregón) ORCID 0000-0001-5902-9201 (Daniel Lozano Borregón), Diabetes mellitus (DM) and aging are associated with bone fragility and increased fracture risk. Both (1-37) N- and (107-111) C-terminal parathyroid hormone-related protein (PTHrP) exhibit osteogenic properties. We here aimed to evaluate and compare the efficacy of either PTHrP (1-37) or PTHrP (107-111) loaded into gelatin-glutaraldehyde-coated hydroxyapatite (HA-Gel) foams to improve bone repair of a transcortical tibial defect in aging rats with or without DM, induced by streptozotocin injection at birth. Diabetic old rats showed bone structural deterioration compared to their age-matched controls. Histological and -computerized tomography studies showed incomplete bone repair at 4 weeks after implantation of unloaded Ha-Gel foams in the transcortical tibial defects, mainly in old rats with DM. However, enhanced defect healing, as shown by an increase of bone volume/tissue volume and trabecular and cortical thickness and decreased trabecular separation, occurred in the presence of either PTHrP peptide in the implants in old rats with or without DM. This was accompanied by newly formed bone tissue around the osteointegrated HA-Gel implant and increased gene expression of osteocalcin and vascular endothelial growth factor (bone formation and angiogenic markers, respectively), and decreased expression of Sost gene, a negative regulator of bone formation, in the healing bone area. Our findings suggest that local delivery of PTHrP (1-37) or PTHrP (107-111) from a degradable implant is an attractive strategy to improve bone regeneration in aged and diabetic subjects. (c) 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2060-2070, 2016., Comunidad de Madrid, Ministerio de Ciencia e Innovación (MICINN), Ministerio de Economía y Competitividad (MINECO), Instituto de Salud Carlos III, RETICEF, Ministerio de Educacion-FPU Program, Depto. de Química en Ciencias Farmacéuticas, Fac. de Farmacia, TRUE, pub

RESEARCHER ID M-3378-2014 (María Vallet Regí) ORCID 0000-0002-6104-4889 (María Vallet Regí) RESEARCHER ID N-4501-2014 (Sandra Sánchez Salcedo) ORCID 0000-0002-1889-2057 (Sandra Sánchez Salcedo) RESEARCHER ID B-5081-2017 (Daniel Lozano Borregón) ORCID 0000-0001-5902-9201 (Daniel Lozano Borregón), Biopolymer-coated nanocrystalline hydroxyapatite (HA) made as macroporous foams which are degradable and flexible are promising candidates as orthopaedic implants. The C-terminal (107-111) epitope of parathyroid hormone-related protein (PTHrP) exhibits osteogenic properties. The main aim of this study was to evaluate whether PTHrP (107-111) loading into gelatin-glutaraldehyde biopolymer-coated HA (HA(GIu)) scaffolds would produce an optimal biomaterial for tissue engineering applications. HA(GIu) scaffolds with and without PTHrP (107-111) were implanted into a cavitary defect performed in both distal tibial metaphysis of adult rats. Animals were sacrificed after 4 weeks for histological, microcomputerized tomography and gene expression analysis of the callus. At this time, bone healing occurred only in the presence of PTHrP (107-111)-containing HA(Giu) implant, related to an increase in bone volume/tissue volume and trabecular thickness, cortical thickness and gene expression of osteocalcin and vascular cell adhesion molecule I, but a decreased gene expression of Wnt inhibitors, SOST and dickkopf homolog 1. The autonomous osteogenic effect of the PTHrP (107-111)-loaded HA(Giu) scaffolds was confirmed in mouse and human osteoblastic cell cultures. Our findings demonstrate the advantage of loading PTHrP (107-111) into degradable HA(GIu) scaffolds for achieving an optimal biomaterial that is promising for low load bearing clinical applications. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved., Ministerio de Economia y Competitividad (MINECO), Ministerio de Ciencia e Innovacion (MICINN), Ministerio de Economia y Competitividad (RE-TICEF), Comunidad de Madrid, RETICEF, Depto. de Química en Ciencias Farmacéuticas, Fac. de Farmacia, TRUE, pub

El remodelado óseo es un proceso que ocurre a lo largo de la vida para la reparación del desgaste óseo y la homeostasis fosfocálcica. Se inicia por una fase de resorción y finaliza con la formación de hueso nuevo; ambos procesos acoplados por la actuación coordinada de factores endocrinos, locales y estímulos mecánicos La alteración del equilibrio en el remodelado óseo da lugar a patologías óseas, como la osteoporosis (OP), asociada a la pérdida y/o al deterioro de la masa y la estructura ósea lo que determina la susceptibilidad a fracturas. Cuando no se identifica ninguna patología causal se habla de OP primaria, mientras que cuando se asocia a condiciones patológicas previamente establecidas se habla de OP secundaria. Uno de los tipos más frecuentes de OP secundaria es la asociada a la Diabetes mellitus (DM). Esta patología metabólica se caracteriza por hiperglucemia crónica debida al déficit de producción y/o acción de la insulina (y de IGF-I). La proteína relacionada con la PTH (PTHrP) se expresa en la mayoría de los tejidos normales, donde ejerce acciones de citoquina tisular tanto durante el desarrollo como en el adulto. La PTHrP difiere completamente de la PTH más allá de la región homóloga N-terminal, siendo su región C-terminal más larga que en la PTH, y contiene distintos epítopos singulares, asociados a efectos auto/paracrinos e intracrinos en distintos tipos celulares. De modo similar a la PTH, la administración continua del fragmento N-terminal de la PTHrP aumenta la resorción ósea, mientras su administración intermitente aumenta fundamentalmente la formación ósea. Considerando los aspectos reseñados anteriormente, en la presente Tesis hipotetizamos que las acciones osteogénicas de la PTHrP en situación diabética se ejercen interaccionando con la vía canónica de Wnt/β-catenina (1) y de manera parcialmente independiente al IGF-I (2). En primer lugar, desarrollamos un modelo in vitro en células osteoblásticas MC3T3-E1 en el que suprimimos mediante silenci