Fibrocartilage Tissue Research Articles

Exercise Induced Endothelial Mesenchymal Transition (EndMT) Facilitates Meniscal Fibrocartilage Regeneration.

The meniscus is a semilunar wedge-shaped fibrocartilage tissue within the knee joint that is important for withstanding mechanical shock during joint motion. The intrinsic healing capacity of meniscus tissue is very limited, which makes meniscectomy the primary treatment method in the clinic. An effective translational strategy for regenerating the meniscus after total or subtotal meniscectomy, particularly for extensive meniscal lesions or degeneration, is yet to be developed. The present study demonstrates that the endothelial mesenchymal transition (EndMT) contributes to meniscal regeneration. The mechanical stimulus facilitated EndMT by activating TGF-β2 signaling. A handheld bioprinter system to intraoperatively fabricate a porous meniscus scaffold according to the resected meniscus tissue is developed; this can simplify the scaffold fabrication procedure and period. The transplantation of a porous meniscus scaffold combined with a postoperative regular exercise stimulus facilitated the regeneration of anisotropic meniscal fibrocartilaginous tissue and protected the joint cartilage from degeneration in an ovine subtotal meniscectomy model. Single-cell RNA sequencing and immunofluorescence co-staining analyses further confirmed the occurrence of EndMT during meniscal regeneration. EndMT-transformed cells gave rise to fibrochondrocytes, subsequently contributing to meniscal fibrocartilage regeneration. Thus, an efficient translational strategy to facilitate meniscal regeneration is developed.

Donor ethnicity, sex, and age impact chondrogenic re-differentiation capacity: a multi-demographic study of human articular chondrocytes in vitro

ABSTRACT To unravel causes of disparities in osteoarthritis (OA) prevalence and to improve cell-based cartilage repair treatments, there is need to investigate the multifactorial impact of patient demographics on a biophysiological level. In this study, we systematically analyse single- and multi-demographic impact on in vitro chondrogenic re-differentiation capacity of human articular chondrocytes (hACs), specifically of an Aotearoa-New Zealand (NZ) patient cohort which displays unique demographic diversity. HACs were isolated from 14 NZ donors with distinct demographics (ethnicity: indigenous Māori vs European descendant Pākehā; sex; age 18–24 vs 25–30 yrs). In vitro chondrogenic re-differentiation capacity of donor chondrocytes was assessed through quantifications of cartilage matrix deposition (GAG, DNA, GAG/DNA) and by histological visualisation. Isolated chondrocytes ranged from low chondrogenic re-differentiation capacity, characterised by fibrocartilage tissue deposition, to high re-differentiation capacity to deposit GAG-rich tissue. Age-related reduction in GAG/DNA content was detected while no impact of ethnicity or sex was observed. Multi-demographic analysis revealed reduced GAG deposition in Māori male (compared to Māori female), and Māori (18–24 yrs) compared to Māori (25–30 yrs) and Pākehā (18–24 yrs) within our cohort. Multi-demographic analysis is a promising strategy to understand disparities in OA prevalence in patient cohorts and can help guide development of cell-based strategies for diverse patient populations.

A rare case of eyelid choriostoma in an adult male: A case report

Choristomas are rare tumors, commonly occurring in the head and neck region. These are defined as the presence of normal tissues, such as muscle, bone, cartilage, dermal appendages, and epidermal components, in abnormal locations. They are mostly seen in the pediatric population. Occurrence in the adult population is fairly rare. Ocular choristomas comprise a substantial portion of all conjunctival and corneal tumors. These are the most common types of epibulbar and orbital tumors in children. Rarely, they may present as a growth in the eyelid region. The authors present one such rare case of eyelid choristoma masquerading as a chalazion, in an elderly patient. The patient presented with an eyelid mass, initially diagnosed as a Chalazion. The mass was excised and sent for histopathological evaluation, which revealed fibrocartilagenous tissue, suggesting a choristoma. The patient was followed up for a period of six months, without any recurrence.

A role for TGFβ signaling in Gli1+ tendon and enthesis cells.

