Development and characterization of cell models harbouring mtDNA deletions for in vitro study of Pearson syndrome.

Julio Montoya,María Concepción García-Jiménez,Rafael Artuch,Marta García Fernández De Villalta,Francisco José Climent-Alcalá,Ester López-Gallardo,Carmen Rodríguez-Vigil,Carmen Hernández-Ainsa,Eduardo Ruiz-Pesini,Sonia Emperador

doi:10.1242/dmm.049083

Abstract

ABSTRACTPearson syndrome is a rare multisystem disease caused by single large-scale mitochondrial DNA deletions (SLSMDs). The syndrome presents early in infancy and is mainly characterised by refractory sideroblastic anaemia. Prognosis is poor and treatment is supportive, thus the development of new models for the study of Pearson syndrome and new therapy strategies is essential. In this work, we report three different cell models carrying an SLMSD: fibroblasts, transmitochondrial cybrids and induced pluripotent stem cells (iPSCs). All studied models exhibited an aberrant mitochondrial ultrastructure and defective oxidative phosphorylation system function, showing a decrease in different parameters, such as mitochondrial ATP, respiratory complex IV activity and quantity or oxygen consumption. Despite this, iPSCs harbouring ‘common deletion’ were able to differentiate into three germ layers. Additionally, cybrid clones only showed mitochondrial dysfunction when heteroplasmy level reached 70%. Some differences observed among models may depend on their metabolic profile; therefore, we consider that these three models are useful for the in vitro study of Pearson syndrome, as well as for testing new specific therapies. This article has an associated First Person interview with the first author of the paper.

Highlights

Pearson syndrome (PS; OMIM #557000) is a rare genetic disorder characterized by pancytopenia with vacuolization of bone marrow precursors and exocrine pancreatic dysfunction in early infancy (Pearson et al, 1979)
Pearson syndrome is still a challenge in medicine since its evolution is usually tragic leading to death in childhood
In all cases we observed the consequences of the presence of deleted mitochondrial DNA (mtDNA) molecules, since mutant cells showed a drop in the amount of mitochondrial ATP, activity and amount of complex IV (CIV) and basal oxygen consumption

Summary

Introduction

Pearson syndrome (PS; OMIM #557000) is a rare genetic disorder characterized by pancytopenia with vacuolization of bone marrow precursors and exocrine pancreatic dysfunction in early infancy (Pearson et al, 1979) It is caused by single large-scale mitochondrial DNA deletions (SLSMDs), leading to severe defects in the mitochondrial respiratory chain (Rötig et al, 1995). Therapy is supportive and based on pancreatic extracts, fat-soluble vitamins (ADEK), transfusions, and treatment of endocrinopathies, metabolic decompensations and other stress-triggering factors (Farruggia, Di Marco and Dufour, 2018). Research in this field and the development of cellular and animal models for the study of the origin, development and treatment of this pathology is essential

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