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The D₃ -creatine dilution method non-invasively measures muscle mass in mice.

ABSTRACT: Developing accurate methods to quantify age-related muscle loss (sarcopenia) could greatly accelerate development of therapies to treat muscle loss in the elderly, as current methods are inaccurate or expensive. The current gold standard method for quantifying sarcopenia is dual-energy X-ray absorptiometry (DXA) but does not measure muscle directly-it is a composite measure quantifying "lean mass" (muscle) excluding fat and bone. In humans, DXA overestimates muscle mass, which has led to erroneous conclusions about the importance of skeletal muscle in human health and disease. In animal models, DXA is a popular method for measuring lean mass. However, instrumentation is expensive and is potentially limited by anesthesia concerns. Recently, the D₃ -creatine (D₃ Cr) dilution method for quantifying muscle mass was developed in humans and rats. This method is faster, cheaper, and more accurate than DXA. Here, we demonstrate that the D₃ Cr method is a specific assay for muscle mass in mice, and we test associations with DXA and body weight. We evaluated the D₃ Cr method compared to DXA-determined lean body mass (LBM) in aged mice and reported that DXA consistently overestimates muscle mass with age. Overall, we provide evidence that the D₃ Cr dilution method directly measures muscle mass in mice. Combined with its ease of use, accessibility, and non-invasive nature, the method may prove to more quickly advance development of preclinical therapies targeting sarcopenia.

SUBMITTER: Wimer L

PROVIDER: S-EPMC10410001 | biostudies-literature | 2023 Aug

REPOSITORIES: biostudies-literature

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The D<sub>3</sub> -creatine dilution method non-invasively measures muscle mass in mice.

Wimer Lauren L Goncharova Elena E Galkina Sofiya S Nyangau Edna E Shankaran Mahalakshmi M Davis Asia A Prado Leandro L Munoz Maria Castro MC Epstein Sharon S Patterson Cavan C Shaum Nicholas N Hellerstein Mark M Evans William W Melov Simon S

Aging cell 20230605 8

Developing accurate methods to quantify age-related muscle loss (sarcopenia) could greatly accelerate development of therapies to treat muscle loss in the elderly, as current methods are inaccurate or expensive. The current gold standard method for quantifying sarcopenia is dual-energy X-ray absorptiometry (DXA) but does not measure muscle directly-it is a composite measure quantifying "lean mass" (muscle) excluding fat and bone. In humans, DXA overestimates muscle mass, which has led to erroneo ...[more]

PMID: 37272263

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Project description:BackgroundGiven limited experience in applying the creatine-(methyl-D3) (D3Cr) dilution method to measure skeletal muscle mass (SMM) in young children, the feasibility of deployment in a fielding setting and performance of the method was assessed in a cohort of 4-year-old children in Dhaka, Bangladesh.MethodsFollowing D3Cr oral dose (10 mg) administration, single fasting urine samples were collected at 2-4 days (n = 100). Twenty-four-hour post-dose collections and serial spot urine samples on days 2, 3 and 4 were obtained in a subset of participants (n = 10). Urinary creatine, creatinine, D3Cr and D3-creatinine enrichment were analyzed by liquid chromatography-tandem mass spectrometry. Appendicular lean mass (ALM) was measured by dual-energy x-ray absorptiometry and grip strength was measured by a hand-held dynamometer.ResultsSMM was measured successfully in 91% of participants, and there were no adverse events. Mean ± SD SMM was greater than ALM (4.5 ± 0.4 and 3.2 ± 0.6 kg, respectively). Precision of SMM was low (intraclass correlation = 0.20; 95% CI: 0.02, 0.75; n = 10). Grip strength was not associated with SMM in multivariable analysis (0.004 kg per 100 g of SMM; 95% CI: -0.031, 0.038; n = 91).ConclusionsThe D3Cr dilution method was feasible in a community setting. However, high within-child variability in SMM estimates suggests the need for further optimization of this approach.ImpactThe D3-creatine (D3Cr) stable isotope dilution method was considered a feasible method for the estimation of skeletal muscle mass (SMM) in young children in a community setting and was well accepted among participants. SMM was weakly associated with both dual-energy x-ray absorptiometry-derived values of appendicular lean mass and grip strength. High within-child variability in estimated values of SMM suggests that further optimization of the D3Cr stable isotope dilution method is required prior to implementation in community research settings.

Project description:The French chemist Michel Eugène Chevreul discovered creatine in meat two centuries ago. Extensive biochemical and physiological studies of this organic molecule followed with confirmation that creatine is found within the cytoplasm and mitochondria of human skeletal muscles. Two groups of investigators exploited these relationships five decades ago by first estimating the creatine pool size in vivo with 14 C and 15 N labelled isotopes. Skeletal muscle mass (kg) was then calculated by dividing the creatine pool size (g) by muscle creatine concentration (g/kg) measured on a single muscle biopsy or estimated from the literature. This approach for quantifying skeletal muscle mass is generating renewed interest with the recent introduction of a practical stable isotope (creatine-(methyl-d3 )) dilution method for estimating the creatine pool size across the full human lifespan. The need for a muscle biopsy has been eliminated by assuming a constant value for whole-body skeletal muscle creatine concentration of 4.3 g/kg wet weight. The current single compartment model of estimating creatine pool size and skeletal muscle mass rests on four main assumptions: tracer absorption is complete; tracer is all retained; tracer is distributed solely in skeletal muscle; and skeletal muscle creatine concentration is known and constant. Three of these assumptions are false to varying degrees. Not all tracer is retained with urinary isotope losses ranging from 0% to 9%; an empirical equation requiring further validation is used to correct for spillage. Not all tracer is distributed in skeletal muscle with non-muscle creatine sources ranging from 2% to 10% with a definitive value lacking. Lastly, skeletal muscle creatine concentration is not constant and varies between muscles (e.g. 3.89-4.62 g/kg), with diets (e.g. vegetarian and omnivore), across age groups (e.g. middle-age, ~4.5 g/kg; old-age, 4.0 g/kg), activity levels (e.g. athletes, ~5 g/kg) and in disease states (e.g. muscular dystrophies, <3 g/kg). Some of the variability in skeletal muscle creatine concentrations can be attributed to heterogeneity in the proportions of wet skeletal muscle as myofibres, connective tissues, and fat. These observations raise serious concerns regarding the accuracy of the deuterated-creatine dilution method for estimating total body skeletal muscle mass as now defined by cadaver analyses of whole wet tissues and in vivo approaches such as magnetic resonance imaging. A new framework is needed in thinking about how this potentially valuable method for measuring the creatine pool size in vivo can be used in the future to study skeletal muscle biology in health and disease.