The development of musculoskeletal tissues such as tendon, enthesis, and bone relies on proliferation and differentiation of mesenchymal progenitor cells. Gli1+ cells have been described as putative stem cells in several tissues and are presumed to play critical roles in tissue formation and maintenance. For example, the enthesis, a fibrocartilage tissue that connects tendon to bone, is mineralized postnatally by a pool of Gli1+ progenitor cells. These cells are regulated by hedgehog signaling, but it is unclear if TGFβ signaling, necessary for tenogenesis, also plays a role in their behavior. To examine the role of TGFβ signaling in Gli1+ cell function, the receptor for TGFβ, TbR2, was deleted in Gli1-lineage cells in mice at P5. Decreased TGFβ signaling in these cells led to defects in tendon enthesis formation by P56, including defective bone morphometry underlying the enthesis and decreased mechanical properties. Immunohistochemical staining of these Gli1+ cells showed that loss of TGFβ signaling reduced proliferation and increased apoptosis. Invitro experiments using Gli1+ cells isolated from mouse tail tendons demonstrated that TGFβ controls cell proliferation and differentiation through canonical and non-canonical pathways and that TGFβ directly controls the tendon transcription factor scleraxis by binding to its distant enhancer. These results have implications in the development of treatments for tendon and enthesis pathologies.

DEVELOPMENT OF PHOTO-CROSSLINKABLE DECELLULARIZED EXTRACELLULAR MATRIX HYDROGELS FOR CARTILAGE TISSUE ENGINEERING

Cartilage lacks the ability to self-repair when damaged, which can lead to the development of degenerative joint disease. Despite intensive research in the field of cartilage tissue engineering, there is still no regenerative treatment that consistently promotes the development of hyaline cartilage. Extracellular matrix (ECM) derived hydrogels have shown to support cell adhesion, growth and differentiation [1,2]. In this study, porcine articular cartilage was decellularized, solubilised and subsequently modified into a photo-crosslinkable methacrylated cartilage ECM hydrogel. Bone marrow derived mesenchymal stem/stromal cells (MSCs) were encapsulated into both methacrylated ECM hydrogels (ECM-MA) and gelatin methacryloyl (GelMA) as control hydrogel, and their chondrogenic potential was assessed using biochemical assays and histological analysis. We found that successful decellularization of the cartilage tissue could be achieved while preserving key ECM components, including collagen and glycosaminoglycans. A live-dead assay demonstrated good viability of MSCs withing both GelMA and ECM-MA hydrogels on day 7. Large increases in sGAG accumulation was observed after 21 days of culture in chondrogenic media in both groups. Histological analysis revealed the presence of a more fibrocartilage tissue in the GelMA group, while cells embedded within the ECM-MA showed a round and chondrocytic-like morphology. Both groups stained positively for proteoglycans and collagen, with limited evidence of calcium deposition following Alizarin Red staining. These results show that ECM-MA hydrogels support a hyaline cartilage phenotype and robust cartilaginous matrix production. Future studies will focus on the printability of ECM-MA hydrogels to enable their use as bioinks for the biofabrication of functional tissues.

Heterogeneous Characteristics of the CD90+ Progenitors in the Fibrocartilage of Different Joints.

This study aimed to isolate and compare the mesenchymal stem cell characteristics of CD90+ cells from different fibrocartilage tissues in the temporomandibular joint (TMJ), the knee joint, and the intervertebral joint to further understand the similarities and differences of these 4 fibrocartilage tissues. CD90+ cells were isolated from TMJ disc, condylar cartilage, meniscus, and intervertebral disc by using magnetic-activated cell sorting. Cellular assays including 4.5-ethynyl-2'-deoxyuridine labeling, multilineage differentiation, colony formation, and cell migration were conducted to compare their mesenchymal stem cell characteristics. Immunofluorescent staining was performed for observing the expression of actively proliferating CD90+ cells within the tissues. H&E staining and Safranine O staining were used to compare the histological features. The CD90+ cells derived from these 4 fibrocartilage tissues exhibited comparable cell proliferation abilities. However, the cells from the TMJ disc displayed limited multilineage differentiation potential, colony formation, and cell migration abilities in comparison with the cells from the other fibrocartilage tissues. In vivo, there was relatively more abundant expression of CD90+ cells in the TMJ disc during the early postnatal stage. The limited EDU+ cell numbers signified a low proliferation capacity of CD90+ cells in the TMJ disc. In addition, we observed a significant decrease in cell density and a restriction in the synthesis of extracellular proteoglycans in the TMJ disc. Our study highlights the spatial heterogeneity of CD90+ cells in the fibrocartilages of different joint tissues, which may contribute to the limited cartilage repair capacity in the TMJ disc.

