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Weng Y, Jian Y, Huang W, Xie Z, Zhou Y, Pei X. Alkaline earth metals for osteogenic scaffolds: From mechanisms to applications. J Biomed Mater Res B Appl Biomater 2023; 111:1447-1474. [PMID: 36883838 DOI: 10.1002/jbm.b.35246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 02/21/2023] [Accepted: 02/23/2023] [Indexed: 03/09/2023]
Abstract
Regeneration of bone defects is a significant challenge today. As alternative approaches to the autologous bone, scaffold materials have remarkable features in treating bone defects; however, the various properties of current scaffold materials still fall short of expectations. Due to the osteogenic capability of alkaline earth metals, their application in scaffold materials has become an effective approach to improving their properties. Furthermore, numerous studies have shown that combining alkaline earth metals leads to better osteogenic properties than applying them alone. In this review, the physicochemical and physiological characteristics of alkaline earth metals are introduced, mainly focusing on their mechanisms and applications in osteogenesis, especially magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba). Furthermore, this review highlights the possible cross-talk between pathways when alkaline earth metals are combined. Finally, some of the current drawbacks of scaffold materials are enumerated, such as the high corrosion rate of Mg scaffolds and defects in the mechanical properties of Ca scaffolds. Moreover, a brief perspective is also provided regarding future directions in this field. It is worth exploring that whether the levels of alkaline earth metals in newly regenerated bone differs from those in normal bone. The ideal ratio of each element in the bone tissue engineering scaffolds or the optimal concentration of each elemental ion in the created osteogenic environment still needs further exploration. The review not only summarizes the research developments in osteogenesis but also offers a direction for developing new scaffold materials.
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Affiliation(s)
- Yihang Weng
- Department of Prosthodontics, State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan Province, China
| | - Yujia Jian
- Department of Prosthodontics, State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan Province, China
| | - Wenlong Huang
- Department of Prosthodontics, State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan Province, China
| | - Zhuojun Xie
- Department of Prosthodontics, State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan Province, China
| | - Ying Zhou
- Department of Prosthodontics, State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan Province, China
| | - Xibo Pei
- Department of Prosthodontics, State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan Province, China
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Heterotropic roles of divalent cations in the establishment of allostery and affinity maturation of integrin αXβ2. Cell Rep 2022; 40:111254. [PMID: 36001965 PMCID: PMC9440770 DOI: 10.1016/j.celrep.2022.111254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 05/23/2022] [Accepted: 08/02/2022] [Indexed: 11/21/2022] Open
Abstract
Allosteric activation and silencing of leukocyte β2-integrins transpire through cation-dependent structural changes, which mediate integrin biosynthesis and recycling, and are essential to designing leukocyte-specific drugs. Stepwise addition of Mg2+ reveals two mutually coupled events for the αXβ2 ligand-binding domain-the αX I-domain-corresponding to allostery establishment and affinity maturation. Electrostatic alterations in the Mg2+-binding site establish long-range couplings, leading to both pH- and Mg2+-occupancy-dependent biphasic stability change in the αX I-domain fold. The ligand-binding sensorgrams show composite affinity events for the αX I-domain accounting for the multiplicity of the αX I-domain conformational states existing in the solution. On cell surfaces, increasing Mg2+ concentration enhanced adhesiveness of αXβ2. This work highlights how intrinsically flexible pH- and cation-sensitive architecture endows a unique dynamic continuum to the αI-domain structure on the intact integrin, thereby revealing the importance of allostery establishment and affinity maturation in both extracellular and intracellular integrin events.
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3
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Feng W, Nguyen H, Shen D, Deng H, Jiang Z, Podolnikova N, Ugarova T, Wang X. Structural Characterization of the Interaction between the α MI-Domain of the Integrin Mac-1 (α Mβ 2) and the Cytokine Pleiotrophin. Biochemistry 2021; 60:182-193. [PMID: 33427449 DOI: 10.1021/acs.biochem.0c00700] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Integrin Mac-1 (αMβ2) is an adhesion receptor vital to many functions of myeloid leukocytes. It is also the most promiscuous member of the integrin family capable of recognizing a broad range of ligands. In particular, its ligand-binding αMI-domain is known to bind cationic proteins/peptides depleted in acidic residues. This contradicts the canonical ligand-binding mechanism of αI-domains, which requires an acidic amino acid in the ligand to coordinate the divalent cation within the metal ion-dependent adhesion site (MIDAS) of αI-domains. The lack of acidic amino acids in the αMI-domain-binding sequences suggests the existence of an as-yet uncharacterized interaction mechanism. In the present study, we analyzed interactions of the αMI-domain with a representative Mac-1 ligand, the cationic cytokine pleiotrophin (PTN). Through NMR chemical shift perturbation analysis, cross saturation, NOESY, and mutagenesis studies, we found the interaction between the αMI-domain and PTN is divalent cation-independent and mediated mostly by hydrophobic contacts between the N-terminal domain of PTN and residues in the α5-β5 loop of αMI-domain. The observation that increased ionic strength weakens the interaction between the proteins indicates electrostatic forces may also play a significant role in the binding. On the basis of the results from these experiments, we formulated a model of the interaction between the αMI-domain and PTN.
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Abstract
Pleiotrophin (PTN) is a potent mitogenic cytokine with a high affinity for the polysaccharide glycosaminoglycan (GAG). Although it is most strongly associated with neural development during embryogenesis and the neonatal period, its expression has also been linked to a plethora of other physiological events including cancer metastasis, angiogenesis, bone development, and inflammation. A considerable amount of research has been carried out to understand the mechanisms by which PTN regulates these events. In particular, PTN has now been shown to bind a diverse collection of receptors including many GAG-containing proteoglycans. These interactions lead to the activation of many intracellular kinases and, ultimately, activation and transformation of cells. Structural studies of PTN in complex with both GAG and domains from its non-proteoglycan receptors reveal a binding mechanism that relies on electrostatic interactions and points to PTN-induced receptor oligomerization as one of the possible ways PTN uses to control cellular functions.
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Berry KN, Brett TJ. Structural and Biophysical Analysis of the CLCA1 VWA Domain Suggests Mode of TMEM16A Engagement. Cell Rep 2020; 30:1141-1151.e3. [PMID: 31995732 PMCID: PMC7050472 DOI: 10.1016/j.celrep.2019.12.059] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 11/14/2019] [Accepted: 12/16/2019] [Indexed: 01/09/2023] Open
Abstract
The secreted protein calcium-activated chloride channel regulator 1 (CLCA1) utilizes a von Willebrand factor type A (VWA) domain to bind to and potentiate the calcium-activated chloride channel TMEM16A. To gain insight into this unique potentiation mechanism, we determined the 2.0-Å crystal structure of human CLCA1 VWA bound to Ca2+. The structure reveals the metal-ion-dependent adhesion site (MIDAS) in a high-affinity "open" conformation, engaging in crystal contacts that likely mimic how CLCA1 engages TMEM16A. The CLCA1 VWA contains a disulfide bond between α3 and α4 in close proximity to the MIDAS that is invariant in the CLCA family and unique in VWA structures. Further biophysical studies indicate that CLCA1 VWA is preferably stabilized by Mg2+ over Ca2+ and that α6 atypically extends from the VWA core. Finally, an analysis of TMEM16A structures suggests residues likely to mediate interaction with CLCA1 VWA.
