Direct Coculture of Human Chondrocytes and Synovium-Derived Stem Cells Enhances In Vitro Chondrogenesis

Co-culture engineering: a promising strategy for production of engineered extracellular vesicle for osteoarthritis treatment

The therapeutic effects of extracellular vesicles (EVs) have been identified as a significant factor in intercellular communication in different disease treatments, including osteoarthritis (OA). Compared to the conventional approaches in treating OA, EV therapy is a non-invasive and cell-free method. However, improving the yield of EVs and their therapeutic effects are the main challenges for clinical applications. In this regard, researchers are using the EV engineering potential to overcome these challenges. New findings suggest that the co-culture strategy as an indirect EV engineering method efficiently increases EV production and quality. The co-culture of mesenchymal stem cells (MSCs) and chondrocytes has improved their chondrogenesis, anti-inflammatory effects, and regenerative properties which are mediated by EVs. Hence, co-culture engineering by considerable systems could be useful in producing engineered EVs for different therapeutic applications. Here, we review various co-culture approaches, including diverse direct and indirect, 2D and 3D cell cultures, as well as static and dynamic systems. Meanwhile, we suggest and discuss the advantages of combined strategies to achieve engineered EVs for OA treatment.

3D-printed PCL scaffolds with anatomy-inspired bionic stratified structures for the treatment of growth plate injuries

The growth plate is a cartilaginous tissue with three distinct zones. Resident chondrocytes are highly organized in a columnar structure, which is critical for the longitudinal growth of immature long bones. Once injured, the growth plate may potentially be replaced by bony bar formation and, consequently, cause limb abnormalities in children. It is well-known that the essential step in growth plate repair is the remolding of the organized structure of chondrocytes. To achieve this, we prepared an anatomy-inspired bionic Poly(ε-caprolactone) (PCL) scaffold with a stratified structure using three-dimensional (3D) printing technology. The bionic scaffold is engineered by surface modification of NaOH and collagen Ⅰ (COL Ⅰ) to promote cell adhesion. Moreover, chondrocytes and bone marrow mesenchymal stem cells (BMSCs) are loaded in the most suitable ratio of 1:3 for growth plate reconstruction. Based on the anatomical structure of the growth plate, the bionic scaffold is designed to have three regions, which are the small-, medium-, and large-pore-size regions. These pore sizes are used to induce BMSCs to differentiate into similar structures such as the growth plate. Remarkably, the X-ray and histological results also demonstrate that the cell-loaded stratified scaffold can successfully rebuild the structure of the growth plate and reduce limb abnormalities, including limb length discrepancies and angular deformities in vivo. This study provides a potential method of preparing a bioinspired stratified scaffold for the treatment of growth plate injuries.

Cartilage Tissue Engineering: An Introduction

Once damaged, cartilage has limited healing capability. This has led to a huge body of research that aims to repair or regenerate this important tissue. Despite the progress made, significant hurdles still need to be overcome. This chapter highlights some of the progress made, while elaborating on areas that need further research. The concept of translation and the route to clinical translation must be kept in mind if some of the promising preclinical research is to make it to routine clinical application.

Co-culture pellet of human Wharton's jelly mesenchymal stem cells and rat costal chondrocytes as a candidate for articular cartilage regeneration: in vitro and in vivo study

BACKGROUND

Seeding cells are key factors in cell-based cartilage tissue regeneration. Monoculture of either chondrocyte or mesenchymal stem cells has several limitations. In recent years, co-culture strategies have provided potential solutions. In this study, directly co-cultured rat costal chondrocytes (CCs) and human Wharton's jelly mesenchymal stem (hWJMSCs) cells were evaluated as a candidate to regenerate articular cartilage.

METHODS

Rat CCs are directly co-cultured with hWJMSCs in a pellet model at different ratios (3:1, 1:1, 1:3) for 21 days. The monoculture pellets were used as controls. RT-qPCR, biochemical assays, histological staining and evaluations were performed to analyze the chondrogenic differentiation of each group. The 1:1 ratio co-culture pellet group together with monoculture controls were implanted into the osteochondral defects made on the femoral grooves of the rats for 4, 8, 12 weeks. Then, macroscopic and histological evaluations were performed.

