Biology subjects

Simmons, C. A.

Publications and source records attributed to Simmons, C. A..

17 recordsLinked to original sources

bioRxiv2026

Transcriptomic analysis of human induced pluripotent stem cell cardiomyocytes and myocardial tissue reveals novel role for miR-9-5p in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is an inherited disease characterized by the thickening of the heart muscle. Mutations in genes encoding contractile proteins, such MYBPC3 and MYH7 account for over half of patients with familial HCM. MicroRNAs (miRNAs) are pivotal regulators of gene expression that may influence disease progression. Despite their potential significance, there is a scarcity of published data on miRNAs in HCM. Induced pluripotent stem cells (iPSCs) have emerged as valuable tools for modeling various cardiovascular diseases, including HCM. However, the miRNA expression profiles associated with HCM remain largely unexplored within iPSC models. Investigating the differential expression of miRNAs in HCM patients offers a promising avenue to identify potential therapeutic targets for individuals affected by this condition. In this study, we performed an unbiased screen using a microarray (NanoString Technologies) that contained 798 miRNAs to identify differentially expressed miRNAs in iPSC-cardiomyocytes (CM) and myocardial tissues derived from healthy donors and HCM patients with MYBPC3 and MYH7 mutations, identifying miR-9-5p as significantly downregulated in all HCM iPSC-CM and myectomy tissue compared to control. KEGG pathway analysis of gene targets using miRTarBase and g:Profiler revealed that miR-9-5p regulates genes in the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor resistance pathway, which is involved in hypercontractility associated with HCM. Modulation of miR-9-5p expression in vitro using mimics significantly reduced cardiomyocyte size and contractility of MYBPC3 mutant iPSC-CMs whereas healthy control iPSC-CMs treated with antagomiRs exhibited hypertrophy. Our findings identify miR-9-5p as a regulator of cardiomyocyte hypertrophy and contractility, and suggest the miR-9-5p/EGFR tyrosine kinase inhibitor resistance axis as a potential therapeutic target to mitigate hypertrophy and hypercontractility exhibited in HCM.

molecular biology↗

bioRxiv2026

Modelling Medial Degenerative Features by Enzymatic Digestion to Evaluate Disease-Relevant Structure-Function Relationships in the Thoracic Aorta

BackgroundAortic microstructure-function relationships and the pathophysiology of how medial degeneration leads to aortic dissection remain poorly defined. We aimed to determine how degeneration of individual components of the extracellular matrix (ECM), namely elastin, collagen, and proteoglycans, influence biomechanical properties of aortic tissue through an improved, disease-motivated enzymatic digestion framework. MethodsPorcine aortic tissue was sectioned into 200 {micro}m thick samples in the media, and progressively digested with elastase or collagenase for selective degradation of these ECM components. Full thickness human aortic tissues were treated with chondroitinase, hyaluronidase, and heparinase to completely remove proteoglycans. Biomechanical characterization was performed using planar biaxial tensile testing, from which low- and high-strain modulus, transition-zone behaviour, strain-energy density, and energy loss were derived. Degree of elastin fiber degradation was analyzed using two photon excitation fluorescence imaging. Analysis of collagen degradation was performed using picrosirius red staining under brightfield and polarized light. Alcian blue staining was used to evaluate proteoglycan content. ResultsInduced fragmentation and disorganization of elastin fibers reduced low-strain load bearing capacity, evidenced by reduced low-strain modulus, strain-energy density, and transition zone stress, along with reduced energy loss. Targeted collagen disorganization similarly reduced strain-energy density and decreased strain at the onset of transition, consistent with premature collagen recruitment, and was accompanied by reductions in high strain modulus and energy loss with increasing collagen degradation. Proteoglycan removal decreased energy loss and was found to modulate low- and high-strain behaviour, including reduced strain-energy density and strain at onset of transition, and increased high strain modulus. ConclusionsThrough targeted modelling of ECM degenerative features on aortic tissue mechanics, we have identified distinct disease-associated biomechanical roles for major matrix constituents, with overlapping effects. These findings delineate mechanical consequences of component-specific matrix degeneration while underscoring the complex, multifactorial nature of structure-function relationships in aortic disease.

