scholarly journals Ductile silica/methacrylate hybrids for bone regeneration

2016 ◽  
Vol 4 (36) ◽  
pp. 6032-6042 ◽  
Author(s):  
Anthony L. B. Maçon ◽  
Siwei Li ◽  
Justin J. Chung ◽  
Amy Nommeots-Nomm ◽  
Anu K. Solanki ◽  
...  
Keyword(s):  
Bone Regeneration ◽  
Class Ii ◽  
Cross Linking ◽  
Scaffold Materials ◽  
New Generation

Hybrids consisting of co-networks of high cross-linking density polymethacrylate and silica (class II hybrid) were synthesised as a potential new generation of scaffold materials.

scholarly journals Early Endosomes Are Required for Major Histocompatiblity Complex Class II Transport to Peptide-loading Compartments

1999 ◽  
Vol 10 (9) ◽  
pp. 2891-2904 ◽  
Author(s):  
Valérie Brachet ◽  
Gérard Péhau-Arnaudet ◽  
Catherine Desaymard ◽  
Graça Raposo ◽  
Sebastian Amigorena
Keyword(s):  
Mhc Class Ii ◽  
Class Ii ◽  
Endocytic Pathway ◽  
Cross Linking ◽  
Histocompatibility Complex ◽  
Early Endosomes ◽  
Peptide Loading ◽  
Golgi Network ◽  
Mhc Class Ii Molecules

Antigen presentation to CD4+ T lymphocytes requires transport of newly synthesized major histocompatibility complex (MHC) class II molecules to the endocytic pathway, where peptide loading occurs. This step is mediated by a signal located in the cytoplasmic tail of the MHC class II-associated Ii chain, which directs the MHC class II-Ii complexes from the trans-Golgi network (TGN) to endosomes. The subcellular machinery responsible for the specific targeting of MHC class II molecules to the endocytic pathway, as well as the first compartments these molecules enter after exit from the TGN, remain unclear. We have designed an original experimental approach to selectively analyze this step of MHC class II transport. Newly synthesized MHC class II molecules were caused to accumulate in the Golgi apparatus and TGN by incubating the cells at 19°C, and early endosomes were functionally inactivated by in vivo cross-linking of transferrin (Tf) receptor–containing endosomes using Tf-HRP complexes and the HRP-insoluble substrate diaminobenzidine. Inactivation of Tf-containing endosomes caused a marked delay in Ii chain degradation, peptide loading, and MHC class II transport to the cell surface. Thus, early endosomes appear to be required for delivery of MHC class II molecules to the endocytic pathway. Under cross-linking conditions, most αβIi complexes accumulated in tubules and vesicles devoid of γ-adaptin and/or mannose-6-phosphate receptor, suggesting an AP1-independent pathway for the delivery of newly synthesized MHC class II molecules from the TGN to endosomes.

scholarly journals On-Chip Fabrication and In-Flow 3D-Printing of Cell-Laden Microgel Constructs: From Chip to Scaffold Materials in One Integral Process

2021 ◽  
Author(s):  
Stephan Förster ◽  
Jürgen Groll ◽  
Benjamin Reineke ◽  
Stephan Hauschild ◽  
Ilona Paulus ◽  
...  
Keyword(s):  
3D Printing ◽  
Three Dimensional ◽  
Cross Linking ◽  
Cell Protection ◽  
Free Standing ◽  
Produce Cell ◽  
Chip Fabrication ◽  
Integral Process ◽  
Scaffold Materials ◽  
On Chip

Bioprinting has evolved into a thriving technology for the fabrication of cell-laden scaffolds. Bioinks are the most critical component for bioprinting. Recently, microgels have been introduced as a very promising bioink enabling cell protection and the control of the cellular microenvironment. However, their microfluidic fabrication inherently seemed to be a limitation. Here we introduce a direct coupling of microfluidics and 3D-printing for the microfluidic production of cell-laden microgels with direct in-flow bioprinting into stable scaffolds. The methodology enables the continuous on-chip encapsulation of cells into monodisperse microdroplets with subsequent in-flow cross-linking to produce cell-laden microgels, which after exiting a microtubing are automatically jammed into thin continuous microgel filaments. The integration into a 3D printhead allows direct in-flow printing of the filaments into free-standing three-dimensional scaffolds. The method is demonstrated for different cross-linking methods and cell lines. With this advancement, microfluidics is no longer a bottleneck for biofabrication. <br>

scholarly journals Ursolic acid loaded-mesoporous hydroxylapatite/ chitosan therapeutic scaffolds promote the bone regeneration

