Human Muscle Tissue Research Articles

Mass spectrometry proteomic profiling of postmortem human muscle degradation for PMI estimation

The discovery of new methods for determining the post-mortem interval is of significant forensic interest. Mass spectrometry has enhanced the accuracy of assessing post-mortem protein decay, with skeletal muscle being the most studied substrate due to its intrinsic properties of postmortem decay. In this pilot study, human skeletal muscle tissue (iliopsoas) was harvested and allowed to decay under controlled temperature and humidity conditions at predetermined intervals.The samples were analyzed using mass spectrometry proteomics for both qualitative and quantitative evaluation of proteins and peptides. Candidate proteins were validated through immunoblotting.The results were significant, identifying several proteins that could aid in estimating the post-mortem interval. Notably, PLIN4, MYOZ2, SYNPO2, and BAG3 were validated by immunoblotting over a broader range of experimental points and temperatures. Furthermore, human results were compared with animal muscle samples from a previous study, revealing similarities in decomposition kinetics.This analysis of human samples marks a step forward in the potential forensic application of proteomic evaluation by mass spectrometry.

Differential Fatty Acid Response of Resident Macrophages in Human Skeletal Muscle Fiber and Intermuscular Adipose Tissue.

Human skeletal muscle contains different types of tissues with skeletal muscle fibers (SMFs) and intermuscular adipose tissues (IMATs) as the main components. We maintained human skeletal muscle tissues from 12 study participants under native conditions in vitro for 11 days to investigate the dynamics of macrophages that reside in adjacent IMATs and SMFs simultaneously. The samples were subjected to immunohistochemical analysis for macrophage phenotyping and mitochondrial mass assessment before and after maintenance in vitro. Multiplex protein analysis was used to determine cytokine/chemokine expression in tissue extracts. The results revealed significant correlations between donor age or body mass index (BMI) and distinct phenotypes of resident macrophages in SMFs and IMATs. The dynamics of SMF- and IMAT-resident macrophages differed significantly in vitro and exhibited inverse correlations with chemokine/cytokine expression levels and mitochondrial activity. Moreover, the responses of macrophages to saturated and unsaturated fatty acids (FAs) differed substantially between SMFs and IMATs. These findings showed the functional diversity of phenotypically identical macrophages in adjacent niches. Thus, the currently available macrophage markers cannot capture the functional diversity of human tissue-resident macrophages. The model used in the present study may help elucidate how macrophages affect muscle homeostasis and disease in humans.

The MyoGravity project to study real microgravity effects on human muscle precursor cells and tissue

Microgravity (µG) experienced during space flights promotes adaptation in several astronauts’ organs and tissues, with skeletal muscles being the most affected. In response to reduced gravitational loading, muscles (especially, lower limb and antigravity muscles) undergo progressive mass loss and alteration in metabolism, myofiber size, and composition. Skeletal muscle precursor cells (MPCs), also known as satellite cells, are responsible for the growth and maintenance of muscle mass in adult life as well as for muscle regeneration following damage and may have a major role in µG-induced muscle wasting. Despite the great relevance for astronaut health, very few data are available about the effects of real µG on human muscles. Based on the MyoGravity project, this study aimed to analyze: (i) the cellular and transcriptional alterations induced by real µG in human MPCs (huMPCs) and (ii) the response of human skeletal muscle to normal gravitational loading after prolonged exposure to µG. We evaluated the transcriptomic changes induced by µG on board the International Space Station (ISS) in differentiating huMPCs isolated from Vastus lateralis muscle biopsies of a pre-flight astronaut and an age- and sex-matched volunteer, in comparison with the same cells cultured on the ground in standard gravity (1×g) conditions. We found that huMPCs differentiated under real µG conditions showed: (i) upregulation of genes related to cell adhesion, plasma membrane components, and ion transport; (ii) strong downregulation of genes related to the muscle contraction machinery and sarcomere organization; and (iii) downregulation of muscle-specific microRNAs (myomiRs). Moreover, we had the unique opportunity to analyze huMPCs and skeletal muscle tissue of the same astronaut before and 30 h after a long-duration space flight on board the ISS. Prolonged exposure to real µG strongly affected the biology and functionality of the astronaut’s satellite cells, which showed a dramatic reduction of responsiveness to activating stimuli and proliferation rate, morphological changes, and almost inability to fuse into myotubes. RNA-Seq analysis of post- vs. pre-flight muscle tissue showed that genes involved in muscle structure and remodeling are promptly activated after landing following a long-duration space mission. Conversely, genes involved in the myelination process or synapse and neuromuscular junction organization appeared downregulated. Although we have investigated only one astronaut, these results point to a prompt readaptation of the skeletal muscle mechanical components to the normal gravitational loading, but the inability to rapidly recover the physiological muscle myelination/innervation pattern after landing from a long-duration space flight. Together with the persistent functional deficit observed in the astronaut’s satellite cells after prolonged exposure to real µG, these results lead us to hypothesize that a condition of inefficient regeneration is likely to occur in the muscles of post-flight astronauts following damage.