bioengineering↗

bioRxiv2025

Generation of Valvular Interstitial Cells from Human Pluripotent Stem Cells

Heart valves are living structures whose sophisticated functions are mediated by a specialized population of mesenchymal cells known as valvular interstitial cells (VICs). Given their central role in valve homeostasis, VICs represent a promising cell population for studying heart valve diseases and developing novel therapies to treat them. Here, we describe a strategy for generating VICs from human pluripotent stem cells (hPSCs) by stage-specific manipulation of developmental signalling pathways. Our results demonstrate that hPSC-derived VICs show a high transcriptional similarity to primary human fetal VICs and can secrete key proteins of the valve extracellular matrix. We further investigate the heterogeneity of hPSC-derived VICs and identify two major subpopulations with distinct molecular and functional properties, mirroring the cellular diversity observed in vivo. Finally, we utilize an in vitro model of Noonan syndrome to demonstrate that hPSC-derived VICs can accurately recapitulate key aspects of valve disease. Collectively, these findings provide a reproducible method for the scaled generation of bona fide hPSC-derived VICs and establish their utility in disease modelling and tissue engineering applications. Clinical PerspectiveO_ST_ABSWhat is new?C_ST_ABS- We established a robust platform to generate bona fide valvular interstitial cells (VICs) from human pluripotent stem cells (hPSCs), recapitulating native VIC identity and function. - We delineated signaling pathways that promote the development of two distinct VIC subsets and identified a surface marker to distinguish between them. What are the clinical implications?- A renewable, human-specific source of VICs enables precise mechanistic studies of valve development and disease that are not possible with limited surgical specimens or animal models. - This platform creates opportunities for therapeutic applications, including drug discovery and tissue engineering approaches for valve repair.

cell biology↗

bioRxiv2025

Biomimetic biaxial mechanical properties enhance hemodynamic performance and prevent adverse tissue remodelling in tissue-engineered heart valves

Heart valve tissue engineering holds the promise of providing an unlimited supply of heart valve replacements for patients with valvular heart disease. While tissue-engineered heart valves show promising performance in the short term, regurgitation due to fibrotic leaflet shortening remains a persistent limitation in most cases. Here we tested the hypothesis that engineering heart valves with native biaxial mechanical properties would mitigate adverse tissue remodeling in vitro. Melt electrowriting and hydrogel casting were used to generate four types of tissue-engineered heart valves with combinatorial biomimetic or non-biomimetic mechanical properties in the radial and circumferential direction of the heart valves. The heart valves were subject to pulmonary hemodynamic conditions in a pulse duplicator bioreactor, and their tissue remodelling, including cell phenotype and orientation and extracellular matrix properties, was investigated. The results showed that tissue-engineered heart valves with native mechanical properties, particularly in the radial direction, outperformed those with non-physiological mechanics in hemodynamic function, maintaining quiescent cell phenotype and cell orientation, and avoiding fibrosis. This study, for the first time, elucidates the impact of native mechanical properties on the performance of tissue- engineered heart valves and their cell and extracellular matrix homeostasis.

bioengineering↗

bioRxiv2024

Adverse structural and mechanical remodelling of main pulmonary artery in experimental pulmonary arterial hypertension is associated with impaired right ventricle-pulmonary artery coupling and function

RationaleCoupling between right ventricular function and the pulmonary vasculature determines outcomes in pulmonary arterial hypertension. The mechanics of the main pulmonary artery is an important but understudied determinant of right ventricular-pulmonary artery coupling. ObjectivesTo investigate the histology and mechanics of the pulmonary artery in relationship to right ventricular remodeling, mechanics, hemodynamics and coupling in experimental pulmonary arterial hypertension. MethodsIn a sugen+hypoxia rat model of pulmonary arterial hypertension, right ventricular hemodynamics were assessed by conductance catheters. Active tension-strain curves were generated using echocardiography. Main pulmonary artery and right ventricle free-wall were harvested to determine their macro- and micro-structure, composition, and mechanical properties. Comprehensive multivariate analyses elucidated relationships between pulmonary artery and right ventricle mechanics, structure and coupling. Measurements and Main ResultsPulmonary hypertensive main pulmonary arteries developed fibrosis relative to healthy controls, as did right ventricles, which also hypertrophied, with re-orientation of muscle fibres toward a tri-layer architecture reminiscent of normal left ventricular architecture. Increased glycosaminoglycan deposition and increased collagen-to-elastin ratio in the pulmonary artery; and increased collagen, as well as hypertrophy and reorganization of myofibers in the right ventricle, led to increased stiffness. This increase in stiffness was more pronounced in the longitudinal direction in the high- and low-strain regime for the pulmonary artery and right ventricle, respectively, causing increased mechanical anisotropy. Main pulmonary artery stiffening correlated significantly with right ventricular tissue mechanical remodelling and reduced systolic performance, cardiac output and right ventricle-pulmonary artery coupling. ConclusionsCompositional, structural, and mechanical changes in the main pulmonary artery correlate with adverse right ventricular remodeling, mechanics, function and coupling in pulmonary arterial hypertension. Therefore, increasing mechanical compliance of the large pulmonary arteries may be an important and novel therapeutic strategy for mitigating right ventricular failure.

