Laboratorio de Investigaciones en Osteopatías y Metabolismo Mineral (LIOMM)

Alginate-HEMA Hydrogels as Promising Biomaterials for Bone Regeneration: In Vitro and In Vivo Studies

Wed, 30 Oct 2024 00:00:00 GMT

Articulo Journal of Biomedical Materials Research; vol. 112, no. 11 In the present work, the osteogenic and angiogenic properties of, previously developed, semi-interpenetrated HEMA-EGDMA polymeric networks (sIPN) with and without alginate with application in bone tissue engineering (BTE) were studied. In vitro characterization studies were performed using rat bone marrow progenitor cells (BMPCs), EA.hy926 endothelial cells, and rat vascular smooth muscle cells (VSMCs). Based on the in vitro results of both this work and previous ones, the hydrogels were selected to carry out in vivo studies to find out their capacity as a biomaterial using a bone regeneration model. Our results indicate that the incorporation of alginate into the HEMA-EGDMA polymeric network promotes osteogenic and angiogenic capacity in cell cultures of BMPCs and both EA.hy926 and VSMCs, respectively, and also increases bone formation and vascular structures in in vivo studies, demonstrating its potential use as a biomaterial in BTE.

A Preclinical Investigation of Estrogenic Bone Protection in a Hypertensive Rat Model Under Gender-Affirming Hormone Therapy

Sun, 01 Jun 2025 00:00:00 GMT

Articulo Biology; vol. 14, no. 6 The goal of gender-affirming hormone therapy (GAHT) is to align an individual’s physical characteristics with their gender identity by suppressing endogenous sex hormones and replacing them with those consistent with their gender. Transgender women undergoing GAHT are at higher risk of cardiovascular complications, and since clinical evidence suggests that hypertension is associated with increased bone loss, we investigated the effects of estrogen treatment on bone health in a hypertensive transgender animal model. Male spontaneously hypertensive rats were orchiectomized (Orch), and half of them received estrogen treatment (Orch + Es), while a third group remained intact as controls. Bone marrow progenitor cells (BMPCs) were isolated to assess osteogenic potential, and femurs were collected for histological and mechanical analysis. BMPCs from Orch + Es rats exhibited enhanced osteogenic potential compared to those from Orch rats. Histological analysis revealed a higher number of osteocytes and fewer adipocytes in the Orch + Es group. Mechanical testing showed reduced bone strength in Orch rats, which was partially preserved in Orch + Es animals. In conclusion, estrogen administration mitigated the deleterious effects of testosterone depletion on BMPCs and provided protective effects on bone structure and strength in this preclinical model of GAHT in hypertensive rats.

Humulus lupulus Promoting Osteoblast Activity and Bone Integrity: Effects and Mechanisms

Thu, 01 May 2025 00:00:00 GMT

Articulo Biology; vol. 14, no. 5 Osteoporosis is characterized by an imbalance between bone formation and resorption, leading to decreased bone mass and an increased fracture risk, mainly associated with aging. Current treatments include anti-resorptive and anabolic drugs. However, these often have side effects, leadingmany patients to seek natural biological alternatives. We have demonstrated previously that hops extract, rich in compounds with estrogenic activity classified as phytoestrogens, exerts osteogenic effects by promoting the osteoblastic differentiation of bone marrowstemcells (BMSCs)while inhibiting osteoclast activity in vitro. In our study, youngmale Sprague Dawley rats were randomized into two groups: one received hops extract (LPL, 1% w/v in drinking water) for two months, and the other drank water alone (C). The rats were euthanized, and their femurs were dissected and processed for static histomorphometry and bone biomechanics. Additionally, BMSCs were isolated from the humeri to evaluate their osteogenic potential. Our result demonstrated that LPL treatment enhanced the osteogenic potential of humeral BMSCs in ex vivo assays, upregulating osteogenic genes and downregulating proresorptivemarkers. These findings correlated with improved femoral bonemicroarchitecture and biomechanical parameters. In conclusion, a two-month treatment with LPL enhanced the osteogenic capacity of BMSCs, improving bonemicroarchitecture and biomechanical properties. These results suggest its potential as a natural alternative for promoting bone health.