RESULTS

Compared to rat CCs pellet group, 3:1 and 1:1 ratio group demonstrated similar extracellular matrix production but less hypertrophy intendency. Immunochemistry staining found the consistent results. RT-PCR analysis indicated that chondrogenesis was promoted in co-cultured rat CCs, while expressions of hypertrophic genes were inhibited. However, hWJMSCs showed only slightly improved in chondrogenesis but not significantly different in hypertrophic expressions. In vivo experiments showed that all the pellets filled the defects but co-culture pellets demonstrated reduced hypertrophy, better surrounding cartilage integration and appropriate subchondral bone remodeling.

CONCLUSION

Co-culture of rat CCs and hWJMSCs demonstrated stable chondrogenic phenotype and decreased hypertrophic intendency in both vitro and vivo. These results suggest this co-culture combination as a promising candidate in articular cartilage regeneration.

Scaffold-Based Tissue Engineering Strategies for Osteochondral Repair

Over centuries, several advances have been made in osteochondral (OC) tissue engineering to regenerate more biomimetic tissue. As an essential component of tissue engineering, scaffolds provide structural and functional support for cell growth and differentiation. Numerous scaffold types, such as porous, hydrogel, fibrous, microsphere, metal, composite and decellularized matrix, have been reported and evaluated for OC tissue regeneration in vitro and in vivo, with respective advantages and disadvantages. Unfortunately, due to the inherent complexity of organizational structure and the objective limitations of manufacturing technologies and biomaterials, we have not yet achieved stable and satisfactory effects of OC defects repair. In this review, we summarize the complicated gradients of natural OC tissue and then discuss various osteochondral tissue engineering strategies, focusing on scaffold design with abundant cell resources, material types, fabrication techniques and functional properties.

Anti-hypertrophic effect of synovium-derived stromal cells on costal chondrocytes promotes cartilage repairs

Background

Costal chondrocytes (CCs), as a promising donor cell source for cell-based therapy for cartilage repair, have strong tendency of hypertrophy and calcification, which limited CCs from further application in cartilage regenerative medicine. Synovium-derived stromal cells (SDSCs), have shown their beneficial effect for chondrocytes to maintain phenotype. This study aims to investigate whether SDSCs could help CCs to maintain chondrogenic phenotype and suppress hypertrophic differentiation in cartilage repairs.

Methods

CCs were directly cocultured with SDSCs in pellet or indirectly cocultured using a conditioned medium in vitro for 3 weeks. Cartilage matrix formation and hypertrophic differentiation of CCs were analyzed by RT-PCR, biochemical assays, and histological staining. Cocultured pellets were implanted into the osteochondral defects made on the femoral groove of the rats. Then, macroscopic and histological evaluations were performed.

Results

Pellets formed by CCs alone and CCs cocultured with SDSCs reveal equal cartilage matrix deposition. However, the gene expression of type X collagen was significantly downregulated in cocultured pellets. Immunohistochemistry analysis revealed suppressed expression of type X collagen in cocultured pellets, indicating SDSCs may suppress hypertrophic differentiation of chondrocytes. Further in indirect coculture experiment, SDSCs suppressed type X collagen expression as well and promoted the proliferation of CCs, indicating SDSCs may influence CCs by paracrine mechanism. The pellets implanted in the osteochondral defects showed good restoration effects, whereas the grafts constructed with CCs and SDSCs showed lower type X expression levels.

Conclusion

These results suggest that SDSCs may maintain the phenotype of CCs and prevent the hypertrophic differentiation of CCs in cartilage repair.

The Translational Potential of this Article: CCs is a promising donor cell source for cell-based therapy for cartilage repair. Based on our study, cocultured with SDSCs weakened the tendency of hypertrophy and calcification of CCs, which provide a potential usage of SDSCs in CCs-based cartilage repair therapy to suppress newly formed cartilage calcification and improve clinical outcomes.

Probing Multicellular Tissue Fusion of Cocultured Spheroids-A 3D-Bioassembly Model

While decades of research have enriched the knowledge of how to grow cells into mature tissues, little is yet known about the next phase: fusing of these engineered tissues into larger functional structures. The specific effect of multicellular interfaces on tissue fusion remains largely unexplored. Here, a facile 3D-bioassembly platform is introduced to primarily study fusion of cartilage-cartilage interfaces using spheroids formed from human mesenchymal stromal cells (hMSCs) and articular chondrocytes (hACs). 3D-bioassembly of two adjacent hMSCs spheroids displays coordinated migration and noteworthy matrix deposition while the interface between two hAC tissues lacks both cells and type-II collagen. Cocultures contribute to increased phenotypic stability in the fusion region while close initial contact between hMSCs and hACs (mixed) yields superior hyaline differentiation over more distant, indirect cocultures. This reduced ability of potent hMSCs to fuse with mature hAC tissue further underlines the major clinical challenge that is integration. Together, this data offer the first proof of an in vitro 3D-model to reliably study lateral fusion mechanisms between multicellular spheroids and mature cartilage tissues. Ultimately, this high-throughput 3D-bioassembly model provides a bridge between understanding cellular differentiation and tissue fusion and offers the potential to probe fundamental biological mechanisms that underpin organogenesis.