physiology↗

bioRxiv2023

A microfluidic platform with integrated porous membrane cell-substrate impedance spectroscopy (PM-ECIS) for biological barrier assessment

Traditionally, biological barriers are assessed in vitro by measuring trans-endothelial/epithelial electrical resistance (TEER) across a monolayer using handheld chopstick electrodes. Implementation of TEER into organ-on-chip (OOC) setups is a challenge however, due to non-uniform current distribution and interference from biomaterials typically found in such systems. In this work, we address the pitfalls of standard TEER measurement through the application of porous membrane electrical cell-substrate impedance sensing (PM-ECIS) to an OOC setup. Gold leaf electrodes (working electrode diameters = 250, 500, 750 {micro}m) were incorporated onto porous membranes and combined with biocompatible tape to assemble microfluidic devices. PM-ECIS resistance at 4 kHz was not influenced by presence of collagen hydrogel in bottom channels, compared to TEER measurements in same devices, which showed a difference of 1723 {+/-} 381.8 {Omega} (p=0.006) between control and hydrogel conditions. A proof of concept, multi-day co-culture model of the blood-brain barrier was also demonstrated in these devices. PM-ECIS measurements were robust to fluid shear (5 dyn/cm2) in cell-free devices, yet were highly sensitive to flow-induced changes in an endothelial barrier model. Initiation of perfusion (0.06 dyn/cm2) in HUVEC-seeded devices corresponded to significant decreases in impedance at 40 kHz (p<0.01 for 750 and 500 {micro}m electrodes) and resistance at 4 kHz (p<0.05 for all electrode sizes) relative to static control cultures, with minimum values reached at 6.5 to 9.5 hours after induction of flow. Our microfluidic PM-ECIS platform enables sensitive, non-invasive, real-time measurements of barrier function in setups integrating critical OOC features like 3D co-culture, biomaterials and shear stress.

bioengineering↗

bioRxiv2023

Characterization of pediatric porcine pulmonary valves as a model for tissue engineered heart valves

Heart valve tissue engineering holds the potential to transform the surgical management of congenital heart defects affecting the pediatric pulmonary valve (PV) by offering a viable valve replacement with the compositional, architectural and mechanical properties required to function in situ. While aiming to recapitulate the native valve, the minimum requirement for tissue engineered heart valves (TEHVs) has historically been adequate mechanical function at implantation. However, long-term in situ functionality of TEHVs remains elusive, suggesting that a closer approximation of the native valve is required. The realization of biomimetic engineered pediatric PV is impeded by insufficient characterization of healthy pediatric tissue. In this study, we comprehensively characterized the planar biaxial tensile behaviour, extracellular matrix (ECM) composition and organization, and valvular interstitial cell (VIC) phenotypes of PVs from piglets to provide benchmarks for TEHVs. The piglet PV possessed an anisotropic and non-linear tension-strain profile from which material constants for a predictive constitutive model were derived. Further, the ECM of the pediatric PV possessed a trilayer organization populated by collagen, glycosaminoglycans, and elastin. Biochemical quantification of ECM proteins normalized to wet weight and DNA content of PV tissue revealed homogenous distribution of proteins across sampled regions of the leaflet. Finally, the predominant phenotype of VICs in the piglet PV was quiescent vimentin-expressing fibroblasts, with a small proportion of activated -smooth muscle actin-expressing myofibroblasts residing primarily at the base of the leaflet. Overall, the properties characterized in this study can be used to inform TEHV design parameters towards generation of biomimetic pediatric PVs. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=80 SRC="FIGDIR/small/553926v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@bff7d2org.highwire.dtl.DTLVardef@1272b90org.highwire.dtl.DTLVardef@9d1b54org.highwire.dtl.DTLVardef@6d3a93_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2023

EHMT2/G9a-Inhibition Reprograms Cancer-Associated Fibroblasts (CAFs) to a More Differentiated, Less Proliferative and Invasive State