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Affiliation(s)
- Kayla N Berry
- Immunology Program and Medical Scientist Training Program, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Internal Medicine, Division of Pulmonary and Critical Care, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Tom J Brett
- Department of Internal Medicine, Division of Pulmonary and Critical Care, Washington University School of Medicine, St. Louis, MO 63110, USA; Center for the Investigation of Membrane Excitability Diseases (CIMED), Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Obata A, Ogasawara T, Kasuga T. Combinatorial effects of inorganic ions on adhesion and proliferation of osteoblast‐like cells. J Biomed Mater Res A 2019; 107:1042-1051. [DOI: 10.1002/jbm.a.36623] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 01/24/2019] [Indexed: 11/06/2022]
Affiliation(s)
- Akiko Obata
- Division of Advanced Ceramics, Graduate School of EngineeringNagoya Institute of Technology Nagoya Japan
| | - Toru Ogasawara
- Division of Advanced Ceramics, Graduate School of EngineeringNagoya Institute of Technology Nagoya Japan
| | - Toshihiro Kasuga
- Division of Advanced Ceramics, Graduate School of EngineeringNagoya Institute of Technology Nagoya Japan
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Hale CS, Ornelas DN, Yang JS, Chang L, Vang K, Batarseh RN, Ozaki N, Rodgers VGJ. Interrogating the Osmotic Pressure of Self-Crowded Bovine Serum Albumin Solutions: Implications of Specific Monovalent Anion Effects Relative to the Hofmeister Series. J Phys Chem B 2018; 122:8037-8046. [PMID: 30074781 DOI: 10.1021/acs.jpcb.8b07000] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The free-solvent-based (FSB) model and osmotic pressure were used to probe the ion binding and protein hydration for self-crowded bovine serum albumin in 0.15 M NaF, NaCl, NaI, and NaSCN solutions. All experiments were conducted with solutions at pH 7.4. The regressed results of the FSB model behavior to the measured osmotic pressure were excellent, albeit, the osmotic pressure data for NaSCN were noisy. The resulting ion binding and hydration were realistic values and the covariance of the two parameters was exceptionally low, providing substantial credibility to the FSB model. The results showed that the kosmotropic F- and neutral Cl- solutions generated significantly higher ion binding and protein hydration than the chaotropic solutions of I- and SCN-. Further, the ionic strength ratio and resulting hydration implied that the chaotropic solutions had substantially higher aggregation than the other salts investigated. Overall, the FSB model provides an additional, complementary tool to contribute to the analysis of crowded protein solutions relative to anions in the Hofmeister series as it can interrogate crowded solutions directly; something that is not possible with many measurement techniques.
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Affiliation(s)
- Christopher S Hale
- Department of Bioengineering, B2K Group (Biotransport and Bioreaction Kinetics Group) , University of California , Riverside , California 92521 , United States
| | - Danielle N Ornelas
- Department of Bioengineering, B2K Group (Biotransport and Bioreaction Kinetics Group) , University of California , Riverside , California 92521 , United States
| | - Jennifer S Yang
- Department of Bioengineering, B2K Group (Biotransport and Bioreaction Kinetics Group) , University of California , Riverside , California 92521 , United States
| | - Larry Chang
- Department of Bioengineering, B2K Group (Biotransport and Bioreaction Kinetics Group) , University of California , Riverside , California 92521 , United States
| | - Kevin Vang
- Department of Bioengineering, B2K Group (Biotransport and Bioreaction Kinetics Group) , University of California , Riverside , California 92521 , United States
| | - Ramsey N Batarseh
- Department of Bioengineering, B2K Group (Biotransport and Bioreaction Kinetics Group) , University of California , Riverside , California 92521 , United States
| | - Noriko Ozaki
- Department of Bioengineering, B2K Group (Biotransport and Bioreaction Kinetics Group) , University of California , Riverside , California 92521 , United States
| | - Victor G J Rodgers
- Department of Bioengineering, B2K Group (Biotransport and Bioreaction Kinetics Group) , University of California , Riverside , California 92521 , United States
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8
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Nanocomposite hydrogels stabilized by self-assembled multivalent bisphosphonate-magnesium nanoparticles mediate sustained release of magnesium ion and promote in-situ bone regeneration. Acta Biomater 2017; 64:389-400. [PMID: 28963020 DOI: 10.1016/j.actbio.2017.09.039] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 09/22/2017] [Accepted: 09/25/2017] [Indexed: 12/13/2022]
Abstract
Hydrogels are appealing biomaterials for applications in regenerative medicine due to their tunable physical and bioactive properties. Meanwhile, therapeutic metal ions, such as magnesium ion (Mg2+), not only regulate the cellular behaviors but also stimulate local bone formation and healing. However, the effective delivery and tailored release of Mg2+ remains a challenge, with few reports on hydrogels being used for Mg2+ delivery. Bisphosphonate exhibits a variety of specific bioactivities and excellent binding affinity to multivalent cations such as Mg2+. Herein, we describe a nanocomposite hydrogel based on hyaluronic acid and self-assembled bisphosphonate-magnesium (BP-Mg) nanoparticles. These nanoparticles bearing acrylate groups on the surface not only function as effective multivalent crosslinkers to strengthen the hydrogel network structure, but also promote the mineralization of hydrogels and mediate sustained release of Mg2+. The released Mg2+ ions facilitate stem cell adhesion and spreading on the hydrogel substrates in the absence of cell adhesion ligands, and promote osteogenesis of the seeded hMSCs in vitro. Furthermore, the acellular porous hydrogels alone can support in situ bone regeneration without using exogenous cells and inductive agents, thereby greatly simplifying the approaches of bone regeneration therapy. STATEMENT OF SIGNIFICANCE In this study, we developed a novel bioactive nanocomposite hydrogel based on hyaluronic acid and self-assembled bisphosphonate-magnesium (BP-Mg) nanoparticles. Such hydrogels are stabilized by the multivalent crosslinking domains formed by the aggregation of Ac-BP-Mg NPs, and therefore show enhanced mechanical properties, improved capacity for mineralization, and controlled release kinetics of Mg2+. Moreover, the released Mg2+ can enhance cell adhesion and spreading, and further promote the osteogenic differentiation of hMSCs. Owing to these unique properties, these acellular hydrogels alone can well facilitate the in vivo bone regeneration at the intended sites. We believe that the strategy reported in this work opens up a new route to develop biopolymer-based nanocomposite hydrogels with enhanced physical and biological functionalities for regenerative medicine.
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9
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Shen D, Podolnikova NP, Yakubenko VP, Ardell CL, Balabiyev A, Ugarova TP, Wang X. Pleiotrophin, a multifunctional cytokine and growth factor, induces leukocyte responses through the integrin Mac-1. J Biol Chem 2017; 292:18848-18861. [PMID: 28939773 DOI: 10.1074/jbc.m116.773713] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 09/08/2017] [Indexed: 12/27/2022] Open
Abstract
Pleiotrophin (PTN) is a multifunctional, cationic, glycosaminoglycan-binding cytokine and growth factor involved in numerous physiological and pathological processes, including tissue repair and inflammation-related diseases. PTN has been shown to promote leukocyte responses by inducing their migration and expression of inflammatory cytokines. However, the mechanisms through which PTN mediates these responses remain unclear. Here, we identified the integrin Mac-1 (αMβ2, CD11b/CD18) as the receptor mediating macrophage adhesion and migration to PTN. We also found that expression of Mac-1 on the surface of human embryonic kidney (HEK) 293 cells induced their adhesion and migration to PTN. Accordingly, PTN promoted Mac-1-dependent cell spreading and initiated intracellular signaling manifested in phosphorylation of Erk1/2. While binding to PTN, Mac-1 on Mac-1-expressing HEK293 cells appears to cooperate with cell-surface proteoglycans because both anti-Mac-1 function-blocking mAb and heparin were required to block adhesion. Moreover, biolayer interferometry and NMR indicated a direct interaction between the αMI domain, the major ligand-binding region of Mac-1, and PTN. Using peptide libraries, we found that in PTN the αMI domain bound sequences enriched in basic and hydrophobic residues, indicating that PTN conforms to the general principle of ligand-recognition specificity of the αMI domain toward cationic proteins/peptides. Finally, using recombinant PTN-derived fragments, we show that PTN contains two distinct Mac-1-binding sites in each of its constitutive domains. Collectively, these results identify PTN as a ligand for the integrin Mac-1 on the surface of leukocytes and suggest that this interaction may play a role in inflammatory responses.
