To our knowledge, this is the first study to comprehensively characterize in vivo sublingual microvascular structure and function (endothelium-dependent and -independent) in healthy patients and those with CVD. Importantly, we used an easy-to-use handheld device that can be easily translated to clinical settings. Our results indicate that baseline microvascular impairments in structure and function can be detected using the CytoCam technology, although reactivity to acetylcholine may be maintained even during disease in the peripheral microcirculation.

The microvasculature is increasingly recognized as a major contributor to many cardiovascular diseases including atherosclerosis and heart failure with preserved ejection fraction (HFpEF). Endothelial microvascular dysfunction, the inability to vasodilate to endothelial-dependent agonists, precedes the development of large artery disease. While microvascular (dys)function can be assessed using invasive techniques (e.g., cardiac catheterization) there are limited strategies in which to assess microvascular function in a non-invasive and cost-effective manner. Recent advances in hand-held vital microscopy allow for reliable direct imaging of the sublingual microcirculation at bedside. One of the latest advancements (Cytocam, Braedius Medical) utilizes state of the art incident dark field (IDF) technology to allow for quantification of total vascular density (TVD). We therefore hypothesized an increase in TVD in response to both an endothelial-dependent, and -independent vasodilator. Cytocam-IDF was optimized to measure in vivo sublingual microvascular response to topical application of the endothelial-independent vasodilator nitroglycerin (NTG) (0.3mg) and the endothelial-dependent dilator acetylcholine (5.5 ·10-2 M). Five images were taken at baseline. Immediately following topical administration of acetylcholine, an additional 5 images were taken to compare TVD pre- and post-treatment. The area was washed and after 30 min of rest, a NTG tablet was administered sublingually and additional 5 images were obtained. Massey's microcirculation image quality score was applied, and TVD was measured using the De Backer score manual analysis by two separate investigators to account for interobserver variability, with consensus achieved. Both NTG (12.6 mm/mm2± 0.5, n=7 compared to baseline 9.9 mm/mm2± 0.42, n=7) (Mean±SEM) and acetylcholine (13.1 mm/mm2± 0.3, n=3 compared to baseline 10.4 mm/mm2± 0.5, n=3) increased TVD. These data suggest that measurement of TVD in response to endothelium-specific pharmacological agonists may allow for assessment of the human systemic microvasculature in vivo. This is a promising strategy that may allow for early detection of endothelial microvascular dysfunction prior to the onset of large artery disease or heart failure.

In Parkinson disease (PD), a complex neurodegenerative disorder that affects nearly 10 million people worldwide, motor skills are significantly impaired. However, onset and progression of motor deficits and the neural correlates of these deficits are poorly understood. We used a genetic mouse model of PD (Pink1-/-), with phenotypic similarities to human PD, to investigate the manifestation of early-onset sensorimotor deficits. We hypothesized this mouse model would show early vocalization and gross motor dysfunction that would be progressive in nature. Pink1-/- mice, compared to wild type (WT) controls, were evaluated at 2, 3, 4, 5, and 6 months of age. To quantify deficit progression, ultrasonic vocalizations and spontaneous locomotor activity (cylinder test and pole test) were analyzed. Although somewhat variable, in general, Pink1-/- mice produced significantly more simple calls with reduced intensity as well as a larger percentage of cycle calls compared to WT counterparts. However, there were no significant differences in duration, bandwidth, or peak frequency for any of the ultrasonic call types between genotypes. Pink1-/- mice showed a significant impairment in limb motor skills with fewer hindlimb steps, forelimb steps, and rears and lands in the cylinder test compared to WT. Additionally, Pink1-/- mice took significantly longer to turn and traverse during the pole test. Immunohistochemical staining showed no significant difference in the number of tyrosine hydroxylase (TH) positive cells in the substantia nigra or density of TH staining in the striatum between genotypes. These data suggest the Pink1-/- mouse model may be instrumental in defining early motor biomarkers of PD in the absence of nigrostriatal dopamine loss. Published by Elsevier B.V.