Cancer-associated fibroblasts (CAFs) have previously been shown to play a pivotal role in multiple cancer dynamics, including mediating tumor cell invasion: their pro-invasive secretory profile and ability to remodel the extracellular matrix (ECM) architecture particularly promote tumor progression through tumor cell invasion into surrounding tissue areas and beyond. Given that reduced CAF abundance in tumors correlates with improved outcomes in various cancers, we set out to identify epigenetic targets involved in CAF activation in the tumor-stromal margin to reduce overall tumor aggressiveness. Using the GLAnCE (Gels for Live Analysis of Compartmentalized Environments) co-culture platform, we performed an image-based, phenotypic screen and identified EHMT2 (also known as G9a), an epigenetic enzyme that targets the methylation of histone 3 lysine 9 (H3K9), as the most potent modulator of CAF abundance and CAF-mediated tumor cell invasion. Transcriptomic and functional analysis of EHMT2-inhibited CAFs revealed the involvement of EHMT2 in driving CAFs towards a pro-invasive phenotype. Further, EHMT2 signaling mediated CAF hyperproliferation, a feature that is typically associated with activated fibroblasts present in tumors, but the molecular basis for which has not thus far been identified. This study suggests a role for EHMT2 as a regulator of CAF hyperproliferation within the tumor mass, which in turn magnifies CAF-induced pro-invasive effects on tumor cells.

cancer biology↗

bioRxiv2023

Sensitivity and validation of porous membrane electrical cell substrate impedance spectroscopy (PM-ECIS) for measuring endothelial barrier properties

Conventional trans-endothelial electrical resistance (TEER) setups are invasive and cannot directly measure monolayer integrity in co-culture. These limitations are addressed by porous membrane electrical cell-substrate impedance sensing (PM-ECIS), which measures barrier integrity in cell monolayers grown directly on permeable membranes patterned with electrodes. Here we advance the design and utility of PM-ECIS by investigating its sensitivity to working electrode size and correlation to TEER. Gold electrodes were fabricated on porous membrane inserts using hot embossing and UV lithography, with working electrode diameters of 250, 500, and 750 {micro}m within the same insert. Frequency scans of confluent primary endothelial monolayers showed normalized resistance peaking at 4 kHz, consistent with traditional solid substrate ECIS. Sensitivity to resistance changes (4 kHz) during endothelial barrier formation was inversely proportional to electrode size, with the smallest electrodes being the most sensitive (p<0.001). Similarly, smaller electrodes were most sensitive to changes in impedance (40 kHz) corresponding to cell spreading and proliferation (p<0.001). Barrier disruption with EGTA was detectable by 250 and 750 {micro}m (p<0.01), and 500 {micro}m electrodes (p=0.058). Resistances measured by PM-ECIS vs. TEER for sodium chloride solutions were positively and significantly correlated for all electrode sizes (r>0.9; p<0.0001), but only with 750 {micro}m electrodes for endothelial monolayers (r=0.71; p=0.058). These data inform design and selection of PM-ECIS electrodes for specific applications, and support PM-ECIS as a promising alternative to conventional TEER due to its capacity for direct, non-invasive, and real-time assessment of cells cultured on porous membranes.

bioengineering↗

bioRxiv2023

Porous membrane electrical cell-substrate impedance spectroscopy for versatile assessment of biological barriers in vitro

Cell culture models of endothelial and epithelial barriers typically use porous membrane inserts (e.g., Transwell inserts) as a permeable substrate on which barrier cells are grown, often in co-culture with other cell types on the opposite side of the membrane. Current methods to characterize barrier function in porous membrane inserts can disrupt the barrier or provide bulk measurements that cannot isolate barrier cell resistance alone. Electrical cell-substrate impedance sensing (ECIS) addresses these limitations but its implementation on porous membrane inserts has been limited by costly manufacturing and low sensitivity. Here we present porous membrane ECIS (PM-ECIS), a cost-effective method to adapt ECIS technology to porous substrate-based in vitro models. We demonstrate high fidelity patterning of electrodes on porous membranes that can be incorporated into well plates of a variety of sizes with excellent cell biocompatibility with mono- and co-culture set ups. PM-ECIS provided sensitive, real-time measurement of isolated changes in endothelial cell barrier impedance with cell growth and barrier disruption. Barrier function characterized by PM-ECIS resistance correlated well with permeability coefficients obtained from molecular tracer permeability assays performed on the same cultures, validating the device. Integration of ECIS into conventional porous cell culture inserts provides a versatile, sensitive, and automated alternative to current methods to measure barrier function in vitro, including molecular tracer assays and transepithelial/endothelial electrical resistance (TEER).