Effect of a subset of adipose-derived stem cells isolated with liposome magnetic beads to promote cartilage repair

This study aimed to investigate the ability of CD146⁺ subset of ADSCs to repair cartilage defects. In this study, we prepared CD146⁺ liposome magnetic beads (CD146⁺LMB) to isolate CD146⁺ADSCs. The cells were induced for chondrogenic differentiation and verified by cartilage‐specific mRNA and protein expression. Then a mouse model of cartilage defect was constructed and treated by filling the induced cartilage cells into the damaged joint, to evaluate the function of such cells in the cartilage microenvironment. Our results demonstrated that the CD146⁺LMBs we prepared were uniform, small and highly stable, and cell experiments showed that the CD146⁺LMB has low cytotoxicity to the ADSCs. ADSCs isolated with CD146⁺LMB were all CD146⁺, CD105⁺, CD166⁺ and CD73⁺. After chondrogenic induction, the cells showed significantly increased expression of cartilage markers Sox9, collagen Ⅱ and aggrecan at protein level and significantly increased Sox9, collagen Ⅱ and aggrecan at mRNA level, and the protein expression and mRNA expression of CD146⁺ADSCs group were higher than those of ADSCs group. The CD146⁺ADSCs group showed superior tissue repair ability than the ADSCs group and blank control group in the animal experiment, as judged by gross observation, histological observation and histological scoring. The above results proved that CD146⁺LMB can successfully isolate the CD146⁺ADSCs, and after chondrogenic induction, these cells successfully promoted repair of articular cartilage defects, which may be a new direction of tissue engineering.

Heterogeneity of mesenchymal stem cells in cartilage regeneration: from characterization to application

Articular cartilage is susceptible to damage but hard to self-repair due to its avascular nature. Traditional treatment methods are not able to produce satisfactory effects. Mesenchymal stem cells (MSCs) have shown great promise in cartilage repair. However, the therapeutic effect of MSCs is often unstable partly due to their heterogeneity. Understanding the heterogeneity of MSCs and the potential of different types of MSCs for cartilage regeneration will facilitate the selection of superior MSCs for treating cartilage damage. This review provides an overview of the heterogeneity of MSCs at the donor, tissue source and cell immunophenotype levels, including their cytological properties, such as their ability for proliferation, chondrogenic differentiation and immunoregulation, as well as their current applications in cartilage regeneration. This information will improve the precision of MSC-based therapeutic strategies, thus maximizing the efficiency of articular cartilage repair.

In Vitro Human Joint Models Combining Advanced 3D Cell Culture and Cutting-Edge 3D Bioprinting Technologies

Joint-on-a-chip is a new technology able to replicate the joint functions into microscale systems close to pathophysiological conditions. Recent advances in 3D printing techniques allow the precise control of the architecture of the cellular compartments (including chondrocytes, stromal cells, osteocytes and synoviocytes). These tools integrate fluid circulation, the delivery of growth factors, physical stimulation including oxygen level, external pressure, and mobility. All of these structures must be able to mimic the specific functions of the diarthrodial joint: mobility, biomechanical aspects and cellular interactions. All the elements must be grouped together in space and reorganized in a manner close to the joint organ. This will allow the study of rheumatic disease physiopathology, the development of biomarkers and the screening of new drugs.