Electrical stimulation of biofidelic engineered muscle enhances myotube size, force, fatigue resistance, and induces a fast-to-slow-phenotype shift.

Therapeutic development for skeletal muscle diseases is challenged by a lack of exvivo models that recapitulate human muscle physiology. Here, we engineered 3D human skeletal muscle tissue in the Biowire II platform that could be maintained and electrically stimulated long-term. Increasing differentiation time enhanced myotube formation, modulated myogenic gene expression, and increased twitch and tetanic forces. When we mimicked exercise training by applying chronic electrical stimulation, the "exercised" skeletal muscle tissues showed increased myotube size and a contractility profile, fatigue resistance, and gene expression changes comparable to invivo models of exercise training. Additionally, tissues also responded with expected physiological changes to known pharmacological treatment. To our knowledge, this is the first evidence of a human engineered 3D skeletal muscle tissue that recapitulates invivo models of exercise. By recapitulating key features of human skeletal muscle, we demonstrated that the Biowire II platform may be used by the pharmaceutical industry as a model for identifying and optimizing therapeutic drug candidates that modulate skeletal muscle function.

464P Advancing preclinical research of myotonic dystrophy type 1 with 3D functional human skeletal muscle tissues

464P Advancing preclinical research of myotonic dystrophy type 1 with 3D functional human skeletal muscle tissues

Engineered myovascular tissues for studies of endothelial/satellite cell interactions

In native skeletal muscle, capillaries reside in close proximity to muscle stem cells (satellite cells, SCs) and regulate SC numbers and quiescence through partially understood mechanisms that are difficult to study in vivo. This challenge could be addressed by the development of a 3-dimensional (3D) in vitro model of vascularized skeletal muscle harboring both a pool of quiescent SCs and a robust network of capillaries. Still, studying interactions between SCs and endothelial cells (ECs) within a tissue-engineered muscle environment has been hampered by the incompatibility of commercially available EC media with skeletal muscle differentiation. In this study, we first optimized co-culture media and cellular ratios to generate highly functional vascularized human skeletal muscle tissues (“myovascular bundles”) with contractile properties (∼10 mN/mm2) equaling those of avascular, muscle-only tissues (“myobundles”). Within one week of muscle differentiation, ECs in these tissues formed a dense network of capillaries that co-aligned with muscle fibers and underwent initial lumenization. Incorporating vasculature within myobundles increased the total SC number by 82%, with SC density and quiescent signature being increased proximal (≤20μm) to EC networks. In vivo, at two weeks post-implantation into dorsal window chambers in nude mice, vascularized myobundles exhibited improved calcium handling compared to avascular implants. In summary, we engineered highly functional myovascular tissues that enable studies of the roles of EC-SC crosstalk in human muscle development, physiology, and disease. Statement of significanceIn native skeletal muscle, intricate relationships between vascular cells and muscle stem cells (“satellite cells”) play critical roles in muscle growth and regeneration. Current methods for in vitro engineering of contractile skeletal muscle do not recreate capillary networks present in vivo. Our study for the first time generates in vitro robustly vascularized, highly functional engineered human skeletal muscle tissues. Within these tissues, satellite cells are more abundant and, similar to in vivo, they are more dense and less proliferative proximal to endothelial cells. Upon implantation in mice, vascularized engineered muscles show improved calcium handling compared to muscle-only implants. We expect that this versatile in vitro system will enable studies of muscle-vasculature crosstalk in human development and disease.

