Additive effects of hyperbaric oxygen and platelet‐derived growth factor‐BB in chondrocyte transplantation via up‐regulation expression of platelet‐derived growth factor‐β receptor

The present study investigated the effects of hyperbaric oxygen (HBO) and platelet‐derived growth factor‐BB (PDGF‐BB) in chondrocyte transplantation. In vitro, chondrocytes were treated with HBO, PDGF‐BB, and HBO combined with PDGF‐BB (H+P). Cell growth was analyzed using cell counting, MTT assay, and FACS analysis. mRNA expression of the PDGF‐α receptor (PDGFR‐α) and β receptor (PDGFR‐β) was detected by RT‐PCR. Protein expression of PDGFR‐β was detected by Western blotting. In vivo, chondrocytes and PDGF‐BB were suspended in alginate as a transplantation system. Cartilage defects were grafted with this system and with or without HBO treatment. Released PDGF‐BB concentration was quantified by ELISA. After 8 weeks, animals were sacrificed and the repaired tissues were examined. In vitro data suggested that each treatment increased cell growth via the up‐regulated mRNA expression of PDGFR‐α and increased cell accumulation in the S‐phase. The H+P treatment was more additive in cell growth and in mRNA and protein expression of PDGFR‐β than HBO or PDGF‐BB. In vivo results suggested that PDGF‐BB delivery lasted for more than 5 weeks. Scoring results showed that each treatment significantly increased the cartilage repair. Safranin‐O and type II collagen staining confirmed the hyaline‐like cartilage regeneration in the repaired tissues. In situ up‐regulation of PDGFR‐β expression partially explains the additive effect of H+P treatment in cartilage repair. Accordingly, H+P offers a potential treatment method for cartilage repair. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:1439–1446, 2009