Cell-sheet technology combined with a thienoindazole derivative small compound TD-198946 for cartilage regeneration

Advances in Polysaccharides for Cartilage Tissue Engineering Repair: A Review

Cartilage repair has been a significant challenge in orthopedics that has not yet been fully resolved. Due to the absence of blood vessels and the almost cell-free nature of mature cartilage tissue, the limited ability to repair cartilage has resulted in significant socioeconomic pressures. Polysaccharide materials have recently been widely used for cartilage tissue repair due to their excellent cell loading, biocompatibility, and chemical modifiability. They also provide a suitable microenvironment for cartilage repair and regeneration. In this Review, we summarize the techniques used clinically for cartilage repair, focusing on polysaccharides, polysaccharides for cartilage repair, and the differences between these and other materials. In addition, we summarize the techniques of tissue engineering strategies for cartilage repair and provide an outlook on developing next-generation cartilage repair and regeneration materials from polysaccharides. This Review will provide theoretical guidance for developing polysaccharide-based cartilage repair and regeneration materials with clinical applications for cartilage tissue repair and regeneration.

Enhanced chondrogenic differentiation of iPS cell-derived mesenchymal stem/stromal cells via neural crest cell induction for hyaline cartilage repair

Background: To date, there is no effective long-lasting treatment for cartilage tissue repair. Primary chondrocytes and mesenchymal stem/stromal cells are the most commonly used cell sources in regenerative medicine. However, both cell types have limitations, such as dedifferentiation, donor morbidity, and limited expansion. Here, we report a stepwise differentiation method to generate matrix-rich cartilage spheroids from induced pluripotent stem cell-derived mesenchymal stem/stromal cells (iMSCs) via the induction of neural crest cells under xeno-free conditions. Methods: The genes and signaling pathways regulating the chondrogenic susceptibility of iMSCs generated under different conditions were studied. Enhanced chondrogenic differentiation was achieved using a combination of growth factors and small-molecule inducers. Results: We demonstrated that the use of a thienoindazole derivative, TD-198946, synergistically improves chondrogenesis in iMSCs. The proposed strategy produced controlled-size spheroids and increased cartilage extracellular matrix production with no signs of dedifferentiation, fibrotic cartilage formation, or hypertrophy in vivo. Conclusion: These findings provide a novel cell source for stem cell-based cartilage repair. Furthermore, since chondrogenic spheroids have the potential to fuse within a few days, they can be used as building blocks for biofabrication of larger cartilage tissues using technologies such as the Kenzan Bioprinting method.

The Combination of Concentrated Growth Factor and Adipose-Derived Stem Cell Sheet Repairs Skull Defects in Rats

BACKGROUND

The goal of this study was to create a biomaterial which combines concentrated growth factor (CGF) with an adipose-derived stem cell (ADSC) sheet to promote the repair of skull defects in rats.

METHODS

We determined the optimal concentration of CGF extract by investigating the effects of different concentrations (0, 5%, 10%, and 20%) on the proliferation and differentiation of ADSCs. Then we created a complex combining CGF with an ADSC sheet, and tested the effects on bone repair in four experimental rat groups: (A) control; (B) ADSC sheet; (C) CGF particles; (D) combination of CGF + ADSCs. Eight weeks after the procedure, osteogenesis was assessed by micro-CT and hematoxylin and eosin staining.

RESULTS

We found that the concentration of CGF extract that promoted optimal ADSC proliferation and differentiation in vitro was 20%. In turn, bone regeneration was promoted the most by the combination of CGF and ADSCs.

CONCLUSION

In this study, we determined the optimal ratio of CGF and ADSCs to be used in a biomaterial for bone regeneration. The resulting CGF/ADSCs complex promotes maxillofacial bone defect repair in rats.

