Synergistic Effect of TGF-β1 And BMP-7 on Chondrogenesis and Extracellular Matrix Synthesis: An In Vitro Study

Comparison of multiple synthetic chondroinductive factors in pellet culture against a TGF-β positive control

Despite the advances in surgical and cell therapy regenerative techniques for cartilage repair, the challenge is to overcome an inferior fibrocartilage repair tissue. In vitro, TGF-β1 and TGF-β3 are the primary growth factors employed to induce chondrogenic differentiation. However, the clinical application of native proteins may present challenges regarding stability, cost, or reproducibility. Therefore, there remains an unmet clinical need for the identification of small chondroinductive synthetic molecules. From the literature, two peptides-CM10 and CK2.1-appear to be promising candidates; however, they have not been directly compared to TGF-β with human bone marrow-derived stem cells (hBMSCs). Similarly, two promising compounds-kartogenin and SM04690-have been reported in the literature to exhibit chondroinductive potential in vivo and in vitro; however, kartogenin was not directly compared against TGF-β. In the current study, we evaluated the chondroinductive potential of CM10, CK2.1, kartogenin, and SM04690, and directly compared them to each other and to a TGF-β3 positive control. Following 21 days of culture, none of the evaluated chondrogenic factors, either individually or even in combinations of two, resulted in a higher gene expression of chondrogenic markers as compared to TGF-β3. Additionally, no collagen II gene expression was detected except in the TGF-β3 positive control group. Given that the evaluated factors have confirmed efficacy in the literature, but not in the current study with a positive control, there may be value in the future identification of new chondroinductive factors that are less situation-dependent, with rigorous evaluations of their effect on chondrogenesis using positive controls.

The Influence of Race/Ethnicity on the Transcriptomic Landscape of Uterine Fibroids

The objective of this study was to determine if the aberrant expression of select genes could form the basis for the racial disparity in fibroid characteristics. The next-generation RNA sequencing results were analyzed as fold change [leiomyomas/paired myometrium, also known as differential expression (DF)], comparing specimens from White (n = 7) and Black (n = 12) patients. The analysis indicated that 95 genes were minimally changed in tumors from White (DF ≈ 1) but were significantly altered by more than 1.5-fold (up or down) in Black patients. Twenty-one novel genes were selected for confirmation in 69 paired fibroids by qRT-PCR. Among these 21, coding of transcripts for the differential expression of FRAT2, SOX4, TNFRSF19, ACP7, GRIP1, IRS4, PLEKHG4B, PGR, COL24A1, KRT17, MMP17, SLN, CCDC177, FUT2, MYO5B, MYOG, ZNF703, CDC25A, and CDCA7 was significantly higher, while the expression of DAB2 and CAV2 was significantly lower in tumors from Black or Hispanic patients compared with tumors from White patients. Western blot analysis revealed a greater differential expression of PGR-A and total progesterone (PGR-A and PGR-B) in tumors from Black compared with tumors from White patients. Collectively, we identified a set of genes uniquely expressed in a race/ethnicity-dependent manner, which could form the underlying mechanisms for the racial disparity in fibroids and their associated symptoms.

Self-assembling peptides with hBMP7 biological activity promote the differentiation of ADSCs into nucleus pulposus-like cells

Functionalized self-assembling peptides, which display functional growth-factor bioactivity, can be designed by connecting the C-terminus of a pure self-assembling peptide with a short functional motif. In this study, we designed a novel functionalized peptide (RADA16-SNVI) in which an SNVI motif with hBMP-7 activity was conjugated onto the C-terminus of the RADA16 peptide via solid-phase synthesis. A mix of RADA16-SNVI and RADA16 solutions was used to create a functionalized peptide nanofiber scaffold (SNVI-RADA16). The hydrogels were analyzed by atomic force microscopy, circular dichroism, and scanning electron microscopy. The results showed that the SNVI-RADA16 solution effectively formed hydrogel. Next, we seeded the SNVI-RADA16 scaffold with adipose-derived stem cells (ADSCs) and investigated whether it displayed biological properties of nucleus pulposus tissue. SNVI-RADA16 displayed good biocompatibility with the ADSCs and induced their expression. Cells in SNVI-RADA16 gel had a greater secretion of the extracellular matrix marker collagen type II and aggrecan compared to ADSCs grown in monolayer and control gel (p < 0.05). The ratio of the aggrecan to collagen in cells in SNVI-RADA16 gel is approximately 29:1 after culture for 21 days. ADSCs in SNVI-RADA16 gels expressed the hypoxia-inducible factor 1α(HIF-1α) mRNA by real-time PCR. However, HIF-1 mRNA is absence in control gel and monolayer. The results suggested that the functionalized self-assembled peptide promotes the differentiation of ADSCs into nucleus pulposus-like cells. Thus, the designed SNVI-RADA16 self-assembling peptide hydrogel scaffolds may be suitable for application in nucleus pulposus tissue regeneration.

