Quantitation of estrogen receptors and relaxin binding in human anterior cruciate ligament fibroblasts.
The significantly higher incidence of anterior cruciate ligament (ACL) injuries in collegiate women compared with men may result from relative ligament laxity. Differences in estrogen and relaxin activity, similar to that seen in pregnancy, may account for this. We quantified estrogen receptors by flow cytometry and relaxin receptors by radioligand binding assay in human ACL cells and compared the presence of these receptors in males and females. ACL stumps were harvested from seven males and eight females with acute ACL injuries. The tissue was placed in M199 cell culture medium. Outgrowth cultures were obtained, and passage 2 cells were used for all studies. Estrogen receptor determination was performed using flow cytometry. Relaxin binding was performed in ACL cells derived from five female and male patients using I(125)-labeled relaxin. Estrogen receptors were identified by flow cytometry in 4 to 10% of ACL cells. Mean fluorescence of cells expressing estrogen receptors was approximately twice that of controls, with no significant differences between males and females. Relaxin studies showed low-level binding of I(125)-relaxin-labeled ACL cells. Relaxin binding was present in four out of five female ACL cells versus one out of five male ACL cells.
Faryniarz
Deborah A
DA
Department of Orthopedic Surgery and Sports Medicine, The Permanente Medical Group, Inc, Santa Clara, CA, USA. dfaryniarz@comcast.net
Bhargava
Madhu
M
Lajam
Claudette
C
Attia
Erik T
ET
Hannafin
Jo A
JA
D000293:Adolescent; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000737:chemistry* / Q000166:cytology / Q000378:metabolism; D002478:Cells, Cultured; D003470:Culture Media; D005260:Female; D005347:Fibroblasts / Q000737:chemistry* / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D008297:Male; D011960:Receptors, Estrogen / Q000032:analysis* / Q000378:metabolism; D012065:Relaxin / Q000032:analysis* / Q000378:metabolism; D012737:Sex Factors
D003470:Culture Media; D011960:Receptors, Estrogen; D012065:Relaxin