TY - JOUR
T1 - Preferential and Increased Uptake of Hydroxyl-Terminated PAMAM Dendrimers by Activated Microglia in Rabbit Brain Mixed Glial Culture
AU - Alnasser, Yossef
AU - Kambhampati, Siva P.
AU - Nance, Elizabeth
AU - Rajbhandari, Labchan
AU - Shrestha, Shiva
AU - Venkatesan, Arun
AU - Kannan, Rangaramanujam M.
AU - Kannan, Sujatha
N1 - Funding Information:
Acknowledgments: This study was supported by the funds from NIH NIBIBRO1EB018306-01-(RMK, SK), NEIRO1EY025304 (RMK) and NICHDRO1HD076901 (SK, RMK). The authors also thank Wilmer Core Module from Microscopy and Imaging for allowing us to use LSM710 confocal. The Wilmer core flow cytometry facility is also highly acknowledged.
Publisher Copyright:
© 2018 by the authors.
PY - 2018
Y1 - 2018
N2 - Polyamidoamine (PAMAM) dendrimers are multifunctional nanoparticles with tunable physicochemical features, making them promising candidates for targeted drug delivery in the central nervous system (CNS). Systemically administered dendrimers have been shown to localize in activated glial cells, which mediate neuroinflammation in the CNS. These dendrimers delivered drugs specifically to activated microglia, producing significant neurological improvements in multiple brain injury models, including in a neonatal rabbit model of cerebral palsy. To gain further insight into the mechanism of dendrimer cell uptake, we utilized an in vitro model of primary glial cells isolated from newborn rabbits to assess the differences in hydroxyl-terminated generation 4 PAMAM dendrimer (D4-OH) uptake by activated and non-activated glial cells. We used fluorescently-labelled D4-OH (D-Cy5) as a tool for investigating the mechanism of dendrimer uptake. D4-OH PAMAM dendrimer uptake was determined by fluorescence quantification using confocal microscopy and flow cytometry. Our results indicate that although microglial cells in the mixed cell population demonstrate early uptake of dendrimers in this in vitro system, activated microglia take up more dendrimer compared to resting microglia. Astrocytes showed delayed and limited uptake. We also illustrated the differences in mechanism of uptake between resting and activated microglia using different pathway inhibitors. Both resting and activated microglia primarily employed endocytotic pathways, which are enhanced in activated microglial cells. Additionally, we demonstrated that hydroxyl terminated dendrimers are taken up by primary microglia using other mechanisms including pinocytosis, caveolae, and aquaporin channels for dendrimer uptake.
AB - Polyamidoamine (PAMAM) dendrimers are multifunctional nanoparticles with tunable physicochemical features, making them promising candidates for targeted drug delivery in the central nervous system (CNS). Systemically administered dendrimers have been shown to localize in activated glial cells, which mediate neuroinflammation in the CNS. These dendrimers delivered drugs specifically to activated microglia, producing significant neurological improvements in multiple brain injury models, including in a neonatal rabbit model of cerebral palsy. To gain further insight into the mechanism of dendrimer cell uptake, we utilized an in vitro model of primary glial cells isolated from newborn rabbits to assess the differences in hydroxyl-terminated generation 4 PAMAM dendrimer (D4-OH) uptake by activated and non-activated glial cells. We used fluorescently-labelled D4-OH (D-Cy5) as a tool for investigating the mechanism of dendrimer uptake. D4-OH PAMAM dendrimer uptake was determined by fluorescence quantification using confocal microscopy and flow cytometry. Our results indicate that although microglial cells in the mixed cell population demonstrate early uptake of dendrimers in this in vitro system, activated microglia take up more dendrimer compared to resting microglia. Astrocytes showed delayed and limited uptake. We also illustrated the differences in mechanism of uptake between resting and activated microglia using different pathway inhibitors. Both resting and activated microglia primarily employed endocytotic pathways, which are enhanced in activated microglial cells. Additionally, we demonstrated that hydroxyl terminated dendrimers are taken up by primary microglia using other mechanisms including pinocytosis, caveolae, and aquaporin channels for dendrimer uptake.
KW - Activated microglia
KW - Enhanced cellular uptake
KW - Intracellular trafficking
KW - Mixed primary glial cultures
KW - Neuroinflammation
KW - PAMAM hydroxyl dendrimers
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U2 - 10.3390/molecules23051025
DO - 10.3390/molecules23051025
M3 - Article
C2 - 29702566
AN - SCOPUS:85046085700
VL - 23
JO - Molecules
JF - Molecules
SN - 1420-3049
IS - 5
M1 - Y
ER -