Desarrollo de estrategias de ingeniería de tejidos para la regeneración del tejido cartilaginoso

Tue, 01 Jan 2013 00:00:00 GMT

Articulo The Journal of the Argentine Chemical Society; vol. 100 Las patologías del tejido cartilaginoso son la principal causa de pérdida de función, trastornos en la marcha y discapacidad en humanos. Entre las estrategias de reparación de este tejido se encuentran en desarrollo técnicas de ingeniería de tejidos. Estas se basan en el empleo de matrices de origen natural o sintéticas, con o sin el agregado de células y/o sustancias que promuevan la condrogénesis. El objetivo de este trabajo es desarrollar y caracterizar matrices poliméricas sintéticas (copolímero acetato de vinilo (AcV)-fumarato de diisopropilo (FIP)) y naturales (quitosano) combinadas, que puedan ser empleadas como scaffold para la regeneración del tejido cartilaginoso. La síntesis del copolímero se realizó usando energía de microondas. Luego el copolímero se aisló, purificó y caracterizó adecuadamente. El mismo se casteó entrecruzado con quitosano para la obtención de las membranas para futuros ensayos biológicos.; Pathologies of cartilaginous tissue are the main cause of loss of function, gait disorders and disability in humans [1]. Techniques of tissue engineering are developing as strategy for repair this kind of tissue. These methodologies are based on use of natural or synthetic matrices, with or without the addition of cells and/or substances that promote chondrogenesis. The aim of this work is to develop and characterize combined synthetic polymer (vinyl acetate (VAc)-diisopropyl fumarate (FIP) copolymer) and natural (chitosan) matrices; they can be used as scaffold for regeneration of cartilage tissue. The copolymer synthesis was carried out under microwave energy. Then, the copolymer was isolated, purified and characterized adequately. The product was casted crosslinked with chitosan for obtaining membranes for further biological assays.

Matrices based on lineal and star fumarate-metha/acrylate copolymers for bone tissue engineering: Characterization and biocompatibility studies

Tue, 01 Jan 2019 00:00:00 GMT

Articulo Journal of Biomedical Materials Research Part A; vol. 107, no. 1 This article presents the preparation of matrices from two new families of fumaric copolymers and the effect of structural differences on their physicochemical and biological behavior. Diisopropyl fumarate (DIPF) and poly(ethylene glycol) methyl ether methacrylate (OEGMA) or N-isopropylacrylamide (NIPAM) were copolymerized by conventional radical and RAFT polymerization to obtain lineal or start architectures, respectively. These copolymers were characterized by spectroscopic (FTIR and ¹HNMR) and chromatographic methods. The thermal stability was studied by thermal gravimetric analysis, showing some differences in relation to the architecture and chemical nature of copolymers. SEM morphological analysis demonstrated that the surface of the matrices derived from OEGMA exhibited an irregular and rough surface, while DIPF–NIPAM copolymers presented smooth surface with nearly no significant porosity. The matrix obtained of both kinds of copolymers presented no cytotoxicity as it was evaluated using a model of macrophages on culture. Moreover, cell growth was better on the surfaces of the DIPF–NIPAM matrices, suggesting a good interaction with this matrix and its potential application as matrices for tissue engineering.

Terpolymer-chitosan membranes as biomaterial

Tue, 01 Feb 2022 00:00:00 GMT

Articulo Journal of Biomedical Materials Research Part A; vol. 110, no. 2 The present study shows a novel copolymer synthesis, its application in the membrane design and the physicochemical and biological characterization of the biomaterial obtained. Terpolymer starting diisopropyl fumarate (F), vinyl benzoate (V) and 2-hydroxyethyl methacrylate (H) was prepared by thermal radical polymerization. This polymer (FVH) was obtained in several monomer ratios and characterized by spectroscopic and chromatographic methods (FTIR, ¹H-NMR and SEC). The best relationship of F:V:H was 5:4:1, which allows efficient interaction with chitosan through cross-linking with borax to achieve scaffolds for potential biomedical applications. The membranes were obtained by solvent casting and analyzed by scanning electron microscopy (SEM), swelling behavior and mechanical properties. In addition, we studied the possible cytotoxicity and biocompatibility of these materials using a murine macrophage-like cell line (RAW 264.7) and bone marrow mesenchymal progenitor cells (BMPC), respectively, taking into account their intended applications. The results of this study show that the terpolymer obtained and its combination with a natural polymer is a very interesting strategy to obtain a biomaterial with possible applications in regenerative medicine and this could be extended to other structurally related systems.

