Glutathione PEGylated liposomes: pharmacokinetics and delivery of cargo across the blood–brain barrier in rats

Figures & data

Table 1. Characteristics of CF containing liposomes.

	Size (PdI)*	HSPC†	Cholesterol†	PEG†	GSH-PEG†
1. GSH-PEG liposomes‡	108 (0.065)	20.9	8.8	2.3	15.14
2. PEG liposomes‡	108 (0.065)	18.8	8.0	12.9	–
3. GSH-PEG liposomes¶	106.5 (0.049)	25.6	13.9	2.8	12.69

*Size in nanometer, PdI is Polydispersity Index †mg/mL ‡liposome batches 1 and 2 were made from one batch of liposomes, splitted and post-inserted with GSH-PEG and PEG micelles, respectively. Batches 1 and 2 were used for the in vitro uptake studies (Figures 1 and 2) and in vivo microdialysis studies (Figures 5 and 6) ¶liposome batch 3 was made separately and used for the PK and biodistribution study after IV and IP administration (Figures 3 and 4).

Figure 1. (A) Stability of liposomal CF formulations in culture medium at 37 °C. No difference in release was observed between GSH-PEG and PEG liposomes. Release reached a maximum of 0.5 ± 0.1% (GSH-PEG) and 0.4 ± 0.1% (PEG) of the total liposomal CF concentration after 24 h. (B) CF in cell lysates of RBE4 cells treated with liposomes. Liposomal CF levels were measured after release of CF from the liposomes in the lysates using isopropanol.

Figure 2. (A) CF signal in RBE4 cells incubated with GSH-PEG liposomes (37 °C). (B) CF in RBE4 cells incubated with PEG liposomes (37 °C). (C) CF in RBE4 cells incubated with GSH-PEG liposomes at 4 °C. Cell nuclei were stained with DAPI.

Figure 3. Plasma levels of liposomal CF after IP and IV administration of GSH-PEG liposomes (2.5 mg/kg CF).

Figure 4. Tissue concentrations of liposomal CF after IV and IP administration of GSH-PEG liposomes (2.5 mg/kg CF). *CF concentration is the amount released from intact liposomes and expressed as ng extracted from 1 mg tissue.

Figure 5. Plasma and brain microdialysate concentrations after IV administration of free CF (5 mg/kg). Two hours after injection of CF fluorescent signal was not detectable in plasma anymore. Fluorescent signal in brain microdialysates remained detectable for at least 4.5 h.

Figure 6. Plasma and brain microdialysate concentrations of CF after IV administration of GSH-PEG and PEG liposomes (7.5 mg/kg CF). Multiple t-tests *p < 0.05 #p < 0.01 GSH-PEG versus PEG.