Feasibility of Human Platelet Lysate as an Alternative to Foetal Bovine Serum for In Vitro Expansion of Chondrocytes

Osteoarthritis (OA) is a degenerative joint disease that affects a lot of people worldwide. Current treatment for OA mainly focuses on halting or slowing down the disease progress and to improve the patient’s quality of life and functionality. Autologous chondrocyte implantation (ACI) is a new treatment modality with the potential to promote regeneration of worn cartilage. Traditionally, foetal bovine serum (FBS) is used to expand the chondrocytes. However, the use of FBS is not ideal for the expansion of cells mean for clinical applications as it possesses the risk of animal pathogen transmission and animal protein transfer to host. Human platelet lysate (HPL) appears to be a suitable alternative to FBS as it is rich in biological factors that enhance cell proliferation. Thus far, HPL has been found to be superior in promoting chondrocyte proliferation compared to FBS. However, both HPL and FBS cannot prevent chondrocyte dedifferentiation. Discrepant results have been reported for the maintenance of chondrocyte redifferentiation potential by HPL. These differences are likely due to the diversity in the HPL preparation methods. In the future, more studies on HPL need to be performed to develop a standardized technique which is capable of producing HPL that can maintain the chondrocyte redifferentiation potential reproducibly. This review discusses the in vitro expansion of chondrocytes with FBS and HPL, focusing on its capability to promote the proliferation and maintain the chondrogenic characteristics of chondrocytes.

A Human Osteochondral Tissue Model Mimicking Cytokine-Induced Key Features of Arthritis In Vitro

Adequate tissue engineered models are required to further understand the (patho)physiological mechanism involved in the destructive processes of cartilage and subchondral bone during rheumatoid arthritis (RA). Therefore, we developed a human in vitro 3D osteochondral tissue model (OTM), mimicking cytokine-induced cellular and matrix-related changes leading to cartilage degradation and bone destruction in order to ultimately provide a preclinical drug screening tool. To this end, the OTM was engineered by co-cultivation of mesenchymal stromal cell (MSC)-derived bone and cartilage components in a 3D environment. It was comprehensively characterized on cell, protein, and mRNA level. Stimulating the OTM with pro-inflammatory cytokines, relevant in RA (tumor necrosis factor α, interleukin-6, macrophage migration inhibitory factor), caused cell- and matrix-related changes, resulting in a significantly induced gene expression of lactate dehydrogenase A, interleukin-8 and tumor necrosis factor α in both, cartilage and bone, while the matrix metalloproteases 1 and 3 were only induced in cartilage. Finally, application of target-specific drugs prevented the induction of inflammation and matrix-degradation. Thus, we here provide evidence that our human in vitro 3D OTM mimics cytokine-induced cell- and matrix-related changes—key features of RA—and may serve as a preclinical tool for the evaluation of both new targets and potential drugs in a more translational setup.

Utility of direct 3D co-culture model for chondrogenic differentiation of mesenchymal stem cells on hyaluronan scaffold (Hyaff-11)

This study presents direct 2D and 3D co-culture model of mesenchymal stem cells (MSCs) line with chondrocytes isolated from patients with osteoarthritis (unaffected area). MSCs differentiation into chondrocytes after 14, 17 days was checked by estimation of collagen I, II, X, aggrecan expression using immunohistochemistry. Visualization, localization of cells on Hyaff-11 was performed using enzymatic technique and THUNDER Imaging Systems. Results showed, that MSCs/chondrocytes 3D co-culture induced suitable conditions for chondrocytes grow and MSCs differentiation than 2D monoculture. Despite that differentiated cells on Hyaff-11 expressed collagen X, they showed high collagen II (80%) and aggrecan (60%) expression with simultaneous decrease of collagen I expression (10%). The high concentration of differentiated cells on Hyaff-11, indicate that this structure has an impact on cells cooperation and communication. In conclusion, we suggest that high expression of collagen II and aggrecan in 3D co-culture model, indicate that cooperation between different subpopulations may have synergistic impact on MSCs chondrogenic potential. Revealed the high concentration and localization of cells growing in deeper layers of membrane in 3D co-culture, indicate that induced microenvironmental enhance cell migration within scaffold. Additionally, we suggest that co-culture model might be useful for construction a bioactive structure for cartilage tissue regeneration.

The use of large animals to facilitate the process of MSC going from laboratory to patient-'bench to bedside'

Large animal models have been widely used to facilitate the translation of mesenchymal stem cells (MSC) from the laboratory to patient. MSC, with their multi-potent capacity, have been proposed to have therapeutic benefits in a number of pathological conditions. Laboratory studies allow the investigation of cellular and molecular interactions, while small animal models allow initial 'proof of concept' experiments. Large animals (dogs, pigs, sheep, goats and horses) are more similar physiologically and structurally to man. These models have allowed clinically relevant assessments of safety, efficacy and dosing of different MSC sources prior to clinical trials. In this review, we recapitulate the use of large animal models to facilitate the use of MSC to treat myocardial infarction-an example of one large animal model being considered the 'gold standard' for research and osteoarthritis-an example of the complexities of using different large animal models in a multifactorial disease. These examples show how large animals can provide a research platform that can be used to evaluate the value of cell-based therapies and facilitate the process of 'bench to bedside'.

