Effect of interleukin-1β treatment on co-cultures of human meniscus cells and bone marrow mesenchymal stromal cells

Current advances in engineering meniscal tissues: insights into 3D printing, injectable hydrogels and physical stimulation based strategies

The knee meniscus is the cushioning fibro-cartilage tissue present in between the femoral condyles and tibial plateau of the knee joint. It is largely avascular in nature and suffers from a wide range of tears and injuries caused by accidents, trauma, active lifestyle of the populace and old age of individuals. Healing of the meniscus is especially difficult due to its avascularity and hence requires invasive arthroscopic approaches such as surgical resection, suturing or implantation. Though various tissue engineering approaches are proposed for the treatment of meniscus tears, three-dimensional (3D) printing/bioprinting, injectable hydrogels and physical stimulation involving modalities are gaining forefront in the past decade. A plethora of new printing approaches such as direct light photopolymerization and volumetric printing, injectable biomaterials loaded with growth factors and physical stimulation such as low-intensity ultrasound approaches are being added to the treatment portfolio along with the contemporary tear mitigation measures. This review discusses on the necessary design considerations, approaches for 3D modeling and design practices for meniscal tear treatments within the scope of tissue engineering and regeneration. Also, the suitable materials, cell sources, growth factors, fixation and lubrication strategies, mechanical stimulation approaches, 3D printing strategies and injectable hydrogels for meniscal tear management have been elaborated. We have also summarized potential technologies and the potential framework that could be the herald of the future of meniscus tissue engineering and repair approaches.

Comparison of temporomandibular joint disc, meniscus, and intervertebral disc in fundamental characteristics and tissue engineering

The temporomandibular joint (TMJ) disc, meniscus and intervertebral disc (IVD) are three fibrocartilage discs, which play critical roles in our daily life. Their degeneration contributes to diseases such as TMJ disorders, osteoarthritis and degenerative disc disease, affecting patients' quality of life and causing substantial morbidity and mortality. Interestingly, similar in some aspects of fundamental characteristics, they exhibit differences in other aspects such as biomechanical properties. Highlighting these similarities and differences can not only benefit a comprehensive understanding of them and their pathology but also assist in future research of tissue engineering. Likewise, comparing their tissue engineering in cell sources, scaffold and stimuli can guide imitation and improvement of their engineered discs. However, the anatomical structure, function, and biomechanical characteristics of the IVD, TMJ, and Meniscus have not been compared in any meaningful depth needed to advance current tissue engineering research on these joints, resulting in incomplete understanding of them and their pathology and ultimately limiting future research of tissue engineering. This review, for the first time, comprehensively compares three fibrocartilage discs in those aspects to cast light on their similarities and differences.

Biomolecules-releasing click chemistry-based bioadhesives for repairing acetabular labrum tears

Currently, there are no effective clinical or experimental treatments to fully restore the function of the torn acetabular labrum. To fill the gap, here, we report the finding of progenitor cells in labral tissue, which can be recruited and stimulated to repair torn acetabular labral tissue. This study aimed to develop a biomolecule releasing bioadhesive which can speed up labral tissue healing by eliciting autologous labral progenitor cellular responses. A click chemistry-based bioadhesive, capable of releasing biomolecules, was synthesized to exert ~3× adhesion strength compared with fibrin glue. Via the release of platelet-derived growth factor (PDGF), the adhesive was shown to actively recruit and stimulate the proliferation of labral progenitor cells to the tear sites and within the adhesive. Finally, the ability of this biomolecules-releasing adhesive designed to promote labral tissue regeneration was evaluated using discarded human acetabular labrum tissue compared with surgical suture ex vivo. Histological analysis shows that PDGF-releasing bioadhesive yielded significantly more labrum cell responses and extracellular matrix protein (proteoglycan and collagen) production at the tear tissue site than surgical suture controls. The results confirm that the new PDGF-releasing bioadhesive can activate the responses of autologous labral progenitor cells to significantly improve labral tissue regeneration. Clinical significance: These PDGF-releasing bioadhesives may serve as a new and effective tool for repairing and regenerating acetabular labrum tears.

Meniscus Repair and Regeneration: A Systematic Review from a Basic and Translational Science Perspective

Meniscus injuries are among the most common athletic injuries and result in functional impairment in the knee. Repair is crucial for pain relief and prevention of degenerative joint diseases like osteoarthritis. Current treatments, however, do not produce long-term improvements. Thus, recent research has been investigating new therapeutic options for regenerating injured meniscal tissue. This review comprehensively details the current methodologies being explored in the basic sciences to stimulate better meniscus injury repair. Furthermore, it describes how these preclinical strategies may improve current paradigms of how meniscal injuries are clinically treated through a unique and alternative perspective to traditional clinical methodology.