Mitochondrial DNA damage in human skeletal muscle tissue correlates with peripheral artery disease development and progression

Mitochondrial DNA damage in human skeletal muscle tissue correlates with peripheral artery disease development and progression

Placenta‐Derived Mesenchymal Stromal‐Like Cells Promote 3D‐Engineered Muscle Tissue Differentiation and Vessel Network Maturation

Placental‐derived stromal‐like cells (PLX‐PAD) have been shown to facilitate muscle tissue recovery after injury and stimulate angiogenesis. This work assesses the impact of PLX‐PAD cells on the vascularization and maturation of engineered skeletal muscle tissue. Specifically, their effects in direct co‐culture with endothelial cells, pericytes, and myoblasts seeded within microporous 3D scaffolds are characterized. Additionally, the impact of hypoxic PLX‐PAD cell‐conditioned medium (CM) on vascularization and muscle differentiation of engineered tissue is monitored. Co‐culture of PLX‐PAD with myocytes stimulated myocyte differentiation while PLX‐PAD CM promoted the formation of vascular networks. Implantation of a multi‐culture system of vascularized human skeletal muscle tissue and PLX‐PAD into a rectus abdominal defect in nude mice promoted myocyte differentiation, host vessel penetration, and tissue integration. These findings indicate the ability of placenta‐derived cells to induce the formation of vascularized engineered muscle constructs with potential therapeutic applications.

Using Stable Nitrogen Isotope Ratios from Human Skeletal Muscle Tissue for Postmortem Interval (PMI) Estimation (Part 1)

Human skeletal muscle tissue was analyzed for stable nitrogen isotope analysis (δ15N) to test the applicability of changes in values (Δ15N) through the putrefaction process for postmortem interval (PMI) estimation. Seasonal differences in Δ15N values of decom-posing skeletal muscle tissue were analyzed from 20 human donors at the University of Tennessee Anthropology Research Facility. This study revealed that change in the δ15N ratios of decomposing muscle tissue has potential as a novel method for PMI estimation. In winter months, when identifiable muscle tissue can be retained on a body for months, the data indicate that there is a systematic increase in Δ15N values with increasing temperatures when putrefaction progresses faster with values shifting as much as 3.0‰. This initial study indicates there is value in further method development of this quantitative approach to PMI estimation for recently deceased individuals, but further work is needed. While the analysis only requires a small amount of tissue, has a user- friendly collection and analysis protocol, and is less subjective than visual methods, there is still significant research to be done prior to widespread applications as a PMI estimation method. Understanding variability in δ15N across decomposing muscle tissue groups, individual variation (i.e., muscle mass, disease, body chem-istry), and an accurate approximation for a perimortem δ15N value necessary to calculate Δ15N all need to be further researched prior to generation of a reliable regression formula and error rates.

Characterizing the skeletal muscle immune microenvironment for sarcopenia: insights from transcriptome analysis and histological validation.

Sarcopenia is a condition characterized by the age-related loss of skeletal muscle mass and function. The pathogenesis of the disease is influenced by chronic low-grade inflammation. However, the specific changes in the immune landscape changes of sarcopenic muscle are not yet fully understood. To gain insights into the immune cell composition and interactions, we combined single-nucleus RNA sequencing data, bulk RNA sequencing dataset, and comprehensive bioinformatic analyses on the skeletal muscle samples from young, aged, and sarcopenic individuals. Histological staining was then performed on skeletal muscles to validate the distribution of immune cells in clinical samples. We analyzed the transcriptomes of 101,862 single nuclei, revealing a total of 10 major cell types and 6 subclusters of immune cell types within the human skeletal muscle tissues. Notable variations were identified in the immune microenvironment between young and aged skeletal muscle. Among the immune cells from skeletal muscle microenvironment, macrophages constituted the largest fraction. A specific marker gene LYVE1 for skeletal muscle resident macrophages was further identified. Cellular subclasses included four distinct groups of resident macrophages, which play different roles in physiological or non-physiological conditions. Utilizing bulk RNA sequencing data, we observed a significant enrichment of macrophage-rich inflammation in sarcopenia. Our findings demonstrate age-related changes in the composition and cross-talk of immune cells in human skeletal muscle microenvironment, which contribute to chronic inflammation in aged or sarcopenia muscle. Furthermore, macrophages emerge as a potential therapeutic target, thus advancing our understanding of the pathogenesis of sarcopenia.

