Chondrocyte Attachment Research Articles

Controlled degradation and kinetics response in calcium silicate doped with sodium alginate/functionalized multi-walled carbon nanotube composite 3D scaffolds for cartilage regeneration

Development of bio-mimetic scaffolds with controlled degradation is a key research area in cartilage regeneration. Therefore, novel scaffold composites and favorable techniques to fabricate essential 3D scaffolds are crucial. In this investigation, we achieved controlled biodegradation of composite scaffolds by incorporating calcium silicate (CS) into sodium alginate (SA)/functionalized with multi-walled carbon nanotubes (f-MWCNT). The SA/f-MWCNT and scaffolds with various amounts of CS (5, 10, and 15%) were shown to enhance scaffold properties. We conducted analyses of the composites using X-ray diffraction and scanning electron microscopy. The findings indicated that CS was successfully loaded onto SA/f-MWCNT, and after inclusion the CS crystal structure remained unaltered. We also evaluated the composites using differential scanning calorimetry, and we determined the mechanical strength, swelling, porosity, degradation, and pH properties. The 15% CS-SA/f-MWCNT scaffolds demonstrated improved mechanical properties, controlled degradation and swelling ratio, increased material density, and strengthened bonds that resulted in a more compact structure and better control of porosity. Furthermore, kinetic investigations of the composite scaffolds to potentially absorb water could be accurately modeled using the pseudo-first-order, pseudo-second-order, Elovich, and diffusion kinetic models. The gradual water absorption rate observed in 15% CS-SA/f-MWCNT could be attributed to controlled intraparticle and micropore diffusion. Further biocompatibility studies showed that the scaffold encouraged chondrocyte attachment, spreading, and division. Additionally, collagen deposition and biomineralization of the 15% CS-SA/f-MWCNT scaffolds were slightly higher compared to the SA/f-MWCNT, 5% CS-SA/f-MWCNT, and 10% CS-SA/f-MWCNT scaffolds. The results indicated that the 15% CS-SA/f-MWCNT fabricated scaffolds are the most suitable for cartilage regeneration.

Hydrogel Based on Chitosan/Gelatin/Poly(Vinyl Alcohol) for In Vitro Human Auricular Chondrocyte Culture.

Three-dimensional (3D) hydrogels provide tissue-like complexities and allow for the spatial orientation of cells, leading to more realistic cellular responses in pathophysiological environments. There is a growing interest in developing multifunctional hydrogels using ternary mixtures for biomedical applications. This study examined the biocompatibility and suitability of human auricular chondrocytes from microtia cultured onto steam-sterilized 3D Chitosan/Gelatin/Poly(Vinyl Alcohol) (CS/Gel/PVA) hydrogels as scaffolds for tissue engineering applications. Hydrogels were prepared in a polymer ratio (1:1:1) through freezing/thawing and freeze-drying and were sterilized by autoclaving. The macrostructure of the resulting hydrogels was investigated by scanning electron microscopy (SEM), showing a heterogeneous macroporous structure with a pore size between 50 and 500 μm. Fourier-transform infrared (FTIR) spectra showed that the three polymers interacted through hydrogen bonding between the amino and hydroxyl moieties. The profile of amino acids present in the gelatin and the hydrogel was determined by ultra-performance liquid chromatography (UPLC), suggesting that the majority of amino acids interacted during the formation of the hydrogel. The cytocompatibility, viability, cell growth and formation of extracellular matrix (ECM) proteins were evaluated to demonstrate the suitability and functionality of the 3D hydrogels for the culture of auricular chondrocytes. The cytocompatibility of the 3D hydrogels was confirmed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, reaching 100% viability after 72 h. Chondrocyte viability showed a high affinity of chondrocytes for the hydrogel after 14 days, using the Live/Dead assay. The chondrocyte attachment onto the 3D hydrogels and the formation of an ECM were observed using SEM. Immunofluorescence confirmed the expression of elastin, aggrecan and type II collagen, three of the main components found in an elastic cartilage extracellular matrix. These results demonstrate the suitability and functionality of a CS/Gel/PVA hydrogel as a 3D support for the auricular chondrocytes culture, suggesting that these hydrogels are a potential biomaterial for cartilage tissue engineering applications, aimed at the regeneration of elastic cartilage.

