Effectiveness of creatine monohydrate in mitochondrial encephalomyopathies

Delivery Systems for Mitochondrial Gene Therapy: A Review

Mitochondria are membrane-bound cellular organelles of high relevance responsible for the chemical energy production used in most of the biochemical reactions of cells. Mitochondria have their own genome, the mitochondrial DNA (mtDNA). Inherited solely from the mother, this genome is quite susceptible to mutations, mainly due to the absence of an effective repair system. Mutations in mtDNA are associated with endocrine, metabolic, neurodegenerative diseases, and even cancer. Currently, therapeutic approaches are based on the administration of a set of drugs to alleviate the symptoms of patients suffering from mitochondrial pathologies. Mitochondrial gene therapy emerges as a promising strategy as it deeply focuses on the cause of mitochondrial disorder. The development of suitable mtDNA-based delivery systems to target and transfect mammalian mitochondria represents an exciting field of research, leading to progress in the challenging task of restoring mitochondria's normal function. This review gathers relevant knowledge on the composition, targeting performance, or release profile of such nanosystems, offering researchers valuable conceptual approaches to follow in their quest for the most suitable vectors to turn mitochondrial gene therapy clinically feasible. Future studies should consider the optimization of mitochondrial genes' encapsulation, targeting ability, and transfection to mitochondria. Expectedly, this effort will bring bright results, contributing to important hallmarks in mitochondrial gene therapy.

Current and Emerging Clinical Treatment in Mitochondrial Disease

Primary mitochondrial disease (PMD) is a group of complex genetic disorders that arise due to pathogenic variants in nuclear or mitochondrial genomes. Although PMD is one of the most prevalent inborn errors of metabolism, it often exhibits marked phenotypic variation and can therefore be difficult to recognise. Current treatment for PMD revolves around supportive and preventive approaches, with few disease-specific therapies available. However, over the last decade there has been considerable progress in our understanding of both the genetics and pathophysiology of PMD. This has resulted in the development of a plethora of new pharmacological and non-pharmacological therapies at varying stages of development. Many of these therapies are currently undergoing clinical trials. This review summarises the latest emerging therapies that may become mainstream treatment in the coming years. It is distinct from other recent reviews in the field by comprehensively addressing both pharmacological non-pharmacological therapy from both a bench and a bedside perspective. We highlight the current and developing therapeutic landscape in novel pharmacological treatment, dietary supplementation, exercise training, device use, mitochondrial donation, tissue replacement gene therapy, hypoxic therapy and mitochondrial base editing.

Creatine in Health and Disease

Although creatine has been mostly studied as an ergogenic aid for exercise, training, and sport, several health and potential therapeutic benefits have been reported. This is because creatine plays a critical role in cellular metabolism, particularly during metabolically stressed states, and limitations in the ability to transport and/or store creatine can impair metabolism. Moreover, increasing availability of creatine in tissue may enhance cellular metabolism and thereby lessen the severity of injury and/or disease conditions, particularly when oxygen availability is compromised. This systematic review assesses the peer-reviewed scientific and medical evidence related to creatine's role in promoting general health as we age and how creatine supplementation has been used as a nutritional strategy to help individuals recover from injury and/or manage chronic disease. Additionally, it provides reasonable conclusions about the role of creatine on health and disease based on current scientific evidence. Based on this analysis, it can be concluded that creatine supplementation has several health and therapeutic benefits throughout the lifespan.

Biochemical and behavioral phenotype of AGAT and GAMT deficient mice following long-term Creatine monohydrate supplementation

The creatine/phosphocreatine system is essential for cellular phosphate coupled energy storage and production. We investigated the utility of creatine monohydrate supplementation in two different creatine deficient knockout mouse models. Following weaning, female Arginine: Glycine Amidinotransferase (AGAT) and Guanidinoacetate: methyltransferase (GAMT) knockouts and wild type mice were studied based on their genotypes and dietary supplementation (creatine free or 2% creatine monohydrate supplemented diet) for 10 weeks, using a series of behavioral tests and biochemical analyzes. An improved Rota rod performance was observed in both AGAT (p = 0.02) and GAMT knockout mice (p < 0.001) supplemented with 2% creatine. During Morris water maze probe trial, creatine supplemented AGAT knockout mice took less time to reach virtual platform (p = 0.03) and more frequently crossed this area (p = 0.001) than mice on creatine free diet. Similar observations were recorded for GAMT knockout mice. Urinary creatinine concentrations for AGAT (p = 0.001) and GAMT (p = 0.05) knockout mice were increased following creatine supplementation. Creatine supplementation has a potential to improve neuro-muscular coordination, spatial learning in both AGAT and GAMT knockout mice. Long term Creatine supplementation results in increased urine creatinine concentrations indicating improved creatine metabolism in knockout mice.

International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine

Creatine is one of the most popular nutritional ergogenic aids for athletes. Studies have consistently shown that creatine supplementation increases intramuscular creatine concentrations which may help explain the observed improvements in high intensity exercise performance leading to greater training adaptations. In addition to athletic and exercise improvement, research has shown that creatine supplementation may enhance post-exercise recovery, injury prevention, thermoregulation, rehabilitation, and concussion and/or spinal cord neuroprotection. Additionally, a number of clinical applications of creatine supplementation have been studied involving neurodegenerative diseases (e.g., muscular dystrophy, Parkinson's, Huntington's disease), diabetes, osteoarthritis, fibromyalgia, aging, brain and heart ischemia, adolescent depression, and pregnancy. These studies provide a large body of evidence that creatine can not only improve exercise performance, but can play a role in preventing and/or reducing the severity of injury, enhancing rehabilitation from injuries, and helping athletes tolerate heavy training loads. Additionally, researchers have identified a number of potentially beneficial clinical uses of creatine supplementation. These studies show that short and long-term supplementation (up to 30 g/day for 5 years) is safe and well-tolerated in healthy individuals and in a number of patient populations ranging from infants to the elderly. Moreover, significant health benefits may be provided by ensuring habitual low dietary creatine ingestion (e.g., 3 g/day) throughout the lifespan. The purpose of this review is to provide an update to the current literature regarding the role and safety of creatine supplementation in exercise, sport, and medicine and to update the position stand of International Society of Sports Nutrition (ISSN).