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Affiliation(s)
- Di Shen
- From the Schools of Molecular and
| | | | - Valentin P Yakubenko
- Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee 37614
| | - Christopher L Ardell
- Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee 37614
| | - Arnat Balabiyev
- Life Sciences, Arizona State University, Tempe, Arizona 85287 and
| | | | - Xu Wang
- From the Schools of Molecular and
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10
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Lange JR, Goldmann WH, Alonso JL. Influence of αvβ3 integrin on the mechanical properties and the morphology of M21 and K562 cells. Biochem Biophys Res Commun 2016; 478:1280-5. [DOI: 10.1016/j.bbrc.2016.08.111] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 08/17/2016] [Indexed: 01/15/2023]
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11
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Pezzotti G, McEntire BJ, Bock R, Zhu W, Boschetto F, Rondinella A, Marin E, Marunaka Y, Adachi T, Yamamoto T, Kanamura N, Bal BS. In Situ Spectroscopic Screening of Osteosarcoma Living Cells on Stoichiometry-Modulated Silicon Nitride Bioceramic Surfaces. ACS Biomater Sci Eng 2016; 2:1121-1134. [DOI: 10.1021/acsbiomaterials.6b00126] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Giuseppe Pezzotti
- Ceramic
Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, 606-8126 Kyoto, Japan
| | - Bryan J. McEntire
- Amedica Corporation, 1885 West
2100 South, Salt Lake City, Utah 84119, United States
| | - Ryan Bock
- Amedica Corporation, 1885 West
2100 South, Salt Lake City, Utah 84119, United States
| | - Wenliang Zhu
- Department
of Medical Engineering for Treatment of Bone and Joint Disorders, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0854, Japan
| | - Francesco Boschetto
- Ceramic
Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, 606-8126 Kyoto, Japan
| | - Alfredo Rondinella
- Ceramic
Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, 606-8126 Kyoto, Japan
| | - Elia Marin
- Ceramic
Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, 606-8126 Kyoto, Japan
| | | | | | | | | | - B. Sonny Bal
- Amedica Corporation, 1885 West
2100 South, Salt Lake City, Utah 84119, United States
- Department
of Orthopaedic Surgery, University of Missouri, Columbia, Missouri 65212, United States
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12
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Yin M, Xu F, Ding H, Tan F, Song F, Wang J. Incorporation of magnesium ions into photo-crosslinked alginate hydrogel enhanced cell adhesion ability. J Tissue Eng Regen Med 2015; 9:1088-92. [PMID: 25694165 DOI: 10.1002/term.2011] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Revised: 12/06/2014] [Accepted: 01/12/2015] [Indexed: 11/08/2022]
Affiliation(s)
- Miao Yin
- Hubei-MOST KLOS and KLOBM, School and Hospital of Stomatology; Wuhan University; People's Republic of China
- Department of Stomatology, Zhongnan Hospital; Wuhan University; People's Republic of China
| | - Fei Xu
- Hubei-MOST KLOS and KLOBM, School and Hospital of Stomatology; Wuhan University; People's Republic of China
| | - Huifen Ding
- Hubei-MOST KLOS and KLOBM, School and Hospital of Stomatology; Wuhan University; People's Republic of China
| | - Fei Tan
- Hubei-MOST KLOS and KLOBM, School and Hospital of Stomatology; Wuhan University; People's Republic of China
| | - Fangfang Song
- Hubei-MOST KLOS and KLOBM, School and Hospital of Stomatology; Wuhan University; People's Republic of China
| | - Jiawei Wang
- Hubei-MOST KLOS and KLOBM, School and Hospital of Stomatology; Wuhan University; People's Republic of China
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13
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Kwon YD, Lee DW, Hong SO. Magnesium vs. machined surfaced titanium - osteoblast and osteoclast differentiation. J Adv Prosthodont 2014; 6:157-64. [PMID: 25006378 PMCID: PMC4085238 DOI: 10.4047/jap.2014.6.3.157] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 03/05/2014] [Accepted: 03/10/2014] [Indexed: 11/26/2022] Open
Abstract
PURPOSE This study focused on in vitro cell differentiation and surface characteristics in a magnesium coated titanium surface implanted on using a plasma ion source. MATERIALS AND METHODS 40 commercially made pure titanium discs were prepared to produce Ti oxide machined surface (M) and Mg-incorporated Ti oxide machined surface (MM). Surface properties were analyzed using a scanning electron microscopy (SEM). On each surface, alkaline phosphatase (ALP) activity, alizarin red S staining for mineralization of MC3T3-E1 cells, and quantitative analysis of osteoblastic gene expression, were evaluated. Actin ring formation assay and gene expression analysis of TRAP and GAPDH performing RT-PCR were performed to characterize osteoclast differentiation on mouse bone marrow-derived macrophages (BMMs). RESULTS MM showed similar surface morphology and surface roughness with M, but was slightly smoother after ion implantation at the micron scale. M was more hydrophobic than MM. No significant difference between surfaces on ALP activity at 7 and 14 days were observed. Real-time PCR analyses showed similar levels of mRNA expression of the osteoblast phenotype genes; osteopontin (OPN), osteocalcin (OCN), bone sialoprotein (BSP), and collagen 1 (Col 1) in cell grown on MM at 7, 14 and 21 days. Alizarin red S staining at 21 days showed no significant difference. BMMs differentiation increased in M and MM. Actin ring formation assay and gene expression analysis of TRAP showed osteoclast differentiation to be more active on MM. CONCLUSION Both M and MM have a good effect on osteoblastic cell differentiation, but MM may speed the bone remodeling process by activating on osteoclast differentiation.
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Affiliation(s)
- Yong-Dae Kwon
- Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyung Hee University, Republic of Korea
| | - Deok-Won Lee
- Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyung Hee University, Republic of Korea
| | - Sung-Ok Hong
- Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyung Hee University, Republic of Korea
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Fischerauer S, Kraus T, Wu X, Tangl S, Sorantin E, Hänzi A, Löffler J, Uggowitzer P, Weinberg A. In vivo degradation performance of micro-arc-oxidized magnesium implants: a micro-CT study in rats. Acta Biomater 2013; 9:5411-20. [PMID: 23022544 DOI: 10.1016/j.actbio.2012.09.017] [Citation(s) in RCA: 169] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 09/15/2012] [Accepted: 09/18/2012] [Indexed: 11/27/2022]
Abstract
Biodegradable Mg alloys are of great interest for osteosynthetic applications because they do not require surgical removal after they have served their purpose. In this study, fast-degrading ZX50 Mg-based implants were surface-treated by micro-arc oxidation (MAO), to alter the initial degradation, and implanted along with untreated ZX50 controls in the femoral legs of 20 male Sprague-Dawley rats. Their degradation was monitored by microfocus computed tomography (μCT) over a total observation period of 24weeks, and histological analysis was performed after 4, 12 and 24weeks. While the MAO-treated samples showed almost no corrosion in the first week, they revealed an accelerated degradation rate after the third week, even faster than that of the untreated ZX50 implants. This increase in degradation rate can be explained by an increase in the surface-area-to-volume ratio of MAO-treated implants, which degrade inhomogeneously via localized corrosion attacks. The histological analyses show that the initially improved corrosion resistance of the MAO implants has a positive effect on bone and tissue response: The reduced hydrogen evolution (due to reduced corrosion) makes possible increased osteoblast apposition from the very beginning, thus generating a stable bone-implant interface. As such, MAO treatment appears to be very interesting for osteosynthetic implant applications, as it delays implant degradation immediately after implantation, enhances fracture stabilization, minimizes the burden on the postoperatively irritated surrounding tissue and generates good bone-implant connections, followed by accelerated degradation in the later stage of bone healing.
