title: Chondrocytes within osteochondral grafts are more resistant than osteoblasts to tissue culture at 37°C.
abstract: It is proposed that an ideal osteochondral allograft for cartilage repair consists of a devitalized bone but functional cartilage. The different modes of nutrient supply in vivo for bone (vascular support) and cartilage (diffusion) suggest that a modulation of storage conditions could differentially affect the respective cells, resulting in the proposed allograft. For this purpose, osteochondral tissues from porcine humeral heads were either cultured at 37°C for up to 24 hr or stored at 4°C for 24 hr, the temperature at which osteochondral allografts are routinely stored. Functionality of the cells was assessed by in situ hybridization for transcripts encoding collagen types I and II. At 37°C, a time-dependent significant reduction of the bone surface covered with functional cells was observed with only 5% ± 5% coverage left at 24 hr compared with 41% ± 10% at 0 hr. Similarly, cartilage area containing functional cells was significantly reduced from 84% ± 7% at 0 hr to 70% ± 3% after 24 hr. After 24 hr at 4°C, a significantly reduced amount of functional cells covering bone surfaces was observed (27% ± 5%) but not of cells within the cartilage (79% ± 8%). In the applied experimental setup, bone cells were more affected by tissue culture at 37°C than cartilage cells. Even though chondrocytes appear to be more sensitive to 37°C than to 4°C, the substantially reduced amount of functional bone cells at 37°C warrants further investigation of whether a preincubation of osteochondral allografts at 37°C--prior to regular storage at 4°C--might result in an optimized osteochondral allograft with devitalized bone but viable cartilage.
authors.affiliation: Group for Bone Biology and Orthopaedic Research, Department of Clinical Research, University of Bern, Bern, Switzerland.
authors.forename: Johannes D
authors.initials: JD
authors.lastname: Bastian
authors.forename: Rainer J
authors.initials: RJ
authors.lastname: Egli
authors.forename: Reinhold
authors.initials: R
authors.lastname: Ganz
authors.forename: Willy
authors.initials: W
authors.lastname: Hofstetter
authors.forename: Michael
authors.initials: M
authors.lastname: Leunig
mesh_terms: D000818:Animals; D016025:Bone Transplantation; D019902:Chondrocytes / Q000502:physiology*; D058430:Humeral Head; D010006:Osteoblasts / Q000502:physiology*; D013552:Swine; D013696:Temperature; D046509:Tissue Culture Techniques; D014184:Transplantation, Homologous