Investigation on Cross-correction of Cystinosis through Genetically Engineered Cells Secreting Cystinosin

Background: Cystinosis is a rare inherited lysosomal storage disease (LSD), caused by a mutation in the Cystinosin Lysosomal Cystine Transporter (CTNS). Novel therapies and strategies are needed to improve patients' clinical conditions and quality of life. Objectives and Methods: This study assessed whether CTNS can be secreted, and investigated a method to enhance its secretion, by adding a secretion signal to the N-terminus. Human Embryonic Kidney (HEK) 293 cells were transfected with the resulting construct. The amount of protein secreted was then measured. Uptake by monolayer cultures of cystinotic cells and enzyme activity were also assessed. Results: The recombinant protein could effectively be secreted, and the secretion signal slightly further increased its secretion. The secreted recombinant protein was taken up by cystinotic cells, and, after internalization, still retained its biological activity. Conclusion: Optimization of the proposed method to increase the secretion of CTNS would provide new insights into the production of recombinant proteins for medical and industrial use. Further identification and screening of alternative signalling peptides and cell types can maximise the secretion and production of recombinant CNTS, to be used as a therapeutic agent in human healthcare.