Evidence that TD-198946 enhances the chondrogenic potential of human synovium-derived stem cells through the NOTCH3 signaling pathway

Human synovium-derived stem cells (hSSCs) are an attractive source of cells for cartilage repair. At present, the quality of tissue and techniques used for cartilage regeneration have scope for improvement. A small compound, TD-198946, was reported to enhance chondrogenic induction from hSSCs; however, other applications of TD-198946, such as priming the cell potential of hSSCs, remain unknown. Our study aimed to examine the effect of TD-198946 pretreatment on hSSCs. HSSCs were cultured with or without TD-198946 for 7 days during expansion culture and then converted into a three-dimensional pellet culture supplemented with bone morphogenetic protein-2 (BMP2) and/or transforming growth factor beta-3 (TGFβ3). Chondrogenesis in cultures was assessed based on the GAG content, histology, and expression levels of chondrogenic marker genes. Cell pellets derived from TD-198946-pretreated hSSCs showed enhanced chondrogenic potential when chondrogenesis was induced by both BMP2 and TGFβ3. Moreover, cartilaginous tissue was efficiently generated from TD-198946-pretreated hSSCs using a combination of BMP2 and TGFβ3. Microarray analysis revealed that NOTCH pathway-related genes and their target genes were significantly upregulated in TD-198946-treated hSSCs, although TD-198946 alone did not upregulate chondrogenesis related markers. The administration of the NOTCH signal inhibitor diminished the effect of TD-198946. Thus, TD-198946 enhances the chondrogenic potential of hSSCs via the NOTCH3 signaling pathway. This study is the first to demonstrate the gradual activation of NOTCH3 signaling during chondrogenesis in hSSCs. The priming of NOTCH3 using TD-198946 provides a novel insight regarding the regulation of the differentiation of hSSCs into chondrocytes.

The Synovium Attenuates Cartilage Degeneration in KOA through Activation of the Smad2/3-Runx1 Cascade and Chondrogenesis-related miRNAs

Knee osteoarthritis (KOA) is a highly prevalent disabling joint disease in aged people. Progressive cartilage degradation is the hallmark of KOA, but its deeper mechanism remains unclear. Substantial evidence indicates the importance of the synovium for joint homeostasis. The present study aimed to determine whether the synovium regulates cartilage metabolism through chondrogenesis-related microRNAs (miRNAs) in the KOA microenvironment. Clinical sample testing and in vitro cell experiments screened out miR-455 and miR-210 as effective miRNAs. The levels of both were significantly reduced in KOA cartilage but increased in KOA synovial fluid compared with controls. We further revealed that transforming growth factor β1 (TGF-β1) can significantly upregulate miR-455 and miR-210 expression in synoviocytes. The upregulated miRNAs can be secreted into the extracellular environment and prevent cartilage degeneration. Through bioinformatics and in vitro experiments, we found that Runx1 can bind to the promoter regions of miR-455 and miR-210 and enhance their transcription in TGF-β1-treated synoviocytes. Collectively, our findings demonstrate a protective effect of the synovium against cartilage degeneration mediated by chondrogenesis-related miRNAs, which suggests that Runx1 is a potential target for KOA therapy.

Small molecule compounds promote the proliferation of chondrocytes and chondrogenic differentiation of stem cells in cartilage tissue engineering

The application of tissue engineering to generate cartilage is limited because of low proliferative ability and unstable phenotype of chondrocytes. The sources of cartilage seed cells are mainly chondrocytes and stem cells. A variety of methods have been used to obtain large numbers of chondrocytes, including increasing chondrocyte proliferation and stem cell chondrogenic differentiation via cytokines, genes, and proteins. Natural or synthetic small molecule compounds can provide a simple and effective method to promote chondrocyte proliferation, maintain a stable chondrocyte phenotype, and promote stem cell chondrogenic differentiation. Therefore, the study of small molecule compounds is of great importance for cartilage tissue engineering. Herein, we review a series of small molecule compounds and their mechanisms that can promote chondrocyte proliferation, maintain chondrocyte phenotype, or induce stem cell chondrogenesis. The studies in this field represent significant contributions to the research in cartilage tissue engineering and regenerative medicine.

