Effect of anesthetics on microglial activation and nanoparticle uptake: Implications for drug delivery in traumatic brain injury.
Traumatic brain injury (TBI) is a serious public health problem, often with devastating consequences for patients and their families. Affordable and timely therapies can have a substantial impact on outcomes in severe TBI. Despite the common use of sedatives and anesthetics in the acute phase of TBI management, their effect on glial cells is not well understood. We investigated the effect of a commonly used sedative, pentobarbital, on glial cells and their uptake of nanoparticles. First, we studied how pentobarbital affects BV2 mouse microglial cells in culture. The cell morphology was imaged by confocal microscopy and analyzed. Our results suggest that microglia change to a more swollen, 'activated' shape with pentobarbital (cell area increased by approximately 20%, p<0.001). Such glial activation may have negative implications for the ability of the injured brain to clear edema. Second, we investigated how pentobarbital treatment affected nanoparticle uptake. BV-2 mouse microglial cells in the presence and absence of pentobarbital were treated with fluorescently-labeled, hydroxyl-functionalized poly(amidoamine) dendrimer nanoparticles (Dendrimer-Cy5). We demonstrated that the presence of pentobarbital increased the dendrimer nanoparticle uptake significantly (~2-fold both 2 and 6h following treatment). This semi-quantitative fluorescence assessment was broadly consistent among confocal image analysis, flow cytometry, and fluorescence quantification of cell-extracted dendrimer-Cy5. Although anesthetics appear to activate microglia, the increased uptake of dendrimer nanoparticles in their presence can be exploited to deliver drug-loaded nanoparticles directly to microglia after TBI. These drugs could restore glial and glymphatic function, enabling efficient drainage of waste and fluid from the brain and effectively improving recovery after TBI. A key future direction is to validate these findings in TBI models.
River Hill High School, Columbia, MD 21029, USA; Center for Nanomedicine, Wilmer Eye Institute, Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Gokul
G
Kannan
Center for Nanomedicine, Wilmer Eye Institute, Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Siva P
SP
Kambhampati
Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD, USA. Electronic address: skudcha1@jhmi.edu.
Sapna R
SR
Kudchadkar
D000777:Anesthetics / Q000008:administration & dosage*; D000818:Animals; D000070642:Brain Injuries, Traumatic / Q000378:metabolism; D002232:Carbocyanines / Q000008:administration & dosage; D002460:Cell Line; D050091:Dendrimers / Q000008:administration & dosage*; D016503:Drug Delivery Systems; D005456:Fluorescent Dyes / Q000008:administration & dosage; D051379:Mice; D017628:Microglia / Q000187:drug effects*; D010424:Pentobarbital / Q000008:administration & dosage*
D000777:Anesthetics; D002232:Carbocyanines; D050091:Dendrimers; D005456:Fluorescent Dyes; C104700:PAMAM Starburst; C085321:cyanine dye 5; D010424:Pentobarbital