title: Secreted collagen ratios in normal human and osteogenesis imperfecta skin fibroblasts.
abstract: We examined the effects of several variables on the ratio of type I:type III collagen secreted by human caucasian skin fibroblasts in normal and osteogenesis imperfecta (OI) phenotypes. Isotopically labelled collagen extracted from fibroblast medium was analyzed by DEAE-cellulose chromatography and identified by appropriate methods. Type I procollagen was the major form of collagen secreted into the medium by normal cells cultured from one mid-term fetus, infants (n = 3), children (n = 3), adolescents (n = 2), and adults (n = 3). Interstrain differences in collagen production under standardized conditions were significantly greater than intrastrain variation (anova, p = 0.0051). There was no significant alteration in the type I:type III collagen ratio due to variation in: phase of cell growth, doublings (between 13th and 22nd), rate of isotope incorporation, labelling time (24-72 hrs) in the presence of ascorbic acid (50 micrograms/ml), age of donor (with the possible exception of adolescence), and site of biopsy (genital and non-genital sites). Variable conversion of type I procollagen to collagen did not perturb the type I:type III collagen ratio. Cell strains from OI patients (Sillence classification): type I (one strain); type II, III and IV (3 strains each) had greater interstrain than intrastrain variation in the collagen ratio (p = 0.0149). Interstrain differences were greater in OI cell strains relative to normal cell strains (p less than 0.01). In the aggregate, OI cells had significantly lower type I collagen production relative to type III (I/III ratio = 1.18) when compared with normal cells (I/III ratio = 2.90; t test, p less than 0.0001). These findings imply abnormal synthesis, secretion or stability of type I procollagen and greater phenotypic heterogeneity in OI skin fibroblasts relative to normal cells.
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D002848:Chromatography, DEAE-Cellulose; D003094:Collagen / Q000032:analysis / Q000096:biosynthesis*; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D006909:Hydroxyproline / Q000032:analysis; D007223:Infant; D008875:Middle Aged; D010013:Osteogenesis Imperfecta / Q000378:metabolism*; D011347:Procollagen / Q000032:analysis
chemical_list: D011347:Procollagen; D003094:Collagen; D006909:Hydroxyproline