Reconstruction of Fibrocartilage with Fibrous Alignment of Type I Collagen in Scaffold-Free Manner.

For functional reconstruction of fibrocartilage, it is necessary to reproduce the essential mechanical property exhibited by natural fibrocartilage. The distinctive mechanical property of fibrocartilage is originated from the specific histological features of fibrocartilage composed of highly aligned type I collagen (Col I) and an abundant cartilaginous matrix. While the application of tensile stimulation induces highly aligned Col I, our study reveals that it also exerts an antichondrogenic effect on scaffold-free tissues constructed with meniscal chondrocytes (MCs) and induces downregulation of Sox-9 expression and attenuated glycosaminoglycan production. Modulation of mechanotransduction by blocking nuclear translocation of Yes-associated protein (YAP) ameliorated the antichondrogenic effect in the presence of tensile stimulation. Since MCs subjected to mechanical doses either by surface stiffness or tensile stimulation showed reversibility of YAP status even after a long-term exposure to mechanotransduction, fibrocartilage tissue was constructed by sequentially inducing tissue alignment by tensile stimulation followed by inducing cartilaginous matrix production in a tension-released state. The minimal tensile dose to constitute durable tissue alignment was screened by investigating the alignment of cytoskeleton and Col I after culturing the scaffold-free tissue constructs with various tensile doses (10% static tension for 1, 3, 7, and 10 days) followed by maintaining in a released state for 5 days. Fluorescence-conjugated phalloidin binding and immunofluorescence of Col I indicated that the duration of static tension for more than 7 days resulted in durable tissue alignment for at least 5 days in the tension-released state. The tissues subjected to tensile stimulation for 7 days followed by 14 days in a released state in chondrogenic media resulted in abundant cartilaginous matrix as well as uniaxial anisotropic alignment. Our results show that the optimized tensile dose can facilitate the successful reconstruction of fibrocartilage by modulating the characteristics of matrix production by MCs.

Scaffold-based tissue engineering strategies for temporomandibular joint disc regeneration and replacement

The temporomandibular joint (TMJ) disc is a fibrocartilage tissue located between the mandibular condyle and the glenoid eminence, which is central to the TMJ functions. The TMJ disc is susceptible to irreparable degenerative changes or post-traumatic injuries, which can lead to the development of a disc-related disease. Scaffold-based tissue engineering offers the potential for regeneration and replacement of the damaged TMJ disc. The present review describes the biomaterials and manufacturing technologies used in scaffold-based TMJ disc engineering strategies and comprehensively evaluates the advantages and disadvantages of each strategy. As an understanding of the extracellular matrix (ECM) is fundamental for succesful TMJ disc tissue engineering, this review defines the key properties and roles of the TMJ disc ECM. Compared with the natural disc, the mechanical properties of the tissue-engineered TMJ disc are not satisfactory. Additionally, the in vivo durability of engineered discs and their long-term impact on the entire TMJ remain to be studied, especially in large-animal preclinical trials.

Investigation of the effect of plasma jet on regeneration of rabbit knee cartilage

Articular cartilage is a connective tissue biomechanically, so the absence of blood vessels, nerves, lymph flow and low metabolism causes its slow and delayed regeneration. Therefore, it is very important to use the correct treatment methods for cartilage healing. Рurpose of study: Investigating the effect of plasma jet on rabbit knee cartilage regeneration. The present research was conducted on 12 New Zealand white adult male rabbits weighing approximately 2.0-2.5 kg. In order to prepare the knee cartilage, its debridement was sanitized by chondrectomy with scraping method in all three treatment groups. After three weeks of treatment, the rabbits were euthanized and the amount of cartilage regeneration was recorded macroscopically and by recording images, and samples were fixed in 10% formalin for histopathology test. The commonly used in pathology laboratories staining method was chosen. Observation and measurement of articular cartilage thickness was done with eye graticule. And at the end, the obtained data were analyzed statistically. The results obtained in the present study indicated that the use of plasma jet method improves the cartilage tissue in such a way that by examining the histopathological sections, it was found that the articular cartilage in the plasma jet group caused the formation of fibrocartilage tissue in the place of injury. Plasma jet has a positive effect on rabbit cartilage regeneration.

