Treatment of articular cartilage lesions remains a clinical challenge. The uses of prosthetic joint replace allograft and/or autograft transplant carry a risk of complications due to infection, loosening of its component, immunological rejection and morbidity at the donor site. There has been an increasing interest in the management of cartilage damages, owing to the introduction of new therapeutic options. Tissue engineering as a method for tissue restoration begins to provide a potential alternative therapy for autologous grafts transplantations. We aimed to evaluate how well a tissue engineered neocartilage implant, consist of human articular chondrocytes cultured with the presence of autologous serum and mixed in a fresh fibrin derived from patient, would perform in subcutaneous implantation in athymic mice.
Biomechanics ; Cartilage, Articular/injuries ; Cartilage, Articular/physiology ; Cartilage, Articular/*transplantation ; Chondrocytes/*cytology ; Culture Media ; Mice, Nude ; *Orthopedic Procedures ; Serum ; *Tissue Engineering

Culture media supplemented with animal serum e.g. fetal bovine serum; FBS is commonly used for human culture expansion. However, for clinical application, FBS is restricted as its carry a risk of viral or prion transmission. Engineering autologous cartilage with autologous human serum supplementation is seen as a better solution to reduce the risk of transmitting infectious diseases and immune rejection during cartilage transplantation. The purpose of this study is to establish and compare the effects of 10% autologous human serum (AHS) and 10% FBS on the growth of chondrocytes and the formation of tissue engineered human articular cartilage.
Cartilage, Articular/growth & development ; Cartilage, Articular/*transplantation ; Cell Count ; Cell Division/physiology ; Chondrocytes/*cytology ; Culture Media ; *Serum ; *Tissue Engineering

OBJECTIVEUsing MR T2-mapping and histopathologic score for articular cartilage to evaluate the effect of structural changes in subchondral bone on articular cartilage.

METHODSTwenty-four male Beagle dogs were randomly divided into a subchondral bone defect group (n = 12) and a bone cement group (n = 12). Models of subchondral bone defectin the medial tibial plateau and subchondral bone filled with bone cement were constructed. In all dogs, the left knee joint was used as the experimental sideand the right knee as the sham side. The T2 value for articular cartilage at the medial tibial plateau was measured at postoperative weeks 4, 8, 16, and 24. The articular cartilage specimens were stained with hematoxylin and eosin, and evaluated using the Mankin score.

RESULTSThere was a statistically significant difference (P < 0.05) in Mankin score between the bone defect group and the cement group at postoperative weeks 16 and 24. There was a statistically significant difference in the T2 values between the bone defect group and its sham group (P < 0.05) from week 8, and between the cement group and its sham group (P < 0.05) from week 16. There was significant difference in T2 values between the two experimental groups at postoperative week 24 (P < 0.01). The T2 value for articular cartilage was positively correlated with the Mankin score (ρ = 0.758, P < 0.01).

CONCLUSIONStructural changes in subchondral bone can lead to degeneration of the adjacent articular cartilage. Defects in subchondral bone cause more severe degeneration of cartilage than subchondral bone filled with cement. The T2 value for articular cartilage increases with the extent of degeneration. MR T2-mapping images and the T2 value for articular cartilage can indicate earlycartilage degeneration.

Animals ; Bone Cements ; Bone and Bones ; physiology ; Cartilage, Articular ; physiology ; Dogs ; Male

BACKGROUNDAcute effects of physical exercise on the deformational behavior of knee articular cartilage and changes in cartilage volume are definite. However, conclusive effects of different exercises on the loss of articular cartilage volume have not been proved. In this parallel-group randomized controlled trial, we tested whether 12 weeks of swimming, powerstriding, cycling, and running exercises would decrease the cartilage volume significantly and whether there would be a difference in the loss of cartilage volume after different types of exercises.

METHODSFrom October 2012 to January 2013 we evaluated 120 healthy volunteer students in Biomechanics Laboratory of Tongji University. Body mass index (BMI), right lower limb strength, and right knee cartilage magnetic resonance imaging (MRI) were obtained before exercise. MRI were conducted in East Hospital. The study was approved by Tongji University Ethical Committee, all subjects were randomly assigned to the running, powerstriding, cycling, swimming, and control groups by a drawing of lots. Each group contained 24 samples. At the end of 12 weeks of regular exercises, the same measurement procedures were applied. Cartilage volume was calculated with OSIRIS software based on the quantitative-MRI. Pre- and post-exercise comparisons were carried out using paired t-tests and one-way analysis of variance (ANOVA) was used to compare differences of cartilage volume loss between groups with Student-Newman-Keuls procedure for multiple comparisons.