Obtención y caracterización de un sistema de liberación de Sr⁺² a partir de entrecruzamiento iónico de alginato

Sun, 01 Jan 2023 00:00:00 GMT

Articulo Obtaining and characterizing a Sr⁺² release system from alginate ionic crosslinking Revista de Ingeniería y Ciencias Aplicadas; vol. 1, no. 2 El hueso es un órgano con funciones críticas para la fisiología humana, ya que no solo se encarga de la protección y soporte de otros tejidos, sino que también interviene en la homeostasis mineral, regula el pH sanguíneo y aloja a múltiples células progenitoras. El tejido óseo posee la capacidad única de poder repararse a sí mismo sin dejar cicatrices, no obstante, bajo algunas situaciones, tales como: grandes fracturas óseas, enfermedades como tumores o situaciones metabólicas, esta capacidad se ve limitada por lo que se requiere la anteversión médica para el tratamiento del daño óseo. Los procedimientos para este tipo de lesiones tienen un impacto clínico y económico enorme. Por ello, en el presente trabajo se aborda dicha problemática mediante la ingeniería de tejido óseo la cual utiliza distintos materiales que puedan servir de relleno del daño óseo para guiar su reparación. Un posible material podría ser a base de alginato ya que posee propiedades acordes para la aplicación buscada: buena biocompatible, baja toxicidad y económicamente accesible, aunque presenta buena solubilidad en agua. A partir de la incorporación de iones Ca⁺² y Sr⁺² a soluciones de alginato de sodio se logró un material entrecruzado, con mayor estabilidad en medios acuosos, como sistema de liberación de Sr⁺². La importancia de este catión se debe a que se ha demostrado su efecto anabólico sobre el hueso. Se analizó la concentración de los iones empleados como entrecruzante y los tiempos de gelación sobre la liberación de estroncio. Dichos sistemas fueron caracterizados por ensayos de hinchamiento y degradación encontrándose que el porcentaje del ion liberado depende del tiempo de gelación de las muestras, ya que al cabo de 6 días se cuantificó en el medio un 28,5 %, 24,8 % y 17,1 % de Sr⁺² para 1, 12 y 24 h de gelación, respectivamente.; Bone is an organ with critical functions for human physiology. Bone tissue has the unique ability to repair itself without scarring, however, under some situations, such as: bone fractures or diseases, this ability is limited and requires expensive clinical interventions for the treatment of bone damage. Thus, in the present work, this problem is addressed through bone tissue engineering, which uses different materials to serve as fillers for bone damage to guide its repair. A possible material could be an alginate base since it has good properties: biocompatible, low toxicity and economically accessible, although it is soluble in water. From the incorporation of Ca⁺² and Sr⁺² ions to sodium alginate solutions, a cross-linked material will be obtained, with greater stability in aqueous media, as a Sr⁺² release system. The concentration of the ions used as crosslinking and the gelation times on the strontium release were analyzed. These systems were characterized by swelling and degradation tests, finding that the percentage of the ion released depends on the gelation time of the samples, since after 6 days 28,5 %, 24,8 % and 17,1 % were quantified in the medium for 1, 12 and 24 h of gelation, respectively.

Purification of alginate improves its biocompatibility and eliminates cytotoxicity in matrix for bone tissue engineering

Sat, 01 Jun 2019 00:00:00 GMT

Articulo Algal Research; vol. 40 There is a growing interest about using natural polymers from renewable sources as biomaterials for applications in tissue engineering. In the present work, alginates were extracted from "Undaria pinnatifida", a brown sea weed invasive in Argentinian coast. The isolated alginate was structurally characterized by IR and ¹H NMR spectroscopies, intrinsic viscosity and TGA. For comparison purposes, commercial sodium alginate was purified and characterized using the same protocol as for raw material. Toxicity and biocompatibility of sodium alginate obtained from algae were studied using a murine macrophage-like cell line (RAW 264.7) and bone marrow stromal cells (BMSC), respectively. The presence of impurities inhibited both RAW 264.7 and bone marrow stromal cell proliferation and increased nitric oxide production from macrophages, while inhibited osteoblastic differentiation of BMSC. All these effects were reverted by the purification of alginate. In conclusion, alginate purification improves biocompatibility and osteo-induction while decreases its toxicity.

