Biology subjects

McCain, M. L.

Publications and source records attributed to McCain, M. L..

3 recordsLinked to original sources

bioRxiv2026

Human iPSC-Derived Cardiomyocytes Maladaptively Remodel to Cyclic Stretch in Hypoplastic Left Heart Syndrome

Background: Hypoplastic Left Heart Syndrome (HLHS) is a severe congenital heart defect characterized by underdevelopment of left-sided cardiac structures, requiring staged surgical palliation that establishes the right ventricle as the single ventricle maintaining systemic circulation. After surgery, patients remain highly susceptible to heart failure, possibly due to the increased hemodynamic load imposed on the single surviving ventricle. Because the etiology of HLHS remains poorly understood, elucidating the mechanisms that drive ventricular dysfunction requires model systems that capture both patient-specific genetics and the dynamic mechanical environment of the ventricle. Thus, our objective was to compare how induced pluripotent stem cell (iPSC)-derived cardiomyocytes (iPSC-CMs) from patients with HLHS differ from control in static culture and in response to cyclic stretch. Methods: Control iPSCs from two unaffected donors and iPSCs from four HLHS patients were differentiated into iPSC-CMs, engineered into aligned tissues, and cultured statically or exposed to cyclic 20% uniaxial stretch at 1 Hz for 48h. Sarcomere organization was quantified in static tissues using images of immunostained -actinin. Calcium transients at 1 Hz pacing frequency in static and stretched tissues were evaluated using Fluo-4 calcium indicator dye. Bulk RNA sequencing was performed to evaluate stretch-induced transcriptomic changes in control and HLHS iPSC-CMs. Results: In static culture, HLHS iPSC-CMs had modest defects in sarcomere organization and calcium transient morphology compared to control. In response to cyclic stretch, control iPSC-CMs exhibited calcium transients with quicker rise time, a response observed in only one of four lines of HLHS iPSC-CMs. Transcriptomic analysis revealed that all four lines of HLHS iPSC-CMs failed to upregulate calcium handling and sarcomere-associated genes in response to stretch, unlike control iPSC-CMs. Stretch also induced HLHS iPSC-CMs to exhibit pronounced activation of inflammatory signaling pathways, a response not observed in control iPSC-CMs. Conclusions: iPSC-CMs from HLHS patients demonstrate aberrant responses to cyclic stretch, including blunted adaptation of calcium transients and heightened inflammatory signaling. These findings implicate defective mechanoadaptation as a potential contributor to single ventricle failure and identify potential candidate biomarkers and new opportunities for therapeutic interventions for HLHS patients.

physiology↗

bioRxiv2024

Human iPSC-derived motor neuron innervation enhances the differentiation of muscle bundles engineered with benchtop fabrication techniques

Engineered skeletal muscle tissues are critical tools for disease modeling, drug screening, and regenerative medicine, but are limited by insufficient maturation. Because innervation is a critical regulator of skeletal muscle development and regeneration in vivo, motor neurons are hypothesized to improve the maturity of engineered skeletal muscle tissues. Although motor neurons have been added to pre-engineered muscle constructs, the impact of motor neurons added prior to the onset of muscle differentiation has not been evaluated. In this study, benchtop fabrication equipment was used to facilely fabricate chambers for engineering 3-dimensional (3-D) skeletal muscles bundles and measuring their contractile performance. Primary chick myoblasts were embedded in an extracellular matrix hydrogel solution and differentiated into engineered muscle bundles, with or without the addition of human induced pluripotent stem cell (hiPSC)-derived motor neurons. Muscle bundles differentiated with motor neurons had neurites distributed throughout their volume and a higher myogenic index compared to muscle bundles without motor neurons. Innervated muscle bundles also generated significantly higher twitch and tetanus forces in response to electrical field stimulation after one and two weeks of differentiation compared to non-innervated muscle bundles cultured with or without neurotrophic factors. Non-innervated muscle bundles also experienced a decline in rise and fall times as the culture progressed, whereas innervated muscle bundles and non-innervated muscle bundles with neurotrophic factors maintained more consistent rise and fall times. Innervated muscle bundles also expressed the highest levels of the genes for slow myosin light chain 3 (MYL3) and myoglobin (MB), which are associated with slow twitch fibers. These data suggest that motor neuron innervation enhances the structural and functional development of engineered skeletal muscle constructs and maintains them in a more oxidative phenotype.

bioengineering↗

bioRxiv2024

Identification of Disease-relevant, Sex-based Proteomic Differences in iPSC-derived Vascular Smooth Muscle

The prevalence of cardiovascular disease varies with sex, and the impact of intrinsic sex-based differences on vasculature is not well understood. Animal models can provide important insight into some aspects of human biology, however not all discoveries in animal systems translate well to humans. To explore the impact of chromosomal sex on proteomic phenotypes, we used iPSC-derived vascular smooth muscle cells from healthy donors of both sexes to identify sex-based proteomic differences and their possible effects on cardiovascular pathophysiology. Our analysis confirmed that differentiated cells have a proteomic profile more similar to healthy primary aortic smooth muscle than iPSCs. We also identified sex-based differences in iPSC- derived vascular smooth muscle in pathways related to ATP binding, glycogen metabolic process, and cadherin binding as well as multiple proteins relevant to cardiovascular pathophysiology and disease. Additionally, we explored the role of autosomal and sex chromosomes in protein regulation, identifying that proteins on autosomal chromosomes also show sex-based regulation that may affect the protein expression of proteins from autosomal chromosomes. This work supports the biological relevance of iPSC-derived vascular smooth muscle cells as a model for disease, and further exploration of the pathways identified here can lead to the discovery of sex-specific pharmacological targets for cardiovascular disease. SignificanceIn this work, we have differentiated 4 male and 4 female iPSC lines into vascular smooth muscle cells, giving us the ability to identify statistically-significant sex-specific proteomic markers that are relevant to cardiovascular disease risk (such as PCK2, MTOR, IGFBP2, PTGR2, and SULTE1).

molecular biology↗