Quantitative analysis of temporal and spatial variations of chondrocytebehavior in engineered cartilage during long-term culture
Park,K; Min,BH; Han,DK; Hasty,K
Abstract In this work, we present the fact that chondrocyte activity differs inrelation to their position in an engineered cartilage construct. Chondrocytes from porcine articularcartilage were cultured in a monolayer. Then the cell/extracellular matrix (ECM) membrane waspeeled off and centrifuged into a three-dimensional (3D) pellet-type construct. Cultivated in astatic condition, the constructs were harvested at specific time intervals (1, 2, 3, and 5 weeks)and manually cored using a biopsy punch to separate the core from the remaining construct. Theresultant parts, core and peripheral remnant were thus obtained and subjected to analysisindividually. Cell density (10(6 )cells/cm(3)) of the core was significantly higher at 1 week thanthat of the periphery but this trend was reversed at later time points. Cell viability wasremarkably better in the peripheral tissue. Alcian blue staining of glycosaminoglycan (GAG) revealedan intense blue staining from the periphery, exhibiting a steep gradient in distribution of GAGconcentration. The gene expression ratio of collagen type II to I appeared to be more altered in theperiphery, possibly suggesting cell dedifferentiation, especially at later time points (>2 weeks).The mRNA levels of matrix metalloproteinase-1 (MMP-1) and MMP-13 remained in the normal range,whereas collagen type X expression was more significantly upregulated at the periphery. This studyshowed that chondrocyte behavior could be highly variable in the extent of their proliferation,differentiation and dedifferentiation, depending on their physical location within 3D engineeredcartilage construct.
Keywords Cartilage, Articular; Chondrocytes
Annals of Biomedical Engineering
0090-6964, Volume 35, Issue 3, 2007, Pages 3-428