Biodegradable polyester networks including hydrophilic groups favor BMSCs differentiation and can be eroded by macrophage action

Mon, 01 Aug 2016 00:00:00 GMT

Articulo Polymer Degradation and Stability; vol. 130 The aim of this study is to show that introducing a small fraction of hydrophilic groups into a hydrophobic polyester favor the macrophage activity by accelerating the degradation action in aqueous media. It is also seen that differentiation of MSCs cultured in monolayer towards bone in specific differentiation media is favored in these materials with respect to the corresponding pristine polyesters. Polymer networks based in polycarpolactone or poly(L-lactide) and containing a small fraction of poly(-hydroxyethyl acrylate) have been synthesized. Degradation kinetics "in vitro" was monitored by mass loss and swelling capacity of the polymer network in good solvents, the later as representative of chain cleavage. Hydrolytic and enzymatic degradation is accelerated by the inclusion of poly(hydroxyethyl acrylate) blocks in the network. Macrophages were cultured on the surface of the network films, showing its capacity to erode the material surface but also to accelerate bulk degradation. Bone marrow mesenchymal stem cells were cultured in monolayer on the membranes in osteogenic media, showing an increase of specific markers expression in comparison to pristine polyesters.

Osteogenic scaffolds based on fumaric/N-isopropylacrylamide copolymers: Designed, properties and biocompatibility studies

Wed, 01 Jan 2020 00:00:00 GMT

Articulo European Polymer Journal; vol. 122 In the present work the creation of a new biomaterial aimed at bone tissue regeneration is shown, covering the synthesis of the polymers, the material design and their exhaustive physicochemical and biological characterization. The copolymers of dioctyl fumarate (DOF) and N-isopropylacrylamide (NIPAM) were synthetized and characterized by size exclusion chromatography, 1H NMR and its thermal properties were studied by DSC and TGA analyses. Based on their properties, two copolymers with different DOF content were selected as raw material to design scaffolds for bone tissue regeneration. The scaffolds were prepared by casting and electrospinning technique, giving rise to biomaterials with particular chemical and topographic surface which were characterized by water contact angle and scanning electron microscopy (SEM) analysis. The cytotoxicity and biodegradation by murine macrophage RAW 264.7 cells was assay, while biocompatibility and osteogenic induction were made using bone marrow progenitor cells (BMPC). None of the biomaterials obtained showed cytotoxicity. The biological properties suggest that the cells adhere and proliferate better on biomaterials with higher DOF content and fibrous morphology. All scaffolds support osteoblastic cell differentiation, but to a greater extent on the biomaterial that has higher DOF content prepared by casting. Altogether, our results suggesting that these biomaterials could be useful in the bone tissue engineering.

Guías argentinas para el diagnóstico, la prevención y el tratamiento de la osteoporosis 2015

Sun, 01 Jan 2017 00:00:00 GMT

Articulo Argentine guidelines for the diagnosis, prevention and treatment of osteoporosis, 2015 Medicina; vol. 77 La osteoporosis es una enfermedad en constante crecimiento y que afecta a más de 200 millones de personas en todo el mundo. Nuestras recomendaciones son guías para el diagnóstico, la prevención y tratamiento, pero no normas para las decisiones clínicas en casos individuales. El médico debe adaptarlas a situaciones en la práctica clínica cotidiana, incorporando factores personales que trascienden los límites de estas guías y hacen al saber y al arte de la práctica médica. Como todo conocimiento científico, deben ser actualizadas periódicamente a medida que se adquieran nuevas, mejores y más efectivas herramientas diagnósticas y terapéuticas.; Osteoporosis is an evolving disease which affects over 200 million people worldwide. Our recommendations are guidelines for its diagnosis, prevention and treatment, but they do not constitute standards for clinical decisions in individual cases. The physician must adapt them to individual special situations, incorporating personal factors that transcend the limits of these guidelines and are dependent on the knowledge and art of the practice of Medicine. These guidelines should be reviewed and updated periodically as new, better and more effective diagnostic and therapeutic tools become available.