Gradient scaffold with spatial growth factor profile for osteochondral interface engineering

Osteochondral (OC) matrix design poses a significant engineering challenge due to the complexity involved with bone-cartilage interfaces. To better facilitate the regeneration of OC tissue, we developed and evaluated a biodegradable matrix with uniquely arranged bone and cartilage supporting phases: a poly(lactic-co-glycolic) acid (PLGA) template structure with a porosity gradient along its longitudinal axis uniquely integrated with hyaluronic acid hydrogel. Micro-CT scanning and imaging confirmed the formation of an inverse gradient matrix. Hydroxyapatite was added to the PLGA template which was then plasma-treated to increase hydrophilicity and growth factor affinity. An osteogenic growth factor (bone morphogenetic protein 2; BMP-2) was loaded onto the template scaffold via adsorption, while a chondrogenic growth factor (transforming growth factor beta 1; TGF-β1) was incorporated into the hydrogel phase. Confocal microscopy of the growth factor loaded matrix confirmed the spatial distribution of the two growth factors, with chondrogenic factor confined to the cartilaginous portion and osteogenic factor present throughout the scaffold. We observed spatial differentiation of human mesenchymal stem cells (hMSCs) into cartilage and bone cells in the scaffolds in vitro: cartilaginous regions were marked by increased glycosaminoglycan production, and osteogenesis was seen throughout the graft by alizarin red staining. In a dose-dependent study of BMP-2, hMSC pellet cultures with TGF-β1 and BMP-2 showed synergistic effects on chondrogenesis. These results indicate that development of an inverse gradient matrix can spatially distribute two different growth factors to facilitate chondrogenesis and osteogenesis along different portions of a scaffold, which are key steps needed for formation of an osteochondral interface.

Effect of dose and release rate of CTGF and TGFβ3 on avascular meniscus healing

Meniscus tears in the avascular region rarely functionally heal due to poor intrinsic healing capacity, frequently resulting in tear propagation, followed by meniscus deterioration. Recently, we have reported that time-controlled application of connective tissue growth factor (CTGF) and transforming tissue growth factor β3 (TGFβ3) significantly improved healing of avascular meniscus tears by inducing recruitment and step-wise fibrocartilaginous differentiation of mesenchymal stem/progenitor cells (MSCs). In this study, we investigated effects of the dose of CTGF and the release rate of TGFβ3 on avascular meniscus healing in our existing explant model. Our hypothesis was that dose and release rate of CTGF and TGFβ3 are contributing factors for functional outcome in avascular meniscus healing by stem cell recruitment. Low (100 ng/ml) and high (1,000 ng/ml) doses of CTGF as well as fast (0.46 ± 0.2 ng/day) and slow (0.29 ± 0.1 ng/day) release rates of TGFβ3 were applied to our established meniscus explant model for meniscus tears in the inner-third avascular region. The release rate of TGFβ3 was controlled by varying compositions of poly(lactic-co-glycolic acids) (PLGA) microspheres. The meniscus explants were then cultured for 8 weeks on top of mesenchymal stem/progenitor cells (MSCs). Among the tested combinations, we found that a high CTGF dose and slow TGFβ3 release are most effective for integrated healing of avascular meniscus, demonstrating improvements in alignment of collagen fibers, fibrocartilaginous matrix elaboration and mechanical properties. This study may represent an important step toward the development of a regenerative therapy to improve healing of avascular meniscus tears by stem cell recruitment. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1555-1562, 2019.

Progress of co-culture systems in cartilage regeneration

INTRODUCTION

Cartilage tissue engineering has rapidly developed in recent decades, exhibiting promising potential to regenerate and repair cartilage. However, the origin of a large amount of a suitable seed cell source is the major bottleneck for the further clinical application of cartilage tissue engineering. The use of a monoculture of passaged chondrocytes or mesenchymal stem cells results in undesired outcomes, such as fibrocartilage formation and hypertrophy. In the last two decades, co-cultures of chondrocytes and a variety of mesenchymal stem cells have been intensively investigated in vitro and in vivo, shedding light on the perspective of co-culture in cartilage tissue engineering.