bioengineering↗

bioRxiv2023

Myosin inhibitor reverses hypertrophic cardiomyopathy in pediatric iPSC-cardiomyocytes to mirror variant correction

Hypertrophic cardiomyopathy (HCM) is mainly caused by sarcomere gene variants in MYH7 and MYBPC3. Targeted drugs like myosin ATPase inhibitors have shown efficacy in adult HCM but have not been evaluated in children. We generated iPSC-cardiomyocytes (CMs) from four children with HCM harboring variants in MYH7 (V606M; R453C) or MYBPC3 (G148R; P955fs and TNNI3_A157P), variant-corrected controls, and a healthy individual. All CMs showed hypertrophy and sarcomere disorganization. All 3 single variant CMs showed higher contractility, slower relaxation, higher calcium transients and higher ATPase activity. Only MYH7 variant CMs showed stronger myosin-actinin binding. Targeted myosin ATPase inhibitor showed complete rescue of the phenotype in affected CMs and in cardiac Biowires to mirror isogenic controls. The response was stronger compared to verapamil or metoprolol, highlighting the need for clinical trials of myosin targeted therapy in pediatric HCM patients. The phenotype and response to drug therapy are influenced by the underlying genotype.

genetics↗

bioRxiv2022

Advanced physiological maturation of iPSC-derived human cardiomyocytes using an algorithm-directed optimization of defined media components

Induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) hold tremendous promise for in vitro modeling to assess native myocardial function and disease mechanisms as well as testing drug safety and efficacy. However, current iPSC- CMs are functionally immature, resembling in vivo CMs of fetal or neonatal developmental states. The use of targeted culture media and organoid formats have been identified as potential high-yield contributors to improve CM maturation. This study presents a novel iPSC-CM maturation medium formulation, designed using a differential evolutionary approach targeting metabolic functionality for iterative optimization. Relative to gold-standard reference formulations, our medium significantly matured morphology, Ca2+ handling, electrophysiology, and metabolism, which was further validated by multiomic screening, for cells in either pure or co-cultured microtissue formats. Together, these findings not only provide a reliable workflow for highly functional iPSC-CMs for downstream use, but also demonstrate the power of high-dimensional optimization processes in evoking advanced biological function in vitro.

bioengineering↗

bioRxiv2022

High-frequency quantitative ultrasound to assess the acoustic properties of engineeredtissues in vitro

Acoustic properties of biomaterials and engineered tissues reflect their structure and cellularity. High-frequency ultrasound (US) can non-invasively characterize and monitor these properties with sub-millimetre resolution. We present an approach to estimate the acoustic properties of cell-laden hydrogels that accounts for frequency-dependent effects of attenuation in coupling media, hydrogel thickness, and interfacial transmission/reflection coefficients of US waves, all of which can bias attenuation estimates. Cell-seeded fibrin hydrogel disks were raster-scanned using a 40 MHz US transducer. Thickness, speed of sound, acoustic impedance, and acoustic attenuation coefficients were determined from the difference in the time-of-flight and ratios of the magnitudes of US signals, interfacial transmission/reflection coefficients, and acoustic properties of the coupling media. With this approach, hydrogel thickness was accurately measured by US, with excellent agreement to confocal microscopy (r2 = 0.97). Accurate thickness measurement enabled acoustic property measurements that were independent of hydrogel thickness, despite up to 60% reduction in thickness due to cell-mediated contraction. Notably, acoustic attenuation coefficients increased with increasing cell concentration (p<0.001), reflecting hydrogel cellularity independent of contracted hydrogel thickness. This approach enables accurate measurement of the intrinsic acoustic properties of biomaterials and engineered tissues to provide new insights into their structure and cellularity.

bioengineering↗

bioRxiv2022

Non-invasive quantification of contractile dynamics in cardiac cells, spheroids and organs-on-a-chip using high frequency ultrasound