Feasibility study on intact human umbilical cord Wharton’s jelly as a scaffold for human autologous chondrocyte: In-vitro study

Placental tissue is an established biomaterial used in many clinical applications. However, its use for tissue engineering purposes has not been fully realized. Though articular cartilage extracellular matrix (ECM)-derived oriented scaffolds for cartilage tissue engineering were developed, resources are a hindrance to its application. In this regard, the present study investigated the feasibility of using intact decellularized human umbilical cord Wharton's jelly (hUC-WJ) as a new material for chondrocyte carrier in cartilage tissue engineering. The developed hUC-WJ scaffold provides a good microenvironment for the attachment, viability, and delivery of seeded human autologous chondrocytes. It has an advantage over other biomaterials in terms of abundant availability and similar biochemistry to cartilage ECM. hUC-WJ obtained from fresh human placenta were decellularized and gamma sterilized. Human cartilage tissue was obtained from the patients with a total knee replacement. The chondrocytes were isolated and expanded in-vitro and seeded onto the hUC-WJ scaffold. The efficiency of the decellularized tissue as a delivery system for human cartilage cells was investigated by histology, immunohistochemistry, cell count, flow cytometry, and scanning electron microscopy (SEM). The results showed that the decellularized hUC-WJ scaffold has supported the microenvironment for chondrocyte attachment and viability without losing its phenotype. In addition, the cells were spread through the hUC-WJ scaffold as confirmed by histology and SEM. Based on obtained results, the hUC-WJ scaffold has great potential as a 3D scaffold for human autologous chondrocyte carriers in tissue engineering and regenerative medicine applications.

Dendrimer as a momentous tool in tissue engineering and regenerative medicine

Dendrimers have been comprehensively used for cargo delivery, nucleic acid delivery (genes, miRNA/siRNAs), delivery of macromolecules, and other various biomedical applications. Dendrimers are highly versatile in function and can be engineered as multifunctional biomacromolecules by modifying the surface for fulfilling different applications. Dendrimers are being used for crosslinking of existing synthetic and natural polymeric scaffolds to regulate their binding efficiency, stiffness, biocompatibility, transfection, and many other properties to mimic the in vivo extracellular matrix in tissue engineering and regenerative medicine (TERM). Dendritic inter-cellular linkers can enhance the linkages between cells and result in scaffold-independent tissue constructs. Effectively engineered dendrimers are the ideal molecules for delivering bioactive molecules such as cytokines, chemokines, growth factors, etc., and other metabolites for efficaciously regulating cell behavior. Dendrimeric nanostructures have shown tremendous results in various TERM fields like stem cells survival, osteogenesis, increased crosslinking for eye and corneal repair, and proliferation in cartilage. This review highlights the role and various aspects of dendritic polymers for TERM in general and with respect to specific tissues. This review also covers novel explorations and insights into the use of dendrimers in TERM, focusing on the developments in the past decade and perspective of the future.

Characterization and In Vitro Cytotoxicity Safety Screening of Fractionated Organosolv Lignin on Diverse Primary Human Cell Types Commonly Used in Tissue Engineering.