Creatine Supplementation and Doxorubicin-Induced Skeletal Muscle Dysfunction: An Ex Vivo Investigation

Supplementing the diet with creatine (Cr) to manage chemotherapy-induced skeletal muscle weakness and fatigue has potential, but little has been done exploring it as an intervention. This study examined the effects of Cr on skeletal muscle dysfunction induced by the chemotherapy drug doxorubicin (Dox). Soleus and extensor digitorum longus (EDL) from male Sprague-Dawley rats maintained in an organ bath were incubated in Krebs-Henseleit (KH) buffer with or without creatine monohydrate (25 mM) for 30 min. Skeletal muscle was then incubated in KH buffer with or without Dox (24 μM) for an additional 30 min. Baths were then refreshed with KH buffer, and a 100-s fatigue protocol was administered. At baseline (0 s time point), no significant differences in force production were observed in the slow, type I soleus, but the Dox-treated soleus fatigued quicker than the non-Dox-treated soleus; however, pretreatment with Cr extended the time to fatigue in the Dox-treated soleus. In the fast, type II EDL, Dox treatment decreased force production at baseline and increased fatigue, and Cr treatment prior to Dox attenuated this dysfunction. Creatine pretreatment mitigated Dox-induced skeletal muscle dysfunction ex vivo suggesting that Cr may play a role in managing Dox-induced skeletal muscle side effects.

Effect of creatine monohydrate supplementation on learning, memory and neuromuscular coordination in female albino mice

BACKGROUND

Research findings made over the last few years have highlighted the important role of creatine (Cr) in health and disease. However, limited information is available regarding the effect of Cr supplementation on cognation. Present study was designed to determine the effect of variable doses of Cr (1% and 3%) on selected parameters of female albino mice behaviour.

METHODS

Following weaning, on 20th postnatal day, female albino mice were divided into three groups on the basis of dietary supplementation. Control group were was fed with normal rodent diet, whereas treated groups received diet supplemented with 1% and 3% Creatine monohydrate (Ssniff, Germany) for 10 weeks. Morris water maze (MWM), Rota rod and open field (OF) tests were carried out at the end of diet supplementation for neurofunctional assessment in all the groups.

RESULTS

Data analysis showed that Cr supplementation did not affect the muscular activity and during rota rod test as well as locomotor and exploratory behaviour during OF test. Results of MWM probe trial indicated that mice supplemented with 3% Cr had significantly more entries in platform area than other two treatments (p=0.03) indicating improved spatial memory. Body weight remained unaffected (p>0.05) when compared between three experimental treatments.

CONCLUSION

Female mice supplemented with 3% Cr showed improved spatial memory than mice fed on 1% Cr-supplemented diet and mice on normal rodent diet.

Therapeutic strategies for mitochondrial disorders

OBJECTIVES

There is currently no curative therapy for mitochondrial disorders, although symptomatic measures can be highly effective and greatly improve the quality of life and outcome of these patients. This review highlights potential strategies for the therapeutic management of mitochondrial disorders.

METHODS

Data for this review were identified by searches of MEDLINE, Current Contents, using various relevant search terms.

RESULTS

Strategies to establish a therapeutic regimen aim to enhance respiratory chain function, eliminate noxious compounds, shift the heteroplasmy rate, alter mitochondrial dynamics, transfer cytoplasm, and promote gene therapy. Symptomatic measures rely on drugs (e.g., antiepileptics), avoidance of mitochondrion-toxic agents, substitution of blood cells, hemodialysis, invasive measures (such as a pacemaker), surgery (e.g., ptosis correction), physiotherapy, speech therapy, occupational therapy, dietary measures (e.g., ketogenic diet, anaplerotic diet), and the avoidance of mitochondrion-toxic agents (e.g., ozone). With the increasing awareness of mitochondrial disorders, the number of treatment studies is growing and its quality is improving. If high quality studies (high Jadad score) yield statistical significance for end points, a treatment is more reliable than with lower quality studies.

CONCLUSIONS

Despite the lack of a proven treatment for mitochondrial disorders, a nihilistic attitude toward treatment is not justified. A number of studies are seeking targeted therapies, and highly effective symptomatic measures are available.

New treatments for mitochondrial disease-no time to drop our standards

Mitochondrial dysfunction is a common cause of inherited multisystem disease that often involves the nervous system. Despite major advances in our understanding of the pathophysiology of mitochondrial diseases, clinical management of these conditions remains largely supportive. Using a systematic approach, we identified 1,039 publications on treatments for mitochondrial diseases, only 35 of which included observations on more than five patients. Reports of a positive outcome on the basis of a biomarker of unproven clinical significance were more common in nonrandomized and nonblinded studies, suggesting a publication bias toward positive but poorly executed studies. Although trial design is improving, there is a critical need to develop new biomarkers of mitochondrial disease. In this Perspectives article, we make recommendations for the design of future treatment trials in mitochondrial diseases. Patients and physicians should no longer rely on potentially biased data, with the associated costs and risks.

Creatine for treating muscle disorders

BACKGROUND

Progressive muscle weakness is a main symptom of most hereditary and acquired muscle diseases. Creatine improves muscle performance in healthy individuals. This is an update of our 2007 Cochrane review that evaluated creatine treatment in muscle disorders. Previous updates were in 2009 and 2011.

OBJECTIVES

To evaluate the efficacy of creatine compared to placebo for the treatment of muscle weakness in muscle diseases.

SEARCH METHODS

On 11 September 2012, we searched the Cochrane Neuromuscular Disease Group Specialized Register, CENTRAL (2012, Issue 9 in The Cochrane Library), MEDLINE (January 1966 to September 2012) and EMBASE (January 1980 to September 2012) for randomised controlled trials (RCTs) of creatine used to treat muscle diseases.