AREAS COVERED

We summarize the recent literature on the application of heterologous cell co-culture systems in cartilage tissue engineering and compare the differences between direct and indirect co-culture systems as well as discuss the underlying mechanisms.

EXPERT OPINION

Co-culture system is proven to address many issues encountered by monocultures in cartilage tissue engineering, including reducing the number of chondrocytes needed and alleviating the dedifferentiation of chondrocytes. With the further development and knowledge of biomaterials, cartilage tissue engineering that combines the co-culture system and advanced biomaterials is expected to solve the difficult problem regarding the regeneration of functional cartilage.

The association between different molecular weights of hyaluronic acid and CHAD, HIF-1α, COL2A1 expression in chondrocyte cultures

The aim of the present study was to investigate the effects of three different formulations of hyaluronic acid (HA): Low molecular weight (MW) Sinovial One^®, medium MW Viscoplus^® and high MW Durolane^®, on chondrocyte proliferation and collagen type II (COL2A1), hypoxia-inducible factor 1α (HIF-1α) and chondroadherin (CHAD) expression in primary chondrocyte cultures. Standard primary chondrocyte cultures were established from osteochondral tissues surgically obtained from 6 patients with gonarthrosis. Cell morphology was evaluated using an inverted light microscope; cell proliferation was determined with a MTT assay and confirmed with acridine orange/propidium iodide staining. Levels of CHAD, COL2A1 and HIF-1α expression were assessed using specific TaqMan gene expression assays. The results demonstrated the positive effect of HA treatment on cell proliferation, which was independent from the MW. COL2A1 expression increased in the medium and high MW HA treated groups. It was observed that HIF-1α expression increased in the high MW treated group alone. CHAD expression increased only in the medium MW HA treated group. Evaluation of gene expression revealed that levels of expression increased as the duration of HA application increased, in the medium and high MW HA treated groups. In terms of increased viability and proliferation, a longer duration of HA application was more effective. Taken together, it may be concluded that the administration of medium and high MW HA may be a successful way of treating diseases affecting chondrocytes in a clinical setting.

Cell-laden hydrogels for osteochondral and cartilage tissue engineering

Despite tremendous advances in the field of regenerative medicine, it still remains challenging to repair the osteochondral interface and full-thickness articular cartilage defects. This inefficiency largely originates from the lack of appropriate tissue-engineered artificial matrices that can replace the damaged regions and promote tissue regeneration. Hydrogels are emerging as a promising class of biomaterials for both soft and hard tissue regeneration. Many critical properties of hydrogels, such as mechanical stiffness, elasticity, water content, bioactivity, and degradation, can be rationally designed and conveniently tuned by proper selection of the material and chemistry. Particularly, advances in the development of cell-laden hydrogels have opened up new possibilities for cell therapy. In this article, we describe the problems encountered in this field and review recent progress in designing cell-hydrogel hybrid constructs for promoting the reestablishment of osteochondral/cartilage tissues. Our focus centers on the effects of hydrogel type, cell type, and growth factor delivery on achieving efficient chondrogenesis and osteogenesis. We give our perspective on developing next-generation matrices with improved physical and biological properties for osteochondral/cartilage tissue engineering. We also highlight recent advances in biomanufacturing technologies (e.g. molding, bioprinting, and assembly) for fabrication of hydrogel-based osteochondral and cartilage constructs with complex compositions and microarchitectures to mimic their native counterparts.

STATEMENT OF SIGNIFICANCE

Despite tremendous advances in the field of regenerative medicine, it still remains challenging to repair the osteochondral interface and full-thickness articular cartilage defects. This inefficiency largely originates from the lack of appropriate tissue-engineered biomaterials that replace the damaged regions and promote tissue regeneration. Cell-laden hydrogel systems have emerged as a promising tissue-engineering platform to address this issue. In this article, we describe the fundamental problems encountered in this field and review recent progress in designing cell-hydrogel constructs for promoting the reestablishment of osteochondral/cartilage tissues. Our focus centers on the effects of hydrogel composition, cell type, and growth factor delivery on achieving efficient chondrogenesis and osteogenesis. We give our perspective on developing next-generation hydrogel/inorganic particle/stem cell hybrid composites with improved physical and biological properties for osteochondral/cartilage tissue engineering. We also highlight recent advances in biomanufacturing and bioengineering technologies (e.g. 3D bioprinting) for fabrication of hydrogel-based osteochondral and cartilage constructs.

