Effect of a Δ9-tetrahydrocannabinol (THC)/cannabidiol (CBD) formulation on cell monolayer viability and mitochondria integrity: Significance of the drug carrier/delivery system

Abstract

Background: The increasing availability and abuse of recreational and medical cannabis has been associated with patients presenting with cyclical nausea, vomiting, intestinal cramps, and other manifestations, referred to as cannabinoid hyperemesis syndrome. An exact etiologic mechanism, especially on the cellular level, remains unclear. Continual studies are needed to address the effect of cannabinoid activity specifically addressing that which occurs in the gastrointestinal tract. Methods: Cannabinoids in general, are immiscible in water-based cell culture media. Homogenization was performed to bring a THC/CBD formulation into a workable state for in vitro testing. The human colon adenocarcinoma (HT-29) epithelia cell line was used throughout this study. Mitochondrial cytotoxicity testing was performed using a fluorescein conjugated monoclonal antibody to the organelle’s outer membrane protein. Mitochondrial morphology was performed by transmission electron microscopy utilizing a commercially available cannabidiol product. Cell cultures, incubated with 50 to 125 µg/ml of a THC/CBD formulation for 72-h, were viewed daily for the appearance of a monolayer degeneration or a cytopathogenic effect. Results: Cell monolayers treated with non-homogenized THC/CBD in phosphate-buffered saline or utilizing DMSO as analyte diluents, proved unremarkable. However, homogenization of the cannabinoid formulation at > 50 µg/ml affected a loss of monolayer confluency and mitochondrial membrane surface protein. Treatment of monolayers with CBD affected a loss of mitochondrial morphology as observed by an absence of organelle cristae and matrix structure. Mitochondrial loss of surface protein integrity occurred prior to monolayer degeneration. Conclusion: A cytotoxic effect was realized in colon cell cultures following treatment with a cannabinoid liquid tincture formulation at concentrations > 50 µg/ml. The degenerative effect by the cannabinoid formulation was directed initially to a marked loss of mitochondrial morphology and loss of [organelle] surface integrity, followed by a monolayer degeneration. Critically, the immiscible THC/CBD analyte mandated a size distribution of lipid globules to single digit of smaller µM particulates. Globule reduction was achieved by high speed homogenization. Additional studies in the animal model are needed to further address our findings in the search for an etiology to cannabinoid hyperemesis syndrome.