The NBL-6 cell line was initiated from the dermis of a 4-year-old female horse (Equus caballus; quarterhorse strain). NBL-6 cells demonstrate susceptibility to many viruses, including reovirus 3, herpes simplex, vesicular stomatitis (Ogden strain), and vaccinia.

The cells are known to be resistant to coxsackieviruses A9 and B5, adenovirus 5, and poliovirus 2. Though utilized in a wide array of research and for equine vaccine production, the NBL-6 line is especially notable for its usage in investigations of equine viral arteritis (EVA), a contagious disease that is thought to be increasingly affecting populations of horses in many countries.

The dermis is a dense layer of connective tissue derived from the mesoderm that is located directly beneath the epidermis. A variety of cell types are found in the dermis, but fibroblasts are the most dominant kind of cell in the tissue. The dermis is essentially divided into two distinct regions. The upper region, called the papillary layer, consists of loosely packed collagen and elastic fibers and contains many capillary loops, which are involved in regulating the temperature of the body and nourishing the cells of the epidermis. The deeper region, termed the reticular layer, is characterized by a thick network of collagen fibers. Mechanoreceptors, sebaceous glands, hair follicles, and sweat glands are resident in the reticular layer of the dermis.

Golgi bodies in a culture of horse dermal fibroblast cells (depicted above) were immunofluorescently targeted with rabbit anti-giantin primary antibodies, followed by goat anti-rabbit secondaries conjugated to Alexa Fluor 568 (yielding red emission). Mitochondria, F-actin, and nuclei present in the culture were also labeled with MitoTracker Deep Red 633, Alexa Fluor 488 conjugated to phalloidin (green emission), and Hoechst 33258, respectively. Images were recorded in grayscale with a 12-bit digital camera coupled to either a Nikon E-600 or Eclipse 80i microscope equipped with bandpass emission fluorescence filter optical blocks. During the processing stage, individual image channels were pseudocolored with RGB values corresponding to each of the fluorophore emission spectral profiles with the exception of MitoTracker Deep Red 633, which was pseudocolored yellow, and Hoechst 33258, which was pseudocolored cyan.

Targeting Focal Adhesions in NBL-6 Cell Cultures with Immunofluorescence - The culture of horse dermal fibroblast cells presented in this section was immunofluorescently labeled with anti-vinculin mouse monoclonal primary antibodies followed by goat anti-mouse Fab fragments conjugated to Alexa Fluor 568. Vinculin is a protein associated with focal adhesions and adherens junctions. In addition, the specimen was stained for DNA with Hoechst 33342, and for F-actin with Alexa Fluor 488 conjugated to phalloidin.

Horse Dermal Fibroblast Cells Triple Labeled with MitoTracker Red CMXRos, Alexa Fluor 633, and SYTOX Green - Mitochondria and the cytoskeletal filamentous actin framework were visualized in a culture of NBL-6 fibroblasts with MitoTracker Red CMXRos and Alexa Fluor 633 conjugated to phalloidin. Cell nuclei were counterstained with the nucleic acid stain SYTOX Green.