Experimental characterization of the human meniscal tissue

The meniscus plays a critical role in load transmission, stability and energy dissipation in the knee joint. Loss of the meniscus leads to joint degeneration and osteoarthritis. In a number of cases replacement of the resected meniscal tissue by a synthetic implant might avoid the articular cartilage degeneration. None of the available implants presents optimal biomechanics characteristic due to the fact the biomechanics functionality of the meniscus is not yet fully understood. Mimicking the native biomechanical characteristics of the menisci seems to be the key factor in meniscus replacement functioning. This is extremely challenging due to its complex inhomogeneous microstructure, the lack of a full experimental characterization of the material properties and the lack of 3D theoretical, numerical and computational models which can reproduce and validate the experimental results. The objective of this work is to present the experimental characterization of the anisotropic meniscal tissue at the macroscale. Innovative Biaxial tests have been conducted and the results are new to the literature

Differential cartilaginous tissue formation by human synovial membrane, fat pad, meniscus cells and articular chondrocytes

Objective: To identify an appropriate cell source for the generation of meniscus substitutes, among those which would be available by arthroscopy of injured knee joints. Methods: Human inner meniscus cells, fat pad cells (FPC), synovial membrane cells (SMC) and articular chondrocytes (AC) were expanded with or without specific growth factors (Transforming growth factor-betal, Fibroblast growth factor-2 and Plate let-derived growth factor bb, TFP) and then induced to form three-dimensional cartilaginous tissues in pellet cultures, or using a hyaluronan-based scaffold (Hyaff(R)-11), in culture or in nude mice. Human native menisci were assessed as reference. Results: Cell expansion with TFP enhanced glycosaminoglycan (GAG) deposition by all cell types (up to 4.1-fold) and messenger RNA expression of collagen type II by FPC and SMC (up to 472-fold) following pellet culture. In all models, tissues generated by AC contained the highest fractions of GAG (up to 1.9 were positively stained for collagen type II (specific of the inner avascular region of meniscus), type IV (mainly present in the outer vascularized region of meniscus) and types I, III and VI (common to both meniscus regions). Instead, inner meniscus, FPC and SMC developed tissues containing negligible GAG and no detectable collagen type II protein. Tissues generated by AC remained biochemically and phenotypically stable upon ectopic implantation. Conclusions: Under our experimental conditions, only AC generated tissues containing relevant amounts of GAG and with cell phenotypes compatible with those of the inner and outer meniscus regions. Instead, the other investigated cell sources formed tissues resembling only the outer region of meniscus. It remains to be determined whether grafts based on AC will have the ability to reach the complex structural and functional organization typical of meniscus tissue. (C) 2006 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights rese

Tissue engineering for total meniscal substitution : Animal study in sheep model

Objective: The aim of the study was to investigate the use of a novel hyaluronic acid/polycaprolactone material for meniscal tissue engineering and to evaluate the tissue regeneration after the augmentation of the implant with expanded autologous chondrocytes. Two different surgical implantation techniques in a sheep model were evaluated. Methods: Twenty-four skeletally mature sheep were treated with total medial meniscus replacements, while two meniscectomies served as empty controls. The animals were divided into two groups: cell-free scaffold and scaffold seeded with autologous chondrocytes. Two different surgical techniques were compared: in 12 animals, the implant was sutured to the capsule and to the meniscal ligament; in the other 12 animals, also a transtibial fixation of the horns was used. The animals were euthanized after 4 months. The specimens were assessed by gross inspection and histology. Results: All implants showed excellent capsular ingrowth at the periphery. Macroscopically, no difference was observed between cell-seeded and cell-free groups. Better implant appearance and integrity was observed in the group without transosseous horns fixation. Using the latter implantation technique, lower joint degeneration was observed in the cell-seeded group with respect to cell-free implants. The histological analysis indicated cellular infiltration and vascularization throughout the implanted constructs. Cartilaginous tissue formation was significantly more frequent in the cell-seeded constructs. Conclusion: The current study supports the potential of a novel HYAFF/polycaprolactone scaffold for total meniscal substitution. Seeding of the scaffolds with autologous chondrocytes provides some benefit in the extent of fibrocartilaginous tissue repair

Novel Approaches in Meniscal Repair Utilizing Mesenchymal Stem Cells, New Generation Bioscaffolds and Biological Adhesives as Cell Delivery Vehicles

Mesenchymal stem cells (MSCs) have been widely applied in the repair of the knee-joint menisci which have a limited ability to undergo spontaneous repair. The menisci stabilise the knee-joint and are weight-bearing structures subjected to considerable tensional and compressive forces during flexion-extension and torsional loading of the knee. Traumatic loading of the knee-joint menisci can generate a number of lesions in the inner avascular meniscal regions. These have a limited capability of intrinsic repair and predispose the underlying articular cartilages to premature osteoarthritis. A number of strategies have therefore been developed for meniscal repair employing MSCs, bioscaffolds, hydrogels, biological glue cell delivery systems and agents which promote cell proliferation/matrix synthesis. Meniscal implants have also been developed in combination with the above procedures. It is important that meniscal defects be repaired not only to maintain knee-joint stability but also to prevent further degenerative changes in other knee joint tissues. Degenerative menisci contribute degradative proteinases and inflammatory mediators to the total synovial degradative proteinase pool. Partial or total surgical removal of the menisci is not a solution since this leads to premature osteoarthritis. Meniscal integrity needs to be maintained or repair strategies implemented in a timely manner to maintain knee joint function

A decellularized and sterilized human meniscus allograft for off-the-shelf meniscus replacement