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15
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Yamaguchi S, Matsushita T, Kokubo T. A bioactive Ti metal with a Ca-enriched surface layer releases Mg ions. RSC Adv 2013. [DOI: 10.1039/c3ra00054k] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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16
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Weinreb PH, Li S, Gao SX, Liu T, Pepinsky RB, Caravella JA, Lee JH, Woods VL. Dynamic structural changes are observed upon collagen and metal ion binding to the integrin α1 I domain. J Biol Chem 2012; 287:32897-912. [PMID: 22847004 PMCID: PMC3463359 DOI: 10.1074/jbc.m112.354365] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Revised: 07/11/2012] [Indexed: 02/05/2023] Open
Abstract
We have applied hydrogen-deuterium exchange mass spectrometry, in conjunction with differential scanning calorimetry and protein stability analysis, to examine solution dynamics of the integrin α1 I domain induced by the binding of divalent cations, full-length type IV collagen, or a function-blocking monoclonal antibody. These studies revealed features of integrin activation and α1I-ligand complexes that were not detected by static crystallographic data. Mg(2+) and Mn(2+) stabilized α1I but differed in their effects on exchange rates in the αC helix. Ca(2+) impacted α1I conformational dynamics without altering its gross thermal stability. Interaction with collagen affected the exchange rates in just one of three metal ion-dependent adhesion site (MIDAS) loops, suggesting that MIDAS loop 2 plays a primary role in mediating ligand binding. Collagen also induced changes consistent with increased unfolding in both the αC and allosteric C-terminal helices of α1I. The antibody AQC2, which binds to α1I in a ligand-mimetic manner, also reduced exchange in MIDAS loop 2 and increased exchange in αC, but it did not impact the C-terminal region. This is the first study to directly demonstrate the conformational changes induced upon binding of an integrin I domain to a full-length collagen ligand, and it demonstrates the utility of the deuterium exchange mass spectrometry method to study the solution dynamics of integrin/ligand and integrin/metal ion interactions. Based on the ligand and metal ion binding data, we propose a model for collagen-binding integrin activation that explains the differing abilities of Mg(2+), Mn(2+), and Ca(2+) to activate I domain-containing integrins.
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Affiliation(s)
| | - Sheng Li
- the Department of Medicine and Biomedical Sciences Graduate Program, University of California San Diego, La Jolla, California 92093-0656
| | - Sharon X. Gao
- From Biogen Idec, Inc., Cambridge, Massachusetts 02142 and
| | - Tong Liu
- the Department of Medicine and Biomedical Sciences Graduate Program, University of California San Diego, La Jolla, California 92093-0656
| | | | | | - Jun H. Lee
- the Department of Medicine and Biomedical Sciences Graduate Program, University of California San Diego, La Jolla, California 92093-0656
| | - Virgil L. Woods
- the Department of Medicine and Biomedical Sciences Graduate Program, University of California San Diego, La Jolla, California 92093-0656
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Novin M, Faghihi S. Mouse bone marrow-derived mesenchymal stem cell response to nanostructured titanium substrates produced by high-pressure torsion. SURF INTERFACE ANAL 2012. [DOI: 10.1002/sia.5101] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Mana Novin
- Tissue Engineering and Biomaterials Division; National Institute of Genetic Engineering and Biotechnology (NIGEB); PO box 14155-6343; Tehran; Iran
| | - Shahab Faghihi
- Tissue Engineering and Biomaterials Division; National Institute of Genetic Engineering and Biotechnology (NIGEB); PO box 14155-6343; Tehran; Iran
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Alonso JL, Goldmann WH. Influence of divalent cations on the cytoskeletal dynamics of K562 cells determined by nano-scale bead tracking. Biochem Biophys Res Commun 2012; 421:245-8. [DOI: 10.1016/j.bbrc.2012.03.145] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Accepted: 03/28/2012] [Indexed: 02/07/2023]
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Park JW, Ko HJ, Jang JH, Kang H, Suh JY. Increased new bone formation with a surface magnesium-incorporated deproteinized porcine bone substitute in rabbit calvarial defects. J Biomed Mater Res A 2012; 100:834-40. [DOI: 10.1002/jbm.a.34017] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2011] [Accepted: 11/11/2011] [Indexed: 11/07/2022]
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Maiguel D, Faridi MH, Wei C, Kuwano Y, Balla KM, Hernandez D, Barth CJ, Lugo G, Donnelly M, Nayer A, Moita LF, Schürer S, Traver D, Ruiz P, Vazquez-Padron RI, Ley K, Reiser J, Gupta V. Small molecule-mediated activation of the integrin CD11b/CD18 reduces inflammatory disease. Sci Signal 2011; 4:ra57. [PMID: 21900205 DOI: 10.1126/scisignal.2001811] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The integrin CD11b/CD18 (also known as Mac-1), which is a heterodimer of the α(M) (CD11b) and β(2) (CD18) subunits, is critical for leukocyte adhesion and migration and for immune functions. Blocking integrin-mediated leukocyte adhesion, although beneficial in experimental models, has had limited success in treating inflammatory diseases in humans. Here, we used an alternative strategy of inhibiting leukocyte recruitment by activating CD11b/CD18 with small-molecule agonists, which we term leukadherins. These compounds increased the extent of CD11b/CD18-dependent cell adhesion of transfected cells and of primary human and mouse neutrophils, which resulted in decreased chemotaxis and transendothelial migration. Leukadherins also decreased leukocyte recruitment and reduced arterial narrowing after injury in rats. Moreover, compared to a known integrin antagonist, leukadherins better preserved kidney function in a mouse model of experimental nephritis. Leukadherins inhibited leukocyte recruitment by increasing leukocyte adhesion to the inflamed endothelium, which was reversed with a blocking antibody. Thus, we propose that pharmacological activation of CD11b/CD18 offers an alternative therapeutic approach for inflammatory diseases.
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Affiliation(s)
- Dony Maiguel
- Division of Nephrology and Hypertension, Department of Medicine, University of Miami, Miami, FL 33136, USA
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Mahalingam B, Ajroud K, Alonso JL, Anand S, Adair B, Horenstein AL, Malavasi F, Xiong JP, Arnaout MA. Stable coordination of the inhibitory Ca2+ ion at the metal ion-dependent adhesion site in integrin CD11b/CD18 by an antibody-derived ligand aspartate: implications for integrin regulation and structure-based drug design. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2011; 187:6393-401. [PMID: 22095715 PMCID: PMC3237904 DOI: 10.4049/jimmunol.1102394] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A central feature of integrin interaction with physiologic ligands is the monodentate binding of a ligand carboxylate to a Mg(2+) ion hexacoordinated at the metal ion-dependent adhesion site (MIDAS) in the integrin A domain. This interaction stabilizes the A domain in the high-affinity state, which is distinguished from the default low-affinity state by tertiary changes in the domain that culminate in cell adhesion. Small molecule ligand-mimetic integrin antagonists act as partial agonists, eliciting similar activating conformational changes in the A domain, which has contributed to paradoxical adhesion and increased patient mortality in large clinical trials. As with other ligand-mimetic integrin antagonists, the function-blocking mAb 107 binds MIDAS of integrin CD11b/CD18 A domain (CD11bA), but in contrast, it favors the inhibitory Ca(2+) ion over the Mg(2+) ion at MIDAS. We determined the crystal structures of the Fab fragment of mAb 107 complexed to the low- and high-affinity states of CD11bA. Favored binding of the Ca(2+) ion at MIDAS is caused by the unusual symmetric bidentate ligation of a Fab-derived ligand Asp to a heptacoordinated MIDAS Ca(2+) ion. Binding of the Fab fragment of mAb 107 to CD11bA did not trigger the activating tertiary changes in the domain or in the full-length integrin. These data show that the denticity of the ligand Asp/Glu can modify the divalent cation selectivity at MIDAS and hence integrin function. Stabilizing the Ca(2+) ion at MIDAS by bidentate ligation to a ligand Asp/Glu may provide one approach for designing pure integrin antagonists.
