Antioxidant treatment improves in vivo cardiac and skeletal muscle bioenergetics in patients with Friedreich's ataxia.код для вставкиСкачать
Antioxidant Treatment Improves In Vivo Cardiac and Skeletal Muscle Bioenergetics in Patients with Friedreich’s Ataxia Raffaele Lodi, MD,1,2 Paul E. Hart, MRCP,3 Bheeshma Rajagopalan, MD,1 Doris J. Taylor, DPhil,1 Jenifer G. Crilley, MD,1 Jane L. Bradley, PhD,3 Andrew M. Blamire, PhD,1 David Manners, BsC,1 Peter Styles, DPhil, Anthony H.V. Schapira, MD,3,4 and J. Mark Cooper, PhD3 Friedreich’s ataxia (FA) is the most common form of autosomal recessive spinocerebellar ataxia and is often associated with a cardiomyopathy. The disease is caused by an expanded intronic GAA repeat, which results in deficiency of a mitochondrial protein called frataxin. In the yeast YFH1 knockout model of the disease there is evidence that frataxin deficiency leads to a severe defect of mitochondrial respiration, intramitochondrial iron accumulation, and associated production of oxygen free radicals. Recently, the analysis of FA cardiac and skeletal muscle samples and in vivo phosphorus magnetic resonance spectroscopy (31P-MRS) has confirmed the deficits of respiratory chain complexes in these tissues. The role of oxidative stress in FA is further supported by the accumulation of iron and decreased aconitase activities in cardiac muscle. We used 31P-MRS to evaluate the effect of 6 months of antioxidant treatment (Coenzyme Q10 400 mg/day, vitamin E 2,100 IU/day) on cardiac and calf muscle energy metabolism in 10 FA patients. After only 3 months of treatment, the cardiac phosphocreatine to ATP ratio showed a mean relative increase to 178% ( p ⴝ 0.03) and the maximum rate of skeletal muscle mitochondrial ATP production increased to 139% ( p ⴝ 0.01) of their respective baseline values in the FA patients. These improvements, greater in prehypertrophic hearts and in the muscle of patients with longer GAA repeats, were sustained after 6 months of therapy. The neurological and echocardiographic evaluations did not show any consistent benefits of the therapy after 6 months. This study demonstrates partial reversal of a surrogate biochemical marker in FA with antioxidant therapy and supports the evaluation of such therapy as a disease-modifying strategy in this neurodegenerative disorder. Ann Neurol 2001;49:590 –596 Friedreich’s ataxia (FA), the most common form (frequency 1:30 –50,000) of the inherited ataxias, is an autosomal recessive degenerative disorder, characterised clinically by onset before the age of 25 years of progressive gait and limb ataxia, absence of deep tendon reflexes and extensor plantar responses, and loss of position and vibration sense in the lower limbs.1 Cardiomyopathy is often present in FA patients.2 The disease is caused in most cases by a GAA repeat expansion in the first intron of the FA gene (chromosome 9),3 which results in deficiency of a mitochondrial protein called frataxin.4 – 6 Although frataxin function is still unknown, from the yeast YFH1 model of the disease there is evidence that deficiency of the yeast frataxin homolog leads to a severe defect of mitochondrial respiration, loss of mitochondrial DNA, intramitochon- drial iron accumulation, and increased sensitivity to oxidative stress.5– 8 Clues provided by the YFH1 knockout yeast strain have been proved to be relevant to the pathogenesis of FA as shown by recent investigations in patients. Studies performed on cardiac muscle samples from FA patients collected by biopsy or at postmortem have shown reduced activities of respiratory chain complexes I, II, and III and aconitase and increased cardiac iron deposition.9 –11 Although the role of frataxin is still not known, these enzymes all contain iron-sulphur (Fe-S) clusters, so frataxin could play a role in mitochondrial iron metabolism and the formation of Fe-S centres, or, alternatively, these enzymes may be targeted because of their particular sensitivity to damage by oxygen free radicals.10 Moreover, support for defective mitochon- From the 1MRC Biochemical and Clinical Magnetic Resonance Unit, Department of Biochemistry, University of Oxford and Oxford Radcliffe Hospital, Oxford, United Kingdom; 2Dipartimento di Medicina Clinica e Biotecnologia Applicata, Universita di Bologna, Bologna, Italy; and 3University Department of Clinical Neurosciences, Royal Free and University College Medical School, and 4Institute of Neurology, University College, London, United Kingdom. Published online 2 April 2001. Received Jan 6, 2000, and in revised form Oct 4, 2000. Accepted for publication Nov 10, 2000. 590 © 2001 Wiley-Liss, Inc. Address correspondence to Dr Lodi, MD, PhD, Dipartimento di Medicina Clinica e Biotecnologia Applicata “D. Campanacci,” Universita di Bologna, Policlinico S. Orsola, Via Massareti 9, 40138 Bologna, Italy. E-mail: email@example.com drial oxidative phosphorylation in FA patients comes from our recent demonstration that phosphorus magnetic resonance spectroscopy (31P-MRS) can detect in vivo defects of cardiac12 and skeletal13 muscle energy metabolism in FA patients. Currently there is no established treatment for FA. However, the biochemical defects observed to date in FA suggest that the mitochondrial respiration deficit may be amenable to treatment with antioxidants. To test this hypothesis, we performed a study in 10 FA patients who were given Coenzyme Q10 (CoQ10; 400 mg/day) and vitamin E (Vit E; 2,100 IU/day) as antioxidant therapy. The effect of such treatment on FA patients’ cardiac and skeletal muscle energy metabolism was assessed in vivo by means of 31P-MRS performed before and after 3 and 6 months of therapy. Subjects and Methods Subjects Ten FA patients (5 males, age range 16 – 40 years, mean ⫾ SD 28 ⫾ 6 years), 10 healthy volunteers for the calf (5 males, age range 22– 41 years, mean ⫾ SD 28 ⫾ 5 years) and 10 different healthy volunteers for the cardiac muscle 31 P-MRS (5 males, age range 16 – 40 years, mean ⫾ SD 28 ⫾ 6 years) were studied. The diagnosis of FA was confirmed by detection of a GAA repeat expansion in the first intron of both alleles of the frataxin gene using methods previously described.11 The GAA expansions were in the range 290 to 900 repeats for the shorter of the two alleles. FA patients were assessed neurologically before and after 6 months of therapy using the semiquantitative International Cooperative Ataxia Rating Scale (ICARS),14 which can be subdivided into kinetic, gait and posture, speech, and ocular categories. On this scale of 0 to 100, higher scores imply more severe disease. Informed consent was obtained from each patient and normal volunteer, and studies were carried out with approval of the Central Oxford and Royal Free Hospital Ethics Committees. Echocardiography 2D- and M-mode imaging from parasternal and apical windows was performed before and after 3 and 6 months of therapy using Sonos-5500 (Hewlett Packard, Bracknell, United Kingdom). Images were recorded on optical disk for subsequent analysis. Standard M-mode measurements were made using established criteria.15 Left ventricular (LV) mass index (LVMi) was derived from the M-mode measurements using the Wikstrand formula and adjusted for height. Ejection fraction (EF) was calculated from LV volumes (derived using modified Simpson’s rule). Magnetic Resonance Spectroscopy 31 P-MRS studies were performed in a 2.0 T whole-body magnet (Oxford Magnet Technology, Oxon, United Kingdom) interfaced to a Bruker Avance spectrometer (Bruker Medical