Cell-based models that mimic in vivo heart physiology are poised to make significant advances in cardiac disease modeling and drug discovery. In these systems, cardiomyocyte (CM) contractility is an important functional metric, but current measurement methods are inaccurate, low-throughput, or require complex set-ups. To address this need, we developed a standalone non-invasive, label-free ultrasound technique operating at 40-200 MHz to measure the beat rate, beat rhythm, and force of contraction of cardiac models, ranging from single adult CMs to 3D microtissue constructs in standard cell culture formats. The high temporal resolution of 1000 fps resolved the beat profile of single mouse CMs paced at up to 9 Hz, revealing limitations of lower speed optical based measurements to resolve beat kinetics or characterize aberrant beats. Coupling of ultrasound with traction force microscopy enabled the measurement of CM longitudinal modulus and facile estimation of adult mouse CM contractile forces of 2.34 {+/-} 1.40 N, comparable to more complex measurement techniques. Similarly, measurements of beat rate, rhythm, and drug responses of CM spheroid and microtissue models were demonstrated. In conclusion, ultrasound can be used for the rapid characterization of CM contractile function in a wide range of commonly-studied configurations ranging from single cells to 3D tissue constructs using standard well plates, with applications in cardiac drug discovery and cardiotoxicity evaluation.

bioengineering↗

bioRxiv2021

Vascular tropism models of blood-borne microbial dissemination

Similar to circulating tumour and immune cells, many blood-borne microbes preferentially "home" to specific vascular sites and tissues during hematogenous dissemination 1-5. For many pathogens, the "postal codes" and mechanisms responsible for tissue-specific vascular tropism are unknown and have been challenging to unravel. Members of the Lyme disease Borreliella burgdorferi species complex infect a broad range of mammalian tissues and exhibit complex strain-, species- and host-specific tissue tropism patterns. Intravenous perfusion experiments and intravital microscopy studies suggest that heterogeneous tissue tropism properties may depend on tissue-specific differences in host and microbial molecules supporting vascular interaction and extravasation. However, interpreting these studies can be complicated because of the immune-protective moonlighting (multitasking) properties of many B. burgdorferi adhesins. Here, we investigated whether B. burgdorferi vascular interaction properties measured by live cell imaging and particle tracking in aorta, bladder, brain, joint and skin microvascular flow chamber models predict strain- and tissue-specific dissemination patterns in vivo These studies identified strain- and endothelial cell type-specific interaction properties that accurately predicted in vivo dissemination of B. burgdorferi to bladder, brain, joint and skin but not aorta, and indicated that dissemination mechanisms in all of these tissues are distinct. Thus, the ability to interact with vascular surfaces under physiological shear stress is a key determinant of tissue-specific tropism for Lyme disease bacteria. The methods and model systems reported here will be invaluable for identifying and characterizing the diverse, largely undefined molecules and mechanisms supporting dissemination of Lyme disease bacteria. These methods and models may be useful for studying tissue tropism and vascular dissemination mechanisms of other blood-borne microbes.

microbiology↗

bioRxiv2020

Combinatorial Screen of Dynamic Mechanical Stimuli for Predictive Control of MSC Mechano-Responsiveness

Mechanobiological-based control of mesenchymal stromal cells (MSCs) to aid in the engineering and regeneration of load-bearing tissues requires systematic investigations of specific dynamic mechanical stimulation protocols. Using deformable membrane microdevice arrays paired with combinatorial experimental design and modeling, we systematically probed the individual and integrative effects of mechanical stimulation parameters (strain magnitude (STRAIN), rate at which strain is changed (RATE) and duty period (DUTY)) on myofibrogenesis and matrix production of MSCs in 3D hydrogels. These functions were found to be dominantly influenced by a novel and higher-order interactive effect between STRAIN and DUTY. Empirical models based on our combinatorial cue-response data predicted an optimal loading regime in which STRAIN and DUTY were increased synchronously over time, which was validated to most effectively promote MSC matrix production. These findings inform the design of loading regimes for MSC-based engineered tissues and validate a broadly applicable approach to probe multifactorial regulating effects of microenvironmental and mechanobiological cues.

bioengineering↗

bioRxiv2019

Long-term functional culture and in vitro manipulation of adult mouse cardiomyocytes

Primary adult cardiomyocyte (aCM) culture is challenged by poor survival and loss of phenotype, rendering extended in vitro experiments unfeasible. Here, we establish murine aCM culture methods that enhance survival and maintain sarcomeric structure and Ca2+ cycling to enable physiologically-relevant contractile force measurements. We also demonstrate genetic and small-molecule manipulations that probe mechanisms underlying myocyte functional performance.

cell biology↗