TY  - JOUR
AB  - Herein we elaborated on methods to load cellular vesicles (CVs) and to incorporate cholesterol (Chol) and PEG lipids in their membrane, for enhancing the potential of such engineered CVs (e-CVs) as drug carriers. Hybrids formed by fusion between PEGylated liposomes (PEG-LIP) and CVs were evaluated as alternatives to e-CV, for the first time. Freeze-thawing cycles (FT) and incubation protocols were tested, and vesicle fusion was monitored by FRET dilution. B16F10, hCMEC/D3, and LLC cells were used for e-CV or hybrid development, and FITC-dextran as a model hydrophilic drug. Results show that dehydration rehydration vesicle (DRV) method is optimal for highest CV loading and integrity, while optimal protocols for Chol/PEG enrichment were identified. FT was found to be more efficient than incubation for hybrid formation. Interestingly, despite their high Chol content, CVs had very low integrity that was not increased by enrichment with Chol, but only after PEG coating; e-CVs demonstrated higher integrity than hybrids. Vesicle uptake by hCMEC cells is in the order: LIP < e-CVs < Hybrids ≤ CVs (verified by confocal microscopy); the higher PEG content of e-CVs is possibly the reason for their reduced cell uptake. While CV and hybrid uptake are highly caveolin-dependent, e-CVs mostly follow clathrin-dependent pathways. In vivo and ex vivo results show that brain accumulation of hybrids is only slightly higher that of CVs, indicating that the surface PEG content of hybrids is not sufficient to prevent uptake by macrophages of the reticuloendothelial system. Taking together with the fact that subjection of CVs to FT cycles reduced their cellular uptake, it is concluded that PEGylated e-CVs are better than hybrids as brain-targeted drug carriers.
AU  - Kannavou, M.*
AU  - Marazioti, A.*
AU  - Stathopoulos, G.T.
AU  - Antimisiaris, S.G.*
C1  - 61078
C2  - 50037
CY  - Tiergartenstrasse 17, D-69121 Heidelberg, Germany
SP  - 547-565
TI  - Engineered versus hybrid cellular vesicles as efficient drug delivery systems: A comparative study with brain targeted vesicles.
JO  - Drug Deliv. Transl. Res.
VL  - 11
IS  - 2
PB  - Springer Heidelberg
PY  - 2021
SN  - 2190-393X
ER  - 

TY  - JOUR
AB  - Development of highly concentrated formulations of protein and peptide drugs is a major challenge due to increased susceptibility to aggregation and precipitation. Numerous drug delivery systems including implantable and wearable controlled-release devices require thermally stable formulations with high concentrations due to limited device sizes and long-term use. Herein we report a highly concentrated insulin gel formulation (up to 80 mg/mL, corresponding to 2200 IU/mL), stabilized with a non-ionic amphiphilic triblock copolymer (i.e., Pluronic F-127 (PF-127)). Chemical and physical stability of insulin was found to be improved with increasing polymer concentration, as evidenced by reduced insulin fibrillation, formation of degradation products, and preserved secondary structure as measured by HPLC and circular dichroism spectroscopy, respectively. This formulation exhibits excellent insulin stability for up to 30 days in vitro under conditions of continuous shear at 37 °C, attributable to the amphiphilic properties of the copolymer and increased formulation viscosity. The mechanism of stabilizing insulin structure by PF-127 was investigated by coarse-grained molecular dynamics (CG-MD), all-atom MD, and molecular docking simulations. The computation results revealed that PF-127 could reduce fibrillation of insulin by stabilizing the secondary structure of unfolded insulin and forming hydrophobic interaction with native insulin. The gel formulations contained in microfabricated membrane-reservoir devices released insulin at a constant rate dependent on both membrane porosity and copolymer concentration. Subcutaneous implantation of the gel formulation-containing devices into diabetic rats resulted in normal blood glucose levels for the duration of drug release. These findings suggest that the thermally stable gel formulations are suitable for long-term and implantable drug delivery applications.
AU  - Li, J.*
AU  - Chu, M.K.*
AU  - Lu, B.*
AU  - Mirzaie, S.*
AU  - Chen, K.*
AU  - Gordijo, C.R.*
AU  - Plettenburg, O.
AU  - Giacca, A.*
AU  - Wu, X.Y.*
C1  - 51624
C2  - 43316
CY  - Heidelberg
SP  - 529-543
TI  - Enhancing thermal stability of a highly concentrated insulin formulation with Pluronic F-127 for long-term use in microfabricated implantable devices.
JO  - Drug Deliv. Transl. Res.
VL  - 7
IS  - 4
PB  - Springer Heidelberg
PY  - 2017
SN  - 2190-393X
ER  -