2005-LB: Optimization of Single Nuclei Isolation from Frozen Human Skeletal Muscle and Pancreatic Tissue Samples for Single Nuclei Multiome ATAC + Gene Expression

2005-LB: Optimization of Single Nuclei Isolation from Frozen Human Skeletal Muscle and Pancreatic Tissue Samples for Single Nuclei Multiome ATAC + Gene Expression

Low-velocity nail penetration response of muscle tissue and gelatin

Quantitative estimation of soft tissue injuries due to penetration of sharp objects is a challenging task for forensic pathologists. The severity of injury depends on the force required to penetrate the tissue. This study focuses on investigating the amount of force required to penetrate porcine muscle tissue and gelatin simulants (10 % wt) to mimic human muscle tissue when subjected to sharp objects like nail at velocities below 5 m/s. A custom-made experimental setup was used to examine the influence of penetration velocity and nail diameter on penetration forces. Images captured by a high-speed camera were used to track the position and velocity of the nail. A finite element (FE) model was established to simulate the penetration behavior of the tissue and gelatin. The FE simulations of the nail penetration were validated through direct comparison with the experimental results. In tissues as well as in the simulant, penetration forces were seen to increase with increasing nail diameter and velocity. Porcine muscle tissue showed 23.9–46.5 % higher penetration forces than gelatin simulants (10 % wt) depending on nail diameter and velocity; the difference being higher for higher nail diameter and velocity. The ranges of maximum penetration forces measured were 8.6–59.1 N for porcine muscle tissue and 6.8–34.9 N for gelatin simulant. This study helps to quantify injuries caused by sharp nails at low velocities and offers insights with potential applications in injury management strategies and forensic studies.

Predicting Myosin Heavy Chain Isoform Through Muscle Fiber Length in Older Adults

Myosin heavy chain (MHC) isoforms directly impact muscle cellular contractile characteristics and are closely associated with other cellular functions (substrate metabolism, calcium handling, etc.). As such, MHC isoform has come to define muscle “fiber type” (MHC I = slow/oxidative and MHC II = fast/glycolytic). Due to the heterogeneity of MHC isoforms expressed within human skeletal muscle tissue, it is essential to determine MHC isoform to allow proper interpretation of tissue level outcomes that may arise from variations within or between fiber types. A priori estimation of fiber type would be a useful tool for ensuring even distribution of fiber type when considering cellular assays in which MHC isoform can only be determined after the fact. Based on the assumption that fibers of various MHC isoform would differently resist mechanical strain, we’ve demonstrated that MHC I fibers can be distinguished from MHC II fibers based on the ratio of fiber to bundle length (degree of stretch) during mechanical dissection. However, our approach used samples from healthy young adults and has not been tested in tissue from older adults, where cellular stiffness is likely elevated. Therefore, our objective is to test our ability to predict MHC isoform in older adults. We hypothesize that muscle fiber strain following dissection will predict MHC isoform in older adults. Methods: Muscle biopsies from the vastus lateralis muscle were obtained from two older adults (one male, one female). A total of 129 muscle fibers were dissected and measured. Fibers were then stored individually and MHC isoform was subsequently identified via sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-Page). Receiver Operating Characteristics (ROC) and confusion matrix were used to assess the predictive capacity for fiber stretch on activation as an index of fiber type. Data: An ROC area under curve (AUC) of 0.634 which indicates that there is a relatively low predictive capacity. Summary: This study aimed to test the feasibility of an approach for predicting muscle fiber type through changes in fiber length upon mechanical dissection. Established in young adults, this study tested samples obtained from older adults to explore the potential effects of age. Preliminary data show that muscle fiber length can predict muscle fiber type in older adults, though the accuracy may be limited when compared with the same approach in younger adults. This lack of accuracy may be attributed to the increase in stiffness that occurs with age, limiting the capacity for strain and thus fiber type variability. A new threshold may need to be determined to increase the accuracy of fiber type prediction. Conclusion: Preliminary data shows that fiber length can provide a prediction for MHC isoform in older adults. NIH National Institute on Aging (1R21AG077125-01A1) and Achievement Rewards for College Scientists (ARCS) Oregon. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Systematic druggable genome-wide Mendelian randomization identifies therapeutic targets for sarcopenia.

