In Vitro and In Vivo Models to Study Nephropathic Cystinosis

Abstract

The development over the past 50 years of a variety of cell lines and animal models has provided valuable tools to understand the pathophysiology of nephropathic cystinosis. Primary cultures from patient biopsies have been instrumental in determining the primary cause of cystine accumulation in the lysosomes. Immortalised cell lines have been established using different gene constructs and have revealed a wealth of knowledge concerning the molecular mechanisms that underlie cystinosis. More recently, the generation of induced pluripotent stem cells, kidney organoids and tubuloids have helped bridge the gap between in vitro and in vivo model systems. The development of genetically modified mice and rats have made it possible to explore the cystinotic phenotype in an in vivo setting. All of these models have helped shape our understanding of cystinosis and have led to the conclusion that cystine accumulation is not the only pathology that needs targeting in this multisystemic disease. This review provides an overview of the in vitro and in vivo models available to study cystinosis, how well they recapitulate the disease phenotype, and their limitations.

Understanding Inborn Errors of Metabolism through Metabolomics

“…Rather, an immediate control is available in the form of the unmodified cell line. Additionally, these immortalized cell lines provide an unlimited and homogeneous population, but keeping the cells for too many passages may result in a genetic drift [ 58 ]. Another downside of genetically altered cell lines is that these cells do not have the whole genetic constitution of patients and can therefore be more difficult to compare with whole-organism data.…”

“…However, these cells are not readily accessible in humans, so either established cell lines (e.g., HepG2) or animal models have to be used as a source of these cells. Another disadvantage of using fibroblasts is that these primary cells can only be used for a limited number of passages [ 58 ]. Moreover, the fact that these cells originate from patients causes them to have higher variability, due to sex, age, and environmental factors.…”

Urine-Derived Kidney Progenitor Cells in Cystinosis

“…In addition, current cystinosis kidney cell models show several limitations [ 20 ]. Primary cells can only be obtained by invasive means via kidney biopsies which are not required for regular clinical care and can be contaminated with several cell types.…”

“…Primary cells can only be obtained by invasive means via kidney biopsies which are not required for regular clinical care and can be contaminated with several cell types. While these primary cells show a limited proliferative capacity, immortalization might affect the transcriptome, interfere with important cellular pathways and may be unreliable at high passage numbers [ 20 , 21 , 22 ]. The development of induced pluripotent stem cells (iPSC) is laborious and expensive and iPSC reprogramming might induce genomic side effects [ 23 ].…”

“…Therefore, alternative cystinosis cell models that demonstrate the primary phenotype of cystinosis and harbor a proliferative capacity without having the disadvantages of immortalization are desirable. These models can further improve our understanding of the cellular pathophysiology of cystinosis and help to elucidate the exclusive functions of cystinosin [ 20 ].…”