Simple SummaryAs global efforts to use eco-friendly and reusable materials increase, the use of lignin from waste biomass will continue to intensify. Lignin is an underutilized biowaste macromolecule that is gaining considerable interest in biomedical research. However, the source of lignin and the extraction process heavily influence its chemistry, which can influence a cell’s reaction to lignin. Organosolv lignin is extracted via an eco-friendly process from leftover waste material. Few studies have tested the biocompatibility of organosolv lignins with human cells. We extensively characterized fractionated organosolv lignin and performed in vitro cytotoxicity safety screening on diverse primary human cell types commonly used in tissue engineering. This is the first study to show that, at a balanced concentration, fractionated low MW beechwood-derived organosolv lignin is non-cytotoxic to highly relevant human cell types used in tissue engineering including human bone marrow-derived mesenchymal stromal cells (MSCs), chondrocytes, osteoblasts, periodontal ligament fibroblasts, gingival fibroblasts and keratinocytes. Additionally, we show that organosolv lignin can be used to fabricate cell scaffolds and that addition of lignin increased the stiffness and viscosity of the scaffolds as well as cell attachment. This suggests that organosolv lignin may be used in the generation of tissue-like biomaterial-based constructs for tissue repair.There is limited data assessing the cytotoxic effects of organosolv lignin with cells commonly used in tissue engineering. Structural and physico-chemical characterization of fractionated organosolv lignin showed that a decrease of the molecular weight (MW) is accompanied by a less branched conformation of the phenolic biopolymer (higher S/G ratio) and an increased number of aliphatic hydroxyl functionalities. Enabling stronger polymer−solvent interactions, as proven by the Hansen solubility parameter analysis, low MW organosolv lignin (2543 g/mol) is considered to be compatible with common biomaterials. Using low MW lignin, high cell viability (70–100%) was achieved after 2 h, 24 h and 7 days using the following lignin concentrations: MSCs and osteoblasts (0.02 mg/mL), gingival fibroblasts and keratinocytes (0.02 to 0.04 mg/mL), periodontal ligament fibroblasts and chondrocytes (0.02 to 0.08 mg/mL). Cell viability was reduced at higher concentrations, indicating that high concentrations are cytotoxic. Higher cell viability was attained using 30/70 (w/v) NaOH vs. 40/60 (w/v) EtOH as the initial lignin solvent. Hydrogels containing low MW lignin (0.02 to 0.3 mg/mL) in agarose dose-dependently increased chondrocyte attachment (cell viability 84–100%) and hydrogel viscosity and stiffness to 3–11 kPa, similar to the pericellular matrix of chondrocytes. This suggests that low MW organosolv lignin may be used in many tissue engineering fields.

Selected physico-chemical properties of composite scaffolds of sintered submicrocrystalline corundum and bioglass

Presented paper contains description and interpretation of the results of selected physicochemical and structural properties of two types of composite sinters. They were constituted of a mixture of sintered microcrystalline corundum and bioglass CaO-P2O5-SiO2-Na2O system intended for scaffolds to cell culture of human chondrocytes. The composites contained a mixture of both above-mentioned components in the volumetric proportion of 50:50 (W5) and 30:70 (W7). They were obtained using powder metallurgy by free sintering in air atmosphere. Phase analysis of composites and verification of theoretical identification using X-ray diffraction were performed. The same phases were found in both cases (Al2O3 SiO2 CaAl2Si2O8, Ca3 (PO4)2, Ca2Al4O7 and NaAlSiO4). Microscopic tests of composite surfaces were performed and some differences were found. W5 sample was not completely covered with bioglass, whilst W7 sample was completely covered with bioglass with few fine pores. Tests of surface topography confirmed the presence of large and small pores. Composite surfaces immersed for 30 days in artificial blood plasma were tested and then electron microscopy analysis was performed. It was found that no significant changes occurred on the surface of the W5 composite, probably partial corrosion of the glass happened. Spherical forms characteristic of HA-hydroxyapatites were observed on the surface of sample W7. Human articular chondrocyte cells were seeded on both types of sinters and proliferation assay was performed. Results indicate that tested scaffolds support cellular attachment and proliferation of chondrocytes.

Comparison of Poly(Lactic-Co-Glycolic Acid) and Poly(Lactic-Co-Glycolic Acid)/Hyaluronic Acid Based Scaffolds for Chondrogenesis of Human Adipose-derived Stem Cells by Avocado/Soybean Unsaponifiables

Background: Corporation of Hyaluronic acid (HA) with PLGA is an effective way to potentially enhance chondrogenesis. The aim of this study was to use HA macroporous biodegradable poly(lactic acid-co-glycolic acid) [PLGA] scaffold to enhance the attachment, proliferation and differentiation of chondrocytes for cartilage tissue engineering and articular cartilage regeneration of human adipose derived stem cells (hADSCs) in the presence of avocado/soybean unsaponifible (ASU).Methods: The PLGA and PLGA/HA scaffolds were prepared and hADSCs were cultured separately on the scaffolds and 14 days after differentiation, chondrogenic genes in each scaffold evaluated using real time PCR and cell viability examined by (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay.Results: The viability and proliferation of cells in-group of PLGA significantly decreased in comparison with the control (P=0.002) and PLGA/HA (P=0.013) groups.The expression of (SOX9), Aggrecan (AGG), and Collagen type II (Col II) genes was significantly higher in the PLGA and PLGA/HA groups compared to the control group (P≥0.05).The gene expression of SOX9 (P=0.003) and AGG (P=0.009) was significantly higher in the PLGA/HA groups compared to the PLGA group. The results of real time PCR showed that collagen type X (Col X) gene expression in the PLGA group, was significantly higher than the control and PLGA/HA groups (P=0.000).Conclusion: The corporation of HA with PLGA is an effective way to potentially enhance chondrogenesis and articular cartilage regeneration of hADSCs in the presence of avocado/soybean unsaponifiables (ASU).