SELECTION CRITERIA

RCTs or quasi-RCTs of creatine treatment compared to placebo in hereditary muscle diseases or idiopathic inflammatory myopathies.

DATA COLLECTION AND ANALYSIS

Two authors independently applied the selection criteria, assessed trial quality and extracted data. We obtained missing data from investigators.

MAIN RESULTS

A total of 14 trials, including 364 randomised participants, met the selection criteria. The risk of bias was low in most studies. Only one trial had a high risk of selection, performance and detection bias. No new studies were identified at this update.Meta-analysis of six trials in muscular dystrophies including 192 participants revealed a significant increase in muscle strength in the creatine group compared to placebo, with a mean difference of 8.47%; (95% confidence intervals (CI) 3.55 to 13.38). Pooled data of four trials including 115 participants showed that a significantly higher number of participants felt better during creatine treatment compared to placebo with a risk ratio of 4.51 (95% CI 2.33 to 8.74). One trial in 37 participants with idiopathic inflammatory myopathies also showed a significant improvement in functional performance. No trial reported any clinically relevant adverse event.In metabolic myopathies, meta-analyses of three cross-over trials including 33 participants revealed no significant difference in muscle strength. One trial reported a significant deterioration of activities of daily living (mean difference 0.54 on a 1 to 10 scale; 95% CI 0.14 to 0.93) and an increase in muscle pain during high-dose creatine treatment in McArdle disease.

AUTHORS' CONCLUSIONS

High quality evidence from RCTs shows that short- and medium-term creatine treatment increases muscle strength in muscular dystrophies. There is also evidence that creatine improves functional performance in muscular dystrophy and idiopathic inflammatory myopathy. Creatine is well tolerated in these people. High quality but limited evidence from RCTs does not show significant improvement in muscle strength in metabolic myopathies. High-dose creatine treatment impaired activities of daily living and increased muscle pain in McArdle disease.

Creatine as a therapeutic strategy for myopathies

Myopathies are genetic or acquired disorders of skeletal muscle that lead to varying degrees of weakness, atrophy, and exercise intolerance. In theory, creatine supplementation could have a number of beneficial effects that could enhance function in myopathy patients, including muscle mass, strength and endurance enhancement, lower calcium levels, anti-oxidant effects, and reduced apoptosis. Patients with muscular dystrophy respond to several months of creatine monohydrate supplementation (~0.075-0.1 g/kg/day) with greater strength (~9%) and fat-free mass (~0.63 kg). Patients with myotonic dystrophy do not show as consistent an effect, possibly due to creatine transport issues. Creatine monohydrate supplementation shows modest benefits only at lower doses and possibly negative effects (cramping) at higher doses in McArdle's disease patients. Patients with MELAS syndrome show some evidence of benefit from creatine supplementation in exercise capacity, with the effects in patients with CPEO being less robust, again, possibly due to limited muscle creatine uptake. The evidence for side effects or negative impact upon serological metrics from creatine supplementation in all groups of myopathy patients is almost non-existent and pale in comparison to the very substantial and well-known side effects from our current chemotherapeutic interventions for some myopathies (i.e., corticosteroids).

Creatine for treating muscle disorders

BACKGROUND

Progressive muscle weakness is a main symptom of most hereditary and acquired muscle diseases. Creatine improves muscle performance in healthy individuals. This is an update of our 2007 Cochrane review that evaluated creatine treatment in muscle disorders.

OBJECTIVES

To evaluate the efficacy of creatine compared to placebo for the treatment of muscle weakness in muscle diseases.

SEARCH STRATEGY

We searched the Cochrane Neuromuscular Disease Group Specialized Register (4 October 2010), the Cochrane Central Register of Controlled Trials (11 October 2010, Issue 4, 2010 in The Cochrane Library), MEDLINE (January 1966 to September 2010) and EMBASE (January 1980 to September 2010) for randomised controlled trials (RCT) of creatine used to treat muscle diseases.

SELECTION CRITERIA

RCTs or quasi-RCTs of creatine treatment compared to placebo in hereditary muscle diseases or idiopathic inflammatory myopathies.

DATA COLLECTION AND ANALYSIS

Two authors independently applied the selection criteria, assessed trial quality and extracted data. We obtained missing data from investigators.

MAIN RESULTS

The updated searches identified two new studies. A total of 14 trials, including 364 randomised participants, met the selection criteria. Meta-analysis of six trials in muscular dystrophies including 192 participants revealed a significant increase in muscle strength in the creatine group compared to placebo, with a weighted mean difference of 8.47%; (95% confidence intervals (CI) 3.55 to 13.38). Pooled data of four trials including 115 participants showed that a significantly higher number of patients felt better during creatine treatment compared to placebo with a risk ratio of 4.51 (95% CI 2.33 to 8.74). One trial in 37 participants with idiopathic inflammatory myopathies also showed a significant improvement in functional performance. No trial reported any clinically relevant adverse event. In metabolic myopathies, meta-analyses of three cross-over trials including 33 participants revealed no significant difference in muscle strength. One trial reported a significant deterioration of ADL (mean difference 0.54 on a 1 to 10 scale; 95% CI 0.14 to 0.93) and an increase in muscle pain during high-dose creatine treatment in McArdle disease.

AUTHORS' CONCLUSIONS

High quality evidence from RCTs shows that short- and medium-term creatine treatment increases muscle strength in muscular dystrophies. There is also evidence that creatine improves functional performance in muscular dystrophy and idiopathic inflammatory myopathy. Creatine is well tolerated in these people. High quality but limited evidence from RCTs does not show significant improvement in muscle strength in metabolic myopathies. High-dose creatine treatment impaired ADL and increased muscle pain in McArdle disease.

Can the use of creatine supplementation attenuate muscle loss in cachexia and wasting?

