scholarly journals Zonal Chondrocytes Seeded in a Layered Agarose Hydrogel Create Engineered Cartilage with Depth-Dependent Cellular and Mechanical Inhomogeneity

2009 ◽  
Vol 15 (9) ◽  
pp. 2315-2324 ◽  
Author(s):  
Kenneth W. Ng ◽  
Gerard A. Ateshian ◽  
Clark T. Hung
Keyword(s):  
Agarose Hydrogel ◽  
Engineered Cartilage

Beneficial Effects of Chondroitinase ABC Release From Lipid Microtubes Encapsulated in Chondrocyte-Seeded Hydrogel Constructs

2011 ◽  
Author(s):  
Grace D. O’Connell ◽  
Clare Gollnick ◽  
Gerard A. Ateshian ◽  
Ravi V. Bellamkonda ◽  
Clark T. Hung
Keyword(s):  
Enzyme Release ◽  
Compressive Properties ◽  
Hydrogel Scaffold ◽  
Beneficial Effects ◽  
Agarose Hydrogel ◽  
Vitro Development ◽  
Engineered Cartilage ◽  
Over Time

Tissue-engineered cartilage using a hydrogel scaffold is capable of achieving native compressive properties and glycosaminglycan (GAG) content [1]; however, promoting collagen growth towards native values has been challenging. As the cells in the cartilage constructs deposit matrix over time in culture, transport of nutrients to the construct center becomes increasingly hindered [2]. Digestion of mature tissue engineered constructs with chondroitinase (chABC) temporarily suppresses the GAG content, allowing an increase in the collagen content and eventually improving the mechanical properties after GAG content recovers [1]. However, adding chABC into the feeding media limits its effectiveness to the construct’s periphery, reflecting enzyme diffusion gradients. Additionally, long-term use of chABC, without re-application, is limited since its enzymatic activity degrades within 5 days at 37°C [3]. Lee and co-workers have developed a method for delivering thermostabilized chABC using sugar trehalose and hydrogel-microtubes for applications desiring extended enzyme release [4]. Lipid microtubes loaded with thermostabilized chABC may be incorporated into an agarose hydrogel scaffold to provide long-term release of the enzyme uniformly throughout the construct [3]. The objective of this study was to test the hypothesis that chABC-filled microtubes will enhance in vitro development of engineered cartilage.

Lipid Mictrotubes as a Nutrient Reservoir or Enzyme Delivery Vehicle in Engineered Cartilage

2012 ◽  
Author(s):  
Grace D. O’Connell ◽  
Clare Gollnick ◽  
Gerard A. Ateshian ◽  
Ravi V. Bellamkonda ◽  
Clark T. Hung
Keyword(s):  
Compressive Properties ◽  
Delivery Vehicle ◽  
Hydrogel Scaffold ◽  
Collagen Production ◽  
Injury Repair ◽  
Agarose Hydrogel ◽  
Spinal Chord ◽  
Nutrient Diffusion ◽  
Enzyme Delivery ◽  
Engineered Cartilage

Tissue-engineered cartilage using a hydrogel scaffold is capable of achieving native compressive properties and glycosaminglycan (GAG) content [1]. However, these tissues are limited in their collagen production and closer inspection of the localized mechanical properties demonstrates that mature constructs consist of a stiffer periphery region surrounding a softer core [1, 2]. Nutrient diffusion becomes increasingly more challenging as the cells in the construct periphery deposit extracellular matrix. Altering the scaffold porosity by adding microscopic porogens can improve the nutrient diffusion into the center of the construct [3]. Furthermore, chondroitinase ABC (chABC) has been shown to improve collagen production of mature engineered cartilage (i.e. tissue cultured for 2–4 weeks before chABC digestion). Lipid microtubes, designed to slowly release chABC for spinal chord injury repair can be incorporated into our agarose hydrogel scaffold in a chABC-loaded or unloaded form. The objective of this study was to explore the use of lipid microtubes in our scaffold as a tubular porogen and as a vehicle to deliver chABC throughout the scaffold to improve nutrient diffusion and collagen production into our engineered constructs.

Human Dentine Remineralization Under Non-colagen Materials Action

2017 ◽  
Vol 68 (5) ◽  
pp. 928-932
Author(s):  
Agripina Zaharia ◽  
Viorica Ghisman Plescan ◽  
Elena Maria Anghel ◽  
Viorica Musat
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Artificial Saliva ◽  
Composite Layer ◽  
X Ray ◽  
Micro Raman Spectroscopy ◽  
Agarose Hydrogel ◽  
Human Dentine ◽  
Dentine Surface ◽  
Scanning Electron