The small compound, TD-198946, protects against intervertebral degeneration by enhancing glycosaminoglycan synthesis in nucleus pulposus cells

Degeneration of the nucleus pulposus (NP) might serve as a trigger for intervertebral disc degeneration (IDD). A recent drug screening study revealed that the thienoindazole derivative, TD-198946, is a novel drug for the treatment of osteoarthritis. Because of the environmental and functional similarities between articular cartilage and intervertebral disc, TD-198946 is expected to prevent IDD. Herein, we sought to evaluate the effects of TD-198946 on IDD. TD-198946 enhanced glycosaminoglycan (GAG) production and the related genes in mouse NP cells and human NP cells (hNPCs). Further, Kyoto Encyclopedia of Genes and Genomes pathway analysis using the mRNA sequence of hNPCs suggested that the mechanism of action of TD-198946 primarily occurred via the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway. The Akt inhibitor suppressed the enhancement of GAG production induced by TD-198946. The effects of TD-198946 on IDD at two different time points (immediate treatment model, immediately after the puncture; latent treatment model, 2 weeks after the puncture) were investigated using a mouse tail-disc puncture model. At both time points, TD-198946 prevented a loss in disc height. Histological analysis also demonstrated the preservation of the NP structures. TD-198946 exhibited therapeutic effects on IDD by enhancing GAG production via PI3K/Akt signaling.

CCL3/CCR1 mediates CD14+CD16- circulating monocyte recruitment in knee osteoarthritis progression

OBJECTIVES

Monocyte-derived macrophages, as the predominant immune cell type that is increased in inflamed synovium, play a vital role during knee osteoarthritis (KOA) progression. However, the mechanisms underlying the recruitment of circulating monocytes to osteoarthritic knees remain uncertain. Based on previous data obtained from plasma, we investigated the contributions of CCL2, CCL3, CCL4 and their cognate receptors in circulating monocyte chemotaxis and KOA development.

METHODS

Using flow cytometry staining, we characterized the expression patterns of the chemokine receptors in CD14⁺CD16^- circulating monocytes from KOA patients and healthy volunteers. The expression of chemokines in synovial fluids, synovium and cartilage was investigated in KOA patients and in patients without KOA. The role of chemokines and their cognate receptors in the chemotaxis of CD14⁺CD16^- circulating monocytes was assessed using chemokine neutralizing antibodies (NA) and receptor antagonists in vitro and in vivo.

RESULTS

The majority of CD14⁺CD16^- circulating monocytes were CCR1-and CCR2-positive. CCL2, CCL3 and CCL4 were elevated in synovial fluid of KOA patients compared with that of controls. The most likely source of these chemokines is inflamed synovium and cartilage in the osteoarthritic knee. The CCL3/CCR1 and CCL2/CCR2 axes showed substantial ability to recruit CD14⁺CD16^- monocytes in transwell assays. Similar results were confirmed in a mouse model of collagenase-induced KOA (CIA) in which blocking either the CCL3/CCR1 axis or the CCL2/CCR2 axis reduced synovial hyperplasia and F4/80⁺ macrophage infiltration.

CONCLUSIONS

Our findings suggested that, analogous to the CCL2/CCR2 axis, CCL3 produced in osteoarthritic knees can chemoattract circulating monocytes to the inflamed synovium through CCR1.

Enhancement of chondrogenic differentiation supplemented by a novel small compound for chondrocyte-based tissue engineering

Purpose

Chondrocyte -based tissue engineering has been a promising option for the treatment of cartilage lesions. In previous literature, TD198946 has been shown to promote chondrogenic differentiation which could prove useful in cartilage regeneration therapies. Our study aimed to investigate the effects of TD198946 in generating engineered cartilage using dedifferentiated chondrocyte-seeded collagen scaffolds treated with TD198946.

Methods

Articular chondrocytes were isolated from mini pig knees and expanded in 2-dimensional cell culture and subsequently used in the experiments. 3-D pellets were then cultured for two weeks. Cells were also cultured in a type I collagen scaffolds for four weeks. Specimens were cultured with TD198946, BMP-2, or both in combination. Outcomes were determined by gene expression levels of RUNX1, SOX9, ACAN, COL1A1, COL2A1 and COL10A1, the glycosaminoglycan content, and characteristics of histology and immunohistochemistry. Furthermore, the maturity of the engineered cartilage cultured for two weeks was evaluated through subcutaneous implantation in nude mice for four weeks.