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Affiliation(s)
- Bhuvaneshwari Mahalingam
- Structural Biology Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129,Leukocyte Biology and Inflammation Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129
| | - Kaouther Ajroud
- Leukocyte Biology and Inflammation Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129
| | - Jose Luis Alonso
- Leukocyte Biology and Inflammation Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129
| | - Saurabh Anand
- Leukocyte Biology and Inflammation Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129
| | - Brian Adair
- Structural Biology Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129,Leukocyte Biology and Inflammation Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129
| | - Alberto L Horenstein
- Lab of Immunogenetics, University of Torino Medical School, 10126, Torino, Italy
| | - Fabio Malavasi
- Lab of Immunogenetics, University of Torino Medical School, 10126, Torino, Italy
| | - Jian-Ping Xiong
- Structural Biology Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129,Leukocyte Biology and Inflammation Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129
| | - M. Amin Arnaout
- Structural Biology Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129,Leukocyte Biology and Inflammation Program, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, 02129,Address correspondence to: M. Amin Arnaout, Division of Nephrology, Massachusetts General Hospital, 149 13th Street, Charlestown, MA, 02129, Tel: 617-726-5663, Fax: 617-726-5671.
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Grillo C, Alvarez F, Fernández Lorenzo de Mele M. Biological effects of magnesium particles degradation on UMR-106 cell line: Influence of fluoride treatments. Colloids Surf B Biointerfaces 2011; 88:471-6. [DOI: 10.1016/j.colsurfb.2011.07.035] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Revised: 06/13/2011] [Accepted: 07/12/2011] [Indexed: 11/28/2022]
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Wang DW, Cao Y, Qiu H, Bi ZG. Improved blood compatibility of Mg-1.0Zn-1.0Ca alloy by micro-arc oxidation. J Biomed Mater Res A 2011; 99:166-72. [DOI: 10.1002/jbm.a.33134] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Revised: 02/24/2011] [Accepted: 03/08/2011] [Indexed: 11/08/2022]
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24
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Understanding the impact of divalent cation substitution on hydroxyapatite: An in vitro multiparametric study on biocompatibility. J Biomed Mater Res A 2011; 98:351-8. [DOI: 10.1002/jbm.a.33126] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2010] [Revised: 03/29/2011] [Accepted: 04/04/2011] [Indexed: 11/07/2022]
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25
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In vitro degradation behavior of M1A magnesium alloy in protein-containing simulated body fluid. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2011. [DOI: 10.1016/j.msec.2010.11.017] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Park JW, An CH, Jeong SH, Suh JY. Osseointegration of commercial microstructured titanium implants incorporating magnesium: a histomorphometric study in rabbit cancellous bone. Clin Oral Implants Res 2011; 23:294-300. [PMID: 21435010 DOI: 10.1111/j.1600-0501.2010.02144.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Recent studies have suggested that magnesium (Mg) ions exert a beneficial effect on implant osseointegration. This study assessed the osseointegration of nanoporous titanium (Ti) surface incorporating the Mg produced by hydrothermal treatment in rabbit cancellous bone to determine whether this surface would further enhance bone healing of moderately rough-surfaced implants in cancellous bone, and compared the result with commercially available micro-arc oxidized Mg-incorporated implants. MATERIAL AND METHODS The Mg-incorporated Ti surfaces (RBM/Mg) were obtained by hydrothermal treatment using an alkaline Mg-containing solution on grit-blasted moderately rough (RBM) implants. Untreated RBM and recently introduced Mg-incorporated microporous Ti implants produced by micro-arc oxidation (M) were used controls in this study. The surface characteristics were evaluated by scanning electron microscopy, X-ray photoelectron spectroscopy and optical profilometry. Twenty-four threaded implants with a length of 10 mm (eight RBM implants, eight RBM/Mg implants and eight M implants) were placed in the femoral condyles of 12 New Zealand White rabbits. Histomorphometric analysis was performed 4 weeks after implantation. RESULTS Hydrothermally treated and untreated grit-blasted implants displayed almost identical surface morphologies and R(a) values at the micron-scale. The RBM/Mg implants exhibited morphological differences compared with the RBM implants at the nano-scale, which displayed nanoporous surface structures. The Mg-incorporated implants (RBM/Mg and M) exhibited more continuous bone apposition and a higher degree of bone-to-implant contact (BIC) than the untreated RBM implants in rabbit cancellous bone. The RBM/Mg implants displayed significantly greater BIC% than untreated RBM implants, both in terms of the all threads region and the total lateral length of implants (P<0.05), but no statistical differences were found between the RBM/Mg and M implants except BIC% values in total lateral length. CONCLUSION These results indicate that a nanoporous Mg-incorporated surface may be effective in enhancing the osseointegration of moderately rough grit-blasted implants by increasing the degree of bone-implant contact in areas of cancellous bone.
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Affiliation(s)
- Jin-Woo Park
- Department of Periodontology, School of Dentistry, Kyungpook National University, 188-I, Samduk 2Ga, Jung-Gu Daegu 700-412, Korea.
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Park JW, Kim YJ, Jang JH, Song H. Osteoblast response to magnesium ion-incorporated nanoporous titanium oxide surfaces. Clin Oral Implants Res 2010; 21:1278-87. [PMID: 20497442 DOI: 10.1111/j.1600-0501.2010.01944.x] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVE This study investigated the surface characteristics and in vitro osteoconductivity of a titanium (Ti) surface incorporated with the magnesium ions (Mg) produced by hydrothermal treatment for future application as an endosseous implant surface. MATERIAL AND METHODS Mg-incorporated Ti oxide surfaces were produced by hydrothermal treatment using Mg-containing solution on two different microstructured surfaces--abraded minimally rough (Ma) or grit-blasted moderately rough (RBM) samples. The surface characteristics were evaluated using scanning electron microscopy, thin-film X-ray diffractometry, X-ray photoelectron spectroscopy, optical profilometry, and inductively coupled plasma atomic emission spectroscopy (ICP-AES). MC3T3-E1 pre-osteoblast cell attachment, proliferation, alkaline phosphatase (ALP) activity, and quantitative analysis of osteoblastic gene expression on Ma, RBM, Mg-incorporated Ma (Mg), and Mg-incorporated grit-blasted (RBM/Mg) Ti surfaces were evaluated. RESULTS Hydrothermal treatment produced an Mg-incorporated Ti oxide layer with nanoporous surface structures. Mg-incorporated surfaces showed surface morphologies and surface roughness values almost identical to those of untreated smooth or micro-rough surfaces at the micron scale. ICP-AES analysis showed Mg ions released from treated surfaces into the solution. Mg incorporation significantly increased cellular attachment (P=0 at 0.5 h, P=0.01 at 1 h) on smooth surfaces, but no differences were found on micro-rough surfaces. Mg incorporation further increased ALP activity in cells grown on both smooth and micro-rough surfaces at 7 and 14 days of culture (P=0). Real-time polymerase chain reaction analysis showed higher mRNA expressions of the osteoblast transcription factor gene (Dlx5), various integrins, and the osteoblast phenotype genes (ALP, bone sialoprotein and osteocalcin) in cells grown on micro-rough (RBM) and Mg-incorporated (Mg and RBM/Mg) surfaces than those on Ma surfaces. Mg incorporation further increased the mRNA expressions of key osteoblast genes and integrins (α1, α2, α5, and β1) in cells grown on both the smooth and the micro-rough surfaces. CONCLUSION These results indicate that an Mg-incorporated nanoporous Ti oxide surface produced by hydrothermal treatment may improve implant bone healing by enhancing the attachment and differentiation of osteoblastic cells.
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Affiliation(s)
- Jin-Woo Park
- Department of Periodontology, School of Dentistry, Kyungpook National University, Daegu, Korea.