Advances in 3D printing techniques for cartilage regeneration of temporomandibular joint disc and mandibular condyle.

Temporomandibular joint (TMJ) osteoarthritis causes fibrocartilage damage to the TMJ disc and mandibular condyle, resulting in local pain and functional impairment that further reduces patients' quality of life. Tissue engineering offers a potential treatment for fibrocartilage regeneration of the TMJ disc and mandibular condyle. However, the heterogeneous structure of TMJ fibrocartilage tissue poses significant challenges for the fabrication of biomimetic scaffolds. Over the past two decades, some researchers have attempted to adopt three-dimensional (3D) printing techniques to fabricate biomimetic scaffolds for TMJ fibrocartilage regeneration, but publications on such attempts are limited and rarely report satisfactory results, indicating an urgent need for further development. This review outlines several popular 3D printing techniques and the significant elements of tissue-engineered scaffolds: seed cells, scaffold materials, and bioactive factors. Current research progress on 3D-printed scaffolds for fibrocartilage regeneration of the TMJ disc and mandibular condyle is reviewed. The current challenges in TMJ tissue engineering are mentioned along with some emerging tissue-engineering strategies, such as machine learning, stimuli-responsive delivery systems, and extracellular vesicles, which are considered as potential approaches to improve the performance of 3D-printed scaffolds for TMJ fibrocartilage regeneration. This review is expected to inspire the further development of 3D printing techniques for TMJ fibrocartilage regeneration.

Chondroitinase ABC Treatment Improves the Organization and Mechanics of 3D Bioprinted Meniscal Tissue.

The meniscus is a fibrocartilage tissue that is integral to the correct functioning of the knee joint. The tissue possesses a unique collagen fiber architecture that is integral to its biomechanical functionality. In particular, a network of circumferentially aligned collagen fibers function to bear the high tensile forces generated in the tissue during normal daily activities. The limited regenerative capacity of the meniscus has motivated increased interest in meniscus tissue engineering; however, the in vitro generation of structurally organized meniscal grafts with a collagen architecture mimetic of the native meniscus remains a significant challenge. Here we used melt electrowriting (MEW) to produce scaffolds with defined pore architectures to impose physical boundaries upon cell growth and extracellular matrix production. This enabled the bioprinting of anisotropic tissues with collagen fibers preferentially oriented parallel to the long axis of the scaffold pores. Furthermore, temporally removing glycosaminoglycans (sGAGs) during the early stages of in vitro tissue development using chondroitinase ABC (cABC) was found to positively impact collagen network maturation. Specially we found that temporal depletion of sGAGs is associated with an increase in collagen fiber diameter without any detrimental effect on the development of a meniscal tissue phenotype or subsequent extracellular matrix production. Moreover, temporal cABC treatment supported the development of engineered tissues with superior tensile mechanical properties compared to empty MEW scaffolds. These findings demonstrate the benefit of temporal enzymatic treatments when engineering structurally anisotropic tissues using emerging biofabrication technologies such as MEW and inkjet bioprinting.

A comparative study on various cell sources for constructing tissue-engineered meniscus.