PURPOSE OF REVIEW

Weight loss and low BMI due to an underlying illness have been associated with increased mortality, reduced functional capacity, and diminished quality of life. There is a need for well tolerated, long-term approaches to maintain body weight in patients with cachexia or wasting. The purpose of this review is to highlight the scientific and clinical evidence derived from the recent literature investigating the rationale for and potential medical use of creatine supplementation in patients with cachexia or wasting.

RECENT FINDINGS

Some studies have demonstrated that supplementation with creatine can increase creatine reserves in skeletal muscle and increase muscle mass and performance in various disease states that affect muscle size and function. The mechanisms underlying these effects are not clear. It has been suggested that creatine supplementation may increase intramuscular phosphocreatine stores and promote more rapid recovery of adenosine triphosphate levels following exercise, thus allowing users to exercise for longer periods or at higher intensity levels. Other hypothesized mechanisms include attenuation of proinflammatory cytokines, stimulation of satellite cell proliferation and upregulation of genes that promote protein synthesis and cell repair.

SUMMARY

Creatine is a generally well tolerated, low-cost, over-the-counter nutritional supplement that shows potential in improving lean body mass and functionality in patients with wasting diseases. However, placebo-controlled studies have shown variable effects, with improvements in some and not in others. Additional studies with longer follow-up are required to identify the populations that might benefit most from creatine supplementation.

Metabolic myopathies: update 2009

Metabolic myopathies are inborn errors of metabolism that result in impaired energy production due to defects in glycogen, lipid, mitochondrial, and possibly adenine nucleotide metabolism. Fatty acid oxidation defects (FAOD), glycogen storage disease, and mitochondrial myopathies represent the 3 main groups of disorders, and some consider myoadenylate deaminase (AMPD1 deficiency) to be a metabolic myopathy. Clinically, a variety of neuromuscular presentations are seen at different ages of life. Newborns and infants commonly present with hypotonia and multisystem involvement (liver and brain), whereas onset later in life usually presents with exercise intolerance with or without progressive muscle weakness and myoglobinuria. In general, the glycogen storage diseases result in high-intensity exercise intolerance, whereas the FAODs and the mitochondrial myopathies manifest predominately during endurance-type activity or under fasted or other metabolically stressful conditions. The clinical examination is often normal, and testing requires various combinations of exercise stress testing, serum creatine kinase activity and lactate concentration determination, urine organic acids, muscle biopsy, neuroimaging, and specific genetic testing for the diagnosis of a specific metabolic myopathy. Prenatal screening is available in many countries for several of the FAODs through liquid chromatography-tandem mass spectrometry. Early identification of these conditions with lifestyle measures, nutritional intervention, and cofactor treatment is important to prevent or delay the onset of muscle weakness and to avoid potential life-threatening complications such as rhabdomyolysis with resultant renal failure or hepatic failure. This article will review the key clinical features, diagnostic tests, and treatment recommendations for the more common metabolic myopathies, with an emphasis on mitochondrial myopathies.

Creatine fails to augment the benefits from resistance training in patients with HIV infection: a randomized, double-blind, placebo-controlled study

BACKGROUND

Progressive resistance exercise training (PRT) improves physical functioning in patients with HIV infection. Creatine supplementation can augment the benefits derived from training in athletes and improve muscle function in patients with muscle wasting. The objective of this study was to determine whether creatine supplementation augments the effects of PRT on muscle strength, energetics, and body composition in HIV-infected patients.

METHODOLOGY/PRINCIPAL FINDINGS

This is a randomized, double blind, placebo-controlled, clinical research center-based, outpatient study in San Francisco. 40 HIV-positive men (20 creatine, 20 placebo) enrolled in a 14-week study. Subjects were randomly assigned to receive creatine monohydrate or placebo for 14 weeks. Treatment began with a loading dose of 20 g/day or an equivalent number of placebo capsules for 5 days, followed by maintenance dosing of 4.8 g/day or placebo. Beginning at week 2 and continuing to week 14, all subjects underwent thrice-weekly supervised resistance exercise while continuing on the assigned study medication (with repeated 6-week cycles of loading and maintenance). The main outcome measurements included muscle strength (one repetition maximum), energetics ((31)P magnetic resonance spectroscopy), composition and size (magnetic resonance imaging), as well as total body composition (dual-energy X-ray absorptiometry). Thirty-three subjects completed the study (17 creatine, 16 placebo). Strength increased in all 8 muscle groups studied following PRT, but this increase was not augmented by creatine supplementation (average increase 44 vs. 42%, difference 2%, 95% CI -9.5% to 13.9%) in creatine and placebo, respectively). There were no differences between groups in changes in muscle energetics. Thigh muscle cross-sectional area increased following resistance exercise, with no additive effect of creatine. Lean body mass (LBM) increased to a significantly greater extent with creatine. CONCLUSIONS / SIGNIFICANCE: Resistance exercise improved muscle size, strength and function in HIV-infected men. While creatine supplementation produced a greater increase in LBM, it did not augment the robust increase in strength derived from PRT.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00484627.

Mitochondrial encephalopathy, lactic acidosis, and strokelike episodes: basic concepts, clinical phenotype, and therapeutic management of MELAS syndrome

Since the initial description almost 25 years ago, the syndrome of mitochondrial encephalopathy, lactic acidosis, and strokelike episodes (MELAS) has been a useful model to study the complex interplay of factors that define mitochondrial disease. This syndrome, most commonly caused by an A-to-G transition mutation at position 3243 of the mitochondrial genome, is typified by characteristic neurological manifestations including seizures, encephalopathy, and strokelike episodes, as well as other frequent secondary manifestations including short stature, cognitive impairment, migraines, depression, cardiomyopathy, cardiac conduction defects, and diabetes mellitus. In this review, we discuss the history, pathogenesis, clinical features, and diagnostic and management strategies of mitochondrial disease in general and of MELAS in particular. We explore features of mitochondrial genetics, including the concepts of heteroplasmy, mitotic segregation, and threshold effect, as a basis for understanding the variability and complicated inheritance patterns seen with this group of diseases. We also describe systemic manifestations of MELAS-associated mutations, including cardiac, renal, endocrine, gastrointestinal, and endothelial abnormalities and pathology, as well as the hypothetical role of derangements to COX enzymatic function in driving the unique pathology and clinical manifestations of MELAS. Although therapeutic options for MELAS and other mitochondrial diseases remain limited, and recent trials have been disappointing, we also consider current and potential therapeutic modalities.