Iopromide- and gadopentetic acid-derived preparates used in MR arthrography may be harmful to chondrocytes

Background

Magnetic resonance arthrography, a procedure through which contrast agents containing gadolinium and/or iopromide are administered intra-articularly, has become a useful tool in musculoskeletal diagnosis. Nevertheless, despite being considered safe for systemic use, certain tissue toxicities have been identified for both drugs. In this study, the effects of short-term exposure of human primary chondrocyte cell cultures to gadolinium and/or iopromide contrast agents were examined by assaying for stage-specific embryonic antigen-1 (SSEA-1) protein expression (a chondrogenic differentiation marker), cell viability, toxicity, and proliferation.

Methods

Human articular chondrocytes were grown in monolayer culture and were exposed to iopromide and/or gadolinium diethylenetriamine-pentaacetate (Gd-DPT) for 2 and 6 h. Cell cultures with no drug exposure were used as the control group. Cell differentiation status was assessed according to SSEA-1 protein expression. Contrast agent effects on cell viability and proliferation were analyzed using MTT analysis. Further, changes in cell morphology in relation to the control group were evaluated using inverted light microscopy, environmental scanning electron microscopy (ESEM), and 3-tesla magnetic resonance imaging. The obtained data were statistically compared.

Results

When compared with the control group, both SSEA-1 protein expression and cell proliferation were lowest in the Gd-DPT group (P = 0.000). There was a statistically significant correlation between SSEA-1 expression and MTT results (rho = 0.351; P = 0.003).

Conclusions

Nevertheless, the data obtained from in vitro experiments may not directly correspond to clinical applications. However, the mere fact that a drug used solely for diagnostic purposes may repress chondrocyte cell proliferation should be carefully considered by clinicians.

Can a Biodegradable Implanted Bilayered Drug Delivery System Loaded with BMP-2/BMP-12 Take an Effective Role in the Biological Repair Process of Bone-Tendon Injuries? A Preliminary Report

Background

Use of biodegradable and biocompatible materials in the orthopedic surgery is gaining popularity. In this research, the rate of controlled release of a bilayered prototype biomaterial designed to promote osteoblastic and tenoblastic activity was calculated using pharmacochemical methods.

Methods

The first part of the design, composed of a sodium tetraborate, polyvinyl alcohol, and starch based hydrogel, was loaded with bone morphogenic protein-2. The second part which was composed of a sodium tetraborate, polyvinyl alcohol, and chitosan based hydrogel was loaded with bone morphogenic protein-12. Osteochondral and tendon tissue specimens were obtained from patients with a diagnosis of gonarthrosis and primary bone cells and tendon cells cultures were prepared following treatment with collagenase enzyme. Cell samples were collected from the groups by means of an invert light microscope and environmental scanning electron microscope underwent at the 1st and 21st days. The level of osteogenic differentiation was measured by the activity of alkaline phosphatase. For the statistical evaluation of the obtained data, groups were compared with post hoc Tukey test following analysis of variance. Level of significance was accepted to be <0,01.

Results

Both osteogenic and tenogenic stimulation were observed in the cultured specimens. In comparison to the control groups, the rate of proliferation of healthy cells was found to be higher in the groups to which the design was added (p < 0.01).

Conclusions

Our research is a preliminary report that describes a study conducted in an in vitro experimental setting. We believe that such prototype systems may be pioneers in targeted drug therapies after reconstructional surgeries.

Chondrocyte proliferation, viability and differentiation is declined following administration of methylphenidate utilized for the treatment of attention-deficit/hyperactivity disorder

PURPOSE

Methylphenidate (MPH) derivative drugs are used because of psychostimulants effects on attention-deficit hyperactivity disorder in children and adults. As far as we know, toxic or anti-proliferative effects of MPH against cartilage tissue were not studied in the literature. The present study was carried out to investigate the possible effects of MPH on the proliferation, viability and differentiation of primary human chondrocytes, in vitro.