Chondrocyte Culture Parameters for Matrix-Assisted Autologous Chondrocyte Implantation Affect Catabolism and Inflammation in a Rabbit Model

Cartilage defects represent an increasing pathology among active individuals that affects the ability to contribute to sports and daily life. Cell therapy, such as autologous chondrocyte implantation (ACI), is a widespread option to treat larger cartilage defects still lacking standardization of in vitro cell culture parameters. We hypothesize that mRNA expression of cytokines and proteases before and after ACI is influenced by in vitro parameters: cell-passage, cell-density and membrane-holding time. Knee joint articular chondrocytes, harvested from rabbits (n = 60), were cultured/processed under varying conditions: after three different cell-passages (P1, P3, and P5), cells were seeded on 3D collagen matrices (approximately 25 mm³) at three different densities (2 × 10⁵/matrix, 1 × 10⁶/matrix, and 3 × 10⁶/matrix) combined with two different membrane-holding times (5 h and two weeks) prior autologous transplantation. Those combinations resulted in 18 different in vivo experimental groups. Two defects/knee/animal were created in the trochlear groove (defect dimension: ∅ 4 mm × 2 mm). Four identical cell-seeded matrices (CSM) were assembled and grouped in two pairs: One pair giving pre-operative in vitro data (CSM-i), the other pair was implanted in vivo and harvested 12 weeks post-implantation (CSM-e). CSMs were analyzed for TNF-α, IL-1β, MMP-1, and MMP-3 via qPCR. CSM-i showed higher expression of IL-1β, MMP-1, and MMP-3 compared to CSM-e. TNF-α expression was higher in CSM-e. Linearity between CSM-i and CSM-e values was found, except for TNF-α. IL-1β expression was higher in CSM-i at higher passage and longer membrane-holding time. IL-1β expression decreased with prolonged membrane-holding time in CSM-e. For TNF-α, the reverse was true. Lower cell-passages and lower membrane-holding time resulted in stronger TNF-α expression. Prolonged membrane-holding time resulted in increased MMP levels among CSM-i and CSM-e. Cellular density was of no significant effect. We demonstrated cytokine and MMP expression levels to be directly influenced by in vitro culture settings in ACI. Linearity of expression-patterns between CSM-i and CSM-e may predict ACI regeneration outcome in vivo. Cytokine/protease interaction within the regenerate tissue could be guided via adjusting in vitro culture parameters, of which membrane-holding time resulted the most relevant one.

Short exposure to tranexamic acid does not affect, in vitro, the viability of human chondrocytes

BACKGROUND

Only few studies have investigated the effect of topical application of tranexamic acid (TXA) on "minimally" invasive joint surgical procedures in which articular cartilage is preserved; for this reason, actually many surgeons avoid the use of topical TXA even if the disadvantage related to a blood loss can occur. The aim of this study was to evaluate the cytotoxicity, on human chondrocytes, of TXA at different concentrations and times of exposure and the mechanisms of cell death.

METHODS

Experiments were carried out on isolated human chondrocytes harvested from eight patients who underwent total knee replacement. Cell viability was determined using XTT assay and was assessed at 0, 24 and 48 h intervals after a 10-min-long treatment, followed by thorough washes, or at 24 and 48 h of treatment at TXA concentrations of 20, 50, 70 and 100 mg/ml. Cell cycle alterations and occurrence of cell death for apoptosis or necrosis were assessed by cytofluorimetry. Data were analyzed using Proc Mixed Procedure; LSMEANS was used to compare multiple group means with Tukey's honestly significant difference test.

RESULTS

A significant correlation between the controlled for factors (type of treatment, time and concentration) was found in the performed experiment. No significant effect on cell viability was observed when the TXA exposure was limited to 10 min, while for increased exposure, 24 and 48 h, a remarkable reduction was found; cell death occurred by apoptosis and was already appreciable after 24 h, reaching a statistical significance after the 48-h-long treatment.

CONCLUSION

A prolonged exposure to TXA may cause cartilage damage, thus its topical application can be expanded also to clinical scenarios that include retention of native cartilage chondrocytes, only if it is limited to few minutes and used at concentrations of 70 mg/ml or less.