2009 Alexandra Kirkley Award Recipient
2^nd Prize Award

THE EFFECT OF HYPOXIA ON CHONDROCYTE PHENOTYPE IN SCAFFOLD REPAIR OF ARTICULAR CARTILAGE DEFECTS

Julian Sernik, M.D.
University of Alberta
Edmonton, AB 

N. Jomha
K. Bagnall
C. Secretan
M. Lund

Traumatic articular cartilage defects are common in young adults, occurring in approximately 2/3 of patients undergoing knee arthroscopy. Lesions are often symptomatic and ultimately progress to osteoarthritis. None of the existing modalities have been shown to produce consistently good to excellent results or emerged as clearly superior.

One therapy under investigation involves cultured chondrocytes implanted into a scaffold which can then be surgically implanted into the defect. The objective of our study was to evaluate the effect of hypoxia on the production of extracellular matrix by chondrocytes embedded such a scaffold.

Chondrocytes were isolated and cultured from two individuals with Outerbridge grade 1 articular cartilage and implanted onto 16 type 1 collagen scaffolds. Half were incubated in hypoxic (5% O₂) conditions and half in normoxic (21% O₂) conditions. Quantitative real-time PCR was performed to evaluate the expression of collagen 1, collagen 2 and aggrecan both before and after implantation and compared to a human chondrocyte standard.

Our results demonstrate that hypoxia results in maintenance of aggrecan and collagen 1 and importantly an increase in collagen 2 production, which approaches that of normal articular chondrocytes suggesting that a hypoxic environment may be a key feature in the maintainence of chondrocyte phenotype.