Nephrology Dialysis Transplantation, Vol 13, Issue 6 1420-1429, Copyright © 1998 by Oxford University Press
C Hoff, J Cusick, E Masse, R Jackman, J Nagy and T Shockley
Background: The efficacy of peritoneal dialysis and
its success as a long-term treatment depends on the preservation of the
integrity of the peritoneal membrane. With increasing time on dialysis, the
membrane may become compromised resulting in decreased dialysing capacity.
We have pursued an innovative strategy, i.e. genetic modification of the
mesothelial cell to change the properties of the membrane to potentially
improve its dialysing capacity and longevity, and have demonstrated the
feasibility of this approach in a rat model of ex vivo
gene transfer. The potential to regulate transgene expression in this model
is examined here. Methods: Rat peritoneal mesothelial
cells (MCs) were stably modified to express human growth hormone (hGH)
under control of the heavy metal ion and glucocorticoid-regulatable murine
metalothionein-1 promoter. The effect of zinc and the synthetic
glucocorticoid dexamethasone on the hGH expression was analysed in MC
clones maintained in continuous passage or stationary phase, and in our rat
model of ex vivo gene transfer.
Results: Exposure of these clones to zinc and
dexamethasone, either singly or in combination, resulted in significant
(i.e. 2-200-fold) increases in hGH production. Zinc-induced modulation of
hGH production was demonstrated in cells in continuous passage and
stationary culture. Regulation was also demonstrated after ex
vivo gene transfer by both the intraperitoneal administration of
zinc ions or the systemic administration of dexamethasone.
Conclusions: Our results demonstrate the modulation of
transgene expression in MCs in vitro and in
vivo , and suggest the potential for the regulation of gene
expression in a genetically modified mesothelium that may ultimately be
used for the delivery of therapeutic proteins to maintain peritoneal
membrane viability in the peritoneal dialysis patient. Key
words: dexamethasone; ex vivo gene
transfer; gene therapy; heavy metal ions; human growth hormone; inducible
promoter; intraperitoneal; mesothelial cells; mMT-1; peritoneal cavity;
peritoneal dialysis; peritoneal mesothelium; systemic delivery
ORIGINAL ARTICLES
Modulation of transgene expression in mesothelial cells by activation of an inducible promoter
Renal Division Scientific Affairs-MPGR-R2, Baxter Healthcare Corporation, 1620 Waukegan Rd, McGaw Park, IL 60085, USA; Departments of Pathology, Beth Israel Deaconness Medical Center and Harvard Medical School, Boston, MA, USA; Corresponding author
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