Increased human dermal microvascular endothelial cell survival induced by cysteamine.
BACKGROUND
Cystinosis is an autosomal recessive disease caused by intralysosomal cystine accumulation, treated with cysteamine. Recently, new adverse effects of cysteamine were reported. Skin biopsies showed microvascular proliferation (angioendotheliomatosis). To examine the mechanism of angioendotheliomatosis associated with cysteamine toxicity, we examined the effect of cysteamine on human dermal microvascular endothelial cells (HDMVEC).


METHODS
After cysteamine exposure (range 0-3.0 mM) during 24 h, cell viability was measured using water soluble tetrazolium salt-1 (WST-1) in both control HDMVEC and fibroblasts. Cell proliferation and apoptosis rate were measured in HDMVEC by bromodeoxyuridine (BrdU) incorporation and caspase 3 and caspase 7 activity, respectively. Intracellular glutathione (GSH) was measured in HDMVEC after cysteamine exposure of 0, 0.1 or 1.0 mM. Medium and cysteamine were refreshed every 6 h to mimic the in vivo situation. Next, cell viability in HDMVEC was measured after 24 h of GSH exposure (range 0-10.0 mM).


RESULTS
HDMVEC viability and proliferation increased after cysteamine exposure 0.03-3.0 mM (p < 0.01) and 0.03-1.0 mM (p = 0.01) respectively; cell viability in fibroblasts was not affected by incubation with cysteamine. Apoptosis remained unaffected by incubation with 0-1.0 mM cysteamine, 3.0 mM caused increased apoptosis. Intracellular GSH was significantly increased after incubation with cysteamine 0.1 mM (p = 0.02) and 1.0 mM (p < 0.01). HDMVEC viability increased after exposure to GSH 1.0-5.0 mM (p < 0.01).


CONCLUSIONS
Cysteamine concentrations, similar to those described in plasma of cystinosis patients, stimulate HDMVEC viability and proliferation and increase intracellular GSH content. We postulate that this mechanism might underlie angioendotheliomatosis induced by cysteamine.
Department of Pediatric Nephrology, University Hospitals Leuven, Herestraat 49, 3000, Leuven, Belgium, martine.besouw@uzleuven.be.
M
M
Besouw
L
L
van den Heuvel
R
R
van Eijsden
I
I
Bongaers
L
L
Kluijtmans
M
M
Dewerchin
E
E
Levtchenko
D017209:Apoptosis / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003543:Cysteamine / Q000494:pharmacology*; D020405:Dermis / Q000098:blood supply / Q000166:cytology* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D005978:Glutathione / Q000032:analysis / Q000378:metabolism / Q000494:pharmacology; D006801:Humans
D003543:Cysteamine; D005978:Glutathione