PEGylated Dendritic Polyglycerol Conjugate Delivers Doxorubicin to the Parasitophorous Vacuole in Leishmania infantum Infections

Abstract

Most drugs against visceral leishmaniasis must be administered parenterally. A controlled drug release at the target site can improve the efficacy and toxicity of antileishmanial drugs in clinical use. Amastigotes live and grow inside the parasitophorous vacuole of host resident macrophages. Therefore, antileishmanial drugs should accumulate in this compartment to kill the parasite and do not produce toxicity to the cell host. PEGylated dendritic polyglycerol conjugates (PG‐PEG) can ensure a controlled drug release and the immune activation efficiency of the host. A dendritic PG conjugate with doxorubicin (DOX) attached through a pH‐cleavable hydrazone linker (PG‐DOX(pH)‐PEG), is tested on murine macrophage cell lines and on ex vivo infected BALB/c splenocytes. As a control, a dendritic PG conjugate attached via a non‐cleavable linker (PG‐DOX(non)‐PEG) is used. DOX fluorescence is useful to monitor the fate of the drug inside the infected cells by flow cytometry and confocal microscopy. The results show that PG‐DOX(pH)‐PEG slowly releases DOX inside the targeted macrophages, protecting the host of toxic drug concentrations. In addition, unlike free DOX, PG‐DOX(pH)‐PEG is actively internalized through the acidic endocytic pathway and colocalized surrounding the amastigotes. These results prove that PG‐DOX(pH)‐PEG is a promising candidate for releasing antileishmanial drugs in a controlled manner.

Mannose-Decorated Dendritic Polyglycerol Nanocarriers Drive Antiparasitic Drugs To Leishmania infantum-Infected Macrophages

“…These results suggest that although PG–PEG–Mann5–FITC is present in different endosomes, it may accumulate in late endosomes and lysosomes of the macrophages. Such localization is in agreement with previously obtained results using the same kind of nanoparticle without mannose decoration [ 26 ].…”

“…The modular character of the synthetic strategy that we developed enables the preparation of multifunctional nanocarriers, provided with solubilization enhancers (PEG, for instance), imaging agents and targeting moieties, in a simple procedure [ 45 , 46 , 47 , 48 , 49 ]. We recently used it to prepare PEGylated pH-sensitive PG-doxorubicin conjugates, which showed their potential on murine macrophage cell lines and on ex vivo infected BALB/c splenocytes [ 26 ]. Although promising, it is expected that such conjugates will not be able to distinguish between healthy and infected cells.…”

“…The amount of each sample internalized by cells should be proportional to the fluorescence intensity of FITC. Taken into account the amount of drug released after 24 h at pH 4.0; a fixed quantity of 100 μg/mL of each nanoparticle (PG–PEG–FITC) bound to different mannose units (0, 5, 10 and 20), was added to one-hundred and fifty thousand RAW 264.7 murine macrophages and incubated at 37 °C for 24 h. The incubation time for this cell line was optimized in a previous report by the authors, using similar type of nanocarriers [ 26 ]. All mannosylated PG–PEG–FITC nanocarriers included in this study were significatively internalized by RAW 264.7 cultures within the first 24 h. Functionalization with only five mannose units (PG–PEG–Mann5–FITC) showed the maximum significant uptake.…”

“…Nanoparticles (NPs) have been considered as a potential solution to deliver antileishmanial drugs inside the phagolysosomal compartment [ 25 ]. Previous studies showed that treatment utilizing dendritic polyglycerol decorated with polyethylene glycol (PG–PEG) conjugated to cytotoxic doxorubicin (DOX) increased the antileishmanial effect of the drug, while having moderate cytotoxicity due to controlled drug release inside the parasitophorous vacuole [ 26 ]. In the present study, we aim at deciphering the role played by the mannose receptor in the phagocytosis of leishmania parasites, for which we prepared PEGylated dendritic PG drug conjugates that were further decorated with mannose as targeting modality.…”

From Polymers to Functional Biomaterials

“…In the following article, Marcelo Calderon and Rosa M. Reguera demonstrate that the conjugation of a Doxorubicin prodrug to PEGylated dendritic polyglycerols provides new perspectives in the therapy of Leishmaniasis, a parasite‐induced disease with often fatal outcome. Since the amastigotes live in parasitophorous vacuoles inside macrophages, drug delivery systems are likely to improve therapeutic outcome …”