RESULTSRunning, cycling, and swimming groups resulted in a significant decrease in BMI. The quadriceps peak torque increased significantly in the swimming and cycling groups. Total cartilage volume significantly decreased in the running and cycling groups after 12 weeks of training, without any significant change in the nonimpact swimming, low-impact powerstriding, and control groups. Loss of total cartilage volume in the running and cycling groups were 2.21% (3.03) and 1.50% (0.42).

CONCLUSIONSTwelve weeks of regular physical exercises (i.e., running and cycling) decrease the total knee cartilage volume. Swimming and powerstriding are recommended for the healthy youth. This finding suggests that articular cartilage has the functional adaptation for exercises, and some sports could be the risk factors for the initiation of osteoarthritis (OA) in young healthy adults.

Adolescent ; Adult ; Cartilage, Articular ; metabolism ; physiology ; Exercise ; physiology ; Female ; Humans ; Knee Joint ; metabolism ; physiology ; Male ; Young Adult

After the articular cartilage injury, the metabolic level is increased during the progressive degeneration, the chondrocytes secrete a variety of inflammatory factors, and the original cell phenotype is gradually changed. For a long time, a large number of researchers have done a lot of researches to promote anabolism of chondrocytes and to maintain the stability of chondrocyte phenotype. There are many molecular signaling pathways involved in the process of promoting cartilage repair. This review focuses on the key signaling molecules in articular cartilage repair, such as transforming growth factor-beta and bone morphogenetic protein, and reveals their roles in the process of cartilage injury and repair, so that researchers in related fields can understand the molecular mechanism of cartilage injury and repair widely and deeply. Based on this, they may find promising targets and biological methods for the treatment of cartilage injury.
Bone Morphogenetic Proteins ; physiology ; Cartilage, Articular ; growth & development ; injuries ; Chondrocytes ; physiology ; Humans ; Regeneration ; Signal Transduction ; Transforming Growth Factor beta ; physiology

BACKGROUNDThe mechanical microenvironment of the chondrocytes plays an important role in cartilage homeostasis and in the health of the joint. The pericellular matrix, cellular membrane of the chondrocytes, and their cytoskeletal structures are key elements in the mechanical environment. The aims of this study are to measure the viscoelastic properties of isolated chondrons and chondrocytes from rabbit knee cartilage using micropipette aspiration and to determine the effect of aging on these properties.

METHODSThree age groups of rabbit knees were evaluated: (1) young (2 months, n = 10); (2) adult (8 months, n = 10); and (3) old (31 months, n = 10). Chondrocytes were isolated from the right knee cartilage and chondrons were isolated from left knees using enzymatic methods. Micropipette aspiration combined with a standard linear viscoelastic solid model was used to quantify changes in the viscoelastic properties of chondrons and chondrocytes within 2 hours of isolation. The morphology and structure of isolated chondrons were evaluated by optical microscope using hematoxylin and eosin staining and collagen-6 immunofluorescence staining.

RESULTSIn response to an applied constant 0.3 - 0.4 kPa of negative pressure, all chondrocytes exhibited standard linear viscoelastic solid properties. Model predictions of the creep data showed that the average equilibrium modulus (E(∞)), instantaneous modulus (E(0)), and apparent viscosity (m) of old chondrocytes was significantly lower than the young and adult chondrocytes (P < 0.001); however, no difference was found between young and adult chondrocytes (P > 0.05). The adult and old chondrons generally possessed a thicker pericellular matrix (PCM) with more enclosed cells. The young and adult chondrons exhibited the same viscoelastic creep behavior under a greater applied pressure (1.0 - 1.1 kPa) without the deformation seen in the old chondrons. The viscoelastic properties (E(∞), E(0), and m) of young and adult chondrons were significantly greater than that observed in young and adult cells, respectively (P < 0.001). The adult chondrons were stiffer than the young chondrons under micropipette aspiration (P < 0.001).

CONCLUSIONSOur findings provide a theoretical model to measure the viscoelastic properties of the chondrons as a whole unit by micropipette aspiration, and further suggest that the properties of the chondrocytes and PCM have an important influence on the biomechanical microenvironment of the knee joint cartilage degeneration that occurs with aging.

Aging ; physiology ; Animals ; Cartilage, Articular ; metabolism ; Chondrocytes ; metabolism ; Elasticity ; Rabbits ; Viscosity

Along with society of modernization and the ageing of population, the amount of the sufferer of articular cartilage defects caused by trauma or degeneration show a clearly increase, how to solve the problem of repair of articular cartilage defects seems to be important. This review will focus on the progress of research for the biological cicatrisation and regeneration of the articular cartilage defects.
Bone Regeneration ; Cartilage, Articular ; pathology ; Humans ; Joint Diseases ; therapy ; Stem Cell Transplantation ; Transplantation, Autologous ; Wound Healing ; physiology

BACKGROUNDThe thermal injury during bipolar radiofrequercy results in chondrocyte death that limits cartilage repair. The purpose was to determine the effects of various factors of bipolar radiofrequency on human articular cartilage after thermal injury, offering suitable working conditions for bipolar radiofrequency during arthroscopy.