Alendronate induces anti-migratory effects and inhibition of neutral phosphatases in UMR106 osteosarcoma cells

Mon, 01 Jan 2007 00:00:00 GMT

Articulo European Journal of Pharmacology; vol. 562, no. 1-2 Bisphosphonates are nonhydrolysable pyrophosphate analogues that prevent bone loss in several types of cancer. However, the mechanisms of anticancer action of bisphosphonates are not completely known. We have previously shown that nitrogen-containing bisphosphonates directly inhibit alkaline phosphatase of UMR106 rat osteosarcoma cells. In this study, we evaluated the effects of alendronate on the migration of UMR106 osteosarcoma using a model of multicellular cell spheroids, as well as the alendronate effect on neutral phosphatases. Alendronate significantly inhibited the migration of osteoblasts in a dose-dependent manner (10−6–10−4 M). This effect was also dependent on calcium availability. The spheroid morphology and distribution of actin fibers were also affected by alendronate treatment. Alendronate dose-dependently inhibited neutral phosphatase activity in cell-free osteoblastic extracts as well as in osteoblasts in culture. Our results show that alendronate inhibits cell migration through mechanisms dependent on calcium, and that seem to involve inhibition of phosphotyrosine-neutral-phosphatases and disassembly of actin stress fibers.

Regulation of advanced glycation end product (AGE) receptors and apoptosis by AGEs in osteoblast-like cells

Sat, 28 Jul 2007 00:00:00 GMT

Articulo Molecular and Cellular Biochemistry; vol. 306 Advanced glycation end products (AGEs) have been proposed as the pathological mechanisms underlying diabetic chronic complications. They may also play a role in the pathogenesis of diabetic osteopenia, although their mechanisms of action remain unclear. We investigated the protein (immunofluorescence) and gene expression (realtime RT-PCR) of two receptors for AGEs, RAGE and galectin-3, as well as their regulation by AGEs, and the apoptotic effect on osteoblast-like cells (UMR106 and MC3T3E1) in culture. AGEs up-regulated the expression of RAGE and galectin-3 in both cells lines. These effects were accompanied by an increase in the corresponding mRNA in the non-tumoral MC3T3E1 but not in the osteosarcoma UMR106 cells. Finally, we demonstrated that a 24 h exposure to AGEs induced apoptosis in both cell lines. Thus, AGEs-receptors may play important roles in the bone alterations described in aging and diabetic patients.

Advanced glycation end products and strontium ranelate promote osteogenic differentiation of vascular smooth muscle cells in vitro: preventive role of vitamin D

Wed, 26 Apr 2017 00:00:00 GMT

Articulo Molecular and Cellular Endocrinology; vol. 450 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.

HEMA and alginate-based chondrogenic semi-interpenetrated hydrogels: synthesis and biological characterization

Tue, 12 Jan 2021 00:00:00 GMT

Preprint Journal of Biomaterials Science. Polymer Edition; vol. 32, no. 4 Cartilage tissue engineering (CTE) has the general objective of restoring and improving damaged cartilage. A very interesting strategy of CTE is to combine different polymers to obtain a viscoelastic material. In the present study we have evaluated the applicability of Poly(2-hydroxyethyl methacrylate) networks semi-interpenetrated with sodium alginate for CTE. Alginate-containing hydrogels show an increase in scaffold porosity and swelling capacity, when compared with nonporous poly(2-hydroxyethyl methacrylate) scaffolds. Primary chondrocytes from young rats were cultured on the hydrogels, and an increase in chondrocyte proliferation and chondrocytic markers was observed in alginate-containing hydrogels. Chondrocytic phenotype was preserved on hydrogels containing the lowest amount of crosslinker and initiator (SEMI 3 and SEMI 4). In addition, Nitric oxide production by RAW264.7 macrophages grown on hydrogels was tested and none of the hydrogels showed high levels of this inflammatory marker after 2 days. These results indicate that our alginate-containing hydrogels could be useful for CTE.

