Non-Invasive Visualization of Nailbed Microvascular Morphology in Mice Using Capillaroscopy

Imaging microcapillary networks of the skin in humans using nailfold capillaroscopy (NFC) has underscored the importance of microcirculation as a target organ system in critical systemic illnesses. Nailfold capillaroscopy is applied clinically to detect peripheral microvascular dysfunction and abnormalities in a range of systemic conditions, including rheumatic, cardiac, ocular (e.g., glaucoma), and endocrine disorders (e.g., hypertension and diabetes mellitus). NFC is useful not only in detecting peripheral systemic microvasculature disruption but also in assessing drug efficacy. However, translating clinical NFC findings to animal disease models can be challenging. Detecting microvascular dysfunction or abnormalities in animals is often invasive (e.g., endoscopic), carried out ex vivo (e.g., post-mortem imaging of tissues), or expensive, requiring specialized equipment such as those used in microcomputed tomography and photoacoustic imaging techniques. Developing quick, non-invasive, and inexpensive techniques to image peripheral microvasculature in animal models of disease is warranted to decrease research expenses and increase translatability to the clinic. Capillaroscopy has previously been used to visualize the nailfold microvasculature in animal models, including in guinea pigs and mice, thus demonstrating the capability of capillaroscopy as a non-invasive imaging tool in animal models. This study provides a protocol that applies capillaroscopy to a mouse nailbed, allowing researchers to easily and inexpensively assess the morphology of its microvasculature. Representative images of typical nailbed microvascular architecture in wild-type mice using two commonly used laboratory strains, SV129/S6 and C57/B6J, are provided. Further studies using this method are essential for applying nailbed capillaroscopy to a wide range of mouse disease models with peripheral microvascular abnormalities.