GmbH, Ettlingen, Germany). Skeletal muscle 31PMRS spectra were obtained from the right calf muscle at rest, during an aerobic incremental exercise of plantar flex- ion, and in the following recovery period as previously described.13 Relative concentrations of inorganic phosphate (Pi), phosphocreatine (PCr), and adenosine triphosphate (ATP) were obtained by a time-domain fitting routine16 using the AMARES algorithm and MRUI software17,18 and were corrected for magnetic saturation. Absolute concentrations were obtained by assuming that the concentration of ATP in normal muscle is 8.2 mM (ie, mmol/litre of intracellular water).13 Free [ADP] was calculated from the creatine kinase equilibrium.13 PCr recovery half-times were calculated from the slope of semilogarithmic plots19 using the end-exercise and the first 3 recovery spectra. Initial rates of PCr resynthesis after exercise, V (mM/min), were calculated from the exponential rate constant of PCr recovery (k ⫽ 0.693/t1/2) and the total fall in [PCr] during exercise (⌬[PCr]) as V ⫽ k. ⌬[PCr].19 Using the hyperbolic ADP control model for mitochondrial respiration and a normal Km for ADP of 30 M,19 we calculated the maximum rate of mitochondrial ATP synthesis (Vmax) from the initial rate of PCr postexercise resynthesis (V) and the end-exercise [ADP] ([ADP]end): Vmax ⫽ V[1 ⫹ (Km/[ADP]end)].19 For the cardiac muscle studies, patients were positioned prone, and standard multislice spin-echo images (TR ⫽ heart rate, TE ⫽ 25 msec, slice ⫽ 10 mm, 5 slices) were acquired using a double rectangular surface coil placed around the chest to confirm subject placement in the magnet and to guide spectral localisation. After shimming was performed (using a 15-cm-diameter circular 1H surface coil centred beneath the heart), the coil system was exchanged for an 8-cm-diameter circular 31P surface coil. Cardiac spectra were acquired using a one-dimensional chemical shift imaging (1D CSI) sequence to encode signals with depth into the chest.20 Spectral localisation was improved by using presaturation bands positioned over the chest wall using the proton images.21 Cardiac signal was acquired from an 8-cm-thick axial slice (again guided by the proton images) and phaseencoded to provide spectra from 1-cm-thick coronal slabs through the heart. All proton and phosphorus data acquisition was cardiac-gated from a pulse oximeter probe placed on a finger. Saturation correction factors for PCr and ATP were measured by obtaining 1D CSI spectra from phosphate phantoms of known T1 at different repetition rates. The pulse angle at the surface of the coil was similar for equivalent power levels whether the load was a phantom or a human subject. T1s of PCr and ATP were assumed to be 4.3 seconds and 2.52 seconds, respectively, these values being the average of published data.20 The proton images were used to determine the location of spectra in the cardiac 1D CSI data set arising from the myocardium. Typically, composite cardiac 31P spectra were obtained by adding 2 or 3 1D CSI rows collected from the apex and part of the septum and the posterior wall. Spectra were then fitted using a purposewritten interactive frequency domain-fitting program.21 Time domain signals were simulated for PCr, the 3 peaks of ATP, PDE, and 2,3-DPG incorporating prior knowledge of peak chemical shifts and j-couplings. Each signal component was simulated allowing for missing initial data points (because of the phase-encoding duration of the acquisition experiment). Signal amplitude and exponential decay of each component were adjustable, and a Gaussian decay could also be applied to the entire free induction decay (FID). The sim- Lodi et al: Antioxidant Therapy in Friedreich’s Ataxia 591 was reduced in FA patients (1.34 ⫾ 0.59, n ⫽ 