Results

Addition of TD198946 demonstrated the upregulation of gene expression level except for ACAN, type II collagen and glycosaminoglycan synthesis in both pellet and 3D scaffold cultures. TD198946 and BMP-2 combination cultures showed higher chondrogenic differentiation than TD198946 or BMP-2 alone. The engineered cartilage maintained its extracellular matrices for four weeks post implantation. In contrast, engineered cartilage treated with either TD198946 or BMP-2 alone was mostly absorbed.

Conclusions

Our results indicate that TD198946 could improve quality of engineered cartilage by redifferentiation of dedifferentiated chondrocytes pre-implantation and promoting collagen and glycosaminoglycan synthesis.

[Construction and preliminary study on biological characteristics of composite cell sheets of mesenchymal stem cells and endothelial progenitor cells derived from peripheral blood]

Objective

To separate peripheral blood mesenchymal stem cells (PBMSC) and peripheral blood endothelial progenitor cells (PBEPC) from peripheral blood, and investigate the biological characteristics of composite cell sheets of PBMSC and PBEPC.

Methods

The peripheral blood of healthy adult New Zealand white rabbits was extracted and PBMSC and PBEPC were separated by density gradient centrifugation. Morphological observation and identification of PBMSC and PBEPC were performed. The 3rd generation of PBMSC and PBEPC were used to construct a composite cell sheet at a ratio of 1∶1, and the 3rd generation of PBMSC was used to construct a single cell sheet as control. The distributions of cells in two kinds of cell sheets were observed by HE staining. In addition, the expression of alkaline phosphatase (ALP), osteocalcin (OCN), and vascular endothelial growth factor (VEGF) in the supernatants of cell sheets were observed by ELISA at 1, 5, and 10 days after osteogenic induction.

Results

The morphology of PBMSC was spindle-shaped or polygonal, and PBMSC had good abilities of osteogenic and adipogenic differentiation. The morphology of PBEPC was paved stone-like, and the tube-forming test of PBEPC was positive. Two kinds of cell sheets were white translucent. The results of HE staining showed that the composite cell sheet had more cell layers and higher cell density than the single cell sheet. The expressions of ALP, OCN, and VEGF in the supernatant of the two groups of cell sheets increased with the time of induction. The expression of OCN in the group of composite cell sheet was significantly higher than that in the group of single cell sheet on the 5th and 10th day, ALP on the 10th day was significantly higher than that in the group of single cell sheet, VEGF expression on the 1st, 5th, and 10th day was significantly higher than that in the group of single cell sheet, all showing significant differences ( P<0.05), and there was no significant difference between the two groups at other time points ( P>0.05).

Conclusion

PBMSC have stable differentiation ability, and they have good application prospects because of their minimally invasive access. Composite cell membranes constructed by co-culture of two kinds of cells and induction of membrane formation provides a new idea and exploration for tissue defect repair.

Recent advances in cell sheet technology for bone and cartilage regeneration: from preparation to application

Bone defects caused by trauma, tumour resection, infection and congenital deformities, together with articular cartilage defects and cartilage-subchondral bone complex defects caused by trauma and degenerative diseases, remain great challenges for clinicians. Novel strategies utilising cell sheet technology to enhance bone and cartilage regeneration are being developed. The cell sheet technology has shown great clinical potential in regenerative medicine due to its effective preservation of cell-cell connections and extracellular matrix and its scaffold-free nature. This review will first introduce several widely used cell sheet preparation systems, including traditional approaches and recent improvements, as well as their advantages and shortcomings. Recent advances in utilising cell sheet technology to regenerate bone or cartilage defects and bone-cartilage complex defects will be reviewed. The key challenges and future research directions for the application of cell sheet technology in bone and cartilage regeneration will also be discussed.