Clinical use of creatine in neuromuscular and neurometabolic disorders

Many of the neuromuscular (e.g., muscular dystrophy) and neurometabolic (e.g., mitochondrial cytopathies) disorders share similar final common pathways of cellular dysfunction that may be favorably influenced by creatine monohydrate (CrM) supplementation. Studies using the mdx model of Duchenne muscular dystrophy have found evidence of enhanced mitochondrial function, reduced intra-cellular calcium and improved performance with CrM supplementation. Clinical trials in patients with Duchenne and Becker's muscular dystrophy have shown improved function, fat-free mass, and some evidence of improved bone health with CrM supplementation. In contrast, the improvements in function in myotonic dystrophy and inherited neuropathies (e.g., Charcot-Marie-Tooth) have not been significant. Some studies in patients with mitochondrial cytopathies have shown improved muscle endurance and body composition, yet other studies did not find significant improvements in patients with mitochondrial cytopathy. Lower-dose CrM supplementation in patients with McArdle's disease (myophosphorylase deficiency) improved exercise capacity, yet higher doses actually showed some indication of worsened function. Based upon known cellular pathologies, there are potential benefits from CrM supplementation in patients with steroid myopathy, inflammatory myopathy, myoadenylate deaminase deficiency, and fatty acid oxidation defects. Larger randomized control trials (RCT) using homogeneous patient groups and objective and clinically relevant outcome variables are needed to determine whether creatine supplementation will be of therapeutic benefit to patients with neuromuscular or neurometabolic disorders. Given the relatively low prevalence of some of the neuromuscular and neurometabolic disorders, it will be necessary to use surrogate markers of potential clinical efficacy including markers of oxidative stress, cellular energy charge, and gene expression patterns.

The neuroprotective role of creatine

Significant progress has been made in identifying neuroprotective agents and their translation to patients with neurological disorders. While the direct causative pathways of neurodegeneration remain unclear, they are under great clinical and experimental investigation. There are a number of interrelated pathogenic mechanisms triggering molecular events that lead to neuronal death. One putative mechanism reported to play a prominent role in the pathogenesis of neurological diseases is impaired energy metabolism. If reduced energy stores play a role in neuronal loss, then therapeutic strategies that buffer intracellular energy levels may prevent or impede the neurodegenerative process. Recent studies suggest that impaired energy production promotes neurological disease onset and progression. Sustained ATP levels are critical to cellular homeostasis and may have both direct and indirect influence on pathogenic mechanisms associated with neurological disorders. Creatine is a critical component in maintaining cellular energy homeostasis, and its administration has been reported to be neuroprotective in a wide number of both acute and chronic experimental models of neurological disease. In the context of this chapter, we will review the experimental evidence for creatine supplementation as a neurotherapeutic strategy in patients with neurological disorders, including Huntington's disease, Parkinson's disease, amyotrophic lateral sclerosis, and Alzheimer's disease, as well as in ischemic stroke, brain and spinal cord trauma, and epilepsy.

Beneficial effects of creatine, CoQ10, and lipoic acid in mitochondrial disorders

Mitochondrial disorders share common cellular consequences: (1) decreased ATP production; (2) increased reliance on alternative anaerobic energy sources; and (3) increased production of reactive oxygen species. The purpose of the present study was to determine the effect of a combination therapy (creatine monohydrate, coenzyme Q(10), and lipoic acid to target the above-mentioned cellular consequences) on several outcome variables using a randomized, double-blind, placebo-controlled, crossover study design in patients with mitochondrial cytopathies. Three patients had mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS), four had mitochondrial DNA deletions (three patients with chronic progressive external ophthalmoplegia and one with Kearns-Sayre syndrome), and nine had a variety of other mitochondrial diseases not falling into the two former groups. The combination therapy resulted in lower resting plasma lactate and urinary 8-isoprostanes, as well as attenuation of the decline in peak ankle dorsiflexion strength in all patient groups, whereas higher fat-free mass was observed only in the MELAS group. Together, these results suggest that combination therapies targeting multiple final common pathways of mitochondrial dysfunction favorably influence surrogate markers of cellular energy dysfunction. Future studies with larger sample sizes in relatively homogeneous groups will be required to determine whether such combination therapies influence function and quality of life.

Creatine for treating muscle disorders

BACKGROUND

Progressive muscle weakness is a main symptom of most hereditary muscle diseases. Creatine is a popular nutritional supplement among athletes. It improves muscle performance in healthy individuals and might be helpful for treating myopathies.

OBJECTIVES

To evaluate the efficacy of oral creatine supplementation in muscle diseases.

SEARCH STRATEGY

We searched the Cochrane Neuromuscular Disease Group Register in May 2004 for randomised trials using the search term 'creatine'. We also searched the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 2, 2005) using the same search term. We adapted this strategy to search MEDLINE (PubMed, from January 1966 to September 2005) and EMBASE (from January 1980 to May 2004). We reviewed the bibliographies of the randomised trials identified, contacted the authors and known experts in the field and approached pharmaceutical companies to identify additional published or unpublished data.

SELECTION CRITERIA

Types of studies: randomised or quasi-randomised controlled trials.

TYPES OF PARTICIPANTS

people of all ages with hereditary muscle disease. Types of intervention: any creatine supplementation of at least 0.03 g/kg body weight/day.

PRIMARY OUTCOME MEASURE

change in muscle strength measured by quantitative muscle testing.

SECONDARY OUTCOME MEASURES

change in muscle strength measured by manual muscle testing, change in energy parameters assessed by 31 phosphorous spectroscopy, change in muscle mass or a surrogate for muscle mass, adverse events.

DATA COLLECTION AND ANALYSIS

Two authors independently applied the selection criteria, assessed trial quality and extracted data. Some missing data were obtained from investigators.

