MATERIALS AND METHODS: Chondrocyte/agarose constructs were treated with varying concentrations of TNFα (0.1-100 ng/ml) and cultured at 5 and 21 % oxygen tension for 48 h. In separate experiments, constructs were subjected to dynamic compression (15 %) and treated with TNFα (10 ng/ml) and/or L-NIO (1 mM) at 5 and 21 % oxygen tension using an ex vivo bioreactor for 48 h. Markers for catabolic activity (NO, PGE2) and tissue remodelling (GAG, MMPs) were quantified by biochemical assay. ADAMTS-5 and MMP-13 expression were examined by real-time qPCR. 2-way ANOVA and a post hoc Bonferroni-corrected t test were used to analyse data.
RESULTS: TNFα dose-dependently increased NO, PGE2 and MMP activity (all p
Methods: The OACs were expanded from passage 0 (P0) to P3, and cells in each passage were analyzed for gross morphology, growth rate, RNA expression and immunochemistry (IHC). The harvested OACs were assigned into two groups: low (1×10[7] cells/ml) and high (3×10[7] cells/ml) cell density. Three-dimensional (3D) constructs for each group were created using polymerised fibrin and cultured for 7, 14 and 21 days in vitro using chondrocyte growth medium. OAC constructs were analyzed with gross assessments and microscopic evaluation using standard histology, IHC and immunofluorescence staining, in addition to gene expression and biochemical analyses to evaluate tissue development.
Results: Constructs with a high seeding density of 3×10[7] cells/ml were associated with better quality cartilage-like tissue than those seeded with 1×10[7] cells/ml based on overall tissue formation, cell association and extracellular matrix distribution. The chondrogenic properties of the constructs were further confirmed by the expression of genes encoding aggrecan core protein and collagen type II.
Interpretation & conclusions: Our results confirmed that cell density was a significant factor affecting cell behaviour and aggregate production, and this was important for establishing good quality cartilage.
METHODS: Literature search was performed to identify all level I and II studies reporting the clinical and structural outcome of any ACI generation in human knees using the following medical electronic databases: PubMed, EMBASE, Cochrane Library, CINAHL, SPORTDiscus and NICE healthcare database. The level of evidence, sample size calculation and risk of bias were determined for all included studies to enable quality assessment.
RESULTS: Twenty studies were included in the analysis, reporting on a total of 1094 patients. Of the 20 studies, 13 compared ACI with other treatment modalities, seven compared different ACI cell delivery methods, and one compared different cell source for implantation. Studies included were heterogeneous in baseline design, preventing meta-analysis. Data showed a trend towards similar outcomes when comparing ACI generations with other repair techniques and when comparing different cell delivery methods and cell source selection. Majority of the studies (80 %) were level II evidence, and overall the quality of studies can be rated as average to low, with the absence of power analysis in 65 % studies.
CONCLUSION: At present, there are insufficient data to conclude any superiority of ACI techniques. Considering its two-stage operation and cost, it may be appropriate to reserve ACI for patients with larger defects or those who have had inadequate response to other repair procedures until hard evidence enables specific clinical recommendations be made.
LEVEL OF EVIDENCE: II.