The Effects of Bilirubin and Lumirubin on the Differentiation of Human Pluripotent Cell-Derived Neural Stem Cells.

Nikola Capková,Veronika Fedorová,Libor Vítek,Veronika Pospíšilová,Aleš Dvořák,Jan Raška,Matteo Dal Ben,Dáša Bohačiaková,Jitka Viktorová,Kateřina Pospíšilová

doi:10.3390/antiox10101532

Abstract

The ‘gold standard’ treatment of severe neonatal jaundice is phototherapy with blue–green light, which produces more polar photo-oxidation products that are easily excreted via the bile or urine. The aim of this study was to compare the effects of bilirubin (BR) and its major photo-oxidation product lumirubin (LR) on the proliferation, differentiation, morphology, and specific gene and protein expressions of self-renewing human pluripotent stem cell-derived neural stem cells (NSC). Neither BR nor LR in biologically relevant concentrations (12.5 and 25 µmol/L) affected cell proliferation or the cell cycle phases of NSC. Although none of these pigments affected terminal differentiation to neurons and astrocytes, when compared to LR, BR exerted a dose-dependent cytotoxicity on self-renewing NSC. In contrast, LR had a substantial effect on the morphology of the NSC, inducing them to form highly polar rosette-like structures associated with the redistribution of specific cellular proteins (β-catenin/N-cadherin) responsible for membrane polarity. This observation was accompanied by lower expressions of NSC-specific proteins (such as SOX1, NR2F2, or PAX6) together with the upregulation of phospho-ERK. Collectively, the data indicated that both BR and LR affect early human neurodevelopment in vitro, which may have clinical relevance in phototherapy-treated hyperbilirubinemic neonates.

Highlights

Bilirubin (BR) is the end product of the heme degradation pathway
The physiological neonatal jaundice spontaneously resolves within a few days after birth, and it is believed to even have a protective role against pathological conditions associated with increased oxidative stress [3,4]
In the initial phase of our studies on self-renewing neural stem cells (NSC) derived from human pluripotent stem cells (hPSC), we intended to assess the possible cytotoxic effects of both BR and its major photoisomer LR

Summary

Introduction

Bilirubin (BR) is the end product of the heme degradation pathway. While in the pastBR was considered a potentially neurotoxic waste product of heme catabolism, numerous in vitro, in vivo, and clinical studies over recent decades have demonstrated that when it is only mildly elevated it is an endogenous antioxidant with potent anti-inflammatory and cytoprotective effects, mediated via true endocrine mechanisms [1].Elevated serum BR concentrations are present in most newborn infants [2]. Bilirubin (BR) is the end product of the heme degradation pathway. BR was considered a potentially neurotoxic waste product of heme catabolism, numerous in vitro, in vivo, and clinical studies over recent decades have demonstrated that when it is only mildly elevated it is an endogenous antioxidant with potent anti-inflammatory and cytoprotective effects, mediated via true endocrine mechanisms [1]. The physiological neonatal jaundice spontaneously resolves within a few days after birth, and it is believed to even have a protective role against pathological conditions associated with increased oxidative stress [3,4]. Severely jaundiced neonates (i.e., with hyperbilirubinemia above 340 μmol/L) are in danger of serious health risks, which may lead to 4.0/).

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