Carbon nanotube-mediated delivery of budesonide to macrophages

A carbon nanotube-based carrier was developed for the delivery of anti-inflammatory budesonide to intracellular compartments of macrophages.

Comparative assessment of the in vitro toxicity of some functionalized carbon nanotubes and fullerenes

Carbon nanotubes and fullerenes with different surface coatings are evaluated for their potential cytotoxicity on a panel of cell lines.

Polyethylenimine-carbon nanotube nanohybrids for siRNA-mediated gene silencing at cellular level

Carbon nanotubes (CNTs) covalently modified with low molecular weight polyethylenimine (PEI) are able to bind and deliver siRNA to cells with higher efficacy than a reference lipidic carrier. The performances of the nanohybrid are rationalized by the combination of the cell penetration and endosomal escape properties of CNTs and PEI, respectively.

Targeted delivery of a proapoptotic peptide to tumors in vivo

RGD peptides recognize the α(v)β(3) integrin, a receptor that is overexpressed on the surface of both tumor blood vessels and cancerous cells. These peptides are powerful tools that act as single antiangiogenic molecules, but recently also have been used for tumor imaging and drug targeting. We designed the molecule RAFT-(c[-RGDfK-])(4), a constrained and chemically defined entity that can be produced at clinical-grade quality. This scaffold was covalently coupled via a labile bridge to the proapoptotic peptide (KLAKLAK)(2) (RAFT-RGD-KLA). A fluorescent, activatable probe was also introduced, allowing intracellular localization. At 2.5 µM, this molecule induced the intracellular release of an active KLA peptide, which in turn caused mitochondrial depolarization and cell death in vitro in tumor cells. In a mouse model, the RAFT-RGD-KLA peptide was found to prevent the growth of remote subcutaneous tumors. This study demonstrated that the antitumor peptide is capable of killing tumor cells in an RGD-dependent manner, thus lowering the nonspecific cytotoxic effects expected to occur when using cationic cytotoxic peptides. Thus, this chemistry is suitable for the design of complex, multifunctional molecules that can be used for both imaging and therapeutics, representing the next generation of perfectly controlled, targeted drug-delivery systems.

Drug development in oncology assisted by noninvasive optical imaging

Early and accurate detection of tumors, like the development of targeted treatments, is a major field of research in oncology. The generation of specific vectors, capable of transporting a drug or a contrast agent to the primary tumor site as well as to the remote (micro-) metastasis would be an asset for early diagnosis and cancer therapy. Our goal was to develop new treatments based on the use of tumor-targeted delivery of large biomolecules (DNA, siRNA, peptides, or nanoparticles), able to induce apoptosis while dodging the specific mechanisms developed by tumor cells to resist this programmed cell death. Nonetheless, the insufficient effectiveness of the vectorization systems is still a crucial issue. In this context, we generated new targeting vectors for drug and biomolecules delivery and developed several optical imaging systems for the follow-up and evaluation of these vectorization systems in live mice. Based on our recent work, we present a brief overview of how noninvasive optical imaging in small animals can accelerate the development of targeted therapeutics in oncology.

Synthesis and biological characterisation of targeted pro-apoptotic peptide

We report herein the synthesis and in vitro assay of new, multimeric RGD-peptide conjugates for cell-targeted drug delivery. We generated a peptide scaffold comprising two functional domains, one a tumour blood vessel "homing" motif and the other a programmed cell-death-inducing peptide sequence. RGD peptides were selected to direct the molecular conjugate to alpha(V)beta(3) integrin-containing tumour cells. The pro-apoptotic (Lys-Leu-Ala-Lys-Leu-Ala-Lys)(2) peptide was found to be nontoxic outside cells, but toxic when internalized into targeted cells as it disrupted the mitochondrial membrane. The synthesis of these targeted pro-apoptotic conjugates was carried out by assembling three different units (that is, scaffold, RGD units and pro-apoptotic peptide) through chemoselective ligations. We show that one compound displays significant biological effect in alpha(V)beta(3) integrin-containing tumour cells.

In vivo optical imaging of integrin alphaV-beta3 in mice using multivalent or monovalent cRGD targeting vectors

Background

The cRGD peptide is a promising probe for early non-invasive detection of tumors. This study aimed to demonstrate how RAFT-c(-RGDfK-)₄, a molecule allowing a tetrameric presentation of cRGD, improved cRGD-targeting potential using in vivo models of α_Vβ₃-positive or negative tumors.

Results

We chose the human embryonic kidney cells HEK293(β₃) (high levels of α_Vβ₃) or HEK293(β₁) (α_Vβ₃-negative but expressing α_V and β1) engrafted subcutaneously (s.c.) in mice. Non-invasive in vivo optical imaging demonstrated that as compared to its monomeric cRGD analogue, Cy5-RAFT-c(-RGDfK-)₄ injected intravenously had higher uptake, prolonged retention and markedly enhanced contrast in HEK293(β₃) than in the HEK293(β₁) tumors. Blocking studies further demonstrated the targeting specificity and competitive binding ability of the tetramer.

Conclusion

In conclusion, we demonstrated that Cy5-RAFT-c(-RGDfK-)₄ was indeed binding to the α_Vβ₃ receptor and with an improved activity as compared to its monomeric analog, confirming the interest of using multivalent ligands. Intravenous injection of Cy5-RAFT-c(-RGDfK-)₄ in this novel pair of HEK293(β₃) and HEK293(β₁) tumors, provided tumor/skin ratio above 15. Such an important contrast plus the opportunity to use the HEK293(β₁) negative control cell line are major assets for the community of researchers working on the design and amelioration of RGD-targeted vectors or on RGD-antagonists.