Extracellular matrix imitation utilizing nanofibers-embedded biomimetic scaffolds for facilitating cartilage regeneration

Repair of cartilage legions remains a big challenge for clinicians due to the limit self-regeneration ability of cartilage. A SF-based scaffold that reinforced by the SF–chitin hybrid nanofibers and impregnated with TGF-β1 is developed to mimic extracellular matrix and facilitate cartilage regeneration. The composite scaffold with an excellent biocompatibility exhibited the suitable elasticity and hardness after incorporation of the SF–chitin hybrid nanofibers. The attachment and proliferation of chondrocytes was also improved by a rough morphology created by the SF–chitin hybrid nanofibers. As a chondrogenic growth factor, TGF-β1 was incorporated into the composite scaffold and modulated the performance of scaffolds by inducing cells homing. In the treatment of rat cartilaginous defects, the SF–chitin hybrid nanofiber-functionalized composite scaffold loaded with TGF-β1 remarkably accelerated the cartilage regeneration. Thus, the SF–chitin hybrid nanofiber/TGF-β1-functionalized scaffold fabricated in this study promotes the adhesion and proliferation of chondrocytes in vitro, and cartilage regeneration in vivo, thus offering a suitable strategy for the repair of cartilage defects.

Integrational Technologies for the Development of Three-Dimensional Scaffolds as Platforms in Cartilage Tissue Engineering.

The prevalence of osteoarthritis is on the rise, and an effective treatment for cartilage defects is still being sought. Cartilage tissue in vivo encompasses complex structures and composition, both of which influence cells and many properties of the native cartilage. The extracellular matrix structure and components provides both morphological cues and the necessary signals to promote cell functions including metabolism, proliferation, and differentiation. In the present study, cryo-printing and electrospinning were combined to produce multizone scaffolds that consist of three distinctive zones. These scaffolds successfully mimic the collagen fiber orientation of the native cartilage. Moreover, in vitro analysis of chondrocyte-seeded scaffolds demonstrated the ability of multizone scaffolds to support long-term chondrocyte attachment and survival over a 5 week culture period. Moreover, multizone scaffolds were found to regulate the expression of key genes in comparison to the controls and allowed the detection of sulfated glycosaminoglycan. Evaluation of the compressive properties revealed that the multizone scaffolds possess more suitable mechanical properties, for the native cartilage, in comparison to the electrospun and phase-separated controls. Multizone scaffolds provide viable initial platforms that capture the complex structure and compressive properties of the native cartilage. They also maintain chondrocyte phenotype and function, highlighting their potential in cartilage tissue engineering applications.

Evaluation of the effects of β-tricalcium phosphate on physical, mechanical and biological properties of Poly (3-hydroxybutyrate)/chitosan electrospun scaffold for cartilage tissue engineering applications

ABSTRACTScaffold designing for cartilage tissue engineering requires suitable physico-mechanical and biological properties. This research was carried out to study the effects of β-tricalcium phosphate nanoparticles (β-TCP) on Poly (3-hydroxybutyrate) (PHB)-chitosan (Cs) electrospun scaffold. Results showed that the addition of different amounts of β-TCP increased fibre diameter, porosity, hydrophilicity and tensile strength in the proper condition. An increase in the degradation rate was observed by an increase in the amount of β-TCP. The biological behaviour of the PHB-Cs/7.5%wt β-TCP electrospun nanocomposite scaffold was investigated through the formation of apatite-like granules and proper attachment and proliferation of chondrocytes on the surface of scaffolds.

Evaluation of physical, mechanical and biological properties of poly 3-hydroxybutyrate-chitosan-multiwalled carbon nanotube/silk nano-micro composite scaffold for cartilage tissue engineering applications.

