Repair Of Articular Cartilage Lesions Research Articles

The Microfracture Technique for the Treatment of Articular Cartilage Lesions in the Knee

Microfracture is a frequently used technique for the repair of articular cartilage lesions of the knee. Despite the popularity of the technique, prospective information about the clinical results after microfracture is still limited. The purpose of our study was to identify the factors that affect the clinical outcome from this cartilage repair technique. Forty-eight symptomatic patients with isolated full-thickness articular cartilage defects of the femur in a stable knee were treated with the microfracture technique. Prospective evaluation of patient outcome was performed for a minimum follow-up of twenty-four months with a combination of validated outcome scores, subjective clinical rating, and cartilage-sensitive magnetic resonance imaging. At the time of the latest follow-up, knee function was rated good to excellent for thirty-two patients (67%), fair for twelve patients (25%), and poor for four (8%). Significant increases in the activities of daily living scores, International Knee Documentation Committee scores, and the physical component score of the Short Form-36 were demonstrated after microfracture (p < 0.05). A lower body-mass index correlated with higher scores for the activities of daily living and SF-36 physical component, with the worst results for patients with a body-mass index of >30 kg/m(2). Significant improvement in the activities of daily living score was more frequent with a preoperative duration of symptoms of less than twelve months (p < 0.05). Magnetic resonance imaging in twenty-four knees demonstrated good repair-tissue fill in the defect in thirteen patients (54%), moderate fill in seven (29%), and poor fill in four patients (17%). The fill grade correlated with the knee function scores. All knees with good fill demonstrated improved knee function, whereas poor fill grade was associated with limited improvement and decreasing functional scores after twenty-four months. Microfracture repair of articular cartilage lesions in the knee results in significant functional improvement at a minimum follow-up of two years. The best short-term results are observed with good fill grade, low body-mass index, and a short duration of preoperative symptoms. A high body-mass index adversely affects short-term outcome, and a poor fill grade is associated with limited short-term durability.

Gene transfer of a human insulin-like growth factor I cDNA enhances tissue engineering of cartilage.

The repair of articular cartilage lesions remains a clinical problem. Two novel approaches to cartilage formation, gene transfer and tissue engineering, have been limited by short-term transgene expression in transplanted chondrocytes and inability to deliver regulatory signals to engineered tissues according to specific temporal and spatial patterns. We tested the hypothesis that the transfer of a cDNA encoding the human insulin-like growth factor I (IGF-I) can provide sustained gene expression in cell-polymer constructs in vitro and in vivo and enhance the structural and functional properties of tissue-engineered cartilage. Bovine articular chondrocytes genetically modified to overexpress human IGF-I were seeded into polymer scaffolds, cultured in bioreactors in serum-free medium, and implanted subcutaneously in nude mice; constructs based on nontransfected or lacZ-transfected chondrocytes served as controls. Transgene expression was maintained throughout the duration of the study, more than 4 weeks in vitro followed by an additional 10 days either in vitro or in vivo. Chondrogenesis progressed toward the formation of cartilaginous tissue that was characterized by the presence of glycosaminoglycans, aggrecan, and type II collagen, and the absence of type I collagen. IGF-I constructs contained increased amounts of glycosaminoglycans and collagen and confined-compression equilibrium moduli as compared with controls; all groups had subnormal cellularity. The amounts of glycosaminoglycans and collagen per unit DNA in IGF-I constructs were markedly higher than in constructs cultured in serum-supplemented medium or native cartilage. This enhancement of chondrogenesis by spatially defined overexpression of human IGF-I suggests that cartilage tissue engineering based on genetically modified chondrocytes may be advantageous as compared with either gene transfer or tissue engineering alone.

N,N-dicarboxymethyl chitosan as delivery agent for bone morphogenetic protein in the repair of articular cartilage.

Bone morphogenetic protein (BMP), associated with N,N-dicarboxymethyl chitosan, is used to induce or facilitate the repair of articular cartilage lesions. This association is intended for the synergistic potentiation of the respective biological effects. Data show that BMP-7 enhances the in vivo proliferation of cells with chondrocytes phenotype in the articular environment, leading to partial healing of the articular surface of the lesions. N,N-dicarboxymethyl chitosan is found to be useful as a molecular carrier or drug delivery agent.