Preparation, characterization, and in vitro activity evaluation of triblock copolymer-based polymersomes for drugs delivery

Mon, 01 Jan 2018 00:00:00 GMT

Articulo Journal of Nanoparticle Research; vol. 20, no. 3 Polymersomes are polymer-based vesicles that form upon hydration of amphiphilic block copolymers and display high stability and durability, due to their mechanical and physical properties. They have hydrophilic reservoirs as well as thick hydrophobic membranes; allowing to encapsulate both water-soluble bioactive agent and hydrophobic drugs. In this study, poly ethylene glycol (PEG3350 and PEG6000) were used as hydrophilic part and poly(vinyl benzoate) (PVBz) as hydrophobic block to synthesize amphiphilic triblock copolymers (PVBz-b-PEG-b-PVBz). Different proportions of hydrophilic/hydrophobic part were assayed in order to obtain polymersomes by solvent injection method. For the synthesis of the copolymers, the initial block of PEG was derived to obtain a macroinitiator through a xanthate functional group (PEGX3 or PEGX6) and the polymerization of vinyl benzoate was carried out through reversible addition-fragmentation chain transfer polymerization (RAFT). The structure of PEGX and copolymers was confirmed by Infrared, ¹H-NMR and UV-Vis spectrometry, while the average molecular weight (Mw) and polydispersity index (PI) were determined by size exclusion chromatography (SEC). The structures adopted by the copolymers in aqueous solution by self-assembly were investigated using transmission electron microscopy (TEM), dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS). Both techniques confirm that polymersomes were obtained for a fraction of hydrophilic block (f) ≈ 35 ± 10%, with a diameter of 38.3 ± 0.3 nm or 22.5 ± 0.7 nm, as determined by TEM and according to the M; w; of the precursor block copolymer. In addition, we analyzed the possible cytotoxicity in view of its potential application as biomedical nanocarrier. The results suggest that polymersomes seem not induce cytotoxicity during the periods of time tested.

Multi-Scale Approach for the Evaluation of Bone Mineralization in Strontium Ranelate-Treated Diabetic Rats

Mon, 01 Jan 2018 00:00:00 GMT

Articulo Biological Trace Element Research; vol. 186, no. 2 Long-term diabetes mellitus can induce osteopenia and osteoporosis, an increase in the incidence of low-stress fractures, and/or delayed fracture healing. Strontium ranelate (SrR) is a dual-action anti-osteoporotic agent whose use in individuals with diabetic osteopathy has not been adequately evaluated. In this study, we studied the effects of an oral treatment with SrR and/or experimental diabetes on bone composition and biomechanics. Young male Wistar rats (half non-diabetic, half with streptozotocin/nicotinamide-induced diabetes) were either untreated or orally administered 625 mg/kg/day of SrR for 6 weeks. After sacrifice, femora from all animals were evaluated by a multi-scale approach (X-ray diffraction, Fourier transform infrared spectroscopy, inductively coupled plasma optical-emission spectrometry, static histomorphometry, pQCT, and mechanical testing) to determine chemical, crystalline, and biomechanical properties. Untreated diabetic animals (versus untreated non-diabetic) showed a decrease in femoral mineral carbonate content, in cortical thickness and BMC, in trabecular osteocyte density, in maximum load supported at rupture and at yield point, and in overall toughness at mid-shaft. Treatment of diabetic animals with SrR further affected several parameters of bone (some already impaired by diabetes): crystallinity index (indicating less mature apatite crystals); trabecular area, BMC, and vBMD; maximum load at yield point; and structural elastic rigidity. However, SrR was also able to prevent the diabetes-induced decreases in trabecular osteocyte density (completely) and in bone ultimate strength at rupture (partially). Our results indicate that SrR treatment can partially but significantly prevent some bone structural mechanical properties as previously affected by diabetes, but not others (which may even be worsened).