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Park JW, Kim YJ, Jang JH. Enhanced osteoblast response to hydrophilic strontium and/or phosphate ions-incorporated titanium oxide surfaces. Clin Oral Implants Res 2010; 21:398-408. [DOI: 10.1111/j.1600-0501.2009.01863.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Staflin K, Krueger JS, Hachmann J, Forsyth JS, Lorger M, Steiniger SCJ, Mee J, Pop C, Salvesen GS, Janda KD, Felding-Habermann B. Targeting activated integrin alphavbeta3 with patient-derived antibodies impacts late-stage multiorgan metastasis. Clin Exp Metastasis 2010; 27:217-31. [PMID: 20225083 DOI: 10.1007/s10585-010-9320-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2010] [Accepted: 03/01/2010] [Indexed: 01/01/2023]
Abstract
Advanced metastatic disease is difficult to manage and specific therapeutic targets are rare. We showed earlier that metastatic breast cancer cells use the activated conformer of adhesion receptor integrin alphavbeta3 for dissemination. We now investigated if targeting this form of the receptor can impact advanced metastatic disease, and we analyzed the mechanisms involved. Treatment of advanced multi-organ metastasis in SCID mice with patient-derived scFv antibodies specific for activated integrin alphavbeta3 caused stagnation and regression of metastatic growth. The antibodies specifically localized to tumor lesions in vivo and inhibited alphavbeta3 ligand binding at nanomolar levels in vitro. At the cellular level, the scFs associated rapidly with high affinity alphavbeta3 and dissociated extremely slowly. Thus, the scFvs occupy the receptor on metastatic tumor cells for prolonged periods of time, allowing for inhibition of established cell interaction with natural alphavbeta3 ligands. Potential apoptosis inducing effects of the antibodies through interaction with caspase-3 were studied as potential additional mechanism of treatment response. However, in contrast to a previous concept, neither the RGD-containing ligand mimetic scFvs nor RGD peptides bound or activated caspase-3 at the cellular or molecular level. This indicates that the treatment effects seen in the animal model are primarily due to antibody interference with alphavbeta3 ligation. Inhibition of advanced metastatic disease by treatment with cancer patient derived single chain antibodies against the activated conformer of integrin alphavbeta3 identifies this form of the receptor as a suitable target for therapy.
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Affiliation(s)
- Karin Staflin
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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Rautray TR, Narayanan R, Kwon TY, Kim KH. Surface modification of titanium and titanium alloys by ion implantation. J Biomed Mater Res B Appl Biomater 2010; 93:581-91. [DOI: 10.1002/jbm.b.31596] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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31
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Park JW, Kim HK, Kim YJ, An CH, Hanawa T. Enhanced osteoconductivity of micro-structured titanium implants (XiVE S CELLplus™) by addition of surface calcium chemistry: a histomorphometric study in the rabbit femur. Clin Oral Implants Res 2009; 20:684-90. [DOI: 10.1111/j.1600-0501.2009.01714.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Nuutila J, Jalava-Karvinen P, Hohenthal U, Laitinen I, Kotilainen P, Rajamäki A, Nikoskelainen J, Lilius EM. Comparison of degranulation of easily mobilizable intracellular granules by human phagocytes in healthy subjects and patients with infectious diseases. Hum Immunol 2009; 70:813-9. [PMID: 19559743 DOI: 10.1016/j.humimm.2009.06.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2008] [Revised: 06/15/2009] [Accepted: 06/22/2009] [Indexed: 11/28/2022]
Abstract
The aim of this study was to compare degranulation of easily mobilizable secretory vesicles (SVs) or secretory vesicle-like granules (SVLGs) in neutrophils, monocytes, and eosinophils of healthy controls (n = 60) and febrile patients with microbiologically confirmed or clinically diagnosed bacterial (n = 89) and viral (n = 46) infections. For this purpose, flow cytometric immunophenotyping of isolated phagocytes was performed using monoclonal antibodies against the phagocytosis receptors CR1 (CD35) and CR3 (CD11b) that are predominantly stored in the SVs of resting neutrophils. Similar to neutrophils, monocytes contain easily mobilizable SVLGs that constitute the main intracellular reservoir of CD35 and CD11b. In both neutrophils and monocytes, activation mechanisms leading to degranulation of SV and SVLG appeared dependent on both intra- and extracellular calcium levels. The kinetics of degranulation of SVLGs in control monocytes was significantly faster than that of SVs of control neutrophils. We conclude that phagocytes in patients with bacterial infections can be arranged in order of decreasing magnitude of SV or SVLG degranulation as follows (from left to right): neutrophils > monocytes " eosinophils. However, in viral infections, the corresponding degranulation order is monocytes > neutrophils approximately eosinophils.
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Affiliation(s)
- Jari Nuutila
- Department of Biochemistry, University of Turku, Vatselankatu 2, 20014 Turku, Finland.
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Park JW, Suh JY, Chung HJ. Effects of calcium ion incorporation on osteoblast gene expression in MC3T3-E1 cells cultured on microstructured titanium surfaces. J Biomed Mater Res A 2008; 86:117-26. [PMID: 17941022 DOI: 10.1002/jbm.a.31618] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The surface characteristics of a calcium ion (Ca)-incorporated titanium (Ti) surface, produced by hydrothermal treatment using an alkaline Ca-containing solution, and its effects on osteoblastic differentiation were investigated. MC3T3-E1 pre-osteoblastic cells were cultured on machined or grit-blasted Ti surfaces with and without Ca incorporation. The MTT assay was used to determine cell proliferation, and real-time PCR was used for quantitative analysis of osteoblastic gene expression. Hydrothermal treatment with a Ca-containing solution produced a crystalline CaTiO(3) nanostructure of approximately 100 nm in dimension, preserving original micron-scaled surface topographies and microroughness caused by machining, blasting, or blasting and etching treatments. After immersion in Hank's balanced salt solution, considerable apatite formation was observed on all surfaces of the Ca-incorporated samples. Significantly more cell proliferation was found on Ca-incorporated Ti surfaces than on untreated Ti surfaces (p < 0.001). Quantitative real-time PCR analysis showed notably higher alkaline phosphatase, osteopontin, and osteocalcin mRNA levels in cells grown on Ca-incorporated blasted surfaces than on other surfaces at an early time point. Thus, Ca incorporation may have a beneficial effect on osseointegration of microstructured Ti implants by accelerating osteoblast proliferation and differentiation during the early healing phase following implantation.
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Affiliation(s)
- Jin-Woo Park
- Department of Periodontology, School of Dentistry, Kyungpook National University, 188-1, Samduk 2Ga, Jung-Gu, Daegu 700-412, Korea.
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Chen Y, Cho MR, Mak AFT, Li JS, Wang M, Sun S. Morphology and adhesion of mesenchymal stem cells on PLLA, apatite and apatite/collagen surfaces. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2008; 19:2563-7. [PMID: 17665108 DOI: 10.1007/s10856-007-3195-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2007] [Accepted: 05/22/2007] [Indexed: 05/16/2023]
Abstract
Biomimetic apatite/collagen composite coating, previously reported particularly with regard to its fabrication, characterization and interaction with osteoblast-like cells, has been investigated in this study to understand the response of human mesenchymal stem cells (hMSC) to such surface. PLLA films and PLLA films with apatite coating were compared with PLLA films with apatite/collagen composite coating. The hMSC morphology in response to such conditions was first observed using fluorescence microscopy. To further understand such cell-material interactions at a molecular level, integrin expression, actin assembly and vinculin-positive focal adhesion plaques were examined. Our results demonstrated that spreading of stem cells on the apatite/collagen composite surface was determined best among the three types of surfaces, followed by the apatite surface and then the PLLA control. Integrin expression on the apatite/collagen surface was higher than those on the apatite surface and PLLA surface. Immunostaining for vinculin and actin suggested that the composite coating on PLLA enhanced the formation of focal adhesion.
