Mesoporous bioglasses enriched with bioactive agents for bone repair, with a special highlight of Maria Vallet-Regi´s contribution

Throughout her impressive scientific career, Prof. María Vallet-Regi opened various research lines aimed at designing new bioceramics, including mesoporous bioactive glasses for bone tissue engineering applica-tions. These bioactive glasses can be considered a spinoff of silica mesoporous materials because they are designed with a similar technical approach. Both materials exhibit ordered mesoporous structures with a very narrow pore size distribution that are achieved by using surfactants during their synthesis. In aqueous solutions the surfactants form mesophases behaving as directing structure agents and after being removed by calcination or extraction the mesoporous bioactive glasses are obtained. The characteristics of these ma-terials made them suitable to be enriched with various osteogenic agents, namely inorganic ions and bio-peptides as well as mesenchymal cells. In the present review, we summarize the evolution of mesoporous bioactive glasses research for bone repair, with a special highlight on the impact of Prof. Maria Val-let-Regi´s contribution to the field

A transgenic mouse model for studying the role of the parathyroid hormone-related protein system in renal injury

Parathyroid hormone- (PTH-) related protein (PTHrP) and its receptor, the PTH1 receptor (PTH1R), are widely expressed in the kidney, where PTHrP exerts a modulatory action on renal function. PTHrP is known to be upregulated in several experimental nephropathies such as acute renal failure (ARF), obstructive nephropathy (ON) as well as diabetic nephropathy (DN). In this paper, we will discuss the functional consequences of chronic PTHrP overexpression in the damaged kidney using a transgenic mouse strain overexpressing PTHrP in the renal proximal tubule. In both ARF and ON, PTHrP displays proinflammatory and profibrogenic actions including the induction of epithelia to mesenquima transition. Moreover, PTHrP participates in the mechanisms of renal hypertrophy as well as proteinuria in experimental DN. Angiotensin II (Ang II), a critical factor in the progression of renal injury, appears to be, at least in part, responsible for endogenous PTHrP upregulation in these pathophysiological settings. These findings provide novel insights into the well-known protective effects of Ang II antagonists in renal diseases, paving the way for new therapeutic approaches.The studies included in this paper were supported in part by Grants from Ministerio de Educación y Cultura of Spain (SAF2002-04356-C03-01, -02, and -03),Ministerio de Ciencia e Innovación (SAF2009- 12009-C02-01), Comunidad Autónoma de Madrid (CAM 08.6/0038.1/2000-2 and GR/SAL/0415/2004), Instituto de Salud Carlos III (RETICEF RD06/0013/1002), Spanish Society of Nephrology, Eugenio Rodríguez Pascual Foundation, and Conchita Rábago de Jiménez Díaz Foundation

Beneficial effects of manually assisted chiropractic adjusting instrument in a rabbit model of osteoarthritis.

Osteoarthritis (OA) is a degenerative disease characterized by injury of all joint tissues. Our previous study showed that in experimental osteoporosis, chiropractic manipulation (CM) exerts protective effects on bone. We here assessed whether CM might ameliorate OA by improving subchondral bone sclerosis, cartilage integrity and synovitis. Male New-Zealand rabbits underwent knee surgery to induce OA by anterior cruciate ligament injury. CM was performed using the chiropractic instrument ActivatorV 3 times/week for 8 weeks as follows: force 2 setting was applied to the tibial tubercle of the rabbit right hind limb (TM-OA), whereas the corresponding left hind limb received a false manipulation (FM-OA) consisting of ActivatorV firing in the air and slightly touching the tibial tubercle. After sacrifice, subchondral bone integrity was assessed in the tibiae by microCT and histology. Cartilage damage and synovitis were estimated by Mankin's and Krenn's scores, respectively, and histological techniques. Bone mineral density and content in both cortical and trabecular compartments of subchondral bone decreased in OA rabbits compared to controls, but partially reversed in the TM-OA group. Trabecular bone parameters in the latter group also showed a significant improvement compared to FM-OA group. Moreover RANKL, OPG, ALP and TRAP protein expression in subchondral bone significantly decreased in TM-OA rabbits with respect to FM-OA group. CM was associated with lower Mankin's and Krenn's scores and macrophage infiltrate together with a decreased protein expression of pro-inflammatory, fibrotic and angiogenic factors, in TM-OA rabbits with respect to FM-OA. Our results suggest that CM may mitigate OA progression by improving subchondral bone as well as cartilage and synovial membrane status.AODM was supported by grants from the Spanish Chiropractic Association (AEQ). AM was supported by grants from Spanish Ministry of Economy and Competitiveness and Carlos III Institute of Health (CP15/00053 and PI16/00991). We thank Dr. Carlos Guillén-Viejo (School of Pharmacy, Universidad Complutense de Madrid) for his help in advising in molecular biology methods. The authors are also grateful to Mark S. Davis for his assistance with editing and proofreading the article.S