MAIN RESULTS

Twelve trials, including 266 participants, met the selection criteria. One trial compared creatine and glutamine treatment with placebo. In trials with 138 participants with muscular dystrophies treated with creatine, there was a significant increase in maximum voluntary contraction in the creatine group compared to placebo, with a weighted mean difference of 8.47% (95% confidence intervals 3.55 to 13.38). There was also an increase in lean body mass during creatine treatment compared to placebo (weighted mean difference 0.63 kg, 95% confidence intervals 0.02 to 1.25). No trial reported any clinically relevant adverse event. In trials with 33 participants with metabolic myopathies treated with creatine, there was no significant difference in maximum voluntary contraction between the creatine and placebo group (weighted mean difference -2.26%, confidence intervals -6.29 to 1.78). One trial reported a significant increase in muscle pain during high-dose creatine treatment (150 mg/kg body weight) in glycogen storage disease type V.

AUTHORS' CONCLUSIONS

Evidence from randomised controlled trials shows that short- and medium-term creatine treatment improves muscle strength in people with muscular dystrophies, and is well-tolerated. Evidence from randomised controlled trials does not show significant improvement in muscle strength in metabolic myopathies. High-dose creatine in glycogenosis type V increased muscle pain.

Prevention of complications related to traumatic brain injury in children and adolescents with creatine administration: an open label randomized pilot study

BACKGROUND

There has been an enormous focus on the discovery and development of neuroprotective agents that might have clinical relevance after traumatic brain injury (TBI). Based on experimental facts, we studied administration of creatine to patients with TBI.

METHODS

A prospective, randomized, comparative, open-labeled pilot study of the possible neuroprotective effect of creatine was performed on 39 children and adolescents, aged between 1 to 18 years old, with TBI. The creatine was administered for 6 months, at a dose of 0.4 gr/kg in an oral suspension form every day. For categorical variables, we used the chi test to identify differences between controls and cases. Statistical significance was defined as a p value <0.05 and not statistically significant if p value >0.1.

RESULTS

The administration of creatine to children with TBI improved results in several parameters, including duration of post-traumatic amnesia (PTA), duration of intubation, intensive care unit (ICU) stay, disability, good recovery, self care, communication, locomotion, sociability, personality/behavior and neurophysical, and cognitive function. Significant improvement was recorded in the categories of Cognitive (p < 0.001), personality/behavior (p < 0.001), Self Care (p = 0.029), and communication (p = 0.018) aspects in all patients. No side effects were seen because of creatine administration.

CONCLUSION

Preliminary data suggest that the administration of creatine may be beneficial to patients with traumatic brain injury.

Mitochondrial myopathies: diagnosis, exercise intolerance, and treatment options

Mitochondrial myopathies are caused by genetic mutations that directly influence the functioning of the electron transport chain (ETC). It is estimated that 1 of 8,000 people have pathology inducing mutations affecting mitochondrial function. Diagnosis often requires a multifaceted approach with measurements of serum lactate and pyruvate, urine organic acids, magnetic resonance spectroscopy (MRS), muscle histology and ultrastructure, enzymology, genetic analysis, and exercise testing. The ubiquitous distribution of the mitochondria in the human body explains the multiple organ involvement. Exercise intolerance is a common but often an overlooked hallmark of mitochondrial myopathies. The muscle consequences of ETC dysfunction include increased reliance on anaerobic metabolism (lactate generation, phosphocreatine degradation), enhanced free radical production, reduced oxygen extraction and electron flux through ETC, and mitochondrial proliferation or biogenesis (see article by Hood in current issue). Treatments have included antioxidants (vitamin E, alpha lipoic acid), electron donors and acceptors (coenzyme Q10, riboflavin), alternative energy sources (creatine monohydrate), lactate reduction strategies (dichloroacetate) and exercise training. Exercise is a particularly important modality in diagnosis as well as therapy (see article by Taivassalo in current issue). Increased awareness of these disorders by exercise physiologists and sports medicine practitioners should lead to more accurate and more rapid diagnosis and the opportunity for therapy and genetic counseling.

What can metabolic myopathies teach us about exercise physiology?

Exercise physiologists are interested in metabolic myopathies because they demonstrate how knocking out a component of a specific biochemical pathway can alter cellular metabolism. McArdle's disease (myophosphorylase deficiency) has often been studied in exercise physiology to demonstrate the influence of removing the major anaerobic energy supply to skeletal muscle. Studies of patients with McArdle's disease have shown the increased reliance on blood-borne fuels, the importance of glycogen to maximal aerobic capacity, and the use of nutritional strategies to bypass metabolic defects. Myoadenylate deaminase deficiency is the most common metabolic enzyme deficiency in human skeletal muscle. It is usually compensated for endogenously and does not have a major influence on high-energy power output. Nutritional interventions such as carbohydrate loading and carbohydrate supplementation during exercise are essential components of therapy for patients with fatty acid oxidation defects. Cases of mitochondrial myopathies illustrate the importance of peripheral oxygen extraction for maximal aerobic capacity and show how both exercise and nutritional interventions can partially compensate for these mutations. In summary, metabolic myopathies provide important insights into regulatory and nutritional aspects of the major biochemical pathways of intermediary metabolism in human skeletal muscle. Key words: myoadenylate deaminase deficiency, MELAS syndrome, McArdle's disease, mitochondrial disease, inborn errors of metabolism.

Treatment for mitochondrial disorders

BACKGROUND

Mitochondrial respiratory chain disorders are the most prevalent group of inherited neurometabolic diseases. They present with central and peripheral neurological features usually in association with other organ involvement including the eye, the heart, the liver, and kidneys, diabetes mellitus and sensorineural deafness. Current treatment is largely supportive and the disorders progress relentlessly causing significant morbidity and premature death. Vitamin supplements, pharmacological agents and exercise therapy have been used in isolated cases and small clinical trials, but the efficacy of these interventions is unclear.

