Combining multiple therapeutic strategies for Friedreich’s ataxia (FRDA): antioxidant metallic nanoclusters as coadjuvants for gene and stem cell therapy

Introduction FRDA pathology is caused by guanine–adenine–adenine trinucleotide repeat expansion within the first intron of frataxin (FTX) gene, leading to epigenetic silencing. Since mitochondrial FTX controls cellular iron use and redox status maintenance, its lack causes an increased level of reactive oxygen species. We report an effective lentivirus FXN gene delivery to FTX deficient mesenchymal stem cells (MSCs), inducing improvement of neurological functionalities when transplanted in vivo. We also identify antioxidant nanoclusters (NCs) able to block ROS–dependent apoptotic pathways in the FRDA pathology. Methods MSCs from FRDA patient bone marrows were transduced with a lentiviral vector for FXN expression. After LV transduced MSC characterization by FACS, IF, and WB analyses, engineered cells were systemically injected in Fxntm1MknTg (FXN)YG8Pook/2J mice. Behaviour tests (rotarod and treadmill) were performed. Brain tissues were harvested for IF staining and WB. FRDA MSCs labelled with AuAg NCs were characterized to evaluate mitochondrial ROS scavenger activity. Results After LV transduction, MSCs showed the preservation of mesenchymal marker expression (CD73, CD44, CD90 and CD105), colony forming abilities, and capacity to differentiate into multilineages. Comparison with untreated animals revealed i) in vivo FTX rescue; ii) increased number of cerebellar cells expressing Tuj1 neuronal marker; and iii) improvement trend of motor skills in mice injected with engineered MSCs. In addiction, AuAg NCs entered the mitochondria of FRDA MSCs where they reduce ROS levels lowering cell sensitivity to oxidative stress. Conclusions The results confirm the gene and stem cells-based therapeutic applicability to treat the neuronal degeneration in FRDA. The suitability of metallic NCs as anti oxidant agents represents a crucial point as implemental strategy for further ameliorating the progressive ROS mediated degeneration. Indeed, a combined approach based on NCs nasal inhalation in autologous transplanted FRDA patients may be considered as a step further into a clinically relevant treatment.