Evaluation of culture conditions for in vitro meniscus repair model systems using bone marrow-derived mesenchymal stem cells

Purpose: Meniscal injury and loss of meniscus tissue lead to osteoarthritis development. Therefore, novel biologic strategies are needed to enhance meniscus tissue repair. The purpose of this study was to identify a favorable culture medium for both bone marrow-derived mesenchymal stem cells (MSCs) and meniscal tissue, and to establish a novel meniscus tissue defect model that could be utilized for in vitro screening of biologics to promote meniscus repair.Materials and Methods: In parallel, we analyzed the biochemical properties of MSC - seeded meniscus-derived matrix (MDM) scaffolds and meniscus repair model explants cultured in different combinations of serum, dexamethasone (Dex), and TGF-β. Next, we combined meniscus tissue and MSC-seeded MDM scaffolds into a novel meniscus tissue defect model to evaluate the effects of chondrogenic and meniscal media on the tissue biochemical properties and repair strength.Results: Serum-free medium containing TGF-β and Dex was the most promising formulation for experiments with MSC-seeded scaffolds, whereas serum-containing medium was the most effective for meniscus tissue composition and integrative repair. When meniscus tissue and MSC-seeded MDM scaffolds were combined into a defect model, the chondrogenic medium (serum-free with TGF-β and Dex) enhanced the production of proteoglycans and promoted integrative repair of meniscus tissue. As well, cross-linked scaffolds improved repair over the MDM slurry.Conclusions: The meniscal tissue defect model established in this paper can be used to perform in vitro screening to identify and optimize biological treatments to enhance meniscus tissue repair prior to conducting preclinical animal studies.

Current Concepts in Meniscus Tissue Engineering and Repair

The meniscus is the most commonly injured structure in the human knee. Meniscus deficiency has been shown to lead to advanced osteoarthritis (OA) due to abnormal mechanical forces, and replacement strategies for this structure have lagged behind other tissue engineering endeavors. The challenges include the complex 3D structure with individualized size parameters, the significant compressive, tensile and shear loads encountered, and the poor blood supply. In this progress report, a review of the current clinical treatments for different types of meniscal injury is provided. The state-of-the-art research in cellular therapies and novel cell sources for these therapies is discussed. The clinically available cell-free biomaterial implants and the current progress on cell-free biomaterial implants are reviewed. Cell-based tissue engineering strategies for the repair and replacement of meniscus are presented, and the current challenges are identified. Tissue-engineered meniscal biocomposite implants may provide an alternative solution for the treatment of meniscal injury to prevent OA in the long run, because of the limitations of the existing therapies.

A review of in-vitro fibrocartilage tissue engineered therapies with a focus on the temporomandibular joint

The inability of fibrocartilage, specifically the temporomandibular joint (TMJ) disc, to regenerate and remodel following injury presents a unique problem for clinicians. Tissue engineering then offers a potential regenerative therapy. In vitro testing provides a valuable screening tool for potential tissue engineered solutions. The conclusions drawn for TMJ in vitro research were compared against state of the art fibrocartilage studies in the knee meniscus, and annulus fibrosus of the intervertebral disc (IVD). For TMJ disc regeneration, in vitro tissue engineered approaches, focused on cellular therapies with fibrochondrocytes, have displayed an inability to produce enough collagen, as well as an inability to recapitulate native mechanical properties. Biomaterial approaches have recapitulated the native properties of the TMJ disc, but their in vivo efficacy has yet to be determined. By comparison, the knee meniscus field is the most progressive in the use of stem cells as a cell source. The knee meniscus field has moved away from measuring mechanical properties, and are instead more focused on biochemistry and gene expression. IVD studies mainly use electrospun scaffolds, and have produced the best success in mechanical properties. The TMJ field, in comparison to knee meniscus and IVD, needs to employ stem cell therapies, new biomaterials and manufacturing techniques, and cutting edge molecular assays, in future in vitro approaches to screen for viable technologies to move to in vivo studies.

Cell-Based Strategies for Meniscus Tissue Engineering

Meniscus injuries remain a significant challenge due to the poor healing potential of the inner avascular zone. Following a series of studies and clinical trials, tissue engineering is considered a promising prospect for meniscus repair and regeneration. As one of the key factors in tissue engineering, cells are believed to be highly beneficial in generating bionic meniscus structures to replace injured ones in patients. Therefore, cell-based strategies for meniscus tissue engineering play a fundamental role in meniscal regeneration. According to current studies, the main cell-based strategies for meniscus tissue engineering are single cell type strategies; cell coculture strategies also were applied to meniscus tissue engineering. Likewise, on the one side, the zonal recapitulation strategies based on mimicking meniscal differing cells and internal architectures have received wide attentions. On the other side, cell self-assembling strategies without any scaffolds may be a better way to build a bionic meniscus. In this review, we primarily discuss cell seeds for meniscus tissue engineering and their application strategies. We also discuss recent advances and achievements in meniscus repair experiments that further improve our understanding of meniscus tissue engineering.