METHODS

Monolayer primary chondrocyte cultures were prepared using osteochondral tissue obtained from patients who underwent a total knee prosthesis operation. Stock solution of MPH was prepared and aliquots having 1-1000 µM concentrations of the drug was composed. These solutions were applied to the wells containing cultured chondrocyte samples within the well plates. Control groups were composed of pure chondrocyte culture and no solution was added into them. All groups were evaluated at 24, 48 and 72 h in order to determine the possible negative effects of the drug on the chondrocytes. The data were evaluated by Tukey's honestly significantly different test following analysis of variance.

RESULTS

In the group where MPH was applied, it was found that viability, proliferation and stage-specific embryonic antigen-1 protein expression were decreased in comparison to the control group.

CONCLUSIONS

It was emphasized that clinicians should not disregard the fact that this drug might suppress chondrocyte cell proliferation and chondrogenic differentiation.

Are We Economically Efficient Enough to Increase the Potential of in Vitro Proliferation of Osteoblasts by Means of Pharmacochemical Agents?

Background:

The aim of this study was to test the necessity of using expensive and unaccesible pharmacological-chemical agents in the proliferation of bone tissue cultures and in the induction of mineralized matrix formation to increase the osteogenic effect.

Methods:

For this purpose, human primary cell cultures were prepared and then divided into two groups. Whereas the cells in group I were fed with an osteoblast stimulator medium containing Dulbecco’s Modified Eagle Medium (DMEM) and β-glycerophosphate, the cells in group II were fed with DMEM containing dexamethasone and 2-phospho-L-ascorbic acid trisodium salt. Both groups were evaluated in terms of viability, toxicity, and proliferation and then compared in terms of cell surface morphology through inverted light and environmental scanning electron microscopy. In addition to immunoflow cytometric analyses, the effects of alkaline phosphatase activities were evaluated using the spectrophotometric method to examine the osteoblastic activities. Costs were calculated in the currency of the European Union (Euros). The Tukey Honestly Significant Difference test was used to reach the statistical evaluation of the data after the analysis of variance.

Results:

It was reported that the level of the alkaline phosphates was higher in group I compared to group II. It was observed that the surface morphology quality, the number of living cells, and proliferation were higher in group II and that the results were deemed statistically significant.

Conclusion:

It was found that the 2-phospho-L-ascorbic acid trisodium salt and dexamethasone mixture was as effective as the expensive commercial kits on the osteogenic effect on human primary bone tissue.

Is there a treatment protocol in which platelet-rich plasma is effective?

AIM

We aimed to reveal whether there are prospective suggestions for effective and standard platelet-rich plasma applications.

METHODS

We searched for clinical trials and traced all the references of incorporated documents.

RESULTS

In literature, there was no study indicating which disease is treated by which mechanism of action, how much dose and content are prepared and applied, when the treatment is applied and how many cures are applied.

CONCLUSION

Guides introducing which concentrations of PRP are used for which diseases are to be prepared immediately by a committee which is comprised of primarily orthopedists, clinical pharmacologists and toxicologists.

Assessing the negative impact of phenyl alkanoic acid derivative, a frequently prescribed drug for the suppression of pain and inflammation, on the differentiation and proliferation of chondrocytes

Background

Non-steroidal anti-inflammatory drugs (NSAIDs) are frequently prescribed to relieve pain and inflammation. These NSAIDs have also analgesic effects and can be administered via oral, injectable, and topical routes. During inflammation, a number of synovial mediators and cytokines are released which decrease the pH level of the synovial fluid. Administration of acidic NSAIDs further decreases the pH levels and hence contributes to the destruction of the cartilage. To our knowledge, no cellular-based study regarding the chondrotoxicity of phenyl alkanoic acid derivatives on NSAIDs was conducted before. Thus, the aim of this pioneering study was to examine the effect of frequently prescribed NSAIDs, a phenyl alkanoic acid derivative, flurbiprofen, on the proliferation and differentiation of human primer chondrocyte cultures in vitro.

Methods

Primer chondrocyte cultures were prepared from osteochondral tissue obtained during surgery for gonarthrosis. Samples not exposed to the pharmacological agent were used as the control group. The samples were treated with 1, 10, 100, 250, 500, or 1000 μM of the agent for 24, 48, and 72 h. The cell viability, toxicity, and proliferation were assessed with MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) analysis and prechondrocytic precursor stage-specific embryonic antigen-1 (SSEA-1) expression using a commercial ELISA kit spectrophotometrically. The surface morphology of the samples in each group was compared using an inverted light microscope and an environmental scanning electron microscope (ESEM). An analysis of variance was used to compare between-group differences. Tukey’s honest significant difference (HSD) method (95 % confidence interval) was used to evaluate the differences and significance in averages. The alpha significance value was considered <0.01.