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Affiliation(s)
- Yun Chen
- Department of Health Technology and Informatics, The Hong Kong Polytechnic University, Hong Hum, China
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Li Z, Gu X, Lou S, Zheng Y. The development of binary Mg-Ca alloys for use as biodegradable materials within bone. Biomaterials 2008; 29:1329-44. [PMID: 18191191 DOI: 10.1016/j.biomaterials.2007.12.021] [Citation(s) in RCA: 1002] [Impact Index Per Article: 62.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Accepted: 12/16/2007] [Indexed: 10/22/2022]
Abstract
Binary Mg-Ca alloys with various Ca contents were fabricated under different working conditions. X-ray diffraction (XRD) analysis and optical microscopy observations showed that Mg-xCa (x=1-3 wt%) alloys were composed of two phases, alpha (Mg) and Mg2Ca. The results of tensile tests and in vitro corrosion tests indicated that the mechanical properties could be adjusted by controlling the Ca content and processing treatment. The yield strength (YS), ultimate tensile strength (UTS) and elongation decreased with increasing Ca content. The UTS and elongation of as-cast Mg-1Ca alloy (71.38+/-3.01 MPa and 1.87+/-0.14%) were largely improved after hot rolling (166.7+/-3.01 MPa and 3+/-0.78%) and hot extrusion (239.63+/-7.21 MPa and 10.63+/-0.64%). The in vitro corrosion test in simulated body fluid (SBF) indicated that the microstructure and working history of Mg-xCa alloys strongly affected their corrosion behaviors. An increasing content of Mg2Ca phase led to a higher corrosion rate whereas hot rolling and hot extrusion could reduce it. The cytotoxicity evaluation using L-929 cells revealed that Mg-1Ca alloy did not induce toxicity to cells, and the viability of cells for Mg-1Ca alloy extraction medium was better than that of control. Moreover, Mg-1Ca alloy pins, with commercial pure Ti pins as control, were implanted into the left and right rabbit femoral shafts, respectively, and observed for 1, 2 and 3 months. High activity of osteoblast and osteocytes were observed around the Mg-1Ca alloy pins as shown by hematoxylin and eosin stained tissue sections. Radiographic examination revealed that the Mg-1Ca alloy pins gradually degraded in vivo within 90 days and the newly formed bone was clearly seen at month 3. Both the in vitro and in vivo corrosion suggested that a mixture of Mg(OH)2 and hydroxyapatite formed on the surface of Mg-1Ca alloy with the extension of immersion/implantation time. In addition, no significant difference (p>0.05) of serum magnesium was detected at different degradation stages. All these results revealed that Mg-1Ca alloy had the acceptable biocompatibility as a new kind of biodegradable implant material. Based on the above results, a solid alloy/liquid solution interface model was also proposed to interpret the biocorrosion process and the associated hydroxyapatite mineralization.
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Affiliation(s)
- Zijian Li
- LTCS, College of Engineering, Peking University, Beijing 100871, China
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Woodruff MA, Jones P, Farrar D, Grant DM, Scotchford CA. Human osteoblast cell spreading and vinculin expression upon biomaterial surfaces. J Mol Histol 2007; 38:491-9. [PMID: 17849222 DOI: 10.1007/s10735-007-9142-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2007] [Accepted: 08/27/2007] [Indexed: 11/29/2022]
Abstract
Any biomaterial implanted within the human body is influenced by the interactions that take place between its surface and the surrounding biological milieu. These interactions are known to influence the tissue interface dynamic, and thus act to emphasize the need to study cell-surface interactions as part of any biomaterial design process. The work described here investigates the relationship between human osteoblast attachment, spreading and focal contact formation on selected surfaces using immunostaining and digital image processing for vinculin, a key focal adhesion component. Our observations show that a relationship exists between levels of cell attachment, the degree of vinculin-associated plaque formation and biocompatibility. It also suggests that cell adhesion is not indicative of how supportive a substrate is to cell spreading, and that cell spreading does not correlate with focal contact formation.
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Affiliation(s)
- Maria Ann Woodruff
- NUS Tissue Engineering Program (NUSTEP), National University of Singapore, Singapore, Singapore.
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37
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Effects of calcium ion incorporation on bone healing of Ti6Al4V alloy implants in rabbit tibiae. Biomaterials 2007; 28:3306-13. [DOI: 10.1016/j.biomaterials.2007.04.007] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2007] [Accepted: 04/03/2007] [Indexed: 11/23/2022]
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Vorup-Jensen T, Waldron TT, Astrof N, Shimaoka M, Springer TA. The connection between metal ion affinity and ligand affinity in integrin I domains. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2007; 1774:1148-55. [PMID: 17702677 PMCID: PMC2040231 DOI: 10.1016/j.bbapap.2007.06.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2007] [Revised: 06/20/2007] [Accepted: 06/21/2007] [Indexed: 11/24/2022]
Abstract
Integrins are cell-surface heterodimeric proteins that mediate cell-cell, cell-matrix, and cell-pathogen interactions. Half of the known integrin alpha subunits contain inserted domains (I domains) that coordinate ligand through a metal ion. Although the importance of conformational changes within isolated I domains in regulating ligand binding has been reported, the relationship between metal ion binding affinity and ligand binding affinity has not been elucidated. Metal and ligand binding by several I domain mutants that are stabilized in different conformations are investigated using isothermal titration calorimetry and surface plasmon resonance studies. This work suggests an inverse relationship between metal ion affinity and ligand binding affinity (i.e. constructs with a high affinity for ligand exhibit a low affinity for metal). This trend is discussed in the context of structural studies to provide an understanding of interplay between metal ion binding and ligand affinities and conformational changes.
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Affiliation(s)
- Thomas Vorup-Jensen
- CBR Institute for Biomedical Research and Department of Pathology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
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Suh JY, Jeung OC, Choi BJ, Park JW. Effects of a novel calcium titanate coating on the osseointegration of blasted endosseous implants in rabbit tibiae. Clin Oral Implants Res 2007; 18:362-9. [PMID: 17298490 DOI: 10.1111/j.1600-0501.2006.01323.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE The purpose of this study was to investigate the effects of a nanostructured calcium coating on the surfaces of blasted Ti implants on peri-implant bone formation in the rabbit tibiae. MATERIAL AND METHODS Threaded implants (3.75 mm in diameter, 6 mm in length) were roughened by hydroxyapatite (HA) blasting (control; blasted implants). The implants were then hydrothermally treated in a Ca-containing solution for 24 h to prepare Ca-incorporated Ti surfaces (experimental; blasted/Ca implants). Surface characterizations were performed by scanning electron microscopy and stylus profilometry before and after Ca coating. Forty-two implants (21 control and 21 experimental) were placed in the proximal tibiae of seven New Zealand White rabbits. Each rabbit received six implants. To evaluate the effects of the nanostructured Ca coating on the peri-implant bone-healing response, removal torque tests and histomorphometric analyses were performed 6 weeks after surgery. RESULTS The Ca coating did not significantly change the surface properties produced by blasting at the micron level. Histologically, active bone apposition was observed in the blasted/Ca implants in the marrow space. Compared with the blasted implants, the blasted/Ca implants showed significantly increased bone-to-implant contact over the total implant length (P<0.01) and greater mean removal torque values (P<0.05). DISCUSSION AND CONCLUSION The nanostructured, Ca-incorporated surface significantly enhanced the peri-implant bone-healing response of HA-blasted Ti implants. It may be concluded that the use of nanostructured, Ca-coated surfaces may have synergic effects in enhancing osseointegration of blasted Ti implants due to their micron-scaled surface properties and biologically active surface chemistry.