Meniscus repair using mesenchymal stem cells - a comprehensive review

The menisci are a pair of semilunar fibrocartilage structures that play an essential role in maintaining normal knee function. Injury to the menisci can disrupt joint stability and lead to debilitating results. Because natural meniscal healing is limited, an efficient method of repair is necessary. Tissue engineering (TE) combines the principles of life sciences and engineering to restore the unique architecture of the native meniscus. Mesenchymal stem cells (MSCs) have been investigated for their therapeutic potential both in vitro and in vivo. This comprehensive review examines the English literature identified through a database search using Medline, Embase, Engineering Village, and SPORTDiscus. The search results were classified based on MSC type, animal model, and method of MSC delivery/culture. A variety of MSC types, including bone marrow-derived, synovium-derived, adipose-derived, and meniscus-derived MSCs, has been examined. Research results were categorized into and discussed by the different animal models used; namely murine, leporine, porcine, caprine, bovine, ovine, canine, equine, and human models of meniscus defect/repair. Within each animal model, studies were categorized further according to MSC delivery/culture techniques. These techniques included direct application, fibrin glue/gel/clot, intra-articular injection, scaffold, tissue-engineered construct, meniscus tissue, pellets/aggregates, and hydrogel. The purpose of this review is to inform the reader about the current state and advances in meniscus TE using MSCs. Future directions of MSC-based meniscus TE are also suggested to help guide prospective research.

The inflammatory cytokine IL-1β is involved in bladder remodeling after bladder outlet obstruction in mice

AIMS

We investigated the relationship between IL-1β and morphological and functional changes following partial bladder outlet obstruction (pBOO).

METHODS

Female wild-type C57/BL6 mice (WT) and IL-1β-/- mice (KO) were used. Animals were sacrificed either 1 or 3 weeks after pBOO or sham surgery, and their bladders were harvested to determine bladder weight, for RT-PCR to measure interleukin-1β (IL-1β), insulin growth factor-1 (IGF-1), and transforming growth factor-β (TGF-β) levels, and for histological analysis with Hematoxylin-Eosin (HE) staining. Cystometry was performed on conscious animals 3 weeks after surgery to evaluate urodynamic parameters. IGF-1 was also administered intraperitoneally to KO with pBOO, and bladder weight was then investigated.

RESULTS

IL-1β-mRNA levels were significantly higher in WT-pBOO than in WT-sham. IGF-1-mRNA and TGF-β-mRNA levels were also significantly higher in WT-pBOO than in WT-sham; however, these increases were smaller in KO-pBOO than in WT-pBOO. Bladder weight was significantly higher in WT-pBOO than in WT-sham, while increases in bladder weight were significantly suppressed in KO-pBOO. HE staining revealed the thickened bladder wall in WT-pBOO, and this phenomenon was less in KO-pBOO than in WT-pBOO. Regarding the urodynamic parameters examined, micturition pressure and bladder capacity were significantly higher in WT-pBOO than in WT-sham, but remained unchanged in KO-pBOO. The administration of IGF-1 to KO-pBOO led to similar increases in bladder weight and the thickened bladder wall as those observed in WT-pBOO.

CONCLUSION

IL-1β has the potential to induce bladder remodeling and deteriorate urodynamic parameters in pBOO.

Human multipotent mesenchymal stem cells improve healing after collagenase tendon injury in the rat

Background

Mesenchymal stromal cells attract much interest in tissue regeneration because of their capacity to differentiate into mesodermal origin cells, their paracrine properties and their possible use in autologous transplantations. The aim of this study was to investigate the safety and reparative potential of implanted human mesenchymal stromal cells (hMSCs), prepared under Good Manufacturing Practice (GMP) conditions utilizing human mixed platelet lysate as a culture supplement, in a collagenase Achilles tendon injury model in rats.

Methods

Eighty-one rats with collagenase-induced injury were divided into two groups. The first group received human mesenchymal stromal cells injected into the site of injury 3 days after lesion induction, while the second group received saline. Biomechanical testing, morphometry and semiquantitative immunohistochemistry of collagens I, II and III, versican and aggrecan, neovascularization, and hMSC survival were performed 2, 4, and 6 weeks after injury.

Results

Human mesenchymal stromal cell-treated rats had a significantly better extracellular matrix structure and a larger amount of collagen I and collagen III. Neovascularization was also increased in hMSC-treated rats 2 and 4 weeks after tendon injury. MTCO2 (Cytochrome c oxidase subunit II) positivity confirmed the presence of hMSCs 2, 4 and 6 weeks after transplantation. Collagen II deposits and alizarin red staining for bone were found in 6 hMSC- and 2 saline-treated tendons 6 weeks after injury. The intensity of anti-versican and anti-aggrecan staining did not differ between the groups.

Conclusions

hMSCs can support tendon healing through better vascularization as well as through larger deposits and better organization of the extracellular matrix. The treatment procedure was found to be safe; however, cartilage and bone formation at the implantation site should be taken into account when planning subsequent in vivo and clinical trials on tendinopathy as an expected adverse event.