Tuning the Size of Nanoassembles: A Hierarchical Transfer of Information from Dendrimers to Polyion Complexes.

The generation of dendrimers is a powerful tool in the control of the size and biodistribution of polyion complexes (PIC). Using a combinatorial screening of six dendrimers (18-243 terminal groups) and five oppositely charged PEGylated copolymers, a dendrimer-to-PIC hierarchical transfer of structural information was revealed with PIC diameters that increased from 80 to 500 nm on decreasing the dendrimer generation. This rise in size, which was also accompanied by a micelle-to-vesicle transition, is interpreted according to a cone- to rod-shaped progression in the architecture of the unit PIC (uPIC). This precise size tuning enabled dendritic PICs to act as nanorulers for controlled biodistribution. Overall, a domino-like control of the size and biological properties of PIC that is not attainable with linear polymers is feasible through dendrimer generation.

mRNA-activated matrices encoding transcription factors as primers of cell differentiation in tissue engineering.

Gene-activated matrices (GAMs) encoding pivotal transcription factors (TFs) represent a powerful tool to direct stem cell specification for tissue engineering applications. However, current TF-based GAMs activated with pDNA, are challenged by their low transfection efficiency and delayed transgene expression. Here, we report a GAM technology activated with mRNAs encoding TFs SOX9 (cartilage) and MYOD (muscle). We find that these mRNA-GAMs induce a higher and faster TF expression compared to pDNA-GAMs, especially in the case of RNase resistant mRNA sequences. This potent TF expression was translated into a high synthesis of cartilage- and muscle-specific markers, and ultimately, into successful tissue specification in vitro. Additionally, we show that the expression of tissue-specific markers can be further modulated by altering the properties of the mRNA-GAM environment. These results highlight the value of this GAM technology for priming cell lineage specification, a key centerpiece for future tissue engineering devices.

A multifunctional drug nanocarrier for efficient anticancer therapy.

So far, the success of anticancer nanomedicines has been moderate due to their lack of adequate targeting properties and/or to their difficulties for penetrating tumors. Here we report a multifunctional drug nanocarrier consisting of hyaluronic acid nanocapsules conjugated with the tumor homing peptide tLyp1, which exhibits both, dual targeting properties (to the tumor and to the lymphatics), and enhanced tumor penetration. Data from a 3D co-culture in vitro model showed the capacity of these nanocapsules to interact with the NRP1 receptors over-expressed in cancer cells. The targeting capacity of the nanocapsules was evidenced in orthotopic lung cancer-bearing mice, using docetaxel as a standard drug. The results showed a dramatic accumulation of docetaxel in the tumor (37-fold the one achieved with Taxotere®). This biodistribution profile correlated with the high efficacy shown in terms of tumor growth regression and drastic reduction of metastasis in the lymphatics. When efficacy was validated in a pancreatic patient-derived tumor, the nanocapsule's activity was comparable to that of a dose ten times higher of Abraxane®. Multi-functionality was found to be the key to the success of this new therapy.

Silver Atomic Quantum Clusters of Three Atoms for Cancer Therapy: Targeting Chromatin Compaction to Increase the Therapeutic Index of Chemotherapy.

Nanomaterials with very low atomicity deserve consideration as potential pharmacological agents owing to their very small size and to their properties that can be precisely tuned with minor modifications to their size. Here, it is shown that silver clusters of three atoms (Ag3 -AQCs)-developed by an ad hoc method-augment chromatin accessibility. This effect only occurs during DNA replication. Coadministration of Ag3 -AQCs increases the cytotoxic effect of DNA-acting drugs on human lung carcinoma cells. In mice with orthotopic lung tumors, the coadministration of Ag3 -AQCs increases the amount of cisplatin (CDDP) bound to the tumor DNA by fivefold without modifying CDDP levels in normal tissues. As a result, CDDP coadministered with Ag3 -AQCs more strongly reduces the tumor burden. Evidence of the significance of targeting chromatin compaction to increase the therapeutic index of chemotherapy is now provided.

New scaffolds encapsulating TGF-ß3/BMP-7 combinations driving strong chondrogenic differentiation.