Injury to the meniscus is a common occurrence in the knee joint and its management remains a significant challenge in the clinic. Appropriate cell source is essential to cell-based tissue regeneration and cell therapy. Herein, three commonly used cell sources, namely, bone marrow mesenchymal stem cell (BMSC), adipose-derived stem cell (ADSC), and articular chondrocyte, were comparatively evaluated to determine their potential for engineered meniscus tissue in the absence of growth factor stimulus. Cells were seeded on electrospun nanofiber yarn scaffolds that share similar aligned fibrous configurations with native meniscus tissue for constructing meniscus tissue in vitro. Our results show that cells proliferated robustly along nanofiber yarns to form organized cell-scaffold constructs, which recapitulate the typical circumferential fiber bundles of native meniscus. Chondrocytes exhibited different proliferative characteristics and formed engineered tissues with distinct biochemical and biomechanical properties compared to BMSC and ADSC. Chondrocytes maintained good chondrogenesis gene expression profiles and produced significantly increased chondrogenic matrix and form mature cartilage-like tissue as revealed by typical cartilage lacunae. In contrast, stem cells underwent predominately fibroblastic differentiation and generated greater collagen, which contributes to improved tensile strengths of cell-scaffold constructs in comparison to the chondrocyte. ADSC showed greater proliferative activity and increased collagen production than BMSC. These findings indicate that chondrocytes are superior to stem cells for constructing chondrogenic tissues while the latter is feasible to form fibroblastic tissue. Combination of chondrocytes and stem cells might be a possible solution to construct fibrocartilage tissue and meniscus repair and regeneration.

Bioprinting of structurally organized meniscal tissue within anisotropic melt electrowritten scaffolds.

The meniscus is characterised by an anisotropic collagen fibre network which is integral to its biomechanical functionality. The engineering of structurally organized meniscal grafts that mimic the anisotropy of the native tissue remains a significant challenge. In this study, inkjet bioprinting was used to deposit a cell-laden bioink into additively manufactured scaffolds of differing architectures to engineer fibrocartilage grafts with user defined collagen architectures. Polymeric scaffolds consisting of guiding fibre networks with varying aspect ratios (1:1; 1:4; 1:16) were produced using either fused deposition modelling (FDM) or melt electrowriting (MEW), resulting in scaffolds with different internal architectures and fibre diameters. Scaffold architecture was found to influence the spatial organization of the collagen network laid down by the jetted cells, with higher aspect ratios (1:4 and 1:16) supporting the formation of structurally anisotropic tissues. The MEW scaffolds supported the development of a fibrocartilaginous tissue with compressive mechanical properties similar to that of native meniscus, while the anisotropic tensile properties of these constructs could be tuned by altering the fibre network aspect ratio. This MEW framework was then used to generate scaffolds with spatially distinct fibre patterns, which in turn supported the development of heterogenous tissues consisting of isotropic and anisotropic collagen networks. Such bioprinted tissues could potentially form the basis of new treatment options for damaged and diseased meniscal tissue. STATEMENT OF SIGNIFICANCE: This study describes a multiple tool biofabrication strategy which enables the engineering of spatially organized fibrocartilage tissues. The architecture of MEW scaffolds can be tailored to not only modulate the directionality of the collagen fibres laid down by cells, but also to tune the anisotropic tensile mechanical properties of the resulting constructs, thereby enabling the engineering of biomimetic meniscal-like tissues. Furthermore, the inherent flexibility of MEW enables the development of zonally defined and potentially patient-specific implants.

Evidence-Based Approach to Orthobiologics for Osteoarthritis and Other Joint Disorders.

Osteoarthritis and cartilage lesions are a major cause of functional limitations which is why the goal of biological treatment is to preserve the native joint to delay the onset of OA. As a result of improvements in surgical techniques and technology, treatment options are more and more available, allowing the treatment of a whole range of injuries, from minor to extensive lesions both acute and chronic. In chondral lesion treatment, restoring hyaline-like cartilage provides improved durability of repaired tissue and desirable wear characteristics. Biological cell-based cartilage restoration treatment was developed to address the need for the long-term viability of repaired tissue. These procedures provide a reliable source of chondrocytes, whether directly or through the differentiation of multipotent precursor cells, capable of producing hyaline-like cartilage, with the minimal formation of fibrocartilage tissue. However, if arthritic changes begin biological therapies offer possibilities to delay. This chapter aims to discuss and give insights into these regenerative, joint preservation techniques for cartilage treatment and possible biological treatment in OA.

Evaluation of the Effect of Granulocyte Colony Stimulating Factor on Spinal Fusion in a Rat Model of Spinal Surgery.

