Expression, content, and localization of insulin-like growth factor I in human achilles tendon.
In animals insulin-like growth factor I (IGF-I) stimulates collagen production by fibroblasts and is expressed in tendons together with its binding protein 4 (IGFBP-4). However, the presence of IGF-I and IGFBP-4 in human tendon tissue is not described. Tissue IGF-I content was examined by immunoflourometric assay, real-time PCR, and immunohistochemistry used to localize and determine expression of IGF-I and IGFBP-4 in 6 postmortem human Achilles tendons. Tendon tissue concentrations of IGF-I were found to be 0.53 +/- 0.10 ng/g. Furthermore, we demonstrated that IGF-I and IGFBP-4 are localized around the tendon fibroblasts and that mRNA for IGF-I and IGFBP-4 can be determined in human tendon tissue. The present study adds support for the roles of IGF-I and IGFBP-4 in the regulation of tendon adaptive responses to mechanical loading.
Olesen
Jens L
JL
Institute of Sports Medicine, Bispebjerg Hospital, Copenhagen, Denmark. olesenjens@yahoo.dk
Heinemeier
Katja M
KM
Langberg
Henning
H
Magnusson
S Peter
SP
Kjaer
Michael
M
Flyvbjerg
Allan
A
D000125:Achilles Tendon / Q000378:metabolism*; D000328:Adult; D019084:Fluorescent Antibody Technique, Indirect; D015870:Gene Expression; D006801:Humans; D018974:Insulin-Like Growth Factor Binding Protein 4 / Q000235:genetics / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
D018974:Insulin-Like Growth Factor Binding Protein 4; D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I