There are no effective pharmacological treatments for sarcopenia. We aim to identify potential therapeutic targets for sarcopenia by integrating various publicly available datasets. We integrated druggable genome data, cis-eQTL/cis-pQTL from human blood and skeletal muscle tissue, and GWAS summary data of sarcopenia-related traits to analyse the potential causal relationships between drug target genes and sarcopenia using the Mendelian Randomization (MR) method. Sensitivity analyses and Bayesian colocalization were employed to validate the causal relationships. We also assessed the side effects or additional indications of the identified drug targets using a phenome-wide MR (Phe-MR) approach and investigated actionable drugs for target genes using available databases. MR analysis identified 17 druggable genes with potential causation to sarcopenia in human blood or skeletal muscle tissue. Six of them (HP, HLA-DRA, MAP 3K3, MFGE8, COL15A1, and AURKA) were further confirmed by Bayesian colocalization (PPH4>90%). The up-regulation of HP [higher ALM (beta: 0.012, 95% CI: 0.007-0.018, P=1.2*10-5) and higher grip strength (OR: 0.96, 95% CI: 0.94-0.98, P=4.2*10-5)], MAP 3K3 [higher ALM (beta: 0.24, 95% CI: 0.21-0.26, P=1.8*10-94), higher grip strength (OR: 0.82, 95% CI: 0.75-0.90, P=2.1*10-5), and faster walking pace (beta: 0.03, 95% CI: 0.02-0.05, P=8.5*10-6)], and MFGE8 [higher ALM (muscle eQTL, beta: 0.09, 95% CI: 0.06-0.11, P=6.1*10-13; blood pQTL, beta: 0.05, 95% CI: 0.03-0.07, P=3.8*10-09)], as well as the down-regulation of HLA-DRA [lower ALM (beta: -0.09, 95% CI: -0.11 to -0.08, P=5.4*10-36) and lower grip strength (OR: 1.13, 95% CI: 1.07-1.20, P=1.8*10-5)] and COL15A1 [higher ALM (muscle eQTL, beta: -0.07, 95% CI: -0.10 to -0.04, P=3.4*10-07; blood pQTL, beta: -0.05, 95% CI: -0.06 to -0.03, P=1.6*10-07)], decreased the risk of sarcopenia. AURKA in blood (beta: -0.16, 95% CI: -0.22 to -0.09, P=2.1*10-06) and skeletal muscle (beta: 0.03, 95% CI: 0.02 to 0.05, P=5.3*10-05) tissues showed an inverse relationship with sarcopenia risk. The Phe-MR indicated that the six potential therapeutic targets for sarcopenia had no significant adverse effects. Drug repurposing analysis supported zinc supplementation and collagenase clostridium histolyticum might be potential therapeutics for sarcopenia by activating HP and inhibiting COL15A1, respectively. Our research indicated MAP 3K3, MFGE8, COL15A1, HP, and HLA-DRA may serve as promising targets for sarcopenia, while the effectiveness of zinc supplementation and collagenase clostridium histolyticum for sarcopenia requires further validation.

Analysis of muscle implanted antenna performance with the variation of implantation depth

Abstract Implantation depth of Implantable Medical Devices (IMDs) is an important factor of communication quality between implantable antennas in IMDs and external devices. Therefore, it is required to study the effect of implantation depth on implantable antenna performance. In this article, dependence of resonant frequency and scattering parameters of a two-antenna system where one miniaturized meander-line antenna is placed within human muscle tissue layer operating at 2.45 GHz ISM (industrial, scientific and medical) band and a rectangular patch antenna placed outside human body, are tested. Here 15 values of implantation depth ranging over 5–35 mm inside muscle layer are taken and for each case resonant frequency and scattering parameters (S 11 and S 21) of the system are recorded. Statistical analysis has been performed to observe how these performance parameters are dependent on depth of implantation which may be varied at the time of surgery.

Mitochondrial function in peripheral blood cells across the human lifespan

Mitochondrial dysfunction is considered a hallmark of aging. Up to now, a gradual decline of mitochondrial respiration with advancing age has mainly been demonstrated in human muscle tissue. A handful of studies have examined age-related mitochondrial dysfunction in human blood cells, and only with small sample sizes and mainly in platelets. In this study, we analyzed mitochondrial respiration in peripheral blood mononuclear cells (PBMCs) and platelets from 308 individuals across the human lifespan (0–86 years). In regression analyses, with adjustment for false discovery rate (FDR), we found age-related changes in respiratory measurements to be either small or absent. The main significant changes were an age-related relative decline in complex I-linked respiration and a corresponding rise of complex II-linked respiration in PBMCs. These results add to the understanding of mitochondrial dysfunction in aging and to its possible role in immune cell and platelet senescence.

Optimization of Xenografting Methods for Generating Human Skeletal Muscle in Mice.