OBJECTIVES

To determine whether there is objective evidence to support the use of current treatments for mitochondrial disease.

SEARCH STRATEGY

We searched the Cochrane Neuromuscular Disease Group trials register (searched September 2003), the Cochrane Central Register of Controlled Trials, MEDLINE (January 1966 to October 3 2003), EMBASE (January 1980 to October 3 2003) and the European Neuromuscular Centre (ENMC) clinical trials register, and contacted experts in the field.

SELECTION CRITERIA

We included randomised controlled trials (including crossover studies) and quasi-randomised trials comparing pharmacological treatments, and non-pharmacological treatments (vitamins and food supplements), and physical training in individuals with mitochondrial disorders. The primary outcome measures included an improvement in muscle strength and/or endurance, or neurological clinical features. Secondary outcome measures included quality of life assessments, biochemical markers of disease and negative outcomes.

DATA COLLECTION AND ANALYSIS

Details of the number of randomised patients, treatment, study design, study category, allocation concealment and patient characteristics were extracted. Analysis was based on intention to treat data. We planned to use meta-analysis, but this did not prove necessary.

MAIN RESULTS

Six hundred and seventy-eight abstracts were reviewed, and six fulfilled the entry criteria. Two trials studied the effects of co-enzyme Q10 (ubiquinone), one reporting a subjective improvement and a significant increase in a global scale of muscle strength, but the other trial did not show any benefit. Two trials used creatine, with one reporting improved measures of muscle strength and post-exercise lactate, but the other reported no benefit. One trial of dichloroacetate showed an improvement in secondary outcome measures of mitochondrial metabolism, and one trial using dimethylglycine showed no significant effect.

AUTHORS' CONCLUSIONS

There is currently no clear evidence supporting the use of any intervention in mitochondrial disorders. Further research is needed to establish the role of a wide range of therapeutic approaches.

The therapeutic role of creatine in Huntington's disease

Huntington's disease (HD) is an autosomal dominant and fatal neurological disorder characterized by a clinical triad of progressive choreiform movements, psychiatric symptoms, and cognitive decline. HD is caused by an expanded trinucleotide CAG repeat in the gene coding for the protein huntingtin. No proven treatment to prevent the onset or to delay the progression of HD currently exists. While a direct causative pathway from the gene mutation to the selective neostriatal neurodegeneration remains unclear, it has been hypothesized that interactions of the mutant huntingtin protein or its fragments may result in a number of interrelated pathogenic mechanisms triggering a cascade of molecular events that lead to the untimely neuronal death observed in HD. One putative pathological mechanism reported to play a prominent role in the pathogenesis of HD is mitochondrial dysfunction and the subsequent reduction of cellular energy. Indeed, if mitochondrial impairment and reduced energy stores play roles in the neuronal loss in HD, then a therapeutic strategy that buffers intracellular energy levels may ameliorate the neurodegenerative process. Sustained ATP levels may have both direct and indirect importance in ameliorating the severity of many of the pathogenic mechanisms associated with HD. Creatine, a guanidino compound produced endogenously and acquired exogenously through diet, is a critical component in maintaining much needed cellular energy. As such, creatine is one of a number of ergogens that may provide a relatively safe and immediately available therapeutic strategy to HD patients that may be the cornerstone of a combined treatment necessary to delay the relentless progression of HD.

Pathology of mitochondrial encephalomyopathies

Muscle biopsy provides the best tissue to confirm a mitochondrial cytopathy. Histochemical features often correlate with specific syndromes and facilitate the selection of biochemical and genetic studies. Ragged-red fibres nearly always indicate a combination defect of respiratory complexes I and IV. Increased punctate lipid within myofibers is a regular feature of Kearns-Sayre and PEO, but not of MELAS and MERRF. Total deficiency of succinate dehydrogenase indicates a severe defect in Complex II; total absence of cytochrome-c-oxidase activity in all myofibres correlates with a severe deficiency of Complex IV or of coenzyme-Q10. The selective loss of cytochrome-c-oxidase activity in scattered myofibers, particularly if accompanied by strong succinate dehydrogenase staining in these same fibres, is good evidence of mitochondrial cytopathy and often of a significant mtDNA mutation, though not specific for Complex IV disorders. Glycogen may be excessive in ragged-red zones. Ultrastructure provides morphological evidence of mitochondrial cytopathy, in axons and endothelial cells as well as myocytes. Abnormal axonal mitochondria may contribute to neurogenic atrophy of muscle, a secondary chronic feature. Quantitative determinations of respiratory chain enzyme complexes, with citrate synthase as an internal control, confirm the histochemical impressions or may be the only evidence of mitochondrial disease. Biological and technical artifacts may yield falsely low enzymatic activities. Genetic studies screen common point mutations in mtDNA. The brain exhibits characteristic histopathological alterations in mitochondrial diseases. Skin biopsy is useful for mitochondrial ultrastructure in smooth erector pili muscles and axons; skin fibroblasts may be grown in culture. Mitochondrial alterations occur in many nonmitochondrial diseases and also may be induced by drugs and toxins.

Creatine has no beneficial effect on skeletal muscle energy metabolism in patients with single mitochondrial DNA deletions: a placebo-controlled, double-blind 31P-MRS crossover study

The purpose of our randomized, double-blind, placebo-controlled crossover study in 15 patients with chronic progressive external ophthalmoplegia (CPEO) or Kearns-Sayre syndrome (KSS) because of single large-scale mitochondrial (mt) DNA deletions was to determine whether oral creatine (Cr) monohydrate can improve skeletal muscle energy metabolism in vivo. Each treatment phase with Cr in a dosage of 150 mg/kg body weight/day or placebo lasted 6 weeks. The effect of Cr was estimated by phosphorus-31 magnetic resonance spectroscopy ((31)P-MRS), clinical and laboratory tests. (31)P-MRS analysis prior to treatment showed clear evidence of severe mitochondrial dysfunction. However, there were no relevant changes in (31)P-MRS parameters under Cr. In particular, phosphocreatine (PCr)/ATP at rest did not increase, and there was no facilitation of post-exercise PCr recovery. Clinical scores and laboratory tests did not alter significantly under Cr, which was tolerated without major side-effects in all patients. Cr supplementation did not improve skeletal muscle oxidative phosphorylation in our series of patients. However, one explanation for our negative findings may be the short study duration or the limited number of patients included.