Results

Statistically significant cytotoxicity was observed in the treatment groups. NSAID had a significant negative effect on the proliferation and differentiation of chondrocytes as compared to the control group (p < 0.01).

Conclusion

Before administering phenyl alkanoic acid derivatives in the clinical setting, their role in suppressing the proliferation and differentiation of chondrocytes should be taken into account. Thus, caution should be given when prescribing these drugs.

Chondrogenesis of Embryonic Stem Cell-Derived Mesenchymal Stem Cells Induced by TGFβ1 and BMP7 Through Increased TGFβ Receptor Expression and Endogenous TGFβ1 Production

For decades stem cells have proven to be invaluable to the study of tissue development. More recently, mesenchymal stem cells (MSCs) derived from embryonic stem cells (ESCs) (ESC-MSCs) have emerged as a cell source with great potential for the future of biomedical research due to their enhanced proliferative capability compared to adult tissue-derived MSCs and effectiveness of musculoskeletal lineage-specific cell differentiation compared to ESCs. We have previously compared the properties and differentiation potential of ESC-MSCs to bone marrow-derived MSCs. In this study, we evaluated the potential of TGFβ1 and BMP7 to induce chondrogenic differentiation of ESC-MSCs compared to that of TGFβ1 alone and further investigated the cellular phenotype and intracellular signaling in response to these induction conditions. Our results showed that the expression of cartilage-associated markers in ESC-MSCs induced by the TGFβ1 and BMP7 combination was increased compared to induction with TGFβ1 alone. The TGFβ1 and BMP7 combination upregulated the expression of TGFβ receptor and the production of endogenous TGFβs compared to TGFβ1 induction. The growth factor combination also increasingly activated both of the TGF and BMP signaling pathways, and inhibition of the signaling pathways led to reduced chondrogenesis of ESC-MSCs. Our findings suggest that by adding BMP7 to TGFβ1-supplemented induction medium, ESC-MSC chondrogenesis is upregulated through increased production of endogenous TGFβ and activities of TGFβ and BMP signaling. J. Cell. Biochem. 118: 172-181, 2017. © 2016 Wiley Periodicals, Inc.

Are chondrocytes damaged when rheumatologic inflammation is suppressed?

AIM

The use of biological agents (BAs) for treating diseases such as rheumatoid arthritis (RA), spondyloarthropathy, and systemic lupus erythematosus to reduce inflammation has been fruitful. Especially as part of the increasing number of studies on the intra-articular application of BAs, the effects of BAs on cartilage have been widely investigated. In the present study, the effects of rituximab, abatacept, and adalimumab, all approved antirheumatic agents, on human primary chondrocytes were investigated comparatively and on the molecular level through viability, proliferation, and toxicity analyses.

MATERIALS AND METHODS

Osteochondral tissues from the distal femur and proximal tibia were resected during total knee arthroplasty from patients (n = 3) with confirmed gonarthrosis in whom all medical or conservative treatments had failed. Standard human primary chondrocyte cell culturing was carried out. Immunophenotyping was performed on the cells that adhered to the flask, and their chondrotoxicity was observed using a flow cytometry device. Images of the cells showing chondrotoxicity were analyzed using invert and environmental scanning microscopes, and microimages were obtained. The MTT-enzyme linked immunosorbent assay was performed to observe the toxic effects of BAs on the proliferation of chondrocytes at 24 and 48 h. The results were analyzed using the number of cells and proliferation; statistical comparisons among the groups were carried out using one-way ANOVA. The alpha significance level was set at <0.01.

RESULTS

These pharmaceutical agents were chondrotoxic, especially on viability and proliferation (p = 0.0000).

CONCLUSION

BAs are generally used during active inflammation, and following the management of inflammation, their dosage should be determined taking into consideration their cellular-level toxic effects on chondrocytes.

A practical way to prepare primer human chondrocyte culture

Biological cartilage repair is one of the most important targets for orthopedic surgeons currently. For this purpose, it is mandatory to know how to prepare a chondrocyte culture. In this study, our purpose was to introduce a method enabling orthopedic surgeons to practice their knowledge and skills on molecular experimental setup at cellular level, based on our experiences from previous pilot studies. Thus, we believe it will encourage orthopedic surgeons.

