Three-Dimensional Culture of Rhipicephalus (Boophilus) microplus BmVIII-SCC Cells on Multiple Synthetic Scaffold Systems and in Rotating Bioreactors

SIMPLE SUMMARY: Ticks feed on blood and transmit microbes that cause disease in their hosts, including humans, domestic animals, and wildlife. Tick cells grown or cultured in the laboratory are tools used in research to better understand tick biology and develop tick control methods. This research adapted three-dimensional (3-D) tissue culture technology for cells derived from the southern cattle fever tick, which transmits the microbes causing bovine babesiosis, or cattle tick fever, that remains a threat to the U.S. livestock industry. The experimental results showed that cells in 3-D culture shifted their shape and aggregated to look more like cells in tick tissues or organs. These findings suggest that 3-D culture could be applied to increase the understanding of tick biology and accelerate research and development of technologies to manage cattle fever ticks. ABSTRACT: Tick cell culture facilitates research on the biology of ticks and their role as vectors of pathogens that affect humans, domestic animals, and wildlife. Because two-dimensional cell culture doesn’t promote the development of multicellular tissue-like composites, we hypothesized that culturing tick cells in a three-dimensional (3-D) configuration would form spheroids or tissue-like organoids. In this study, the cell line BmVIII-SCC obtained from the cattle fever tick, Rhipicephalus (Boophilus) microplus (Canestrini, 1888), was cultured in different synthetic scaffold systems. Growth of the tick cells on macrogelatinous beads in rotating continuous culture system bioreactors enabled cellular attachment, organization, and development into spheroid-like aggregates, with evidence of tight cellular junctions between adjacent cells and secretion of an extracellular matrix. At least three cell morphologies were identified within the aggregates: fibroblast-like cells, small endothelial-like cells, and larger cells exhibiting multiple cytoplasmic endosomes and granular vesicles. These observations suggest that BmVIII-SCC cells adapted to 3-D culture retain pluripotency. Additional studies involving genomic analyses are needed to determine if BmVIII-SCC cells in 3-D culture mimic tick organs. Applications of 3-D culture to cattle fever tick research are discussed.