Safe and efficient intracellular delivery of functional antibodies into cultured neural cells shows a role for Alzheimer’s-relevant tau phosphorylation in cell integrity
- 1Department of Neurobiology, Northwestern University, Evanston, IL, United States
Abstract
Introduction: Protein proteoforms generated by post-translational modification are increasingly recognized as important regulators of neuronal function and neurodegenerative disease. However, methods for acutely interrogating specific intracellular proteoforms in living neuronal populations remain limited. We evaluated cationic liposomal delivery (CLD) as a strategy for introducing full-length functional antibodies into living neurons and used this approach to investigate the role of a phosphorylated tau proteoform recognized by the monoclonal antibody PHF-1.
Methods: Cationic liposomes composed of DOPC+ were complexed with antibodies or molecular probes and applied to cultured neuronal cell lines and primary mouse cortical neurons. Intracellular delivery, cellular localization, viability, and biological activity were assessed using fluorescence microscopy and live-cell imaging.
Results: CLD efficiently delivered full-length antibodies and molecular probes into living neuronal cells and primary neurons without detectable toxicity. Internalized antibodies retained target specificity, producing intracellular staining patterns consistent with the known localization of tau, vinculin, paxillin, and Fyn. Delivery was observed across essentially all cells in treated cultures and remained effective under standard culture conditions. Intracellular delivery of PHF-1 produced a rapid and striking morphological response characterized by neurite retraction and cell-body rounding within hours of treatment. These effects were not observed with heat-inactivated PHF-1, vehicle controls, or other intracellular antibodies, supporting a specific effect of intracellular engagement of PHF-1-reactive tau species.
Discussion: These findings establish CLD as a practical platform for the intracellular delivery of functional full-length antibodies into living neuronal populations. Beyond validating a delivery technology, the study demonstrates that acute intracellular engagement of PHF-1-reactive phosphorylated tau rapidly alters neuronal morphology, suggesting that this tau proteoform contributes to the maintenance of neurite integrity. CLD provides a versatile approach for probing the function of intracellular proteoforms that are difficult to study using conventional genetic or biochemical methods.
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BibTeX
@article{viola2026safe,
title = {{Safe and efficient intracellular delivery of functional antibodies into cultured neural cells shows a role for Alzheimer’s-relevant tau phosphorylation in cell integrity}},
author = {Kirsten L. Viola and Brett A. Chromy and Raghad Nowar and Mary P. Lambert and William L. Klein},
journal = {Frontiers in Dementia},
year = {2026},
month = oct,
doi = {10.3389/frdem.2026.1737082},
url = {https://doi.org/10.3389/frdem.2026.1737082},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Safe and efficient intracellular delivery of functional antibodies into cultured neural cells shows a role for Alzheimer’s-relevant tau phosphorylation in cell integrity
AU - Kirsten L. Viola
AU - Brett A. Chromy
AU - Raghad Nowar
AU - Mary P. Lambert
AU - William L. Klein
PY - 2026
DA - 2026/10/13
JO - Frontiers in Dementia
DO - 10.3389/frdem.2026.1737082
UR - https://doi.org/10.3389/frdem.2026.1737082
AB - Introduction: Protein proteoforms generated by post-translational modification are increasingly recognized as important regulators of neuronal function and neurodegenerative disease. However, methods for acutely interrogating specific intracellular proteoforms in living neuronal populations remain limited. We evaluated cationic liposomal delivery (CLD) as a strategy for introducing full-length functional antibodies into living neurons and used this approach to investigate the role of a phosphorylated tau proteoform recognized by the monoclonal antibody PHF-1. Methods: Cationic liposomes composed of DOPC+ were complexed with antibodies or molecular probes and applied to cultured neuronal cell lines and primary mouse cortical neurons. Intracellular delivery, cellular localization, viability, and biological activity were assessed using fluorescence microscopy and live-cell imaging. Results: CLD efficiently delivered full-length antibodies and molecular probes into living neuronal cells and primary neurons without detectable toxicity. Internalized antibodies retained target specificity, producing intracellular staining patterns consistent with the known localization of tau, vinculin, paxillin, and Fyn. Delivery was observed across essentially all cells in treated cultures and remained effective under standard culture conditions. Intracellular delivery of PHF-1 produced a rapid and striking morphological response characterized by neurite retraction and cell-body rounding within hours of treatment. These effects were not observed with heat-inactivated PHF-1, vehicle controls, or other intracellular antibodies, supporting a specific effect of intracellular engagement of PHF-1-reactive tau species. Discussion: These findings establish CLD as a practical platform for the intracellular delivery of functional full-length antibodies into living neuronal populations. Beyond validating a delivery technology, the study demonstrates that acute intracellular engagement of PHF-1-reactive phosphorylated tau rapidly alters neuronal morphology, suggesting that this tau proteoform contributes to the maintenance of neurite integrity. CLD provides a versatile approach for probing the function of intracellular proteoforms that are difficult to study using conventional genetic or biochemical methods.
SN - 2813-3919
ER -