In vitro simulation of cellular exercise environments: advancements in methodology and signal simulation

Abstract

BACKGROUND: With an increasing understanding of the health benefits of exercise, research on the mechanisms of exercise intervention has become a focal point. Traditional studies rely on in vivo animal models or multi-omics techniques to indirectly infer exercise intervention mechanisms, but the research is not in-depth enough, and many disease models cannot achieve the prescribed exercise intensity. Therefore, in vitro cell-based exercise environment simulation techniques are of particular significance. Existing technologies primarily focus on the replication of single signals, failing to comprehensively simulate the interaction of multi-dimensional signals during exercise, which limits the understanding of exercise adaptation mechanisms. OBJECTIVE: To explore the technological advancements in in vitro cell-based exercise environment simulation, analyze the advantages of existing signal simulation techniques, and propose a new framework integrating multi-dimensional signals to promote the precise replication of exercise mechanisms and application research in related fields. METHODS: This study conducted a search in the PubMed and Web of Science databases using keywords such as Exercise, Physiology, Molecular Signals, Myokines, Exerkines, etc. After initial screening and removal of duplicates, 5,046 relevant articles were identified, and 99 were finally included after further screening. RESULTS AND CONCLUSION: Existing in vitro cell exercise simulation techniques have made some progress in simulating specific attributes of exercise (e.g., mechanical stretching, electrical signals), but they still fail to fully replicate the multi-dimensional signal interactions during exercise. By integrating multiple signals such as mechanical forces, electrophysiological stimuli, and biological factors, future simulation technologies are expected to more realistically reproduce the effects of exercise on cellular metabolism, gene expression, and phenotypic remodeling, providing a more precise experimental platform for studying exercise mechanisms. Furthermore, innovations and optimizations in in vitro exercise simulation technologies will provide important support for sports medicine, drug development, and regenerative medicine.

1. Introduction

With the deepening understanding of exercise physiology and mechanics, it has become increasingly recognized that exercise training not only shapes the body's appearance and enhances function but also triggers complex and dynamic signal remodeling at the cellular level. These signals involve changes in mechanical stretch, shear stress, electrical activity, and biological factors [1-2]. For instance, muscles and the cardiovascular system undergo cyclic mechanical stretching during exercise, local tissues experience shear stress and oxygen partial pressure fluctuations due to blood flow, neuromuscular excitation is accompanied by rhythmic action potentials and electrical signals, and endocrine glands and the immune system release myokines, tumor necrosis factor, and metabolic factors into the blood, forming a unique humoral environment [3-5]. These physical, chemical, and electrophysiological factors collectively constitute the exercise microenvironment, which determines cellular metabolic regulation, gene expression, and tissue remodeling. However, most current research relies on in vivo models or multi-omics techniques (e.g., single-cell sequencing, spatial transcriptomics) to indirectly infer exercise intervention mechanisms, making it difficult to directly study the physiological mechanisms during exercise. Therefore, precisely simulating the in vivo exercise microenvironment for in vitro cellular intervention is a key focus for future research.

In cell biology research, investigators often face the challenge of how to simulate exercise intervention mechanisms in in vitro cell models. For some fragile animal models, such as tumor-bearing mice, the physiological state may limit their ability to complete prescribed exercise intervention protocols. Additionally, observing the physiological and biochemical changes induced by exercise intervention in in vitro cells poses technical difficulties, as it is challenging to effectively simulate cellular responses to exercise stimuli and the corresponding metabolic and physiological reactions in the absence of exercise conditions. Consequently, researchers have attempted to use special methods to confer certain exercise attributes to cells, reproducing mechanical, electrical, and biochemical stimuli in vitro. For example, different uniaxial tensile strains and loading frequencies have been applied to cells encapsulated in three-dimensional collagen scaffolds [6]; electrode arrays generate electrical pulses mimicking action potentials; microfluidics regulate shear stress and oxygen concentration [7]; and even multiple organs can be coupled with real-time sensors [8]. Such 'exercise-on-a-chip' systems not only provide credible models for basic research but also offer new technological platforms for drug screening, regenerative medicine, and personalized exercise interventions. Furthermore, given the important role of biochemical signals and cytokines produced during exercise in regulating cellular behavior, an increasing number of studies employ synthetic exercise mimetics, exercise-conditioned serum, exosomes, and other bioactive factors to dynamically replicate the molecular signatures of exercise in vitro.