Novel role of parathyroid hormone-related protein in the pathophysiology of the diabetic kidney: Evidence from experimental and human diabetic nephropathy

Parathyroid hormone-related protein (PTHrP) and its receptor type 1 (PTH1R) are extensively expressed in the kidney, where they are able to modulate renal function. Renal PTHrP is known to be overexpressed in acute renal injury. Recently, we hypothesized that PTHrP involvement in the mechanisms of renal injury might not be limited to conditions with predominant damage of the renal tubulointerstitium and might be extended to glomerular diseases, such as diabetic nephropathy (DN). In experimental DN, the overexpression of both PTHrP and the PTH1R contributes to the development of renal hypertrophy as well as proteinuria. More recent data have shown, for the first time, that PTHrP is upregulated in the kidney from patients with DN. Collectively, animal and human studies have shown that PTHrP acts as an important mediator of diabetic renal cell hypertrophy by a mechanism which involves the modulation of cell cycle regulatory proteins and TGF-β1. Furthermore, angiotensin II (Ang II), a critical factor in the progression of renal injury, appears to be responsible for PTHrP upregulation in these conditions. These findings provide novel insights into the well-known protective effects of Ang II antagonists in renal diseases, paving the way for new therapeutic approaches.N. Olea is the recipient of a Research Contract from the Comunidad Autónoma de Madrid (S-BIO-2083-2006) and the University of Alcalá. A. Izquierdo is currently Assistant Professor at the Rey Juan Carlos University, Alcorc´on, Madrid. This work was supported in part by Grants from Ministerio de Educaci´on y Cultura of Spain (SAF2002- 04356-C03-01, -02, and -03) Ministerio de Ciencia e Innovación (SAF2009-12009-C02-01), Instituto de Salud Carlos III (RETICEF RD06/0013/1002 and RD12/0043/0008 and PI12/02825), the Spanish Society of Nephrology, and the Eugenio Rodr´ıguez Pascual Foundation

Effects of bleaching on osteoclast activity and their modulation by osteostatin and fibroblast growth factor 2

Hypothesis: Dental bleaching with H2O2 is a common daily practice in dentistry to correct discoloration of anterior teeth. The aim of this study has been to determine whether this treatment of human teeth affects growth, differentiation and activity of osteoclast-like cells, as well as the putative modulatory action of osteostatin and fibroblast growth factor 2 (FGF-2). Experiments: Previously to the in vitro assays, structural, physical-chemical and morphological features of teeth after bleaching were studied. Osteoclast-like cells were cultured on human dentin disks, pre-treated or not with 38% H2O2 bleaching gel, in the presence or absence of osteostatin (100 nM) or FGF-2 (1 ng/ml). Cell proliferation and viability, intracellular content of reactive oxygen species (ROS), pro-inflammatory cytokine (IL-6 and TNF alpha) secretion and resorption activity were evaluated. Findings: Bleaching treatment failed to affect either the structural or the chemical features of both enamel and dentin, except for slight morphological changes, increased porosity in the most superficial parts (enamel), and a moderate increase in the wettability degree. In this scenario, bleaching produced an increased osteoclast-like cell proliferation but decreased cell viability and cytokine secretion, while it augmented resorption activity on dentin. The presence of either osteostatin or FGF-2 reduced the osteoclast-like cell proliferation induced by bleaching. FGF-2 enhanced ROS content, whereas osteostatin decreased ROS but increased TNF alpha secretion. The bleaching effect on resorption activity was increased by osteostatin, but this effect was less evident with FGF-2. Conclusions: These findings further confirm the deleterious effects of tooth bleaching by affecting osteoclast growth and function as well as different modulatory actions of osteostatin and FGF-2. (C) 2015 Elsevier Inc. All rights reserved