PURPOSE: Meniscus tears are one of the most frequent orthopedic knee injuries, which are currently often treated performing meniscectomy. Clinical concerns comprise progressive degeneration of the meniscus tissue, a change in knee biomechanics, and an early onset of osteoarthritis. To overcome these problems, meniscal transplant surgery can be performed. However, adequate meniscal replacements remain to be a great challenge. In this research, we propose the use of a decellularized and sterilized human meniscus allograft as meniscal replacement.METHODS: Human menisci were subjected to a decellularization protocol combined with sterilization using supercritical carbon dioxide (scCO 2). The decellularization efficiency of human meniscus tissue was evaluated via DNA quantification and Hematoxylin &amp; Eosin (H&amp;E) and DAPI staining. The mechanical properties of native, decellularized, and decellularized + sterilized meniscus tissue were evaluated, and its composition was determined via collagen and glycosaminoglycan (GAG) quantification, and a collagen and GAG stain. Additionally, cytocompatibility was determined in vitro. RESULTS: Human menisci were decellularized to DNA levels of ~ 20 ng/mg of tissue dry weight. The mechanical properties and composition of human meniscus were not significantly affected by decellularization and sterilization. Histologically, the decellularized and sterilized meniscus tissue had maintained its collagen and glycosaminoglycan structure and distribution. Besides, the processed tissues were not cytotoxic to seeded human dermal fibroblasts in vitro.CONCLUSIONS: Human meniscus tissue was successfully decellularized, while maintaining biomechanical, structural, and compositional properties, without signs of in vitro cytotoxicity. The ease at which human meniscus tissue can be efficiently decellularized, while maintaining its native properties, paves the way towards clinical use.</p

Bio-Engineered Meniscus for Tissue Engineering

Meniscus plays fundamental roles in the knee mechanisms and functions. It acts as a shock absorber where it enables even distribution of forces, and also lubricates knee joints. Meniscal injuries could result to the onset of degenerative osteoarthritis if proper treatments are delayed. To date, treatment of meniscal injuries are more towards conservative methods and surgical approach commonly known as meniscectomy. Attempts to develop scaffolds for meniscus implants from synthetic and biological sources have been done in the recent years. This approach involves a multidisciplinary study known as tissue engineering and regenerative medicine. It involves the combination of three crucial aspects; the choice of chondrogenic/stem cells, bioscaffolds and favourable environmental factors such as growth factors. This chapter discusses and highlights on the currently available meniscal scaffolds that have been explored before. Focus is also directed on the potential of decellularized extracellular matrix (ECM), prepared through sonication treatment that produced scaffolds which mimics natural meniscus. The evaluation of decellularized scaffolds was portrayed through recellularization using cells namely chondrocytes, fibrochondrocytes and stem cells in order to regenerate new functional tissue. In short, this chapter serves as a representation of current approaches aiming in bio-engineering the meniscal scaffolds as meniscus tissue replacement

Meniscal ossicles as micro-CT imaging biomarker in a rodent model of antigen-induced arthritis: A synchrotron-based x-ray pilot study

It is increasingly recognized that early detection of bone erosion plays an important role in the overall evaluation of rheumatoid arthritis and in the choice of the correct treatment approach. Since an appropriate use of imaging biomarkers in preclinical settings offers the prospect of smaller and optimized sample size, in the present study we define an anatomical imaging biomarker that could be objectively measured from micro-CT imaging data as an indicator of bone erosion in arthritis process. The well-characterized antigen-induced arthritis (AIA) model in rats was used. The animals were divided into 2 groups: arthritic disease control and arthritic having been administrated with the tumor necrosis factor alpha-blocking agent (Humira). Rats were sacrificed in the acute phase of AIA; peripheral blood and synovial tissue were collected for assessment of arthritis. Ex vivo micro-CT tomography of knee joints was performed at the Elettra synchrotron light source (Trieste, Italy). Overall, results from this study suggest that use of high-resolution micro-CT analysis coupled with meniscal ossicles bone parameters quantification provide a powerful combination to enhance data interpretation and assessment of disease-modifying drugs in an animal model of arthritis

Synovial mesenchymal stem cells promote healing after meniscal repair in microminipigs

SummaryObjectiveThe induction of synovial tissue to the meniscal lesion is crucial for meniscal healing. Synovial Mesenchymal stem cells (MSCs) are an attractive cell source because of their high proliferative and chondrogenic potentials. We examined whether transplantation of synovial MSCs promoted healing after meniscal repair of extended longitudinal tear of avascular area in a microminipig model.DesignLongitudinal tear lesion was made in medial menisci and sutured in both knees, and then a synovial MSC suspension was administered for 10 min only in unilateral knee. The sutured meniscus was evaluated morphologically and biomechanically at 2, 4, and 12 weeks. The behavior of transplanted MSCs was also examined.ResultsThe meniscal healing at 12 weeks was significantly better in the MSC group than in the control group; macroscopically, histologically and by T1rho mapping analysis. Transmission electron microscopic analysis demonstrated that the meniscus lesion was occupied by dense collagen fibrils only in the MSC group. Biomechanical analysis revealed that the tensile strength to failure of the meniscus higher in the MSC group than in the control group in each microminipig. Synovial tissue covered better along the superficial layer from the outer zone into the lesion of the meniscus in the MSC group at 2 and 4 weeks in each microminipig. Synovial MSCs labeled with ferucarbotran were detected in the meniscus lesion and adjacent synovium by MRI at 2 weeks.ConclusionTransplantation of synovial MSCs promoted healing after meniscal repair with induction of synovium into the longitudinal tear in the avascular zone of meniscus in pigs