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Peptide growth factor regulation of cell growth in isolated fetal hepatocytes
WP-B 1
PEPTIDE GROWTH FACTOR REGULATION OF CELL GROWTH IN ISOLATED FETAL HEPATOCYTES A.J. Strain, D.J. Hill, R.D.G. Milner Department Sheffield, Children's Hospital, Sheffield, U.K.
of Paediatrics,
University of
In post-natal life, the liver synthesises and releases insulin-like growth factors (IGFs) into the circulation which act as endocrine factors in mediating the growth promoting action of growth hormone. Current evidence suggests that in fetal life circulating levels of growth factors are less meaningful since tissue growth may occur by paracrine mechanisms. We have investigated the ability of human foetal hepatocytes both to synthesise and release, and to respond to various peptide hormones and growth factors. Isolated hepatocytes, from fetuses of 10-18 weeks gestation, were maintained in selective arginine-free culture medium on collagen coated 2 cm 2 wells for up to 72 h. DNA synthesis was determined by autoradiography following addition of 3H-thymidine for 24 h. Hepatocytes were found to respond to insulin-like growth factor I (IGF I, 1.3 nM - 6.5 nM), human placental lactogen (HPL, 2.3 nM - 11.6 nM) and human growth hormone (HGH, 2.3 nM - 11.6 nM) with a 3-5 fold increase in nuclear labelling index. Approximately 30% of hepatocytes showed selective positive immunoperoxidase staining with a monoclonal antibody raised against IGF I, and release of immunoassayable IGF I into culture medium was enhanced by both HPL and HGH. In parallel experiments, purified human transforming growth factor 8 (TGF~) was found to be a highly potent inhibitor of both basal and IGF I stimulated DNA synthesis in these cells, with half-maximal inhibition at 0.65 pM. Although cultures contained predominantly hepatocytes, small numbers of fibroblast-like cells were also present. Notably, these cells retained the ability to incorporate 3H-thymidine into DNA in the presence of greater than 50 fold higher doses of TGFB. These observations indicate that both IGF I and TGFB may be important growth regulators in the human fetal liver.
WP-B 2
WITHDRAWN
$45
PEPTIDE GROWTH FACTOR REGULATION OF CELL GROWTH IN ISOLATED FETAL HEPATOCYTES A.J. Strain, D.J. Hill, R.D.G. Milner Department Sheffield, Children's Hospital, Sheffield, U.K.
of Paediatrics,
University of
In post-natal life, the liver synthesises and releases insulin-like growth factors (IGFs) into the circulation which act as endocrine factors in mediating the growth promoting action of growth hormone. Current evidence suggests that in fetal life circulating levels of growth factors are less meaningful since tissue growth may occur by paracrine mechanisms. We have investigated the ability of human foetal hepatocytes both to synthesise and release, and to respond to various peptide hormones and growth factors. Isolated hepatocytes, from fetuses of 10-18 weeks gestation, were maintained in selective arginine-free culture medium on collagen coated 2 cm 2 wells for up to 72 h. DNA synthesis was determined by autoradiography following addition of 3H-thymidine for 24 h. Hepatocytes were found to respond to insulin-like growth factor I (IGF I, 1.3 nM - 6.5 nM), human placental lactogen (HPL, 2.3 nM - 11.6 nM) and human growth hormone (HGH, 2.3 nM - 11.6 nM) with a 3-5 fold increase in nuclear labelling index. Approximately 30% of hepatocytes showed selective positive immunoperoxidase staining with a monoclonal antibody raised against IGF I, and release of immunoassayable IGF I into culture medium was enhanced by both HPL and HGH. In parallel experiments, purified human transforming growth factor 8 (TGF~) was found to be a highly potent inhibitor of both basal and IGF I stimulated DNA synthesis in these cells, with half-maximal inhibition at 0.65 pM. Although cultures contained predominantly hepatocytes, small numbers of fibroblast-like cells were also present. Notably, these cells retained the ability to incorporate 3H-thymidine into DNA in the presence of greater than 50 fold higher doses of TGFB. These observations indicate that both IGF I and TGFB may be important growth regulators in the human fetal liver.
WP-B 2
WITHDRAWN
$45