Differential effects of IGF-1 ans TGFβ-2 on the assembly of proteoglycans in pericellular and territorial matrix by cultured bovine articular chondrocytes

Objectives: Knowledge of matrix assembly is necessary to understand the pathogenesis of disease processes and to find solutions for repair of articular cartilage lesions. The influence of growth factors on matrix assembly is largely unknown. We investigated whether, and to what degree, insulin-like growth factor (IGF-1) and transforming growth factor β-2 (TGFβ-2) influence proteoglycan synthesis and accumulation in the cell-associated matrix compartment (consisting of pericellular and territorial matrix) compared to the further-removed matrix compartment (consisting of the interterritorial matrix).Design: Bovine articular chondrocytes were cultured in alginate beads for day 13. The effect of addition of 25 ng/ml IGF-1 or 25 ng/ml TGFβ-2 during the last 7 days in culture was determined. Cell-associated and further-removed matrix compartments were separated by centrifugation after sodium citrate/EDTA treatment. The amount of DNA, the total amount of proteoglycans and the amount of newly synthesized proteoglycans were analyzed biochemically. Morphometric analysis on electron micrographs was used to calculate the volumes of the cell-associated and further-removed matrix components.Results: It was demonstrated in control beads that 25±8% of the proteoglycans were laid down in the cell-associated matrix compartment compared with 75±8% in the further-removed matrix compartment. The cell-associated matrix compartment in intact beads could be recognized in electron microscopy by a delineation of dense amorph material. Morphometric evaluation showed a relative volume of the cell-associated matrix compartment of 5.2±0.6% compared with 91.3±0.8% of the further-removed matrix compartment and 3.5±0.3% of the area occupied by cells. Combination of biochemical and morphometric results showed that the concentration of proteoglycans in the cell-associated matrix compartment was 3.63±0.32 mg/ml. By adding IGF-1 or TGFβ-2, the amount of both total accumulated proteoglycans and newly synthesized [35S]proteoglycans at day 13 in culture increased. In addition to an overall rise in proteoglycan content, IGF-1 significantly increased (24%) the percentage of proteoglycans laid down in the cell-associated matrix compartment while not changing the relative volume of this compartment (5.2±0.8%). This leads to a 82% (P<0.05) increase in the proteoglycan concentration in the cell-associated matrix compartment compared to control beads. In contrast, TGFβ-2 significantly decreased (24%) the relative amount of proteoglycans in the cell-associated matrix compartment which was paralleled by a reduction of the relative volume from 5.2±0.6 to 3.6±1.4%. This leads to a significant increase of 87% of the proteoglycan concentration in the cell-association matrix compartment.Conclusions: This study demonstrates that both IGF-1 and TGFβ-2 significantly but differently influence proteoglycan synthesis and accumulation in the cell-associated matrix compartment of cultured bovine chondrocytes in alginate. Both growth factors increase the concentration of proteoglycans in the cell-associated matrix compartment. However, addition of TGFβ-2 to bovine articular chondrocytes cultured in alginate beads for 13 days results in a significant reduction of the relative volume of the pericellular matrix compartment compared to controls, indicating differences in assembly of the matrix.

A New Approach to Cartilage Tissue Engineering Using Human Dermal Fibroblasts Seeded on Three-Dimensional Polymer Scaffolds

AbstractCurrent methods for correcting articular cartilage defects are limited by a scarcity of cartilage cells. Here we describe a novel method for the conversion of human dermal fibroblasts to chondrocyte-like cells and the potential application of this methodology to cartilage tissue engineering. Human neonatal foreskin fibroblasts were seeded on two-dimensional, tissue culture polystyrene (TCPS) in high density micromass cultures in the presence of staurosporine (50-200 nM), a protein kinase C (PKC) inhibitor, and lactic acid (40 mM) to induce functional hypoxia. Dermal fibroblasts were similarly cultured on three-dimensional polymer scaffolds composed of a non-woven polyglycolic acid (PGA) fiber mesh reinforced in a dilute solution of poly(L-lactic acid) (PLLA). At 24 hours, northern analysis revealed a staurosporine dose-dependent increase in aggrecan core protein expression in lactate-treated micromass cultures on TCPS, while type I collagen gene expression was virtually abolished in all cultures supplemented with staurosporine. The cells in these cultures displayed a rounded, cobblestone-shaped morphology typical of differentiated chondrocytes (most pronounced at 200 n.M staurosporine and 40 mM lactate), and were organized into nodules which stained positively with Alcian blue. When seeded on PGA/PLLA matrices under identical conditions as described for TCPS, a chondrocyte-like morphology was observed in cultures treated with lactate and staurosporine in contrast to the flattened sheets of fibroblast-like cells seen in untreated controls. Taken together, the above findings suggest that staurosporine treatment coupled with high density micromass culture in the presence of lactate induces chondrogenic differentiation in human dermal fibroblasts, and that these cells may be used in concert with three-dimensional polymer scaffolds for the repair of articular cartilage lesions.