9) compared to controls (2.40 ⫾ 0.14, p ⫽ 0.0003; Table 1), as shown previously.12 After 3 months of CoQ10 and Vit E therapy, the cardiac PCr/ATP in the 9 FA patients was significantly increased (2.02 ⫾ 0.42, p ⫽ 0.03 relative to pretherapy values), and this improvement was sustained after 6 months of therapy (2.02 ⫾ 0.43, p ⫽ 0.03 relative to pretherapy values; Table 1, Fig 2). Cardiac PCr/ATP did not increase in patients 9 and 10, both with left ventricular hypertrophy (LVH), but it should be noted that patient 9 was the only patient with normal cardiac PCr/ATP before therapy. The extent of cardiac PCr/ATP increase after therapy was independent of the patients’ GAA repeat length (data not shown). In general there was a greater degree of PCr/ATP recovery in the 4 FA patients without LVH than in the 5 patients with LVH (Table 1). In fact, although before treatment the mean PCr/ATP ratio in the 4 FA patients with no LVH was lower (1.24 ⫾ 0.57) than in those with LVH (1.42 ⫾ 0.61), after 3 months of CoQ10 and Vit E administration, PCr/ATP was higher in patients without (2.30 ⫾ 0.30) than in those with (1.79 ⫾ 0.38) hypertrophy, which was confirmed at 6 months. The rate of skeletal muscle oxidative metabolism is conveniently assessed in vivo by stimulating mitochondrial respiration with an in-magnet exercise protocol. As was shown previously,13 the skeletal muscle maximum rate of mitochondrial ATP synthesis (Vmax), calculated from the initial rate of PCr recovery and the end-exercise [ADP],19 was severely reduced in FA pa- ulated FID was Fourier-transformed and compared to the actual spectrum and root mean square residuals calculated as a measure of the fit. After fitting, the ATP signal was corrected for blood contamination based on the amplitude of the 2,3-DPG22 and the final PCr/ATP ratio was calculated. Statistical Analysis Individual results were taken as abnormal when they fell outside the normal range. In view of the low number of subjects, nonparametric tests were used. The Mann-Whitney U-test was used to compare independent groups and the Wilcoxon’s matched pair test to compare dependent groups (ie, data collected from FA patients before and during therapy). Statistical significance was taken as p ⬍ 0.05. Correlation coefficients were calculated by linear regression. Results CoQ10 and Vit E administration was well tolerated by all patients and did not cause noticeable side effects. The 31P-MRS and echocardiography results are shown in Table 1 and Figures 1 and 2, and the patient details and neurological evaluations are shown in Table 2. Patient 5 was in asymptomatic atrial fibrillation at the 3 and 6 month study points, so cardiac 31P-MRS was not performed and his cardiac data were excluded from the pre- and posttreatment cardiac 31P-MRS evaluation. After baseline 31P-MRS studies, patient 7 received botulinum toxin injections in both calves to alleviate severe spasticity, and, in view of the chemical denervation caused by the toxin, her skeletal muscle pre- and posttreatment results were not included in the study. Before therapy the mean cardiac PCr/ATP, which is a measure of the energetic state of cardiac muscle,23,24 Table 1. Patient Details, Cardiac and Skeletal Muscle (M) of Antioxidant Treatmenta Cardiac 31 31 P-MRS Data, and Echocardiography Before and after 3 and 6 Months P-MRS Skeletal Muscle PCr/ATP Patient 1 2 3 4 5 6 7 8 9 10 Mean SD Normal 27/F 27/F 32/F 40/F 28/M 16/M 25/F 26/M 26/M 32/M 27.9 6.1 GAA Repeat Number Disease Duration (Years) Baseline 3 M (%) 6 M (%) 390 590 290 450 650 900 460 630 620 400 538 176 ⬎40 11 7 12 20 14 4 6 10 2 14 10.0 5.4 148 128 305 283 – 266 187 109 88 89 178 86 137 111 281 265 – 355 194 114 92 82 181 98 1.84 1.62 0.77 0.74 – 0.68 1.21 1.33 2.35 1.55 1.34 0.56 ⬎2.20 Echocardiography P-MRS Vmax CoQ10/Vit E Age/Sex (Years) 31 IVSd CoQ10/Vit E Baseline (mM/min) 20.0 27.3 29.9 23.7 14.4 11.6 – 19.9 15.6 16.3 19.8 6.14 ⬎37 3 M (%) 6 M (%) 170 102 89 138 133 247 – 118 127 124 139 47 149 105 82 170 170 255 – 128 116 108 143 52 PWd CoQ10/Vit E Baseline (cm) 0.98 1.07 1.00 0.90 1.00 1.70 1.10 1.00 1.10 1.26 1.11 0.23 ⬍1.10 3 M (%) 6 M (%) 76 75 93 116 106 73 102 131 102 109 98 19 87 87 91 120 104 83 92 134 77 101 98 18 CoQ10/Vit E Baseline (cm) 1.09 0.70 0.90 1.00 1.00 1.24 1.20 1.20 1.10 1.59 1.10 0.24 ⬍1.10 3 M (%) 6 M (%) 64 131 94 92 106 119 97 111 98 87 100 18 74 141 93 93 116 108 88 113 95 87 101 19 IVSd and PWd baseline values in cm; % ⫽ 3 or 6 month treatment examination as a percentage of the baseline value; PCr ⫽ phosphocreatine; Vmax ⫽ maximum rate of mitochondrial adenosine triphosphate (ATP) production. a 592 Annals of Neurology Vol 49 No 5 May 2001 Fig 1. 31P-MRS cardiac spectra from control and Friedreich’s ataxia (FA) cases 3 and 4 before and after 3 months of CoQ10 plus Vit E therapy. The phosphocreatine (PCr) peak [relative to adenosine triphosphate (ATP)] is reduced in the pretreatment spectra of the two FA patients compared to the control spectrum. After 3 months of antioxidant therapy, the PCr peak increases in both patients compared to the pretherapy levels. 2,3 DPG ⫽ 2,3-diphosphoglycerate; ␥, ␣, and ␤ ⫽ the three phosphate groups of ATP. tients (19.8 ⫾ 6.1 mM/min, n ⫽ 9) compared to controls (57.8 ⫾ 19.0, p ⫽ 0.0001; Table 1, Fig 2). After 3 and 6 months of CoQ10 and Vit E treatment, mitochondrial Vmax increased to 25.8 ⫾ 5.5 ( p ⫽ 0.01) and 26.5 ⫾ 6.7 ( p ⫽ 0.02), respectively, in the 9 FA patients (Table 1, Fig 2). It can be seen in Table 1 that only patients 2 and 3 did not show any improvement in their Vmax. The extent of muscle Vmax increase after therapy was higher in patients with longer GAA repeat length (r ⫽ 0.63, p ⫽ 0.06 after 3 months of therapy; r ⫽ 0.71, p ⫽ 0.03 after 6 months of therapy). The echocardiographic analyses performed before therapy indicated that 5 patients (patients 6 –10; Table 1) showed LVH as defined on the basis of a posterior wall (PWd) and/or septal (IVSd) thickness ⱖ1.1 cm in diastole (1.27 ⫾ 0.19 and 1.23 ⫾ 0.28, respectively), whereas in the other 5 patients (patients 1–5; Table 1) Fig 2. Cardiac phosphocreatine to adenosine triphosphate ratio (PCr/ATP; A) and calf muscle maximum rate of mitochondrial ATP production (Vmax; B) in controls and in an Friedreich’s ataxia (FA) patient before (0M) and after 3 months (3M) and 6 months (6M) of CoQ10 plus Vit E therapy. PWd and IVSd thickness were ⬍ 1.1 cm (0.94 ⫾ 0.15 and 0.99 ⫾ 0.06, respectively). After 3 months of therapy, PWd and IVSd thickness were unchanged both in patients with LVH (1.29 ⫾ 0.16, p ⫽ 0.8; 1.23 ⫾ 0.11, p ⫽ 0.5, respectively) and in patients without LVH (0.89 ⫾ 0.13, p ⫽ 0.6; 0.91 ⫾ 0.14, p ⫽ 0.3, respectively). LVMi was unchanged before and after therapy in patients with LVH (40 ⫾ 12 vs 46 ⫾ 8 g/m, p ⫽ 0.6) and in patients without LVH (34 ⫾ 8 vs 34 ⫾10 g/m, p ⫽ 0.5). Similarly, fractional shortening (FS) was unchanged after therapy in FA patients either with (36% ⫾ 3% vs 38% ⫾ 9%, p ⫽ 0.6) or without (34% ⫾ 10% vs 35% ⫾ 7%, p ⫽ 0.6) LVH. These findings were confirmed after 6 months of therapy (Table 2). The ICARS score14 increased in 6 of the patients and just failed to reach statistical significance ( p ⫽ 0.06) after 6 months of therapy. Patients 2, 6, and 8 showed the most marked deterioration in their clinical scores, which reflected a marked increase in the kinetic Lodi et al: Antioxidant Therapy in Friedreich’s Ataxia 593 Table 2. Neurological Evaluation of Friedreich’s Ataxia Patients at Baseline and after 6 Months (M) of Therapy (Maximum