A human neuronal cell line shows greater bilirubin cytotoxicity and uptake than a non-neuronal cell line

CRISTINA BELLAROSA, PABLO GIRAUDI, SEBASTIAN D. CALLIGARIS, JAY D. OSTROW, CLAUDIO TIRIBELLI

Toronto, Canada

Congreso; 2007 Pediatric Academic Societies' Meeting; 2007

Background: Neonates with severe hyperbilirubinemia may develop encephalopathy with multifocal deposition of bilirubin in selected brain regions. Neurotoxicity correlates best with the plasma concentration of the unbound, free fraction (Bf) of unconjugated bilirubin (UCB). Objective: To compare the cytotoxic effects of UCB on a human neuroblastoma-derived cell line (SHSY5Y) vs. non-neuronal Hela cells and to correlate cytotoxicity with UCB uptake. Design/Methods: Each cell line was exposed for 2, 4 and 6 h to FCS 15%+UCB at Bf of 10, 40 and 70 nM. Viability was assessed by MTT reduction test. [3H]UCB uptake (pmol/mg prot) at 4 h was measured by exposing each cell lines to the same Bf. Results: At Bf 10 nM, UCB caused a significant, time-dependent decrease in the viability of SHSY5Y whereas HeLa suffered a significant loss of viability only at 6 h. The significantly greater UCB toxicity to SHSY5Y than HeLa cells was evident also at Bf 40 and 70 nM at all three time points. At each Bf, the greater sensitivity of SHSY5Y was associated with a much greater 4 hour intracellular accumulation of [3H]UCB. Interestingly, after 6 h exposure to UCB, SHSY5Y showed a similar loss of viability of about 40% at all three Bf. Conclusions: The neuronal cell line SHSY5Y is much more sensitive to UCB toxicity than non-neuronal HeLa cells and other neuronal and glial cell lines (toxicity reported only at Bf >70 nM). The greater sensitivity of SHSY5Y to UCB toxicity correlates with a vastly greater uptake of UCB than HeLa. The well characterized SHSY5Y cells should be a good model to study the intracellular mechanisms of UCB neurotoxicity.