Nano-micro scaffolds are developed for long-term healing tissue engineering like cartilage. The poly 3-hydroxybutyrate (P3HB)-chitosan/silk and P3HB-chitosan-1 wt% multi-walled carbon nanotubes functionalized by COOH (MWNTs)/silk nano-micro scaffolds are fabricated through electrospinning the solution on a knitted silk which is saturated (S) or unsaturated (U) with P3HB as a mediator to enhance the interaction at nano/microinterface. Consuming MWNTs lead to a decrease in fiber diameter, while an increase in specific surface area, tensile strength and bioactivity properties. The saturation condition as well as MWNTs leads to intensification in the hydrophilicity properties. The nanolayer in all scaffolds lead to an increase in tensile strength in comparison with the pure knitted silk. The scaffold containing MWNTs showed slower degradation rate. MWNTs beside the chitosan and silk provide an appropriate environment for attachment and growth of chondrocytes. The P3HB-chitosan-MWNTs/silk (S) nano-microscaffold can be appropriate for a long-term tissue engineering application like cartilage.

Aligned porous fibrous membrane with a biomimetic surface to accelerate cartilage regeneration

Due to the poor self-regenerative capacity of native cartilage, the treatment of articular cartilage defects is a significant clinical challenge. The cartilage tissue engineered scaffolds with high chondrogenic capacity might provide an efficient strategy for the repair of cartilage defects. Herein, we report an aligned porous poly (l-lactic acid) (PLLA) electrospun fibrous membrane with a biomimetic surface for the rapid regeneration of cartilage tissue. The PLLA electrospun fibers aligned in a single direction and generated ellipse-shaped nanopores in situ onto the surface of the fibers. Subsequently, chondroitin sulfate (CS) was coated on the surface of the fibers using polydopamine (PDA) as an adhesive polymeric bridge. The in vitro results revealed that the aligned porous composite membranes with a biomimetic surface (PL/PDA/CS) could stimulate the attachment and proliferation of chondrocytes and rabbit bone marrow mesenchymal stem cells (rBMSCs), as well as inducing chondrogenic gene expression in rBMSCs. Furthermore, the PL/PDA/CS membranes significantly facilitated the filling of defects and the regeneration of hyaline cartilage-like tissue in vivo. The results suggested that the hierarchical aligned porous fibrous electrospun membrane with a biomimetic surface modification is a potential therapeutic strategy for highly efficient cartilage defect repair.

The chondrocyte cell proliferation of a chitosan/silk fibroin/egg shell membrane hydrogels

Articular cartilage is a poorly cellularized, non-vascularized connective tissue that undergoes alterations due to trauma and osteoarthritis. Tissue engineering strategies involving the combination of cells, biomaterials and bioactive agents have been of interest notably for the repair of damaged articular cartilage. The aim of this study was to design Chitosan/Silk Fibroin/Egg Shell Membrane (CHI/SF/ESM) hydrogels and analyse the cell proliferation activity of human chondrocyte cells. The FTIR spectrophotometer, XRD analysis, ICP-MS, SEM analysis, swelling kinetics and biodegradation tests with protease enzyme, and antibacterial activity test with Escherichia coli, Candida albicans have been used for characterization of hydrogels. CHI/SF/ESM hydrogel structures, and chemical homogeneity of the ECM was well-reproduced. Human articular chondrocytes were seeded on hydrogels and cultured up to 2 weeks under the standard culture conditions. The attachment and cell growth of chondrocytes were examined by phase contrast microscopy and by MTT assay at 24 h, 72 h and 7 days. The hydrogel supported better adhesion, growth and differentiation of chondrocyte cells under standard culture conditions. The results obtained have suggested that, CHI/SF/ESM hydrogels can potentially function as a promising cartilage substitute for tissue engineering application.

Advanced Silk Fibroin Biomaterials for Cartilage Regeneration.

Silk fibroin is regarded as a natural fibrous protein with tunable mechanical properties, acceptable biocompatibility, and favorable capability of enhancing attachment, proliferation, and differentiation of chondrocytes. These properties make it suitable for the fabrication of scaffolds and a broad range of silk fibroin-based biomaterials for cartilage regenerative therapy, which can heal functional cartilage without scar tissue. It can be used as a single material for making different kinds of scaffolds or as a composite with other types of biomaterials. Together with some growth factors, silk fibroin scaffolds can form a support for the growth and differentiation of seeding cells, such as chondrogenic lineage cells and mesenchymal stem cells. Recent advancements of silk fibroin in cartilage regeneration are summarized in this review. Furthermore, the manufacturing methods of silk fibroin materials and their applications in the regeneration of cartilage are also discussed.