Possible Scores in Parentheses) International Cooperative Ataxia Ratings Scalea Posture and Gait (34) Kinetic (52) Speech (8) Oculomotor (6) Total (100) Patient Baseline CoQ10/Vit E (6 M) Baseline CoQ10/Vit E (6 M) Baseline CoQ10/Vit E (6 M) Baseline CoQ10/Vit E (6 M) Baseline CoQ10/Vit E (6 M) 1 2 3 4 5 6 7 8 9 10 Mean SD 25 23 11 22 32 24 24 27 11 11 21.0 7.4 27 29 10 24 31 27 29 28 13 14 23.2b 7.8 23 27 12 30 29 15 27 20 22 31 23.6 6.4 23 27 13 30 31 25 27 26 21 26 24.9 5.1 2 3 2 5 4 2 4 4 4 3 3.3 1.1 2 3 2 4 4 2 4 4 2 3 3.0 0.9 3 1 1 4 4 3 3 2 1 3 2.5 1.2 3 2 2 3 3 2 1 2 2 3 2.3 0.7 53 54 26 61 69 44 58 53 38 48 50.4 12.2 55 61 27 61 69 56 61 60 38 46 53.4 12.7 a b J. Neurol. Sci. 1997;145:L05–L11. P ⬍ 0.05. score in 2 cases (patient 6 and 8) and an increase in the posture and gait score of the third (patient 2). The breakdown of the scores into posture and gait, kinetic, speech, and ocular categories indicated that there were no marked changes in these categories; however, the posture and gait scores deteriorated in 8 of the patients, which reached statistical significance ( p ⫽ 0.02; Table 2). Hand clicker scores were not significantly different between baseline and 6 month values for either the right (75 ⫾ 13 and 78 ⫾ 16 clicks in 30 sec, p ⫽ 0.2) or the left (65.1 ⫾ 13.1 and 63 ⫾ 14.5 clicks in 30 sec, p ⫽ 0.2) hand. Discussion We report here for the first time that antioxidant therapy based on oral CoQ10 and Vit E administration can improve cellular bioenergetics in FA, as measured directly and in vivo in cardiac and skeletal muscle. The duration of our study was relatively short, and a longer period may be required to show whether 31P-MRS bioenergetic indices improve in all FA patients. The Vit E and CoQ10 doses used in our study were similar to those administered to patients with other neurodegenerative disorders for which no side effects were reported.25,26 Both drugs localise to cellular membranes, including mitochondrial membranes, and act as free radical scavengers in addition to the role of CoQ10 in electron transfer. We combined the two antioxidants to amplify their efficacy. Vit E has been shown in vitro to reduce the formation of the ubisemiquinone-10 radical, thus increasing the lipophilicity of CoQ1027; on the other hand, CoQ10 is necessary for the regeneration of ␣-tocopherol from its phenoxyl radical.28 594 Annals of Neurology Vol 49 No 5 May 2001 Many FA patients have echocardiographic evidence of cardiomyopathy, including LVH.2 This may be a reflection of the relatively high cardiac expression of frataxin3 and of the low antioxidant defences of cardiac tissue,29 which may also explain the more severe mitochondrial abnormalities in FA heart compared to skeletal muscle.11 The more marked bioenergetic improvement after therapy that we found in cardiac compared to skeletal muscle may reflect a greater dependence on frataxin and greater accumulation of iron and free radical mitochondrial damage in the FA heart. We have previously shown that a profound reduction in the PCr/ATP ratio is also present in FA patients without LVH, which led us to hypothesise that LVH in FA may be a direct effect of the cardiac energy metabolism deficit.12 The greater degree of PCr/ATP improvement in the 4 FA patients without LVH than in the 5 patients with LVH may indicate that the presence of LVH reduces the rate of bioenergetic recovery and that antioxidant treatment may be more effective when started before cardiomyopathy becomes established. Indeed, if the bioenergetic deficit precedes cardiac hypertrophy, the early initiation of antioxidant therapy in FA patients may prevent the development of cardiac hypertrophy by reversing the bioenergetic abnormality. Despite these bioenergetic improvements, echocardiography