2020 ◽  
Author(s):  
Xijiao Yu ◽  
Yuxuan Wang ◽  
Xiao-Liang Liu ◽  
Degang Yu ◽  
Shanyong Zhang
Keyword(s):  
Bone Regeneration ◽  
Ursolic Acid ◽  
Control Release ◽  
The Novel ◽  
Alizarin Red ◽  
Biomaterial Scaffolds ◽  
Scaffold Materials ◽  
Related Proteins

Abstract Background: Mesoporous hydroxylapatite (MHAP) could play an important role in bone regeneration, and UA (Ursolic acid) also promote the osteogenic differentiation. Accordingly, we developed the UA loaded MHAP scaffolds to cure bone defects. In vitro, we synthesize biomaterial scaffolds. By SEM, XRD, EDS and FTIR, we test the performance of the hybrid scaffolds. By drug release, ALP staining, Alizarin red staining, and Western blotting, we test the osteo-inductive properties of scaffold materials. In vivo, We verify bone regeneration through a rat skull defect model.Results: The MHAP is a rod-shaped structure with a length of 100~300nm and a diameter of 40~60nm. The critical structure gives the micro scaffold a property of control release due to the pore sizes of 1.6~4.3 nm in hydroxyapatite and the hydrogen bonding between the scaffolds and UA drugs. The released UA drugs could notably promote the expression of osteogenic-related genes (COL1, ALP, OPG) and osteogenic-related proteins (BMP-2, RUNX2 and COL1). Both the images of μCT and the results of double fluorochrome labelling demonstrated that therapeutic scaffolds promoted the bone regeneration. We obtained the similar results through immunohistochemistry. Conclusions: The MHAP-CS-UA scaffolds have good osteo-inductivity and bone regeneration. And they will be the novel and promising candidates to cure the bone disease.

scholarly journals Cross-linking of major histocompatibility complex class II molecules by staphylococcal enterotoxin A superantigen is a requirement for inflammatory cytokine gene expression.

1995 ◽  
Vol 182 (5) ◽  
pp. 1573-1577 ◽  
Author(s):  
K Mehindate ◽  
J Thibodeau ◽  
M Dohlsten ◽  
T Kalland ◽  
R P Sékaly ◽  
...  
Keyword(s):  
Gene Expression ◽  
Mhc Class Ii ◽  
Messenger Rna ◽  
Class Ii ◽  
Cytokine Gene Expression ◽  
Cross Linking ◽  
Staphylococcal Enterotoxin A ◽  
Cytokine Gene ◽  
Histocompatibility Complex ◽  
Mhc Class Ii Molecules

Staphylococcal enterotoxin A (SEA) has two distinct binding sites for major histocompatibility complex (MHC) class II molecules. The aspartic acid located at position 227 (D227) in the COOH terminus of SEA is one of the three residues involved in its interaction with the DR beta chain, whereas the phenylalanine 47 (F47) of the NH2 terminus is critical for its binding to the DR alpha chain. Upon interaction with MHC class II molecules, SEA triggers several cellular events leading to cytokine gene expression. In the present study, we have demonstrated that, contrary to wild-type SEA, stimulation of the THP1 monocytic cell line with SEA mutated at position 47 (SEAF47A) or at position 227 (SEAD227A) failed to induce interleukin 1 beta and tumor necrosis factor-alpha messenger RNA expression. Pretreatment of the cells with a 10-fold excess of either SEAF47A or SEAD227A prevented the increase in cytokine messenger RNA induced by wild-type SEA. However, cross-linking of SEAF47A or SEAD227A bound to MHC class II molecules with F(ab')2 anti-SEA mAb leads to cytokine gene expression, whereas cross-linking with F(ab) fragments had no effect. Taken together, these results indicate that cross-linking of two MHC class II molecules by one single SEA molecule is a requirement for cytokine gene expression.

scholarly journals Physiological and Clinical Significance of Disordered Cross-Linking of Fibrin

1977 ◽  
Author(s):  
L. Lorand
Keyword(s):  
Class Ii ◽  
Class I ◽  
Cross Linking ◽  
Type I ◽  
Type Ii ◽  
Zymogen Activation ◽  
Primary Defect ◽  
Plasma Clot ◽  
Autoimmune Antibodies ◽  
Hereditary Disorders

