Nanomedicine for autophagy modulation in cancer therapy: a clinical perspective.

In recent years, progress in nanotechnology provided new tools to treat cancer more effectively. Advances in biomaterials tailored for drug delivery have the potential to overcome the limited selectivity and side effects frequently associated with traditional therapeutic agents. While autophagy is pivotal in determining cell fate and adaptation to different challenges, and despite the fact that it is frequently dysregulated in cancer, antitumor therapeutic strategies leveraging on or targeting this process are scarce. This is due to many reasons, including the very contextual effects of autophagy in cancer, low bioavailability and non-targeted delivery of existing autophagy modulatory compounds. Conjugating the versatile characteristics of nanoparticles with autophagy modulators may render these drugs safer and more effective for cancer treatment. Here, we review current standing questions on the biology of autophagy in tumor progression, and precursory studies and the state-of-the-art in harnessing nanomaterials science to enhance the specificity and therapeutic potential of autophagy modulators.

Gelatin as Biomaterial for Tissue Engineering.

Tissue engineering is considered one of the most important therapeutic strategies of regenerative medicine. The main objective of these new technologies is the development of substitutes made with biomaterials that are able to heal, repair or regenerate injured or diseased tissues and organs. These constructs seek to unlock the limited ability of human tissues and organs to regenerate. In this review, we highlight the convenient intrinsic properties of gelatin for the design and development of advanced systems for tissue engineering. Gelatin is a natural origin protein derived from collagen hydrolysis. We outline herein a state of the art of gelatin-based composites in order to overcome limitations of this polymeric material and modulate the properties of the formulations. Control release of bioactive molecules, formulations with conductive properties or systems with improved mechanical properties can be obtained using gelatin composites. Many studies have found that the use of calcium phosphate ceramics and diverse synthetic polymers in combination with gelatin improve the mechanical properties of the structures. On the other hand, polyaniline and carbon-based nanosubstrates are interesting molecules to provide gelatin-based systems with conductive properties, especially for cardiac and nerve tissue engineering. Finally, this review provides an overview of the different types of gelatin-based structures including nanoparticles, microparticles, 3D scaffolds, electrospun nanofibers and in situ gelling formulations. Thanks to the significant progress that has already been made, along with others that will be achieved in a near future, the safe and effective clinical implementation of gelatin-based products is expected to accelerate and expand shortly.

Design and characterization of a magnetite/PEI multifunctional nanohybrid as non-viral vector and cell isolation system.

It is described the reproducible formulation and complete physicochemical characterization of nanohybrids based on magnetite (Fe3O4) cores embedded within a polyethylenimine (PEI) matrix. Particle size, surface electrical charge, X-ray diffraction and Fourier transform infrared spectroscopy (FTIR) analyses, and magnetic field-responsive behaviour characterizations defined that the 4:3 (Fe3O4:PEI) weight proportion led to the best production performances of magnetically responsive nanocomposites in which the magnetic nuclei are completely covered by the polymeric shell. Agarose gel electrophoresis assays demonstrated the capacity of the Fe3O4/PEI particles to condense, release, and protect the DNA against enzymatic degradation. In vitro assays were performed to evaluate the transfection efficiency (up to 4.5% of transfected HEK-293 cells at a 10/1 PEI/DNA ratio), iron absorption by D1-mesenchymal stem cells (D1-MSCs, high values after only 15min of magnetic incubation), influence on metabolic activity (negligible effect up to 44µg nanocomposites/105 cells), and cell isolation capacity of the core/shell particles (significant increase in the retention of D1-MSCs transduced with green fluorescent protein). The Fe3O4/PEI nanohybrids hold promising characteristics suggestive of their capacity for transfection and cell isolation applications.

Elaboration and Physicochemical Characterization of Niosome-Based Nioplexes for Gene Delivery Purposes.

Niosome formulations for gene delivery purposes are based on nonionic surfactants, helper lipids, and cationic lipids that interact electrostatically with negatively charged DNA molecules to form the so-called nioplexes. Niosomes are elaborated by different techniques, such as solvent emulsion-evaporation, thin film hydration, hand-shaking, dissolvent injection, and microfluidization method, among many others. In this chapter, we have described some protocols for the elaboration of niosomes and nioplexes and their physicochemical characterization that guarantees the quality criteria of the formulation in terms of size, morphology, ζ-potential, and stability.

Drug delivery technologies and stem cells for tissue repair and regeneration.

In the last few years several technologies are being developed for eventually repairing or replacing damaged or injured tissues and even organs. Some of these emerging technologies include the design and development of new biomaterials, the optimization of nano- and micro-technologies for drug and cell delivery, the use of autologous proteins or the application of stem cells as therapeutics. Thus, several types of stem cells, e.g. ESCs, iPSCs, MSCs, CD133+ stem cells are being evaluated for tissue regeneration purposes. The present review describes some of these emerging technologies and discusses their potential benefits and challenges.

