Biology subjects

D'Hulst, G.

Publications and source records attributed to D'Hulst, G..

4 recordsLinked to original sources

bioRxiv2026

Stimulatrix: An open-source automated platform for high-throughput functional characterization of engineered contractile tissues

Engineered cardiac and skeletal muscle tissues suspended between flexible posts support disease modeling and pharmacology, yet their stimulation, longitudinal imaging and quantitative analysis often remain fragmented and labor-intensive. Here we present Stimulatrix, an open-source platform integrating automated video acquisition within a cell culture incubator, synchronized electrical stimulation and deep learning for longitudinal assessment of contractile tissues in multiwell plates. The platform quantifies tissue compaction, force generation and contraction kinetics with optional cloud processing reducing dependence on local GPU hardware. We demonstrate the workflow in cardiac tissues comprising human induced pluripotent stem cell-derived cardiomyocytes and cardiac fibroblasts, and in primary human skeletal muscle constructs. Force and kinetic measurements were benchmarked against manual annotations. Longitudinal profiling resolved responses to matrix composition and pacing regimens and tracked doxorubicin-associated loss of cardiac contractile force. Stimulatrix provides an accessible workflow for automated functional phenotyping of engineered muscle tissues.

bioengineering↗

bioRxiv2023

Physiological Profiles of Male and Female CrossFit Athletes

ObjectiveTo 1) establish extensive physiological profiles of highly-trained CrossFit athletes using gold-standard tests and 2) investigate which physiological markers best correlate with CrossFit(R) Open performance. MethodsThis study encompassed sixty participants (30 males and 30 females), all within the top 5% of the CrossFit(R) Open, including 7 CrossFit(R) Semi-finalists and 3 Games finalists. Isokinetic dynamometers were employed to measure maximum isometric and isokinetic leg and trunk strength. Countermovement jump height and maximum isometric mid-thigh pull strength were assessed on a force plate. V{square}O2peak was measured by a cardiopulmonary exercise test, while critical power and W were evaluated during a 3-minute all-out test, both on a cycle ergometer. ResultsMale and female athletes median (IQR) V{square}O2peak was 4.64 (4.43, 4.80) and 3.21 (3.10, 3.29) (L{middle dot}min-1), critical power 314.5 (285.9, 343.6) and 221.3 (200.9, 238.9) (W) and mid-thigh pull 3158 (2690, 3462) and 2035 (1728, 2347) (N). Linear regression analysis shows strong evidence for associations between different anthropometric variables and CrossFit(R) Open performance in men and women, whereas for markers of cardiorespiratory fitness such as V{square}O2peak this was only true for women but not men. Conventional laboratory evaluations of strength, however, manifest minimal evidence for associations with Open performance across both sexes. ConclusionsThis study provides the first detailed insights into the physiology of high-performing CrossFit(R) athletes and informs training optimization. Further the results emphasize the advantage of athletes with shorter limbs and suggests potential modifications to Open workout designs to level the playing field for athletes across different anthropometrics characteristics.

physiology↗

bioRxiv2020

Exercise promotes satellite cell contribution to myofibers in a load-dependent manner

Satellite cells (SCs) are required for muscle repair following injury and are involved in muscle remodeling upon muscular contractions. Exercise stimulates SC accumulation and myonuclear accretion. To what extent exercise training at different mechanical loads drive SC contribution to myonuclei however is unknown. By performing SC fate tracing experiments, we show that 8-weeks of voluntary wheel running increased SC contribution to myonuclei in mouse plantar flexor muscles in a load-dependent but fiber type-independent manner. Increased SC fusion however was not exclusively linked to muscle hypertrophy as wheel running without external load substantially increased SC fusion in the absence of fiber hypertrophy. Due to nuclear propagation, nuclear fluorescent fate tracing mouse models were inadequate to quantify SC contribution to myonuclei. Ultimately, by performing fate tracing at the DNA level, we show that SC contribution mirrors myonuclear accretion during exercise. Collectively, these findings provide direct evidence that mechanical load during exercise independently promotes SC contribution to existing myofibers.

cell biology↗

bioRxiv2019

Hallmarks of frailty and osteosarcopenia in prematurely aged PolgAD257A/D257A mice: a preclinical model to test anabolic interventions

BackgroundFrailty is a geriatric syndrome characterized by increased susceptibility to adverse health outcomes. One major determinant thereof is the gradual weakening of the musculoskeletal system and the associated osteosarcopenia. To improve our understanding of the underlying pathophysiology and, more importantly, to test potential interventions aimed at counteracting frailty suitable animal models are needed. MethodsTo evaluate the relevance of prematurely aged PolgA(D257A/D257A) mice as a model for frailty and osteosarcopenia, we quantified the clinical mouse frailty index in PolgA(D257A/D257A) and wild type littermates (PolgA(+/+), WT) with age and concertedly assessed the quantity and quality of bone and muscle tissue. Lastly, the anabolic responsiveness of skeletal muscle, muscle progenitors and bone was assessed. ResultsPolgA(D257A/D257A) accumulated health deficits at a higher rate compared to WT, resulting in a higher frailty index at 40 and 46 weeks of age (+166%, +278%, p<0.0001), respectively, with no differences between genotypes at 34 weeks. Concomitantly, PolgA(D257A/D257A) displayed progressive musculoskeletal deterioration such as reduced bone and muscle mass as well as impaired functionality thereof. In addition to lower muscle weights (-14%, p<0.05, -23%, p<0.0001) and fiber area (-20%, p<0.05, -22%, p<0.0001) at 40 and 46 weeks, respectively, PolgA(D257A/D257A) showed impairments in grip-strength and concentric muscle forces (p<0.05). PolgA(D257A/D257A) mutation altered the acute response to various anabolic stimuli in skeletal muscle and muscle progenitors. While PolgA(D257A/D257A) muscles were hypersensitive to eccentric contractions as well as leucine administration, shown by larger downstream signaling response of the mechanistic target of rapamycin complex 1 (mTORC1), myogenic progenitors cultured in vitro showed severe anabolic resistance to leucine and robust impairments in cell proliferation. Longitudinal micro-CT analysis of the 6th caudal vertebrae showed that PolgA(D257A/D257A) had lower bone morphometric parameters (e.g. bone volume fraction, trabecular and cortical thickness, p<0.05) as well as reduced remodeling activities (e.g. bone formation and resorption rate, p<0.05) compared to WT. When subjected to 4 weeks of cyclic loading, young but not aged PolgA(D257A/D257A) caudal vertebrae showed load-induced bone adaptation suggesting reduced mechanosensitivity with age. ConclusionsPolgA(D257A/D257A) mutation leads to hallmarks of age-related frailty and osteosarcopenia and provides a powerful model to better understand the relationship between frailty and the aging musculoskeletal system.

physiology↗