Fig 2: Survival of TAT-MTScs-Frataxin-treated MCK mice. (A) Kaplan–Meier curve generated by GraphPad Prism showing the lifespan increase in MCK-conditional mouse model treated with TAT-MTScs-FXN, P = 0.0162 using log-rank (Mantel–Cox) test. (B) Age of death, average was calculated using Gehan–Breslow–Wilcoxon test generated by GraphPad Prism, P = 0.0251. Mice treated with 10 mg/kg of TAT-MTScs-FXN or vehicle (IP injection) were tested for survival (as described in Materials and methods). N = 11 for each group.

Fig 3: TAT-MTScs-FXN treatment FXN-KO mice. (A) Study design: FA mice model 25 was treated with TAT-MTScs-FXN for 4 weeks followed by 2-week washout. Mice were killed, muscles were harvested at the indicated time-points (n = 4 per time-point), and frataxin amounts were evaluated in mitochondrial fractions as described in Materials and methods. (B) Frataxin amounts (expressed in pg/mg of total protein) present in muscle mitochondria of mice treated with 10 mg/kg with TAT-MTScs-FXN compared to untreated control (as indicated in the first column). Error bars represent mean ± S.E.M., n = 4 per time-point.

Fig 4: Neurite degeneration is reduced by TAT-MTScs-FXN treatment. (A) Histogram showing the significant decreased percentage of neurite degeneration (measured as described in Materials and methods) produced by TAT-MTScs-FXN treatment using 7 µg/ml after 12 hrs compared to untreated cells. Error bars represent mean ± S.D., n = 4. (B) Representative images of 5-day cultures of Scr, Fxn1 and Fxn2 treated with 7 µg/ml TAT-MTScs-FXN or vehicle solution 12 hrs after lentiviral transduction. Note the decrease in neurite aggregates (indicated by arrows) in treated cells (lower panels) compared with untreated cultures (upper panels). (C) Histogram showing the significant decreased percentage of neurite degeneration (measured as described in Materials and methods) produced by TAT-MTScs-FXN treatment (using 1 µg/ml, 3 µg/ml and 7 µg/ml) compared to untreated cells. Error bars represent mean ± S.D., n = 4.

Fig 5: TAT-MTScs-FXN is processed and functional in mice muscle (A) A representative image of frataxin present in mitochondrial fractions obtained from mice treated for 3 weeks—twice a week—with 10 mg/kg TAT-MTScs-FXN (lanes 1–6) or vehicle (lanes 7–8 where frataxin is almost undetectable). The same protocol was executed by administrating 4 mg/kg (not shown). Each lane (1–6) represents individual mouse. Unprocessed external TAT-MTScs-FXN protein was run in parallel (lane 9). Lower panel shows the levels of COX-IV that was used as internal mitochondrial marker. The frataxin levels normalized against COX-IV are shown in (B). Dashed line indicates the frataxin levels of heterozygous, healthy mice. Bars represent mean ± S.E.M., n = 4. In (C), the activity of mitochondrial complex II (succinate dehydrogenase) is shown. Values were obtained in samples of muscle mitochondrial fractions from mice treated with 4 and 10 mg/kg of TAT-MTScs-FXN and vehicle. Dashed line indicates the frataxin values for heterozygous, healthy mice. Results are presented as ?OD at 0–10 min. per total protein (bars represent mean ± S.E.M., n = 4, P < 0.05,anova).