Delivery of an adenovirus vector plasmid by ultrapure oligochitosan based polyplexes.

Ultrapure oligochitosans have been recently reported as efficient non-viral vectors for the delivery of pCMS-EGFP plasmid (5.5kbp) to the cornea and retina. However, the delivery of oncolytic adenoviral plasmids (40kbp) represents a unique challenge. In this work, we elaborated self assembled O15 and O25 UOC/pAdTLRGD polyplexes, and we studied the influence of the N/P ratio, the pH of the transfection medium and the salt concentration on the particle size and zeta potential by an orthogonal experimental design. All polyplexes showed a particle size lower than 200nm and a positive zeta potential. These parameters were influenced by the N/P ratio, salt concentration, and pH of the transfection medium. The selected polyplexes were able to bind, release, and protect the plasmid from DNase degradation. Transfection experiments in HEK293 and A549 cell lines demonstrated that UOC/pAdTLRGD polyplexes were able to deliver the plasmid and transfect both cell lines. These results suggest that O15 and O25 UOC based polyplexes are suitable for future in vivo applications.

A perspective on bioactive cell microencapsulation.

Bioactive cell encapsulation has emerged as a promising tool for the treatment of patients with various disorders including diabetes mellitus, central nervous system diseases, and cardiovascular diseases. The implantation of encapsulated cells that secrete a therapeutic product (protein, peptide, or antibody) within a semipermeable membrane provides a physical barrier to mask the implant from immune surveillance at a local level without the need for systemic immunosuppression; this serves to achieve a successful therapeutic function following in vivo implantation. The aim of this review article is to provide an update on the progress in this field. The current state of cell encapsulation technology as a controlled drug delivery system will be covered in detail, and the essential requirements of the technology, the challenges, and the future directions under investigation will be highlighted. The technical and biological advances, together with the increasing experience in the field, may lead to the realization of the full potential of bioactive cell encapsulation in the coming years.

Comparison of the adjuvanticity of two different delivery systems on the induction of humoral and cellular responses to synthetic peptides.

The aim of this work was to test, evaluate, and compare the immunogenicity of the S3 malarial short synthetic model peptide in Balb/c mice when it was delivered with different adjuvants. Specifically, it studied the adjuvanticity of two different particulate delivery systems, human compatible Montanide((R)) ISA 720 w/o emulsion and poly-lactide-co-glycolide acid microparticles, in terms of the enhancement and sub-set type of the immune response elicited following immunization. Aditionally, conventional aluminum hydroxide gel adjuvant was included as a reference. Aluminum adjuvant failed to improve the lack of immunogenicity of this antigenic peptide on its own. On the other hand, Montanide and microparticles given subcutaneously resulted in effective adjuvants and revealed mixed Th1/Th2 immune responses, with moderate antibody and lymphoproliferative responses, and higher IFN-gamma secretion for Montanide. Hence, microparticles administered intradermally (not possible with Montanide) elicited superior and potent antibody levels, including higher cytophilic isotype (IgG2a), and the greatest limphoproliferation and IFN-gamma levels. The results here presented support the capability and suitability of microparticle delivery systems to reach the adequate adjuvanticity necessary for future malaria vaccine development.

The effect of encapsulated VEGF-secreting cells on brain amyloid load and behavioral impairment in a mouse model of Alzheimer's disease.

Cerebrovascular dysfunction contributes to cognitive decline and neurodegeneration in Alzheimer's disease (AD). Vascular endothelial growth factor (VEGF), an angiogenic protein with important neurotrophic and neuroprotective actions, is under investigation as a therapeutic agent for the treatment of neurodegenerative disorders. The aim of this study was to generate encapsulated VEGF-secreting cells and implant them in a transgenic mouse model of AD, the double mutant amyloid precursor protein/presenilin 1 (APP/Ps1) mice, which shows a disturbed vessel homeostasis. We report that, after implantation of VEGF microcapsules, brain Abeta burden, hyperphosphorylated-tau and cognitive impairment attenuated in APP/Ps1 mice. Based on the neurovascular hypothesis, our findings suggest a new potential therapeutic approach that could be developed for AD, to enhance Abeta clearance and neurovascular repair, and to protect the cognitive behavior. Stereologically-implanted encapsulated VEGF-secreting cells could offer an alternative strategy in the treatment of AD.

Biocompatibility and in vivo evaluation of oligochitosans as cationic modifiers of alginate/Ca microcapsules.