Nanotechnology for mesenchymal stem cell therapies

Mesenchymal stem cells (MSC) display great proliferative, differentiative, chemotactic, and immune-modulatory properties required to promote tissue repair. Several clinical trials based on the use of MSC are currently underway for therapeutic purposes. The aim of this article is to examine the current trends and potential impact of nanotechnology in MSC-driven regenerative medicine. Nanoparticle-based approaches are used as powerful carrier systems for the targeted delivery of bioactive molecules to ensure MSC long-term maintenance in vitro and to enhance their regenerative potential. Nanostructured materials have been developed to recapitulate the stem cell niche within a tissue and to instruct MSC toward the creation of regeneration-permissive environment. Finally, the capability of MSC to migrate toward the site of injury/inflammation has allowed for the development of diagnostic imaging systems able to monitor transplanted stem cell bio-distribution, toxicity, and therapeutic effectiveness.

Are the leading drugs against Staphylococcus aureus really toxic to cartilage?

Many studies have shown that the toxic effects of local antibiotics on bone and cartilage limit orthopedic surgeons. In this study, we evaluated three antibacterial agents used locally to treat highly mortal and morbid diseases in the field of orthopedics, such as septic arthritis. Are vancomycin, teicoplanin, and linezolid, which are archenemies of Staphylococcus aureus, really toxic to chondrocytes? The purpose of the study was to investigate the effects of antibiotics, which are used against S. aureus, on human chondrocytes in vitro. Primary cell cultures obtained from gonarthrosis patients were divided into two main groups. One of these groups was designated as the control chondrocyte culture. The other group was divided into three subgroups, and each group was exposed to vancomycin, teicoplanin, or linezolid. Cell culture samples were characterized by immunophenotyping following incubation with the three different antibiotics. Before and after the agents were administered, the cultures were subjected to inverted and environmental scanning electron microscopy. The number of live cells and the proliferation rate were monitored with the MTT-assay. We found that vancomycin, teicoplanin, and linezolid do not have chondrotoxic effects. Vancomycin, teicoplanin, and linezolid had no chondrotoxic activity during in vitro culture, which supports the argument that these agents can safely be used in orthopedic surgery, especially against methicillin-resistant S. aureus agents.

In vitro analysis of a novel controlled release system designed for intratympanic administration of N-acetylcysteine: a preliminary report

The aim of this in-vitro experimental study was to design a novel drug delivery system that may permit controlled release of N-acetylcysteine (NAC) following intratympanic administration. The system was composed of two different solutions that attained a hydrogel form within seconds after getting into contact with each other. The authors performed swelling, pH and temperature tests and analysis of controlled release of NAC from this novel controlled release system. For the structure and porosity analysis of the hydrogel, an environmental scanning electron microscope (SEM) was used. The diameter of designed hydrogel showed an increase when pH was increased. In addition, in comparison to acidic values, the pore diameter of the hydrogel increased significantly especially in physiological level. The increase in the pore diameter was also directly proportional to the increase in temperature. Spectrophotometric analysis showed that the amount of NAC released into the medium was statistically significant (p=0.038, t=-2.18, 95% CI; DF: 27). SEM analysis of the samples revealed a smooth surface topography and numerous porous structures. The authors are of the opinion that the designed hydrogel may be used as an alternative method for intratympanic delivery of NAC for otoprotective purposes. The disadvantages of intratympanic injection of the drug in its liquid form, including leakage through eustachian tube, restraining the patient in an uncomfortable position, necessity for repetitive injections and dose dependent inflammation of the middle ear epithelium, may also be avoided. Further in vivo studies should be conducted to assess its tolerability and effectivity.

Are biological agents toxic to human chondrocytes and osteocytes?

Purpose

The aim of the present study is to investigate the effects of biological agents (BAs) on human chondrocytes and osteocytes in vitro.

Methods

Primary cell cultures obtained from gonarthrosis patients were divided into four groups, two of which were designated as control cultures of chondrocyte and osteocyte, and the other two groups were exposed to BAs administered via the culture medium. Cultured cells were characterized by immunophenotyping. Before and after administration of the agents, the cultures were observed by inverted and environmental scanning electron microscopy (ESEM). The number of live cells and the proliferation rate were monitored by MTT assay.

Results

Rituximab and adalimumab were the least toxic agents to chondrocytes, whereas adalimumab and etanercept were to osteocytes.