Parathyroid Hormone-Related Protein Promotes Inflammation in the kidney with an Obstructed ureter

Parathyroid hormone-related protein (PTHrP) promotes fibrogenesis in the acutely damaged kidney. Considering the relation between fibrosis and inflammation, we studied transgenic mice that overexpress PTHrP in the proximal tubule. When unilateral ureteric obstruction was induced in these transgenic mice, we found that they had more renal tubulointerstitial damage, leukocyte influx, and expression of proinflammatory factors than their control littermates. Reversal of PTHrP constitutive overexpression in these transgenic mice or treatment of control mice with the PTHrP antagonist (7–34) decreased this inflammatory response. Losartan, which abolished obstruction-induced endogenous PTHrP upregulation, also decreased the latter response but less effectively in transgenic mice. The PTHrP fragment (1–36) induced nuclear factor-jB (NF-jB) activation and proinflammatory cytokine overexpression in mouse cortical tubule cells in culture as well as migration of the macrophage cell line Raw 264.7. All these effects were decreased by PTHrP (7–34) and NF-jB or extracellular signal-regulated kinase (ERK) activation inhibitors. Our findings suggest a critical role of PTHrP in the renal inflammatory process that results from ureteral obstruction and indicate that ERK-mediated NF-jB activation seems to be an important mechanism whereby PTHrP triggers renal inflammatio

Parathyroid hormone-related protein exhibits antioxidant features in osteoblastic cells through its N-terminal and osteostatin domains

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 (H 2 O 2 )-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 H 2 O 2 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.This work has been funded by grants from the Fundacion para la Investigacion Osea y Metabolismo Mineral-FEIOMM and the Instituto de Salud Carlos III (PI11/00449, PI15/00340, PI1600065, RD12/0043/0029, RD12/0043/0008 and RD12/0043/0018,). J. A. Ardua, D. Lozano, and S. Portal-Nunez are recipients of postdoctoral contracts from the Ministerio de Economia y Competitividad, Juan de la Cierva program JCI-2011-09548, FPDI-2013-17268, and RETICEF [FEDER “una manera de hacer Europa” (RD12/0043/0008)

Parathyroid hormone-related protein (107-111) improves the bone regeneration potential of gelatin-glutaraldehyde biopolymer-coated hydroxyapatite

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

Parathyroid hormone-related protein as a renal regulating factor: From Vessels to Glomeruli and Tubular Epithelium

Parathyroid hormone (PTH) and PTH-related protein (PTHrP) produce similar biological effects through the PTH/PTHrP receptor. Less is known about the physiological role of PTHrP, which was first identified as the agent of the humoral hypercalcemia of malignancy. Despite the widespread production of PTHrP in healthy individuals, the concentration of the protein is below the detectable limit of current assays, suggesting that PTHrP normally functions locally in an autocrine or paracrine manner. Thus, some differences in their biological activities have been described and they may be related to the presence of different receptors. In this regard, a second receptor that binds selectively to PTH has also been found. Recent studies have demonstrated the expression of both PTH/PTHrP receptor and protein in the renal glomeruli. Moreover, there are convincing data that support a direct role of PTH and PTHrP in modulating renal blood flow and glomerular filtration rate. This multifunctional protein, PSHrP, also has a proliferative effect on both glomerular mesangial cells and tubular epithelial cells. Increases in the expression of PTHrP have been observed in several experimental models of nephropathies, suggesting that PTHrP upregulation is a common event associated with the mechanism of renal injury and repair