Disorders of fibrin stabilization are hemorrhagic conditions in which the patient’s plasma clot is lacking in inter-fibrin γ-glutamyl-ε-lysine isopeptide linkages. The primary defect occurs either because no fibrinoligase (FXIIIa) activity can be generated or because the enzyme cannot act on fibrin in the patient’s plasma. Distinction is made between hereditary disorders (Class I) and those appearing later in life because of an acquired inhibitor (Class II) directed against one of the steps on the pathway of fibrin stabilization: Of the genetic deficiencies (Class I), Type I is characterized by a lack of zymogen activity in plasma and Type II by the unreactivity of the cross-linking sites of the patient’s fibrin [“dysfibrin(ogen)emias”] towards fibrinoligase.There are three varieties of Class II abnormalities. In Type I, the acquired inhibitor interferes with zymogen activation. Type II inhibitors affect transamidation by competing against fibrin for the enzyme. The Type III inhibitor combines with fibrin rendering it unreactive towards fibrinoligase. The Type I and III inhibitors appear to be autoimmune antibodies.(Ann. N. Y. Acad. Sei., 202, 6, 1972).Differential diagnostic criteria for this family of molecular disorders will be discussed.

scholarly journals Current Progress in Cross-Linked Peptide Self-Assemblies

2020 ◽  
Vol 21 (20) ◽  
pp. 7577
Author(s):  
Noriyuki Uchida ◽  
Takahiro Muraoka
Keyword(s):  
Self Assembly ◽  
Three Dimensional ◽  
Chemical Properties ◽  
Water Soluble ◽  
Cross Linking ◽  
Physical And Chemical Properties ◽  
Cell Scaffold ◽  
Scaffold Materials ◽  
Physical And Chemical ◽  
And Chemical Properties

Peptide-based fibrous supramolecular assemblies represent an emerging class of biomaterials that can realize various bioactivities and structures. Recently, a variety of peptide fibers with attractive functions have been designed together with the discovery of many peptide-based self-assembly units. Cross-linking of the peptide fibers is a key strategy to improve the functions of these materials. The cross-linking of peptide fibers forming three-dimensional networks in a dispersion can lead to changes in physical and chemical properties. Hydrogelation is a typical change caused by cross-linking, which makes it applicable to biomaterials such as cell scaffold materials. Cross-linking methods, which have been conventionally developed using water-soluble covalent polymers, are also useful in supramolecular peptide fibers. In the case of peptide fibers, unique cross-linking strategies can be designed by taking advantage of the functions of amino acids. This review focuses on the current progress in the design of cross-linked peptide fibers and their applications.

scholarly journals Utility of Thermal Cross-Linking in Stabilizing Hydrogels with Beta-Tricalcium Phosphate and/or Epigallocatechin Gallate for Use in Bone Regeneration Therapy

Polymers ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 40
Author(s):  
Beiyuan Gao ◽  
Yoshitomo Honda ◽  
Yoichi Yamada ◽  
Tomonari Tanaka ◽  
Yoshihiro Takeda ◽  
...  
Keyword(s):  
Bone Regeneration ◽  
Orthopedic Surgery ◽  
Tricalcium Phosphate ◽  
High Stability ◽  
Epigallocatechin Gallate ◽  
Cross Linking ◽  
Tartrate Resistant Acid Phosphatase ◽  
Beta Tricalcium Phosphate ◽  
Heating Treatment ◽  
Vacuum Heating

β-tricalcium phosphate (β-TCP) granules are commonly used materials in dentistry or orthopedic surgery. However, further improvements are required to raise the operability and bone-forming ability of β-TCP granules in a clinical setting. Recently, we developed epigallocatechin gallate (EGCG)-modified gelatin sponges as a novel biomaterial for bone regeneration. However, there is no study on using the above material for preparing hydrogel incorporating β-TCP granules. Here, we demonstrate that vacuum heating treatment induced thermal cross-linking in gelatin sponges modified with EGCG and incorporating β-TCP granules (vhEc-GS-β) so that the hydrogels prepared from vhEc-GS-β showed high stability, β-TCP granule retention, operability, and cytocompatibility. Additionally, microcomputed tomography morphometry revealed that the hydrogels from vhEc-GS-β had significantly higher bone-forming ability than β-TCP alone. Tartrate-resistant acid phosphatase staining demonstrated that the number of osteoclasts increased at three weeks in defects treated with the hydrogels from vhEc-GS-β compared with that around β-TCP alone. The overall results indicate that thermal cross-linking treatment for the preparation of sponges (precursor of hydrogels) can be a promising process to enhance the bone-forming ability. This insight should provide a basis for the development of novel materials with good operativity and bone-forming ability for bone regenerative medicine.

scholarly journals On-Chip Fabrication and In-Flow 3D-Printing of Cell-Laden Microgel Constructs: From Chip to Scaffold Materials in One Integral Process