The regeneration of articular cartilage remains an unresolved question despite the current access to a variety of tissue scaffolds activated with growth factors relevant to this application. Further advances might result from combining more than one of these factors; here, we propose a scaffold composition optimized for the dual delivery of BMP-7 and TGF-ß3, two proteins with described chondrogenic activity. First, we tested in a mesenchymal stem cell micromass culture with TGF-ß3 whether the exposure to microspheres loaded with BMP-7 would improve cartilage formation. Histology and qRT-PCR data confirmed that the sustained release of BMP-7 cooperates with TGF-ß3 towards chondrogenic differentiation. Then, we optimized a scaffold prototype for tissue culture and dual encapsulation of BMP-7 and TGF-ß3. The scaffolds were prepared from poly(lactic-co-glycolic acid), and BMP-7/TGF-ß3 were loaded as nanocomplexes with heparin and Tetronic 1107. The scaffolds showed the sustained release of both proteins over four weeks, with minimal burst effect. We finally cultured human mesenchymal stem cells on these scaffolds, in the absence of exogenous chondrogenic factor supplementation. The cells cultured on the scaffolds loaded with BMP-7 and TGF-ß3 showed clear signs of cartilage formation macroscopically and histologically. RT-PCR studies confirmed a clear upregulation of cartilage markers SOX9 and Aggrecan. In summary, scaffolds encapsulating BMP-7 and TGF-ß3 can efficiently deliver a cooperative growth factor combination that drives efficient cartilage formation in human mesenchymal stem cell cultures. These results open attractive perspectives towards in vivo translation of this technology in cartilage regeneration experiments.

Docetaxel-loaded polyglutamic acid-PEG nanocapsules for the treatment of metastatic cancer.

The design of nanomedicines with suitable physicochemical characteristics for the lymphatic targeting of drugs is critical in order to reach the lymph nodes, where metastatic cells often accumulate. Based on the known effect of particle size and surface hydrophilicity on the capacity of nanocarriers to reach the lymph nodes, here we report the formation and characterization of 100nm polyglutamic acid-polyethylene glycol (PGA-PEG) nanocapsules together with the assessment of their potential for the treatment of cancer with lymphatic metastatic spread. To this purpose, we first studied the biodistribution of fluorescently labeled PGA-PEG nanocapsules (100nm), following, either intravenous or subcutaneous administration. The results confirmed the accumulation of nanocapsules in the lymphatic system, especially upon subcutaneous administration. Next, we evaluated the efficacy and toxicity of the docetaxel-loaded nanocapsules in an orthotopic lung cancer model that metastasizes to the lymph nodes. As expected from the rational design, DCX-loaded PGA-PEG nanocapsules exhibited a greatly enhanced antitumoral efficacy and a reduced toxicity when compared with the commercial formulation Taxotere®. Furthermore, the administration of DCX-loaded PGA-PEG nanocapsules resulted in the practical elimination of the metastatic load in the mediastinal lymph nodes, whereas the treatment with the commercial formulation had a minor effect. Overall, these findings underscore the potential of PGA-PEG nanocapsules for the delivery of anticancer drugs to both, the tumor tissue and the metastatic lymph nodes. Therefore, they represent a promising therapy for the treatment of lung metastatic cancer.

Polyaminoacid nanocapsules for drug delivery to the lymphatic system: Effect of the particle size.

Previous work by our group showed the possibility to reduce the toxicity of docetaxel upon its encapsulation in polyaminoacid nanocapsules with a size of 200nm. The objective of this study was to elucidate whether a reduction in the nanocapsules size might facilitate their access to the lymphatic system. To do so, we analyzed the effect of several formulation parameters on the characteristics of polyglutamic acid, PEGylated polyglutamic acid and polyasparagine nanocapsules. From these experiments, we could identify the best conditions to produce nanocapsules with a small size (close to 100nm) and adequate capacity to encapsulate and sustain the release of the antitumor drug docetaxel. Moreover, the results of the stability study made evident the critical role of the polyaminoacid shell on the colloidal stability of the nanocapsules in biologically relevant media. Finally, we studied the influence of the particle size (100nm vs. 200nm) on the biodistribution of PGA-PEG nanocapsules following subcutaneous injection. The results showed that the 100 nm-size nanocapsules accumulate faster in the lymph nodes, than those with a size of 200nm. In summary, these data suggest the potential of 100nm-size polyaminoacid nanocapsules as lymphatic drug delivery carriers.