Chondrocyte Attachment, Proliferation, and Differentiation on Three-Dimensional Polycaprolactone Fumarate Scaffolds.

Current treatment options for cartilage injuries are limited. The goals of this study are to create a biodegradable polymer scaffold with the capabilities of sustaining chondrocyte growth and proliferation, enable cell-to-cell communication and tissue regeneration through large pores, and assess the biological augmentation of the scaffold capabilities using platelet lysate (PL). We synthesized biodegradable polycaprolactone fumarate (PCLF) scaffolds to allow cell-cell communication through large interconnected pores. Molds were printed using a three-dimensional printer and scaffolds synthesized through UV crosslinking. Culture medium included alpha modified Eagle's media with either 10% fetal bovine serum (FBS) or 5% PL, a mixture of platelet release products, after being seeded onto scaffolds through a dynamic bioreactor. Assays included cellular proliferation (MTS), toxicity and viability (live/dead immunostaining), differentiation (glycosaminoglycan [GAG], alkaline phosphatase [ALP], and total collagen), and immunostaining for chondrogenic markers collagen II and Sox 9 (with collagen I as a negative control). The large interconnected pores (500 and 750 μm) enable cell-to-cell communication and cellular infiltration into the scaffolds, as the cells remained viable and proliferated for 2 weeks. Chondrocytes cultured in PL showed increased rates of proliferation when compared with FBS. The chondrogenic markers GAG and total collagen contents increased over 2 weeks at each time point, whereas the osteogenic marker ALP did not significantly change. Immunostaining at 2 and 4 weeks for the expression of chondrogenic markers Collagen II and Sox 9 was increased when compared with control human fibroblasts. These results show that the PCLF polymer scaffold enables chondrocytes to attach, proliferate, and retain their chondrogenic phenotypes, demonstrating potential in chondrocyte engineering and cartilage regeneration.

A Dual-Bonded Approach for Improving Hydrogel Implant Stability in Cartilage Defects.

Integration and stability of hydrogels and surrounding cartilage/bone tissue is crucial for both immediate functionality and long-term performance of the tissue. In this work, chondroitin sulphate (CS) a polysaccharide found in cartilage and other tissues was used to synthesize a tough hydrogel that was chemically functionalized with methacrylate and aldehyde groups, bonding to surrounding tissue via a dual-bonded approach. The hydrogel can not only chemically anchor onto implanted titanium at the subchondral bone, but also on cartilage tissue via the Schiff-base reaction. In vitro experiments confirmed that the strategy improved hydrogel implant stability with cartilage tissue, was favorable for chondrocyte attachment, and has the potential to quickly and effectively repair cartilage defects and maintain joint functionality for a long time.

A Novel Cross-Linked Hyaluronic Acid Porous Scaffold for Cartilage Repair: An In Vitro Study With Osteoarthritic Chondrocytes.

An important feature of biomaterials used in cartilage regeneration is their influence on the establishment and stabilization of a chondrocytic phenotype of embedded cells. The purpose of this study was to examine the effects of a porous 3-dimensional scaffold made of cross-linked hyaluronic acid on the expression and synthesis performance of human articular chondrocytes. Osteoarthritic chondrocytes from 5 patients with a mean age of 74 years were passaged twice and cultured within the cross-linked hyaluronic acid scaffolds for 2 weeks. Analyses were performed at 3 different time points. For estimation of cell content within the scaffold, DNA-content (CyQuant cell proliferation assay) was determined. The expression of chondrocyte-specific genes by embedded cells as well as the total amount of sulfated glycosaminoglycans produced during the culture period was analyzed in order to characterize the synthesis performance and differentiation status of the cells. Cells showed a homogenous distribution within the scaffold. DNA quantification revealed a reduction of the cell number. This might be attributed to loss of cells from the scaffold during media exchange connected with a stop in cell proliferation. Indeed, the expression of cartilage-specific genes and the production of sulfated glycosaminoglycans were increased and the differentiation index was clearly improved. These results suggest that the attachment of osteoarthritic P2 chondrocytes to the investigated material enhanced the chondrogenic phenotype as well as promoted the retention.