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Affiliation(s)
- Jo-Young Suh
- Department of Periodontology, College of Dentistry, Kyungpook National University, Daegu, South Korea
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San Sebastian E, Mercero JM, Stote RH, Dejaegere A, Cossío FP, Lopez X. On the affinity regulation of the metal-ion-dependent adhesion sites in integrins. J Am Chem Soc 2006; 128:3554-63. [PMID: 16536528 DOI: 10.1021/ja054142a] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Density functional theory and a polarizable continuum model are used to (i) understand the affinity modulating mechanisms of the interaction between the metal-ion-dependent adhesion site (MIDAS) of a selected integrin, lymphocyte function-associated antigen-1 (LFA-1) and a ligand mimetic acetate molecule and to (ii) propose a new, promising family of inhibitors to block the interaction of the integrin with intercellular adhesion molecule-1 (ICAM-1). We quantify the effect of isolated factors, such as the metal coordination, the nature of the ligand or the cation present on the MIDAS, and the effect of the permittivity of the media. We show that the affinity for ligand decreases when metal coordination changes from the open conformation to the closed conformation. In addition, Mn2+ and Zn2+ showed to be good competitors for the octahedrically coordinated Mg2+ and yielded excellent affinity values, whereas Ca2+ in an octahedric environment would decrease the affinity for the ligand. Our affinity studies of the open MIDAS showed that nitronate-derived or carboxylic acid-containing ligands may represent new promising scaffolds of future inhibitors. Finally, we show that affinities are always highly favored by low-dielectric environments, which explains the propensity of MIDAS motifs to be surrounded by hydrophobic residues in integrins and highlights the importance of including hydrophobic groups in the inhibitors.
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Affiliation(s)
- Eider San Sebastian
- Kimika Fakultatea, Euskal Herriko Unibertsitatea and Donostia International Physics Center, P. K. 1072, 20080 Donostia, Spain
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Abstract
Alphabeta heterodimeric integrins mediate dynamic adhesive cell-cell and cell-extracellular matrix (ECM) interactions in metazoa that are critical in growth and development, hemostasis, and host defense. A central feature of these receptors is their capacity to change rapidly and reversibly their adhesive functions by modulating their ligand-binding affinity. This is normally achieved through interactions of the short cytoplasmic integrin tails with intracellular proteins, which trigger restructuring of the ligand-binding site through long-range conformational changes in the ectodomain. Ligand binding in turn elicits conformational changes that are transmitted back to the cell to regulate diverse responses. The publication of the integrin alphaVbeta3 crystal structure has provided the context for interpreting decades-old biochemical studies. Newer NMR, crystallographic, and EM data, reviewed here, are providing a better picture of the dynamic integrin structure and the allosteric changes that guide its diverse functions.
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Affiliation(s)
- M A Arnaout
- Structural Biology Program, Leukocyte Biology and Inflammation Program, Nephrology Division, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachussetts 02129, USA.
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Nayab SN, Jones FH, Olsen I. Effects of calcium ion implantation on human bone cell interaction with titanium. Biomaterials 2005; 26:4717-27. [PMID: 15763251 DOI: 10.1016/j.biomaterials.2004.11.044] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2004] [Accepted: 11/24/2004] [Indexed: 11/30/2022]
Abstract
The use of calcium ion (Ca) implantation of titanium (Ti), previously reported to encourage osseointegration in vivo, has been investigated using an in vitro model in order to understand the basic mechanisms involved in the response of target cells to such surfaces. Polished Ti discs were implanted with high, medium and low (1x10(17), 1x10(16), 1x10(15)ionscm-2) doses of Ca ions at 40 keV. The effects of different levels of Ca implantation on morphology, attachment and spreading of MG-63 cells seeded on the surface of control (non-implanted) Ti and Ca-Ti discs were assessed. Further, to understand cell-material interactions at a molecular level, the expression of beta1 and alpha5beta1 integrins and the formation of vinculin-positive focal adhesion plaques were examined. In addition, the effects of pre-immersion of the Ca (high)-Ti in tissue culture medium on cell attachment were measured and correlated with specific chemical changes at the Ti surface. Our findings suggest that Ca implantation can affect the adhesion of MG-63 cells both qualitatively and quantitatively. However, this effect appears to depend on the level at which Ca ions are implanted. Results showed that although cell adhesion on Ca (high)-Ti was initially reduced, it nevertheless was not only restored but substantially increased with progressing culture times. In addition, a significantly enhanced cell spreading, formation of focal adhesion plaques and expression of integrins were measured on this particular surface. In contrast, no marked differences were observed in cell behaviour on Ca-Ti (low and medium). Pre-immersion studies indicated that the decrease in cell attachment to Ca (high)-Ti at early time periods may be linked to the presence of Ca- and P-rich particles on the surface. The absence of these particles at 24 h was consistent with a significant increase in cell attachment.
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Affiliation(s)
- Saima N Nayab
- Division of Biomaterials and Tissue Engineering, Eastman Dental Institute for Oral Health Care Sciences, University College London, 256 Gray's Inn Road, London WC1X 8LD, UK
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Choi J, Leyton L, Nham SU. Characterization of αX I-domain binding to Thy-1. Biochem Biophys Res Commun 2005; 331:557-61. [PMID: 15850796 DOI: 10.1016/j.bbrc.2005.04.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2005] [Indexed: 11/26/2022]
Abstract
The beta2 integrins are found exclusively in leukocytes and they are composed of a common beta chain, CD18, and one of four unique alpha chains, CD11a (alphaL subunit), CD11b (alphaM subunit), CD11c (alphaX subunit), or CD11d (alphaD subunit). alphaX-beta2 which binds several ligands including fibrinogen and iC3b is expressed in monocytes/macrophages and dendritic cells playing an important role in the host defense. Despite the unique characteristics on expression and regulation, alphaX-beta2 is less functionally characterized than other beta2 integrins. To understand the biological function of alphaX-beta2 more, we tested the possibility that alphaX-beta2 binds Thy-1, a membrane protein involved in cell adhesion and signaling regulation in neurons and T cells. Here we report that a ligand binding moiety of alphaX-beta2, the I-domain, bound Thy-1 in a specific and divalent cation-dependent manner. The dissociation constant (K(D)) of alphaX I-domain binding to Thy-1 was 1.16muM and the affinity of the binding was roughly 2-fold higher than that of alphaM I-domain. Amino acid substitutions on the betaD-alpha5 of alphaX I-domain (D249, KE243/244) showed low affinities for Thy-1 while other point mutations on alpha3-alpha4 and betaE-alpha6 loops of I-domain did not, suggesting that Thy-1 recognizes the portion of a betaD-alpha5 loop, possibly alpha5 helix. Taken together, these results indicate that alphaX-beta2 specifically interacts with Thy-1. Additionally, kinetic analysis reveals a moderate affinity interaction in the presence of divalent cations. Given the reported role of Thy-1 in the regulation of T cell homeostasis and proliferation, it is tempting to speculate that alphaX-beta2 may be involved in Thy-1 function.
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Affiliation(s)
- Jeongsuk Choi
- Divisions of Science Education and Biology, Kangwon National University, Choonchun, Kangwon, Republic of Korea
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Abstract
The year 2004 represents a milestone for the biosensor research community: in this year, over 1000 articles were published describing experiments performed using commercially available systems. The 1038 papers we found represent an approximately 10% increase over the past year and demonstrate that the implementation of biosensors continues to expand at a healthy pace. We evaluated the data presented in each paper and compiled a 'top 10' list. These 10 articles, which we recommend every biosensor user reads, describe well-performed kinetic, equilibrium and qualitative/screening studies, provide comparisons between binding parameters obtained from different biosensor users, as well as from biosensor- and solution-based interaction analyses, and summarize the cutting-edge applications of the technology. We also re-iterate some of the experimental pitfalls that lead to sub-optimal data and over-interpreted results. We are hopeful that the biosensor community, by applying the hints we outline, will obtain data on a par with that presented in the 10 spotlighted articles. This will ensure that the scientific community at large can be confident in the data we report from optical biosensors.
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Affiliation(s)
- Rebecca L Rich
- Center for Biomolecular Interaction Analysis, University of Utah, Salt Lake City, UT 84132, USA
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