Targeting of chondrocyte plasticity via connexin43 modulation attenuates cellular senescence and fosters a pro-regenerative environment in osteoarthritis

Osteoarthritis (OA), a chronic disease characterized by articular cartilage degeneration, is a leading cause of disability and pain worldwide. In OA, chondrocytes in cartilage undergo phenotypic changes and senescence, restricting cartilage regeneration and favouring disease progression. Similar to other wound-healing disorders, chondrocytes from OA patients show a chronic increase in the gap junction channel protein connexin43 (Cx43), which regulates signal transduction through the exchange of elements or recruitment/release of signalling factors. Although immature or stem-like cells are present in cartilage from OA patients, their origin and role in disease progression are unknown. In this study, we found that Cx43 acts as a positive regulator of chondrocyte-mesenchymal transition. Overactive Cx43 largely maintains the immature phenotype by increasing nuclear translocation of Twist-1 and tissue remodelling and proinflammatory agents, such as MMPs and IL-1β, which in turn cause cellular senescence through upregulation of p53, p16^INK4a and NF-κB, contributing to the senescence-associated secretory phenotype (SASP). Downregulation of either Cx43 by CRISPR/Cas9 or Cx43-mediated gap junctional intercellular communication (GJIC) by carbenoxolone treatment triggered rediferentiation of osteoarthritic chondrocytes into a more differentiated state, associated with decreased synthesis of MMPs and proinflammatory factors, and reduced senescence. We have identified causal Cx43-sensitive circuit in chondrocytes that regulates dedifferentiation, redifferentiation and senescence. We propose that chondrocytes undergo chondrocyte-mesenchymal transition where increased Cx43-mediated GJIC during OA facilitates Twist-1 nuclear translocation as a novel mechanism involved in OA progression. These findings support the use of Cx43 as an appropriate therapeutic target to halt OA progression and to promote cartilage regeneration.

Chasing Chimeras - The elusive stable chondrogenic phenotype

The choice of the best-suited cell population for the regeneration of damaged or diseased cartilage depends on the effectiveness of culture conditions (e.g. media supplements, three-dimensional scaffolds, mechanical stimulation, oxygen tension, co-culture systems) to induce stable chondrogenic phenotype. Herein, advances and shortfalls in in vitro, preclinical and clinical setting of various in vitro microenvironment modulators on maintaining chondrocyte phenotype or directing stem cells towards chondrogenic lineage are critically discussed. Chondrocytes possess low isolation efficiency, limited proliferative potential and rapid phenotypic drift in culture. Mesenchymal stem cells are relatively readily available, possess high proliferation potential, exhibit great chondrogenic differentiation capacity, but they tend to acquire a hypertrophic phenotype when exposed to chondrogenic stimuli. Embryonic and induced pluripotent stem cells, despite their promising in vitro and preclinical data, are still under-investigated. Although a stable chondrogenic phenotype remains elusive, recent advances in in vitro microenvironment modulators are likely to develop clinically- and commercially-relevant therapies in the years to come.

Cartilage regeneration and ageing: Targeting cellular plasticity in osteoarthritis

Ageing processes play a major contributing role for the development of Osteoarthritis (OA). This prototypic degenerative condition of ageing is the most common form of arthritis and is accompanied by a general decline, chronic pain and mobility deficits. The disease is primarily characterized by articular cartilage degradation, followed by subchondral bone thickening, osteophyte formation, synovial inflammation and joint degeneration. In the early stages, osteoarthritic chondrocytes undergo phenotypic changes that increase cell proliferation and cluster formation and enhance the production of matrix-remodelling enzymes. In fact, chondrocytes exhibit differentiation plasticity and undergo phenotypic changes during the healing process. Current studies are focusing on unravelling whether OA is a consequence of an abnormal wound healing response. Recent investigations suggest that alterations in different proteins, such as TGF-ß/BMPs, NF-Kß, Wnt, and Cx43, or SASP factors involved in signalling pathways in wound healing response, could be directly implicated in the initiation of OA. Several findings suggest that osteoarthritic chondrocytes remain in an immature state expressing stemness-associated cell surface markers. In fact, the efficacy of new disease-modifying OA drugs that promote chondrogenic differentiation in animal models indicates that this may be a drug-sensible state. In this review, we highlight the current knowledge regarding cellular plasticity in chondrocytes and OA. A better comprehension of the mechanisms involved in these processes may enable us to understand the molecular pathways that promote abnormal repair and cartilage degradation in OA. This understanding would be advantageous in identifying novel targets and designing therapies to promote effective cartilage repair and successful joint ageing by preventing functional limitations and disability.