Saxagliptin affects long-bone microarchitecture and decreases the osteogenic potential of bone marrow stromal cells

Tue, 28 Jan 2014 00:00:00 GMT

Articulo European journal of pharmacology; vol:727 Diabetes mellitus is associated with a decrease in bone quality and an increase in fracture incidence. Additionally, treatment with anti-diabetic drugs can either adversely or positively affect bone metabolism. In this study we evaluated: the effect of a 3-week oral treatment with saxagliptin on femoral microarchitecture in young male non-type-2-diabetic Sprague Dawley rats; and the in vitro effect of saxagliptin and/or fetal bovine serum (FBS), insulin or insulin-like growth factor-1 (IGF1), on the proliferation, differentiation (Runx2 and PPAR-gamma expression, type-1 collagen production, osteocalcin expression, mineralization) and extracellular-regulated kinase (ERK) activation, in bone marrow stromal cells (MSC) obtained from control (untreated) rats and in MC3T3E1 osteoblast-like cells. In vivo, oral saxagliptin treatment induced a significant decrease in the femoral osteocytic and osteoblastic density of metaphyseal trabecular bone and in the average height of the proximal cartilage growth plate; and an increase in osteoclastic tartrate-resistant acid phosphatase (TRAP) activity of the primary spongiosa. In vitro, saxagliptin inhibited FBS-, insulin- and IGF1-induced ERK phosphorylation and cell proliferation, in both MSC and MC3T3E1 preosteoblasts. In the absence of growth factors, saxagliptin had no effect on ERK activation or cell proliferation. In both MSC and MC3T3E1 cells, saxagliptin in the presence of FBS inhibited Runx2 and osteocalcin expression, type-1 collagen production and mineralization, while increasing PPAR-gamma expression. In conclusion, orally administered saxagliptin induced alterations in long-bone microarchitecture that could be related to its in vitro down-regulation of the ERK signaling pathway for insulin and IGF1 in MSC, thus decreasing the osteogenic potential of these cells.

Evaluation of Strontium-Containing PCL-PDIPF Scaffolds for Bone Tissue Engineering: In Vitro and In Vivo Studies

Fri, 01 Mar 2019 00:00:00 GMT

Articulo Annals of Biomedical Engineering; vol. 47, no. 3 Bone tissue engineering (BTE) has the general objective of restoring and improving damaged bone. A very interesting strategy for BTE is to combine an adequate polymeric scaffold with an osteoinductive compound. Strontium is a divalent cation that can substitute calcium in hydroxyapatite and induce both anabolic and anti-catabolic effects in bone. On the other hand, systemic increases in Sr²⁺ levels can provoke adverse cardiovascular effects. In the present study we have developed a compatibilized blend of poly-ε-caprolactone (PCL) and polydiisopropyl fumarate (PDIPF) enriched with 1% or 5% Sr²⁺ and evaluated the applicability of these biomaterials for BTE, both in vitro and in vivo. In vitro, whereas Blend + 5% Sr²⁺ was pro-inflammatory and anti-osteogenic, Blend + 1% Sr²⁺ released very low quantities of the cation; was not cytotoxic for cultured macrophages; and showed improved osteocompatibility when used as a substratum for primary cultures of bone marrow stromal cells. In vivo, implants with Blend + 1% Sr²⁺ significantly increased bone tissue regeneration and improved fibrous bridging (vs. Blend alone), while neither inducing a local inflammatory response nor increased serum levels of Sr²⁺. These results indicate that our compatibilized blend of PCL-PDIPF enriched with 1% Sr²⁺ could be useful for BTE.

Insulin-deficient diabetes-induced bone microarchitecture alterations are associated with a decrease in the osteogenic potential of bone marrow progenitor cells: Preventive effects of metformin

Sat, 01 Jun 2013 00:00:00 GMT

Articulo Diabetes Research and Clinical Practice; vol. 101, no. 2 Aims: Diabetes mellitus is associated with metabolic bone disease and increased lowimpact 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 microarchitecture, ex vivo osteogenic potential of BMPC, and BMPC expression of Runx-2, PPARg 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/PPARg 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/PPARg ratio and up-regulation of RAGE. These diabetes-induced alterations can be totally or partially prevented by oral administration of metformin.