Abstract
Our objective is to determine if digital holography can be applied to monitor real-time changes in the size and motility of cardiac myocytes and non-myocytes when exposed to the sympathetic neurotransmitter, norepinephrine (NE). Neonatal rodents possess a robust capacity for heart regeneration, which depends on the proliferation of pre-existing cardiomyocytes and then subsequent migration of cardiac cells into the site of injury. Sympathetic activity and activation of adrenergic receptor (AR) signaling promote the loss of heart regenerative capacity after birth. While AR activation has been reported to restrict cardiomyocyte cell cycle activity and drive hypertrophic growth, the role of AR signaling in regulating the motility of cardiomyocytes and non-cardiomyocytes (e.g., fibroblasts) remains little understood. We hypothesize that NE, an adrenergic receptor agonist, reduces cardiac cell motility, which could play a role in limiting heart regenerative capacity. Here, we innovate the application of a commercially available digital holographic imaging microscope, the Holomonitor M4, which enables us to observe the three-dimensional cellular dynamics of cultured primary cells with minimal phototoxicity over long imaging durations.
Forts...
Mixed cardiac cultures, containing both cardiomyocytes and non-cardiomyocytes, were then imaged on the Holomonitor M4 for 24 hours, with images captured every 20 minutes at 37°C and 5% CO2. Cardiomyocytes were distinguished from non-cardiomyocytes based on their overall larger size and slower movement. Time-lapse recordings were then analyzed using the Holomonitor App Suite software to measure the optical volume dynamics (μm3) and motility (μm) of both cardiomyocytes and non-cardiomyocytes over the imaging period.
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