The present article investigates the substitution of poly-L-lysine by two different oligochitosans as membrane-coating capsule, and its effect on different functionality parameters of cell microencapsulation. To address this issue, initially the biocompatibility of the two types of oligochitosan solutions was evaluated using erythropoietin secreting C2C12 myoblast cell line as model. In a second step, we encapsulated the cells within alginate microcapsules coated with each oligochitosan and a complete morphological and mechanical evaluation was performed. Finally, the in vivo functionality of the enclosed cells in the alginate-oligochitosan microcapsules was studied in Balb/c mice. Results show that both oligochitosans were biocompatible, not detecting statistical differences between them. The alginate-oligochitosan microcapsules were totally spherical and uniform and resulted in high hematocrit levels after subcutaneous implantation in mice. In fact, significantly higher hematocrit levels were found in the animals transplanted with the encapsulated cells compared with the control group. Finally, the histological analysis showed a mild fibroblastic reaction around the capsule membrane. These results suggest that alginate-oligochitosan capsules may be an interesting alternative to conventional alginate- poly-L-lysine capsules.

Long-term expression of erythropoietin from myoblasts immobilized in biocompatible and neovascularized microcapsules.

The present paper investigates the long-term functionality of an ex vivo gene therapy approach based on cell microencapsulation for the continuous delivery of erythropoietin (EPO) without implementation of immunosuppressive protocols. Polymer microcapsules (0.5 ml) loaded with EPO-secreting C(2)C(12) myoblasts and releasing 15,490 +/- 600 IU EPO/24 h were implanted in the peritoneum and subcutaneous tissue of syngeneic and allogeneic mice. High and constant hematocrit levels were maintained for more than 100 days in all implanted mice. Capsules retrieved from the peritoneum were free-floating or forming small capsule clusters, and we detected only a weak fibroblast outgrowth in capsules adhered to organs, whereas capsules explanted from the subcutaneous region appeared altogether as a richly vascularized structure with no signs of major host reaction. Interestingly, the functionality of capsules implanted in the allogeneic mice persisted until day 210 after implantation. These results highlight the feasibility of cell encapsulation technology for the long-term delivery of EPO independent of the method of administration and the mouse strain.

Enhancing immunogenicity and reducing dose of microparticulated synthetic vaccines: single intradermal administration.

PURPOSE: Our purpose was to evaluate the ability of a polymeric vehicle to release a model synthetic vaccine to the skin in order to reach a potent activation of the specific immune response. METHODS: The peptide-loaded poly-D,L-lactide-co-glycolide acid (PLGA) microparticles were prepared by a double emulsion technique and administered to Balb/c mice. The immune response (antibody and T cell activation) obtained by the intradermal (i.d.) and the subcutaneous (s.c.) routes was tested. RESULTS: When similar doses of peptide-loaded microparticles were injected s.c. or i.d. in mice, the antipeptide IgG antibody immune response was found to be significantly higher after i.d. injection into the skin. We could also reduce the dose of antigen 10 times by the i.d. route and find a similar antibody response to that obtained by the s.c. immunization. At the lowest i.d. dose level, the IgG2a/IgG1 ratio was also incremented and the IgE production decreased. The i.d. microparticles induced, at both dose levels, a marked IFN-gamma secretion by peptide-stimulated splenocytes and lymph node cells and a significant T cell proliferation in spleen cell cultures. CONCLUSIONS: The results demonstrate that peptide-loaded microparticles were efficiently administered by the i.d. route because lower doses were required and powerful antibody and T cell responses were obtained compared to the conventional s.c. administration.

Microesferas de PLGA: un sistema para la liberación controlada de moléculas con actividad inmunogénica / PLGA Microspheres: A controlled release system of molecules with immunogenic activity

En el campo de la tecnología farmacéutica se presenta actualmente considerable interés en el desarrollo de micropartículas biodegradables como un sistema para la liberación controlada de moléculas con actividad biológica. Son una buena alternativa, teniendo en cuenta que una de las principales desventajas de los productos disponibles es la necesidad de realizar varias administraciones para cumplir totalmente con el tratamiento. Esta contribución examina el papel actual de la microencapsulación de moléculas con actividad antigénica en microesferas elaboradas con polímeros biodegradables derivados de los ácidos láctico y glicólico (PLGA). Aquí se describen las propiedades fisicoquímicas de los biopolímeros empleados, los métodos de obtención de las micropartículas y de algunos de las variables que influyen en las propiedades del producto final. Además, se realiza una breve descripción del modo de acción propuesto para este sistema microparticular.

At the present time, there is a great interest in pharmaceutical technology focused on the development of biodegradable microparticles as a controlled release system of molecules with biological activity. This strategy arises as a good alternative; mainly if it is keep in mind that one of the principal disadvantages of the available products currently is that those products require several administrations to fulfilled the treatment. Here in is examined the role of microencapsulated antigens into microespheres performed with biodegradable copolymers derived from lactic and glycolic acid (PLGA). Physicochemical properties of biopolymers used, microspheres formulation as well as the parameters that affected the properties of the final product are also described. Additionally, there is a brief review of the action mechanism raised for this microparticular system.