To evaluate the effects of granulocyte colony stimulating factor (G-CSF) on spinal fusion through manual palpation, radiological examinations, and histopathological analyses in a rat model. A total of 21 rats were evaluated in this study. The rats were divided into the following three groups, each consisting of seven rats: preoperative G-CSF, postoperative G-CSF, and a control group. L4-L5 posterolateral fusion was performed in all three groups. The preoperative G-CSF group received 5 μg/kg G-CSF subcutaneously for 5 days in the preoperative period, while the postoperative G-CSF group received the same intervention in the postoperative period. No additional postoperative procedures were performed in the control group. All rats were euthanized at 6 weeks, and the fusion site was evaluated using manual palpation, radiological examinations, and histopathological analyses. According to the classification of subjects according to manual examination, preoperative and postoperative G-CSF groups had significantly higher rates of "single prominent callus formation + fusion" (p < 0.05). When direct radiography scores were evaluated, the number of subjects with "unilateral solid new bone density - contralateral nonsolid bone density" was significantly greater in the preoperative G-CSF group, while "bilateral solid new bone densities" was more prevalent in the postoperative G-CSF group (p < 0.05). In regards to histopathological scores, the number of subjects rated as "fibrocartilage tissue is more than bone tissue" was higher in the preoperative G-CSF group, the number of subjects rated as-bone tissue is more than fibrocartilage tissue" was higher in the postoperative G-CSF group, and the number of subjects rated as "fibrous tissue is more than fibrocartilage tissue" was greaterin the control group (p=0.01). Preoperative and postoperative G-CSF groups had significantly higher manual examination, radiological, and histopathological scores and greater volume of new bone formation on 3D CT compared to the control group (p < 0.05). The results of our study demonstrated that preoperative and postoperative administration of G-CSF had positive effects on spinal fusion in a rat model.

A triphasic biomimetic BMSC-loaded scaffold for osteochondral integrated regeneration in rabbits and pigs.

Osteochondral tissue involves cartilage, calcified cartilage and subchondral bone. These tissues differ significantly in chemical compositions, structures, mechanical properties and cellular compositions. Therefore, the repairing materials face different osteochondral tissue regeneration needs and rates. In this study, we fabricated an osteochondral tissue-inspired triphasic material, which was composed of a poly(lactide-co-glycolide) (PLGA) scaffold loaded with fibrin hydrogel, bone marrow stromal cells (BMSCs) and transforming growth factor-β1 (TGF-β1) for cartilage tissue, a bilayer poly(L-lactide-co-caprolactone) (PLCL)-fibrous membrane loaded with chondroitin sulfate and bioactive glass, respectively, for calcified cartilage, and a 3D-printed calcium silicate ceramic scaffold for subchondral bone. The triphasic scaffold was press-fitted into the osteochondral defects in rabbit (cylindrical defects with a diameter of 4 mm and a depth of 4 mm) and minipig knee joints (cylindrical defects with a diameter of 10 mm and a depth of 6 mm). The μ-CT and histological analysis showed that the triphasic scaffold was partly degraded, and significantly promoted the regeneration of hyaline cartilage after they were implanted in vivo. The superficial cartilage showed good recovery and uniformity. The calcified cartilage layer (CCL) fibrous membrane was in favor of a better cartilage regeneration morphology, a continuous cartilage structure and less fibrocartilage tissue formation. The bone tissue grew into the material, while the CCL membrane limited bone overgrowth. The newly generated osteochondral tissues were well integrated with the surrounding tissues too.

Osteochondral lesions of the talar dome in the athlete: what evidence leads to which treatment

Osteochondral lesions of the talar dome in the athlete: what evidence leads to which treatment

L’implantation de fragments méniscaux autologues enveloppés par du fascia induit la régénération du fibrocartilage en cas de pertes de substance méniscales sévères chez le mouton : étude histologique et biomécanique