[Application of cell sheet technology in bone and cartilage tissue engineering]

Objective

To review the progress of cell sheet technology and its application in bone and cartilage engineering.

Methods

The recent literature concerning the cell sheet technology used in treatment of bone and cartilage defects was extensively reviewed and summarized.

Results

Cell sheet built through many different ways can protect extracellular matrix from proteolytic enzymes. As a three-dimensional structure, cell sheet can repair bone and cartilige defects via folding, wrapping scaffold, or be created by the layering of individual cell sheets.

Conclusion

The cell sheet technology would have a very broad prospects in bone and cartilage tissue engineering in future.

Improved osseointegrating functionality of cell sheets on anatase TiO2 nanoparticle surfaces

Bone marrow mesenchymal stem cell sheets (BMSC sheets) have been reported as a powerful tool for bioengineering applications in accelerating osseointegration.

A Tissue-Engineered Chondrocyte Cell Sheet Induces Extracellular Matrix Modification to Enhance Ventricular Biomechanics and Attenuate Myocardial Stiffness in Ischemic Cardiomyopathy

There exists a substantial body of work describing cardiac support devices to mechanically support the left ventricle (LV); however, these devices lack biological effects. To remedy this, we implemented a cell sheet engineering approach utilizing chondrocytes, which in their natural environment produce a relatively elastic extracellular matrix (ECM) for a cushioning effect. Therefore, we hypothesized that a chondrocyte cell sheet applied to infarcted and borderzone myocardium will biologically enhance the ventricular ECM and increase elasticity to augment cardiac function in a model of ischemic cardiomyopathy (ICM). Primary articular cartilage chondrocytes of Wistar rats were isolated and cultured on temperature-responsive culture dishes to generate cell sheets. A rodent ICM model was created by ligating the left anterior descending coronary artery. Rats were divided into two groups: cell sheet transplantation (1.0 × 10(7) cells/dish) and no treatment. The cell sheet was placed onto the surface of the heart covering the infarct and borderzone areas. At 4 weeks following treatment, the decreased fibrotic extension and increased elastic microfiber networks in the infarct and borderzone areas correlated with this technology's potential to stimulate ECM formation. The enhanced ventricular elasticity was further confirmed by the axial stretch test, which revealed that the cell sheet tended to attenuate tensile modulus, a parameter of stiffness. This translated to increased wall thickness in the infarct area, decreased LV volume, wall stress, mass, and improvement of LV function. Thus, the chondrocyte cell sheet strengthens the ventricular biomechanical properties by inducing the formation of elastic microfiber networks in ICM, resulting in attenuated myocardial stiffness and improved myocardial function.

Small molecules and their controlled release that induce the osteogenic/chondrogenic commitment of stem cells

Stem cell-based tissue engineering plays a significant role in skeletal system repair and regenerative therapies. However, stem cells must be differentiated into specific mature cells prior to implantation (direct implantation may lead to tumour formation). Natural or chemically synthesised small molecules provide an efficient, accurate, reversible, and cost-effective way to differentiate stem cells compared with bioactive growth factors and gene-related methods. Thus, investigating the influences of small molecules on the differentiation of stem cells is of great significance. Here, we review a series of small molecules that can induce or/and promote the osteogenic/chondrogenic commitment of stem cells. The controlled release of these small molecules from various vehicles for stem cell-based therapies and tissue engineering applications is also discussed. The extensive studies in this field represent significant contributions to stem cell-based tissue engineering research and regenerative medicine.

Chondrocytes behaviors within type I collagen microspheres and bulk hydrogels: an in vitro study

Cell niche, which is considered to be critical to the proliferation and differentiation of cells, is one of the most important aspects for the design and development of ideal scaffolds in tissue engineering.