Cytochrome c oxidase deficiency in a child with isolated myopathy

Cytochrome c oxidase (COX) deficiency is the most commonly recognized respiratory chain defect in childhood. The disease is clinically heterogeneous with phenotypes including Leigh syndrome, hepatic failure and myopathies. COX deficiency has been associated with mitochondrial DNA mutations in COX I, II, and III with large-scale deletions of the mitochondrial genome and with point mutations in mitochondrial tRNA genes. Here we report on a 3.5-year-old girl with a rare type of isolated myopathy due to COX deficiency.

Targeting cellular energy production in neurological disorders

The concepts of energy dysregulation and oxidative stress and their complicated interdependence have rapidly evolved to assume primary importance in understanding the pathophysiology of numerous neurological disorders. Therefore, neuroprotective strategies addressing specific bioenergetic defects hold particular promise in the treatment of these conditions (i.e., amyotrophic lateral sclerosis, Huntington's disease, Parkinson's disease, Friedreich's ataxia, mitochondrial cytopathies and other neuromuscular diseases), all of which, to some extent, share 'the final common pathway' leading to cell death through either necrosis or apoptosis. Compounds such as creatine monohydrate and coenzyme Q(10) offer substantial neuroprotection against ischaemia, trauma, oxidative damage and neurotoxins. Miscellaneous agents, including alpha-lipoic acid, beta-OH-beta-methylbutyrate, riboflavin and nicotinamide, have also been shown to improve various metabolic parameters in brain and/or muscle. This review will highlight the biological function of each of the above mentioned compounds followed by a discussion of their utility in animal models and human neurological disease. The balance of this work will be comprised of discussions on the therapeutic applications of creatine and coenzyme Q(10).

Symptomatic and Disease-Modifying Therapy for the Progressive Ataxias

BACKGROUND

The progressive ataxias are a diverse group of neurologic diseases that share features of degeneration of the cerebellum and its inflow/outflow pathways but differ in etiology, course, and associated noncerebellar system involvement. Some will have treatable causes, but for most, the pathophysiology is incompletely known.

REVIEW SUMMARY

Treatment strategies will include (1) definitive therapy when available, (2) symptomatic treatment and prevention of complications, and (3) rehabilitation and support resources. The physician will have to decide whether to introduce or approve the use of therapies based on as yet-unproven mechanisms or the use of complementary medicine approaches.

CONCLUSIONS

There are as yet no drugs that have been approved by the Food and Drug Administration for the treatment of the progressive ataxias and relatively few disease-modifying therapies, but symptomatic and rehabilitation interventions can greatly improve the quality of life of individuals with these disabling neurodegenerative disorders.

Induction of oxidative stress by L-2-hydroxyglutaric acid in rat brain

L-2-hydroxyglutaric acid (LGA) is the biochemical hallmark of L-2-hydroxyglutaric aciduria (L-OHGA), an inherited neurometabolic disorder characterized by progressive neurodegeneration with cerebellar and pyramidal signs, mental deterioration, epilepsy, and subcortical leukoencephalopathy. Because the underlying mechanisms of the neuropathology of this disorder are virtually unknown, in this study we tested the in vitro effect of LGA on various parameters of oxidative stress, namely, chemiluminescence, thiobarbituric acid-reactive substances (TBA-RS), protein carbonyl formation (PCF), total radical-trapping antioxidant potential (TRAP), total antioxidant reactivity (TAR), and the activities of the antioxidant enzymes catalase, glutathione peroxidase, and superoxide dismutase in cerebellum and cerebral cortex of 30-day-old rats. LGA significantly increased chemiluminescence, TBA-RS, and PCF measurements and markedly decreased TAR values in cerebellum, in contrast to TRAP and the activity of the antioxidant enzymes, which were not altered by the acid. Similar but less pronounced effects were provoked by LGA in cerebral cortex. Moreover, the LGA-induced increase of TBA-RS was significantly attenuated by melatonin (N-acetyl-5-methoxytryptamine) and by the combinations of ascorbic acid plus Trolox (soluble alpha-tocopherol) and of superoxide dismutase plus catalase but not by the inhibitor of nitric oxide synthase Nomega-nitro-L-arginine methyl ester (L-NAME), creatine, or superoxide dismutase or catalase alone in either cerebral structure. The data indicate that LGA provokes oxidation of lipids and proteins and reduces the brain capacity to modulate efficiently the damage associated with an enhanced production of free radicals, possibly by inducing generation of superoxide and hydroxyl radicals, which are trapped by the scavengers used. Thus, in case these findings can be extrapolated to human L-OHGA, it may be presumed that oxidative stress is involved in the pathophysiology of the brain damage observed in this disorder.

Mitochondrial disorders

We present here a discussion on the most relevant recent publications on mitochondrial disease. In addition to many papers concerning the description of the genotype-to-phenotype correlations in mitochondrial DNA-related disorders, this very broad area of neurogenetics includes a number of novel observations on the basic aspects of mitochondrial biogenesis that can be relevant in explaining the molecular mechanisms of mitochondrial abnormalities. The completion of the human genome project and the wealth of knowledge gained on the genetics of oxidative phosphorylation in yeast have promoted a substantial acceleration in the discovery of a remarkable number of nuclear genes associated with specific mitochondrial disorders. A further development of these contributions has been the generation of several cellular and animal models of disease that can now be exploited for testing both pathogenetic hypotheses and therapeutic strategies. Most of the latter are based on the use of chemical compounds aimed at reducing the negative impact of mitochondrial defects on both energy production and generation of reactive oxygen species. The first successful attempts for gene therapy of some mitochondrial diseases have recently been achieved and will hopefully increase in the near future.