IntroductionCurrently, various studies have been reported to regenerate the meniscus tissue in a large defect after partial meniscectomy using biological or synthetic scaffolds with or without fibrochondrocytes. However, the clinical utility of those treatments has not been established as of yet. HypothesisPurposes of this study were to develop a sheep model to evaluate feasibility of this new surgical strategy to treat the irreparable meniscus injury, and to test the hypothesis that implantation of autogenous meniscal fragments wrapped with a fascia sheath may significantly induce fibrocartilage regeneration in a large meniscal defect in the sheep model. Methods and methodsTwenty Suffolk sheep were used. In each animal, an anterior 10-mm width of the right medial meniscus was resected. Then, the animals were divided into the following 2 groups. In Group I, the defect was enveloped with a fascia from the left thigh. In Group II, the resected meniscus fragmented into small pieces was grafted into the defect. Then the defect was enveloped with a fascia. In each group, 5 of 10 sheep were used for histological and biomechanical evaluations, respectively, at 12 weeks after surgery. ResultsIn Group I, the defect was incompletely filled with thin fibrous tissues, while fibrocartilage tissues rarely regenerated in the tissue. In Group II, all defects were completely filled with thick fibrocartilage tissues, which were richly stained with the safranin O staining. Both the gross and histological observation score of Group II was significantly (p=0.0005, p=0.0005) greater than that of Group I. Concerning the cross-sectional area of the regenerated tissue, Group II was significantly (p=0.0002) greater than Group I. In the biomechanical evaluation, the maximal load and the linear stiffness of the meniscus-tibia complex were significantly (p=0.0015, p=0.0283) greater in Group II than in Group I. DiscussionsImplantation of autogenous meniscal fragments wrapped with a fascia sheath significantly induces fibrocartilage regeneration into a large meniscal defect in the sheep model. Level of evidencenot applicable; Controlled Laboratory Study, Experimental in vivo study.

Shock Response of Porcine Meniscus along with Axial and Radial Directions

The meniscus is a multifunctional fibrocartilage tissue in the knee joint which stables joint movement, bears load and absorbs impact. Improper collisions will cause damage to meniscus tissue and lose its original functionality. However, it is difficult to fully evaluate the mechanical properties of the meniscus based on static test results alone. In this study, Split Hopkinson Pressure Bar (SHPB) and hydraulic material testing system (MTS) were utilized to examine the quasi-static and dynamic properties of the porcine meniscus along with two different orientations. The results showed that the meniscus is a strain rate sensitive material and its mechanical properties mainly depend on the orientation of collagen fiber bundles in the peripheral direction. The meniscus tissue did not show obvious yield characteristics under quasi-static test conditions. However, the meniscus showed clear yield behavior under dynamic loading. When the strain rate increased, the elastic modulus of the radial meniscus remained around 35 MPa while the elastic modulus of the axial meniscus increased from 30 MPa to 80 MPa. This study demonstrates that the meniscus is sensitive to strain rate at both dynamic and quasi-static conditions, and the meniscus is an anisotropic biological tissue.

Genipin-crosslinked collagen scaffolds inducing chondrogenesis: a mechanical and biological characterization.

Articular cartilage degeneration is still an unsolved issue owing to its weak repairing capabilities, which usually result in fibrocartilage tissue formation. This fibrous tissue lacks of structural and bio-mechanical properties, degrading over time. Currently, arthroscopic techniques and autologous transplantation are the most used clinical procedures. However, rather than restoring cartilage integrity, these methods only postpone further cartilage deterioration. Therefore, tissue engineering strategies aimed at selecting scaffolds that remarkably support the chondrogenic differentiation of human mesenchymal stem cells (hMSCs) could represent a promising solution, but they are still challenging for researchers. In this study, the influence of two different genipin (Gp) crosslinking routes on collagen (Coll)-based scaffolds in terms of hMSCs chondrogenic differentiation and biomechanical performances was investigated. Three-dimensional (3D) porous Coll scaffolds were fabricated by freeze-drying techniques and were crosslinked with Gp following a "two-step" and an in "bulk" procedure, in order to increase the physico-mechanical stability of the structure. Chondrogenic differentiation efficacy of hMSCs and biomechanical behavior under compression forces through unconfined stress-strain tests were assessed. Coll/Gp scaffolds revealed an isotropic and highly homogeneous pore distribution along with an increase in the stiffness, also supported by the increase in the Coll denaturation temperature (Td =57-63°C) and a significant amount of Coll and GAG deposition during the 3weeks of chondrogenic culture. In particular, the presence of Gp in "bulk" led to a more uniform and homogenous chondral-like matrix deposition by hMSCs if compared to the results obtained from the Gp "two-step" functionalization procedure.