Ionic solutes impact collagen scaffold bioactivity.

The structure of ice-templated collagen scaffolds is sensitive to many factors. By adding 0.5 wt% of sodium chloride or sucrose to collagen slurries, scaffold structure could be tuned through changes in ice growth kinetics and interactions of the solute and collagen. With ionic solutes (sodium chloride) the entanglements of the collagen molecule decreased, leading to fibrous scaffolds with increased pore size and decreased attachment of chondrocytes. With non-ionic solutes (sucrose) ice growth was slowed, leading to significantly reduced pore size and up-regulated cell attachment. This highlights the large changes in structure and biological function stimulated by solutes in ice-templating systems.Graphical

Chondrogenesis of human bone marrow mesenchymal stromal cells in highly porous alginate-foams supplemented with chondroitin sulfate.

To overcome the limited intrinsic cartilage repair, autologous chondrocyte or bone-marrow-derived mesenchymal stromal cell (BM-MSC) was implanted into cartilage defects. For this purpose suitable biocompatible scaffolds are needed to provide cell retention, chondrogenesis and initial mechanical stability. The present study should indicate whether a recently developed highly porous alginate (Alg) foam scaffold supplemented with chondroitin sulfate (CS) allows the attachment, survival and chondrogenesis of BM-MSCs and articular chondrocytes. The foams were prepared using a freeze-drying method; some of them were supplemented with CS and subsequently characterized for porosity, biodegradation and mechanical profile. BM-MSCs were cultured for 1-2 weeks on the scaffold either under chondrogenic or maintenance conditions. Cell vitality assays, histology, glycosaminoglycan (sGAG) assay, and type II and I collagen immunolabelings were performed to monitor cell growth and extracellular matrix (ECM) synthesis in the scaffolds. Scaffolds had a high porosity ~93-95% with a mean pore sizes of 237±48 μm (Alg) and 197±61 μm (Alg/CS). Incorporation of CS increased mechanical strength of the foams providing gradually CS release over 7 days. Most of the cells survived in the scaffolds. BM-MSCs and articular chondrocytes formed rounded clusters within the scaffold pores. The BM-MSCs, irrespective of whether cultured under non/chondrogenic conditions and chondrocytes produced an ECM containing sGAGs, and types II and I collagen. Total collagen and sGAG contents were higher in differentiated BM-MSC cultures supplemented with CS than in CS-free foams after 14 days. The cell cluster formation induced by the scaffolds might stimulate chondrogenesis via initial intense cell-cell contacts.

Silk fibroin‐chondroitin sulfate‐alginate porous scaffolds: Structural properties and in vitro studies

ABSTRACTThe development of porous biodegradable scaffolds is of great interest in tissue engineering. In this regard, exploration of novel biocompatible materials is needed. Silk fibroin‐chondroitin sulfate‐sodium alginate (SF‐CHS‐SA) porous hybrid scaffolds were successfully prepared via lyophilization method and crosslinked by 1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide‐ethanol treatment. According to the scanning electron microscopy studies, mean pore diameters of the scaffolds were in the range of 60–187 μm. The porosity percentage of the scaffold with SF‐CHS‐SA ratio of 70 : 15 : 15 (w/w/w %) was 92.4 ± 3%. Attenuated total reflectance Fourier transform infrared spectroscopy, X‐ray diffraction, and differential scanning calorimetry results confirmed the transition from amorphous random coil to crystalline β‐sheet in treated SF‐CHS‐SA scaffold. Compressive modulus was significantly improved in hybrid scaffold with SF‐CHS‐SA ratio of 70 : 15 : 15 (3.35 ± 0.15 MPa). Cytotoxicity assay showed that the scaffolds have no toxic effects on chondrocytes. Attachment of chondrocytes was much more improved within the SF‐CHS‐SA hybrid scaffold. Real‐time polymerase chain reaction analyses showed a significant increase in gene expression of collagen type II, aggrecan, and SOX9 and decrease in gene expression of collagen type I for SF‐CHS‐SA compared with SF scaffold. This novel hybrid scaffold can be a good candidate to be utilized as an efficient scaffold for cartilage tissue engineering. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41048.