2021 ◽  
Author(s):  
Stephan Förster ◽  
Jürgen Groll ◽  
Benjamin Reineke ◽  
Stephan Hauschild ◽  
Ilona Paulus ◽  
...  
Keyword(s):  
3D Printing ◽  
Three Dimensional ◽  
Cross Linking ◽  
Cell Protection ◽  
Free Standing ◽  
Produce Cell ◽  
Chip Fabrication ◽  
Integral Process ◽  
Scaffold Materials ◽  
On Chip

Bioprinting has evolved into a thriving technology for the fabrication of cell-laden scaffolds. Bioinks are the most critical component for bioprinting. Recently, microgels have been introduced as a very promising bioink enabling cell protection and the control of the cellular microenvironment. However, their microfluidic fabrication inherently seemed to be a limitation. Here we introduce a direct coupling of microfluidics and 3D-printing for the microfluidic production of cell-laden microgels with direct in-flow bioprinting into stable scaffolds. The methodology enables the continuous on-chip encapsulation of cells into monodisperse microdroplets with subsequent in-flow cross-linking to produce cell-laden microgels, which after exiting a microtubing are automatically jammed into thin continuous microgel filaments. The integration into a 3D printhead allows direct in-flow printing of the filaments into free-standing three-dimensional scaffolds. The method is demonstrated for different cross-linking methods and cell lines. With this advancement, microfluidics is no longer a bottleneck for biofabrication. <br>

scholarly journals HLA-DR–Mediated Signals for Hematopoiesis and Induction of Apoptosis Involve But Are Not Limited to a Nitric Oxide Pathway

Blood ◽  
1997 ◽  
Vol 90 (1) ◽  
pp. 217-225 ◽  
Author(s):  
Jong Wook Lee ◽  
Cassandra Beckham ◽  
Bryce R. Michel ◽  
Henry Rosen ◽  
H. Joachim Deeg
Keyword(s):  
Nitric Oxide ◽  
Mhc Class Ii ◽  
Affect Regulation ◽  
Combined Treatment ◽  
Class Ii ◽  
Cross Linking ◽  
No Production ◽  
Hla Dr ◽  
Low Concentrations ◽  
Induced Apoptosis

Cross-linking of major histocompatibility complex (MHC) class II antigens by anti-HLA-DR monoclonal antibody (MoAb; H81.9; IgG2a) results in inhibition of hematopoiesis in canine and human models. Inhibition of hematopoiesis is associated with apoptosis in a proportion of marrow cells. Since in murine macrophages class II cross-linking triggers nitric oxide (NO) production, and NO is thought to affect regulation of hematopoiesis, we investigated whether NO was involved in our models. In murine J774 monocytes/macrophages, MoAb H81.9 did induce NO. NO production was blocked by NG-monomethyl-L-arginine (NMMA), an inhibitor of NO synthase (NOS), and by the antioxidant N-acetylcysteine (NAC). In human and canine long-term marrow cultures (LTMCs) and in enriched marrow monocytes, however, no measurable increase in NO production was noted after H81.9 exposure. Nevertheless, NAC protected LTMCs against H81.9 induced inhibition of hematopoiesis. Therefore, we determined the effect of an exogenous NO donator, sin-1 (3-morpholinosydnonimine), on canine and human LTMCs and on apoptosis. Sin-1 at concentrations ≥100 μg/mL inhibited LTMCs and induced apoptosis; at low concentrations (1 μg/mL), however, sin-1 stimulated the generation of colony-forming unit granulocyte-macrophage. Combined treatment with sin-1 at 100 μg/mL and MoAb H81.9 resulted in profound inhibition of hematopoiesis in both canine and human LTMCs, and had an additive effect on apoptosis. At 1 μg/mL sin-1 counteracted the effect of H81.9 on hematopoiesis. The effect of sin-1 on apoptosis and hematopoiesis in LTMC was largely prevented by NAC. These results are consistent with the hypothesis that HLA-DR mediated apoptosis and inhibition of hematopoiesis involve oxidative stress. However, the biphasic response of hematopoiesis to sin-1 suggests a complex regulatory network possibly related to differences in NO sensitivity of distinct subpopulations of cells. Signals in addition to NO appear to be involved in the effect of anti-HLA-DR MoAb on hematopoiesis.

scholarly journals Synthesis of bioactive class II poly(γ-glutamic acid)/silica hybrids for bone regeneration

2010 ◽  
Vol 20 (40) ◽  
pp. 8952 ◽  
Author(s):  
Gowsihan Poologasundarampillai ◽  
Claudia Ionescu ◽  
Olga Tsigkou ◽  
Muthu Murugesan ◽  
Robert G. Hill ◽  
...  
Keyword(s):  
Glutamic Acid ◽  
Bone Regeneration ◽  
Class Ii ◽  
Silica Hybrids
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