Project description:ObjectivesIt is unknown whether muscle mass measured by the D3-creatine dilution method is a superior predictor of incident mobility disability than traditional components of sarcopenia definitions (including grip strength, walking speed, appendicular lean mass). The objective of this study was to determine the relative importance of strength; physical performance; and lean, fat, and muscle mass in predicting incident mobility disability in older men.DesignLongitudinal cohort study of participants in the Osteoporotic Fractures in Men (MrOS) study.Setting and participantsMuscle mass was assessed by D3-creatine dilution in 1098 men (aged 83.7 ± 3.7 years). Participants also completed anthropomorphic measures, 6-m walking speed (m/s), grip strength (kg), chair stands (seconds), and dual x-ray absorptiometry appendicular lean mass (ALM), and total body fat percentage. Men self-reported incident mobility disability defined by the development of an inability to complete at least one of walking 2-3 blocks, climbing 10 steps, or carrying 10 lb over 2.2 ± 0.3 years.MethodsClassification and regression tree analysis was conducted to determine relative variable importance and algorithm cutpoints for predicting incident mobility disability. Given the proximity of walking speed with the primary outcome (mobility disability), analyses were conducted with and without walking speed.ResultsWalking speed followed by D3Cr muscle mass/weight were the most important variables (variable importance: 53% and 12%, respectively) in the prediction of self-reported incident mobility disability. D3Cr muscle mass was the most important variable in predicting incident mobility disability when walking speed was excluded, followed by chair stands (variable importance: 35% and 33%, respectively). Body fat percentage, ALM, and grip strength were not selected as nodes in either analysis and had low or negligible variable importance.Conclusions and implicationsThis study has provided valuable insights into the importance of different variables in predicting incident mobility disability in older men. Muscle mass by D3Cr may be a key tool for predicting the risk of negative outcomes in older adults in the future, particularly in post-acute and long-term care settings.

Project description:BackgroundTraditionally, weight loss (WL) trials utilize dual energy X-ray absorptiometry (DXA) to measure lean mass. This method assumes lean mass, as the sum of all non-bone and non-fat tissue, is a reasonable proxy for muscle mass. In contrast, the D3 -creatine (D3 Cr) dilution method directly measures whole body skeletal muscle mass, although this method has yet to be applied in the context of a geriatric WL trial. The purpose of this project was to (1) describe estimates of change and variability in D3 Cr muscle mass in older adults participating in an intentional WL intervention and (2) relate its change to other measures of body composition as well as muscle function and strength.MethodsThe INVEST in Bone Health trial (NCT04076618), used as a scaffold for this ancillary pilot project, is a three-armed, 12-month randomized, controlled trial designed to determine the effects of resistance training or weighted vest use during intentional WL on a battery of musculoskeletal health outcomes among 150 older adults living with obesity. A convenience sample of 24 participants (n = 8/arm) are included in this analysis. At baseline and 6 months, participants were weighed, ingested a 30 mg D3 Cr tracer dose, provided a fasted urine sample 3-6 days post-dosage, underwent DXA (total body fat and lean masses, appendicular lean mass) and computed tomography (mid-thigh and trunk muscle/intermuscular fat areas) scans, and performed 400-m walk, stair climb, knee extensor strength, and grip strength tests.ResultsParticipants were older (68.0 ± 4.4 years), mostly White (75.0%), predominantly female (66.7%), and living with obesity (body mass index: 33.8 ± 2.7 kg/m2 ). Six month total body WL was -10.3 (95% confidence interval, CI: -12.7, -7.9) kg. All DXA and computed tomography-derived body composition measures were significantly decreased from baseline, yet D3 Cr muscle mass did not change [+0.5 (95% CI: -2.0, 3.0) kg]. Of muscle function and strength measures, only grip strength significantly changed [+2.5 (95% CI: 1.0, 4.0) kg] from baseline.ConclusionsAmong 24 older adults, significant WL with or without weighted vest use or resistance training over a 6-month period was associated with significant declines in all bioimaging metrics, while D3 Cr muscle mass and muscle function and strength were preserved. Treatment assignment for the trial remains blinded; therefore, full interpretation of these findings is limited. Future work in this area will assess change in D3 Cr muscle mass by parent trial treatment group assignment in all study participants.

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The D₃ -creatine dilution method non-invasively measures muscle mass in mice.

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The D<sub>3</sub> -creatine dilution method non-invasively measures muscle mass in mice.

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The D3 -creatine dilution method non-invasively measures muscle mass in mice.

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The D<sub>3</sub> -creatine dilution method non-invasively measures muscle mass in mice.

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OmicsDI is part of the ELIXIR infrastructure

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The D₃ -creatine dilution method non-invasively measures muscle mass in mice.