Lyophilisomes are a novel class of proteinaceous biodegradable nano/micro drug delivery capsules prepared by freezing, annealing and Iyophilization. In the present study, lyophilisomes were functionalized for active targeting by antibody conjugation in order to obtain a selective drug-carrier system.
Lyophilisomes were vapor crosslinked for 2 h, resulting in stable capsules, while leaving sufficient primary amines for further modification. The humanized KC4 (hKC4) antibody was conjugated to lyophilisomes to achieve specific targeting to mucin 1 (MUC1)-overexpressing tumor cells. For this, thiolated antibodies were conjugated to maleimide-activated lyophilisomes, resulting in an hKC4 specific drug targeting system toward MUC1-overexpressing human ovarian and cervical tumor cells. FACS analysis demonstrated that hKC4-conjugated lyophilisomes bound specifically to MUC1-overexpressing tumor cells (HeLa, OVCAR-3, and SKOV-3 cells), compared to MUC1-negative cells (LS174T). In addition, control non-specific IgG-conjugated lyophilisomes did not bind to MUC1-overexpressing tumor cells. When MUC1-positive and -negative cells were combined in one culture, hKC4-conjugated lyophilisomes specifically targeted MUC1-positive cells, whereas negative cells showed merely background levels. Transmission electron microscopy showed uptake of hKC4-conjugated lyophilisomes via phagocytosis or macropinocytosis.
In conclusion, hKC4-conjugated albumin-based lyophilisomes represent a potential drug delivery system for targeted drug transport to MUC1-overexpressing tumor cells.