Xenografts of human skeletal muscle generated in mice can be used to study muscle pathology and to test drugs designed to treat myopathies and muscular dystrophies for their efficacy and specificity in human tissue. We previously developed methods to generate mature human skeletal muscles in immunocompromised mice starting with human myogenic precursor cells (hMPCs) from healthy individuals and individuals with facioscapulohumeral muscular dystrophy (FSHD). Here, we examine a series of alternative treatments at each stage in order to optimize engraftment. We show that (i) X-irradiation at 25Gy is optimal in preventing regeneration of murine muscle while supporting robust engraftment and the formation of human fibers without significant murine contamination; (ii) hMPC lines differ in their capacity to engraft; (iii) some hMPC lines yield grafts that respond better to intermittent neuromuscular electrical stimulation (iNMES) than others; (iv) some lines engraft better in male than in female mice; (v) coinjection of hMPCs with laminin, gelatin, Matrigel, or Growdex does not improve engraftment; (vi) BaCl2 is an acceptable replacement for cardiotoxin, but other snake venom preparations and toxins, including the major component of cardiotoxin, cytotoxin 5, are not; and (vii) generating grafts in both hindlimbs followed by iNMES of each limb yields more robust grafts than housing mice in cages with running wheels. Our results suggest that replacing cardiotoxin with BaCl2 and engrafting both tibialis anterior muscles generates robust grafts of adult human muscle tissue in mice.

MATHEMATICAL INVESTIGATION OF OXYGEN TRANSPORT IN INTACT MUSCLES VIS-A-VIS TISSUE METABOLISM

The human muscle tissue is an active cite with varied aerobic consumption. The supply of oxygen to the muscle cells is governed by the demand for oxygen that varies across different metabolic states of the body tissues. Most of the models designed to simulate oxygen flow in the body are based on the assumption of constant rate of oxygen consumption in muscle tissues. This generates a picture contrary to the physiological ambience where the rates vary in response to level of activity in which muscles are involved. In this context, we have taken recourse to a comparative analysis of zero-order, first-order and Michaelis-Menten oxygen consumption rate inside the muscle tissue. The model is based on the reaction-diffusion equation, and the exact solution is obtained and compared with the numerical solution using MATLAB and both are in good agreement.

Draft genome sequence of an Atlantibacter hermannii clinical strain isolated from human muscle tissue.

Atlantibacter hermannii is a species of the family Enterobacteriaceae and a rare opportunistic pathogen. The draft genome sequence of an Atlantibacter hermannii clinical strain that had been isolated from infected muscle tissue was obtained. The genome contains about 4.4 million bases and has no known plasmid replicons.

Carnosine supplementation improves delayed recall: a systematic review and meta‐analysis

AbstractBackgroundCarnosine is a histidine‐containing dipeptide found in human muscle tissue and other organs like the brain. Data in rodents and humans indicate that administration of exogenous carnosine improved cognitive performance. However, RCTs results RCTs vary.MethodsWe searched OVID Medline, Medline, EBM Reviews, Embase, and Cumulative Index to Nursing and Allied Health Literature databases from 1/1/1965 to 1/6/2022 for all RCT of carnosine and other histidine‐containing dipeptides. 2653 abstracts were screened, identifying ninety‐four full‐text articles which were assessed for eligibility. 11 articles reporting use of carnosine supplementation were meta‐analysed. The random effects model has been applied using the DerSimonian‐Laird method.ResultsCarnosine treatment significantly increased performance on Wechsler Memory Scale (WMS) ‐2 Delayed recall (Z = 3.28, p<0.01). Treatment with carnosine had no effect on Alzheimer’s Disease Assessment Scale‐Cognitive (Weighted mean difference (WMD) (95% CI) = ‐0.2 (‐1.1, 0.7), P = 0.65, I2 = 0%), Mini‐Mental State Examination (WMD (95% CI) = 0.7 (‐0.2, 1.5), P = 0.14, I2 = 42%), The Wechsler Adult Intelligence Scale (WAIS) Digit span Backward (95% CI) = 0.1 (‐0.3, 0.5), P = 0.51, I2 = 0%), WAIS digit span Forward (WMD (95% CI) = 0.0 (‐0.3, 0.4), P = 0.85, I2 = 33%) and the WMS‐1 Immediate recall (WMD (95% CI) = 0.7 (‐0.2, 1.5), P = 0.11, I2 = 0%). The effect on delayed recall remained in subgroup meta‐analysis performed on studies of patients without mild cognitive impairment (MCI), and in those without MCI where average age in the study was above 65.ConclusionsCarnosine supplementation improved scores on the Delayed recall examination, a neuropsychological test affected early in Alzheimer’s disease. Further studies are needed in people with early cognitive impairment with longer follow‐up duration and standardisation of carnosine doses to delineate the true effect.