Conclusion

During periods of intense active inflammation, the concentration of the preferred BAs after inhibition of inflammation needs to be emphasized when their effects on cartilage and bone tissue are considered at the cellular level if the clinical practice is to continue.

Rate-programming of nano-particulate delivery systems for smart bioactive scaffolds in tissue engineering

Development of smart bioactive scaffolds is of importance in tissue engineering, where cell proliferation, differentiation and migration within scaffolds can be regulated by the interactions between cells and scaffold through the use of growth factors (GFs) and extra cellular matrix peptides. One challenge in this area is to spatiotemporally control the dose, sequence and profile of release of GFs so as to regulate cellular fates during tissue regeneration. This challenge would be addressed by rate-programming of nano-particulate delivery systems, where the release of GFs via polymeric nanoparticles is controlled by means of the methods of, such as externally-controlled and physicochemically/architecturally-modulated so as to mimic the profile of physiological GFs. Identifying and understanding such factors as the desired release profiles, mechanisms of release, physicochemical characteristics of polymeric nanoparticles, and externally-triggering stimuli are essential for designing and optimizing such delivery systems. This review surveys the recent studies on the desired release profiles of GFs in various tissue engineering applications, elucidates the major release mechanisms and critical factors affecting release profiles, and overviews the role played by the mathematical models for optimizing nano-particulate delivery systems. Potentials of stimuli responsive nanoparticles for spatiotemporal control of GF release are also presented, along with the recent advances in strategies for spatiotemporal control of GF delivery within tissue engineered scaffolds. The recommendation for the future studies to overcome challenges for developing sophisticated particulate delivery systems in tissue engineering is discussed prior to the presentation of conclusions drawn from this paper.

Tissue-engineered cartilage: the crossroads of biomaterials, cells and stimulating factors

Damage to cartilage represents one of the most challenging tasks of musculoskeletal therapeutics due to its limited propensity for healing and regenerative capabilities. Lack of current treatments to restore cartilage tissue function has prompted research in this rapidly emerging field of tissue regeneration of functional cartilage tissue substitutes. The development of cartilaginous tissue largely depends on the combination of appropriate biomaterials, cell source, and stimulating factors. Over the years, various biomaterials have been utilized for cartilage repair, but outcomes are far from achieving native cartilage architecture and function. This highlights the need for exploration of suitable biomaterials and stimulating factors for cartilage regeneration. With these perspectives, we aim to present an overview of cartilage tissue engineering with recent progress, development, and major steps taken toward the generation of functional cartilage tissue. In this review, we have discussed the advances and problems in tissue engineering of cartilage with strong emphasis on the utilization of natural polymeric biomaterials, various cell sources, and stimulating factors such as biophysical stimuli, mechanical stimuli, dynamic culture, and growth factors used so far in cartilage regeneration. Finally, we have focused on clinical trials, recent innovations, and future prospects related to cartilage engineering.

ADAMTS5 is required for biomechanically-stimulated healing of murine tendinopathy

A recently developed murine model of tendinopathy, induced by TGF-β1 injection, has been used to examine the reparative capacity of tendinopathic Achilles in Adamts5(-/-) mice. After TGF-β1 injection and 2 weeks of treadmill exercise, the Achilles from Adamts5(-/-) mice exhibited a reduction in maximum tensile stress of approximately 60%. However, in contrast to wild type mice previously characterized by this model, Adamts5(-/-) mice subjected to further treadmill exercise were unable to reverse this biomechanical deficit. This nonreparative phenotype was accompanied by a major deficiency, relative to wild-type, in expression of Col1a1 and Col3a1 and an abnormally elevated expression of a wide range of integrins. In addition, the tendinopathic Adamts5(-/-) mice showed a persistent accumulation of chondrogenic cells in the tendon body and an aggrecan-rich fibrocartilaginous matrix within disorganized collagen fiber bundles. Moreover, consistent with the compromised biomechanical properties of the Achilles in the Adamts5(-/-) mice, in vivo gait analysis revealed a strong trend (p = 0.07) towards increased swing time of the injected limb in Adamts5(-/-) relative to wild-type mice. These findings demonstrate that a deficiency in ADAMTS5 promotes a chondrogenic response to TGF-β1 injection that is not reversed by treadmill exercise. Hence, repair of biomechanically compromised tendons exhibiting midsubstance chondroid accumulation requires ADAMTS5.