METHODSOsteochondral explants from 28 patients undergoing total knee arthroplasty (TKA) in Department of Orthopaedic, Peking University Reople's Hospital from October 2013 to May 2014, were harvested and treated using bipolar radiofrequency in a light contact mode under the following conditions: various power setting of levels 2, 4 and 6; different durations of 2 seconds, 5 seconds and 10 seconds; irrigation with fluids of different temperatures of 4°C, 22°C, and 37°C; two different bipolar radiofrequency probes ArthroCare TriStar 50 and Paragon T2. The percentage of cell death and depth of cell death were quantified with laser confocal microscopy. The content of proteoglycan elution at different temperatures was determined by spectrophotometer at 530 nm.

RESULTSChondrocyte mortality during the treatment time of 2 seconds and power setting of level 2 was significantly lower than that with long duration or in higher level groups (time: P = 0.001; power: P = 0.001). The percentage of cell death after thermal injury was gradually reduced by increasing the temperature of the irrigation solutions (P = 0.003), the depth of dead chondrocytes in the 37°C solution group was significantly less than those in the 4°C and 22°C groups (P = 0.001). The proteoglycan elution was also gradually reduced by increasing the temperature (P = 0.004). Compared with the ArthroCare TriStar 50 group, the percentage of cell death in the Paragon T2 group was significantly decreased (P = 0.046).

CONCLUSIONSThermal chondroplasty with bipolar radiofrequency resulted in defined margins of chondrocyte death under controlled conditions. The least cartilage damage during thermal chondroplasty could be achieved with lower power, shorter duration, suitable temperature of irrigation solutions and chondroprotective probes. The recommendations for the use of bipolar radiofrequency to minimize cartilage damage could be achieved with a power setting of level 2, treatment duration of 2 seconds, suitable fluid temperature (closer to body temperature of 37°C) and chondroprotective Paragon T2 probes.

Arthroplasty, Replacement, Knee ; methods ; Cartilage, Articular ; surgery ; Catheter Ablation ; methods ; Cell Survival ; physiology ; Chondrocytes ; pathology ; Humans ; Microscopy, Confocal

OBJECTIVETo determine the stress distribution on endplate after lumbar prosthetic disc nucleus (PDN) replacement.

METHODSSix fresh lumbar vertebrae with normal Modic classification were harvested. The specimens were used to establish L4-5 intact, nucleotomy, prosthetic nucleus pulposus replacement models. Vertical compression tests were performed with MTS machine at the rate 50 N per second to maximum load of 1300 N. The stress under the endplate were measured directly with accurate pressure sensors.

RESULTSFor intact specimens, the stress on the endplate maintained higher in the central zone of the endplate, and decreased gradually to the periphery, and was well-distributed. After nucleotomy, the stress on the central zone of endplate was significantly decreased, and increased stress occurred in the periphery of endplate. After PDN replacement, the stress on the central zone of endplate was found more 15.1% higher than that in intact disc (P < 0.05), and the neighboring zone also showed higher stress measurements.

CONCLUSIONSAfter lumbar prosthetic disc nucleus replacement, the stress concentration on endplate may occur in the central zone of prosthetic disc nucleus insertion. Therefore, the prosthetic nucleus pulposus with suitable shape, proper biomechanical functions and updated materials need further study.

Adult ; Arthroplasty, Replacement ; Cartilage, Articular ; physiology ; Humans ; Intervertebral Disc ; surgery ; Joint Prosthesis ; Lumbar Vertebrae ; surgery ; Middle Aged ; Stress, Mechanical

Natural articular cartilage is well known as a special connective tissue with multiple effects and functions, which are important and irreplaceable, in human synovial joints. Biomedical, histological and pathological characteristics of articular cartilage, as well as biomaterial, biomechanical and bio-tribological properties thereof, are summarized from a novel aspect of bionics. Bionic design of articualr cartilage at macro-level and micro-level is carried out from three aspects, i.e., structure, material, and function; and a bionic design model of articular cartilage is set up. As a result, this basic research would be helpful to providing theoretical and practical basis for innovational design and manufacturing of new-style artificial joint with "soft-cushion bearing", and of bionic artificial cartilage.
Biocompatible Materials ; Biomechanical Phenomena ; Cartilage, Articular ; physiology ; Computer-Aided Design ; Humans ; Joint Prosthesis ; Prosthesis Design ; Tissue Engineering ; methods