after 3 and 6 months of therapy failed to identify a consistent reduction in LVMi, PWd, or IVSd, even in the subgroup of patients with LVH. Although 8 of the 10 patients showed decreases in either the PWd or the IVSd thickness, these changes were not statistically significant and were within the reproducibility error of the echocardiography technique. It is possible that a longer period of therapy would be required to achieve significant regression of LVH. A preliminary report showed a decrease in lVSd, PWd, and LVMi in 3 FA patients treated for 4 –9 months with idebenone, a short-chain quinone analogue that acts as a powerful free radical scavenger.30 In skeletal muscle, the increase in the Vmax correlated positively with the number of GAA repeats in the smaller allele: The higher the number of repeats, the higher the relative improvement after therapy. As was previously shown,13 the degree of deficit of skeletal muscle bioenergetics is more severe in FA patients with higher GAA repeat number, and skeletal muscle bioenergetics of these patients may benefit relatively more from CoQ10/Vit E therapy. On the other hand, cardiac PCr/ATP levels did not relate to the length of GAA repeats,12 and relative improvement in PCr/ATP after therapy was also not correlated with GAA repeat length. The improved MRS findings in the cardiac and calf muscles in FA patients after 3 and 6 months of therapy confirm the potential benefits of this therapy to the energy supply to the heart and skeletal muscles. If these benefits extrapolate to the other cells in the body, in particular nerve cells, it might be hoped that the improvement in cell function and prevention of cell death would contribute to a slowing of the progression of the disease and possibly to some improvements in symptoms. After 6 months of therapy, we failed to detect improvements in the ICARS score in the 10 FA patients. The evaluation of the clinical efficacy of a new therapy in progressive degenerative disorders such as FA is particularly difficult in that it is complicated by many factors, not least the fact that the neurological symptoms associated with FA are predominantly due to neuronal loss. This study was designed as a pilot to test whether combined CoQ10 plus Vit E therapy could improve tissue bioenergetics in FA patients and thereby promote trials oriented to evaluation of the clinical response to such a therapy. Extension of the therapy regime will help to determine whether the clinical symptoms are affected. However, both improved clinical tests and a larger controlled trial will be required to evaluate the efficacy of treatment on disease progression. In conclusion, our in vivo observations suggest that antioxidant therapy may be of clinical benefit to FA patients. The dramatic improvement of cardiac and skeletal muscle bioenergetics was detectable after only 3 months of therapy and provides a strong rationale for the continuation of the present study and for designing larger randomised trials focusing on the response to such a therapy of both neurological and cardiological symptoms. Such investigations will confirm whether an early diagnosis of FA can be exploited to initiate anti- oxidant treatment and prevent the progression of this disorder. This work was supported by the Friedreich’s Ataxia Group (United Kingdom), the National Lottery Charities Board, the Medical Research Council, the British Heart Foundation, and the Royal Free Hampstead NHS Trust, which received a proportion of its funding from the NHS Executive (the views expressed in this publication are those of the authors and not necessarily those of the Trust or the NHS Executive). At the time when the work was carried out, R. 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