Combined in vivo muscle mass, muscle protein synthesis and muscle protein breakdown measurement: a ‘Combined Oral Stable Isotope Assessment of Muscle (COSIAM)’ approach

Abstract

Optimising approaches for measuring skeletal muscle mass and turnover that are widely applicable, minimally invasive and cost effective is crucial in furthering research into sarcopenia and cachexia. Traditional approaches for measurement of muscle protein turnover require infusion of expensive, sterile, isotopically labelled tracers which limits the applicability of these approaches in certain populations (e.g. clinical, frail elderly). To concurrently quantify skeletal muscle mass and muscle protein turnover i.e. muscle protein synthesis (MPS) and muscle protein breakdown (MPB), in elderly human volunteers using stable-isotope labelled tracers i.e. Methyl-[D3]-creatine (D3-Cr), deuterium oxide (D2O), and Methyl-[D3]-3-methylhistidine (D3-3MH), to measure muscle mass, MPS and MPB, respectively. We recruited 10 older males (71 ± 4 y, BMI: 25 ± 4 kg.m2, mean ± SD) into a 4-day study, with DXA and consumption of D2O and D3-Cr tracers on day 1. D3-3MH was consumed on day 3, 24 h prior to returning to the lab. From urine, saliva and blood samples, and a single muscle biopsy (vastus lateralis), we determined muscle mass, MPS and MPB. D3-Cr derived muscle mass was positively correlated to appendicular fat-free mass (AFFM) estimated by DXA (r = 0.69, P = 0.027). Rates of cumulative myofibrillar MPS over 3 days were 0.072%/h (95% CI, 0.064 to 0.081%/h). Whole-body MPB over 6 h was 0.052 (95% CI, 0.038 to 0.067). These rates were similar to previous literature. We demonstrate the potential for D3-Cr to be used alongside D2O and D3-3MH for concurrent measurement of muscle mass, MPS, and MPB using a minimally invasive design, applicable for clinical and frail populations.

A ‘virtual’ revolution: non‐invasive methods to probe skeletal muscle metabolism in Duchenne muscular dystrophy

“…Compared with information on the response of MPS to various interventions, less information is available on the response of MPB, partly because its assessment using traditional stable-isotope methodologies is difficult and invasive. Recently, methyl-[D 3 ]-3-methylhistidine (D 3 -3MH) has been applied along with D 2 O and D 3 Cr as part of a combined stable-isotope approach to assess MM, MPS and MPB in vivo (Cegielski et al 2021). 3-Methylhistidine can be sampled in blood or urine and is a post-translational modification of contractile protein histidine residues, which are not used for MPS because there is no aminoacyl-tRNA for 3-MH.…”

“…Recently, methyl‐[D 3 ]‐3‐methylhistidine (D 3 ‐3MH) has been applied along with D 2 O and D 3 Cr as part of a combined stable‐isotope approach to assess MM, MPS and MPB in vivo (Cegielski et al . 2021). 3‐Methylhistidine can be sampled in blood or urine and is a post‐translational modification of contractile protein histidine residues, which are not used for MPS because there is no aminoacyl‐tRNA for 3‐MH.…”

The Combined Oral Stable Isotope Assessment of Muscle (COSIAM) reveals D-3 creatine derived muscle mass as a standout cross-sectional biomarker of muscle physiology vitality in older age

“…MPS and MPB. We recently developed a minimally invasive Combined Oral Stable Isotope Assessment of Muscle (COSIAM) approach where we provide a protocol capable of simultaneous quantification of muscle mass (via a deuterated creatine dilution technique [ 5 , 16 , 17 ]), muscle protein synthesis (via D 2 O [ 2 , 18 , 19 ]) and muscle protein breakdown (via deuterated 3-methylhistidine dilution [ 5 , 14 ]). The purpose of setting up this approach was to offer researchers a single protocol to determine these variables in older, clinical (vs. healthy) and difficult to study populations, and also in response to candidate interventions.…”

“…In our previous paper [ 5 ], we conducted a pilot study in a small number ( N = 10) of subjects aimed at validation of the COSIAM approach from a purely technical and logistical perspective. The aim of the present study was to expand this pilot work and determine relationships between COSIAM facets and cross-sectional muscle health parameters in a larger group of older men and women.…”

Determining the Influence of Habitual Dietary Protein Intake on Physiological Muscle Parameters in Youth and Older Age

“…Future research needs to include a wider range of older adults, including those with sarcopenia, and potentially those in residential care facilities who represent a growing proportion of older adults [54], and who are known to present with distinct characteristics (e.g., dysphagia [55], polypharmacy [54]) with potential to impact nutrient intake and absorption [56]. Studying protein metabolism in such populations is not without challenges, but the development of new oral tracer techniques such as those using D 2 O which can measure MPS in longer-term 'free-living' scenarios may provide additional insight into the impact of habitual protein intake on muscle mass and function in these 'at-risk' populations [57,58]. In addition, given inter-individual variation in dietary habits due to lifestyle constraints (i.e., cost) and food preferences across all ages, a larger sample size is needed to confirm the findings of this work.…”