Purpose: To investigate the best carrier technology for our β-amyloid (Aβ)
aggregation inhibitors by developing three types of liposomes (a) plain liposomes, (b)
MAL-PEG liposomes, and finally the combination of retro-inverted peptide RI-OR2-
TAT (Ac-rGffvlkGrrrrqrrkkrGyc-NH2) attached onto the surface of MAL-PEG
liposomes, creating Peptide Inhibitor Nanoparticles (PINPs) of three different sizes
(50, 100 and 200 nm). In addition, these nanoliposomes (NLPs) (with particular focus
on PINPs) were examined for their ability to affect Aβ aggregation, and to protect
against Aβ cytotoxicity.
Methods: The creation of NLPs was carried out by the use of a mini extruder, while
the elution of PINPs from a size exclusion column was assessed by Dynamic Light
Scattering (DLS). The quantification of peptide bound to liposomes was determined
by bicinchoninic acid (BCA) assay, while phospholipid content was quantified by
Wako phospholipid assay. The effects of the different types of liposomes on Aβ
toxicity and viability of SHSY-5Y neuronal cells were examined by MTS assay, whereas
effects on Aβ aggregation were determined by Thioflavin-T (Th-T) assay. In addition,
a cell penetration assay was carried out in order to examine the ability of liposomes
to penetrate into neuroblastoma SHSY-5Y cells.
Results: Low concentrations of PINPs 0.1 μM inhibited Aβ aggregation and toxicity in
vitro. MAL-PEG liposomes and PINPs were able to penetrate into neuroblastoma
SHSY-5Y cells and were also more stable than simple liposomes. Stability means the
ability of liposomes to keep their size and their shape stable for long time. In
addition, the three types of liposomes were not toxic towards SHSY-5Y
neuroblastoma cells. Cytotoxicity is the quality of being toxic to cells. So, none of the
three types of our liposomes showed any negative effect on the viability towards
SHSY-5Y neuroblastoma cells.
Conclusion: NLPs are an ideal carrier for our aggregation inhibitors because they
affect Aβ aggregation and toxicity at low doses, and according to other data
generated by our group, can cross the Blood Brain Barrier (BBB).