title: Competing regulation of matrix biosynthesis by mechanical and IGF-1 signalling in elderly human articular cartilage in vitro.
abstract: This study investigates the separate and combined effects of IGF-1 and mechanical loads on chondrocytes in elderly human femoral head articular cartilage. Full depth biopsies of articular cartilage were subjected to either no load, static or cyclic (2 s on/2 s off) loading in unconfined compression at a stress of 1 MPa for 48 h with or without IGF-1 (300 ng ml(-1)). Chondrocyte biosynthetic activity was measured using 35S-sulphate and 3H-leucine during the last 24 h of loading. IGF-1 alone increased the rates of isotope incorporation, by 80% for 35S-SO4 and 40% for 3H-leucine, whereas loading alone reduced matrix biosynthesis. Applying load (cyclic or static) in the presence of IGF-1 returned the incorporation rates to their unstimulated levels. This study suggests elderly human articular cartilage is responsive to stimulation by IGF-1 but mechanical factors seem to act sufficiently strongly in the opposite direction to cancel this response.
authors.affiliation: Department of Orthopaedics, University of Aberdeen, IMS Building, Foresterhill, Aberdeen AB25 2ZD, UK.
authors.forename: Mandy S
authors.initials: MS
authors.lastname: Plumb
authors.forename: Katrina
authors.initials: K
authors.lastname: Treon
authors.forename: Richard M
authors.initials: RM
authors.lastname: Aspden
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002358:Cartilage, Articular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D019902:Chondrocytes / Q000187:drug effects / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism*; D005260:Female; D005270:Femur Head / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology* / Q000502:physiology; D007930:Leucine / Q000378:metabolism; D008297:Male; D040542:Mechanotransduction, Cellular / Q000502:physiology*; D008875:Middle Aged; D011868:Radioisotopes; D015398:Signal Transduction; D013314:Stress, Mechanical; D013431:Sulfates / Q000378:metabolism
chemical_list: D011868:Radioisotopes; D013431:Sulfates; D007334:Insulin-Like Growth Factor I; D007930:Leucine