The purpose of this work is to induce biomimetic remineralization of acid etched coronal human dentine in artificial saliva (AS) under agarose (A) hydrogel or chitosan (CS)-A hydrogel action. The investigations focused on the morphology, chemical composition and crystalline structure of the new remineralized layers grown onto the etched dentinal surface (R) using scanning electron microscopy coupled with energy dispersive X-ray spectrometry and micro-Raman spectroscopy. Experimental results showed that remineralized layers grown in the presence of A or CS-A hydrogels consist in B-type Ca-deficient hydroxyapatite (HAP). After 7 days treatment into artificial saliva under agarose hydrogel, nanorod-like extrafibrilar HAP crystals randomly self-assembled in a discontinuous layer were formed, while in presence of chitosan-agarose hydrogel a continuous compact CS-HAP composite layer was obtained. The new biomimetic layer (A-CS4) formed after 4 days on dentine surface under A-CS hydrogel has higher crystallinity. Longer exposed (7 days) dentine in the presence of agarose hydrogel shows a higher mineral-to-collagen ratio (A7). Since dentine mineralization increases, the collagen quality factor decreases in succession A-CS4]R]A7. Results show a benefic effect of chitosan on remineralization of etched dentine.

scholarly journals Heparan Sulfate Deficiency in Cartilage: Enhanced BMP-Sensitivity, Proteoglycan Production and an Anti-Apoptotic Expression Signature after Loading

2021 ◽  
Vol 22 (7) ◽  
pp. 3726
Author(s):  
Matthias Gerstner ◽  
Ann-Christine Severmann ◽  
Safak Chasan ◽  
Andrea Vortkamp ◽  
Wiltrud Richter
Keyword(s):  
Heparan Sulfate ◽  
Pain Perception ◽  
Biological Process ◽  
Transcriptome Profiling ◽  
Mrna Levels ◽  
Unconfined Compression ◽  
Expression Signature ◽  
Hypomorphic Allele ◽  
Underlying Mechanisms ◽  
Engineered Cartilage

Osteoarthritis (OA) represents one major cause of disability worldwide still evading efficient pharmacological or cellular therapies. Severe degeneration of extracellular cartilage matrix precedes the loss of mobility and disabling pain perception in affected joints. Recent studies showed that a reduced heparan sulfate (HS) content protects cartilage from degradation in OA-animal models of joint destabilization but the underlying mechanisms remained unclear. We aimed to clarify whether low HS-content alters the mechano-response of chondrocytes and to uncover pathways relevant for HS-related chondro-protection in response to loading. Tissue-engineered cartilage with HS-deficiency was generated from rib chondrocytes of mice carrying a hypomorphic allele of Exostosin 1 (Ext1), one of the main HS-synthesizing enzymes, and wildtype (WT) littermate controls. Engineered cartilage matured for 2 weeks was exposed to cyclic unconfined compression in a bioreactor. The molecular loading response was determined by transcriptome profiling, bioinformatic data processing, and qPCR. HS-deficient chondrocytes expressed 3–6% of WT Ext1-mRNA levels. Both groups similarly raised Sox9, Col2a1, and Acan levels during maturation. However, HS-deficient chondrocytes synthesized and deposited 50% more GAG/DNA. TGFβ and FGF2-sensitivity of Ext1gt/gt chondrocytes was similar to WT cells but their response to BMP-stimulation was enhanced. Loading induced similar activation of mechano-sensitive ERK and P38-signaling in WT and HS-reduced chondrocytes. Transcriptome analysis reflected regulation of cell migration as major load-induced biological process with similar stimulation of common (Fosl1, Itgα5, Timp1, and Ngf) as well as novel mechano-regulated genes (Inhba and Dhrs9). Remarkably, only Ext1-hypomorphic cartilage responded to loading by an expression signature of negative regulation of apoptosis with pro-apoptotic Bnip3 being selectively down-regulated. HS-deficiency enhanced BMP-sensitivity, GAG-production and fostered an anti-apoptotic expression signature after loading, all of which may protect cartilage from load-induced erosion.

scholarly journals Investigation of the biological activity, mechanical properties and wound healing application of a novel scaffold based on lignin–agarose hydrogel and silk fibroin embedded zinc chromite nanoparticles

RSC Advances ◽  
2021 ◽  
Vol 11 (29) ◽  
pp. 17914-17923
Author(s):  
Reza Eivazzadeh-Keihan ◽  
Hooman Aghamirza Moghim Aliabadi ◽  
Fateme Radinekiyan ◽  
Mohammad Sobhani ◽  
Farzane khalili ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Wound Healing ◽  
Biological Activity ◽  
Silk Fibroin ◽  
Agarose Hydrogel ◽  
Novel Scaffold ◽  
Fibroin Solution ◽  
Zinc Chromite

Given the important aspects of wound healing approaches, in this work, an innovative biocompatible nanobiocomposite scaffold was designed and prepared based on cross-linked lignin–agarose hydrogel, extracted silk fibroin solution, and zinc chromite (ZnCr2O4) nanoparticles.

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