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- 3D tumor spheroids: an overview on the tools and techniques used for their analysisPublication . Costa, Elisabete C.; Moreira, André; Diogo, Duarte Miguel de Melo; Gaspar, V. M.; Carvalho, Marco António Paulo de; Correia, I.J.In comparison with 2D cell culture models, 3D spheroids are able to accurately mimic some features of solid tumors, such as their spatial architecture, physiological responses, secretion of soluble mediators, gene expression patterns and drug resistance mechanisms. These unique characteristics highlight the potential of 3D cellular aggregates to be used as in vitro models for screening new anticancer therapeutics, both at a small and large scale. Nevertheless, few reports have focused on describing the tools and techniques currently available to extract significant biological data from these models. Such information will be fundamental to drug and therapeutic discovery process using 3D cell culture models. The present review provides an overview of the techniques that can be employed to characterize and evaluate the efficacy of anticancer therapeutics in 3D tumor spheroids.
- Sensitive Detection of Peptide–Minicircle DNA Interactions by Surface Plasmon ResonancePublication . Gaspar, Vítor Manuel Abreu; Cruz, Carla Patrícia Alves Freire Madeira; Queiroz, João; Pichon, Chantal; Correia, Ilídio; Sousa, FaniMinicircle DNA (mcDNA) is recently becoming an exciting source of genetic material for therapeutic purposes due to its exceptional biocompatibility and efficiency over typical DNA. However, its widespread use is yet restrained because of the absence of an efficient technology that allows its purification. Here, the precise conditions of mcDNA interaction with novel arginine-arginine dipeptide ligands were explored to promote binding and recovery of these biopharmaceuticals. Such interactions were investigated by taking advantage of a highly sensitive method based on surface plasmon resonance (SPR) to screen, in real-time, for ligand-coupled biomolecules, while preserving mcDNA integrity. Through this analytic approach, we detected dynamic binding responses that are dependent on buffer type, mcDNA electrokinetic potential, and temperature conditions. Remarkably, the results obtained revealed that the ligands possess high affinity to mcDNA molecules under low salt buffers, and low affinity in the presence of salt, suggesting that electrostatic interactions mainly govern ligand–analyte coupling. These findings provide important insights for an active manipulation of parameters that promote mcDNA recovery and purification. Above all, this study showed the crucial importance of SPR for future screening of other ligands that, like the one described herein, can be used to design mcDNA recovery platforms which will have significant impact in biopharmaceutical-based therapeutics.
- Evaluation of Nanoparticle Uptake in Co-culture Cancer ModelsPublication . Costa, Elisabete C.; Gaspar, Vítor Manuel Abreu; Marques, João Filipe Gonçalves; Coutinho, Paula; Correia, Ilídio Joaquim SobreiraCo-culture models are currently bridging the gap between classical cultures and in vivo animal models. Exploring this novel approach unlocks the possibility to mimic the tumor microenvironment in vitro, through the establishment of cancer-stroma synergistic interactions. Notably, these organotypic models offer a perfect platform for the development and pre-clinical evaluation of candidate nanocarriers loaded with anti-tumoral drugs in a high throughput screening mode, with lower costs and absence of ethical issues. However, this evaluation was until now limited to co-culture systems established with precise cell ratios, not addressing the natural cell heterogeneity commonly found in different tumors. Therefore, herein the multifunctional nanocarriers efficiency was characterized in various fibroblast-MCF-7 co-culture systems containing different cell ratios, in order to unravel key design parameters that influence nanocarrier performance and the therapeutic outcome. The successful establishment of the co-culture models was confirmed by the tissue-like distribution of the different cells in culture. Nanoparticles incubation in the various co-culture systems reveals that these nanocarriers possess targeting specificity for cancer cells, indicating their suitability for being used in this illness therapy. Additionally, by using different co-culture ratios, different nanoparticle uptake profiles were obtained. These findings are of crucial importance for the future design and optimization of new drug delivery systems, since their real targeting capacity must be addressed in heterogenous cell populations, such as those found in tumors.
- Development of a new drug delivery system for future application in cancer therapyPublication . Gaspar, Vítor Manuel Abreu; Correia, Ilídio Joaquim Sobreira; Sousa, Fani Pereira deDuring the past few decades gene therapy has become a promising alternative for the treatment of many incurable diseases such as cancer. This extremely complex disease possesses characteristics that make most of the generally used treatments rather ineffective. The research work presented in this thesis attempts to take advantage of novel non-viral gene therapeutic approaches based on plasmidic DNA and nanoparticulated systems that might provide the foundation for the development of a novel therapeutic treatment from the production to a real application in the everyday life of cancer patients. Hence the production of an expression vector that encodes for a tumor suppressor, p53 was promoted in recombinant organisms. Subsequently the different plasmid DNA isoforms were isolated and the supercoiled isoform, the one biologically active and with enhanced transfection efficiency was purified by affinity chromatography. Following this purification and recovery the development of novel nanoparticle systems that could deliver the exogenous DNA into the malignant cells was promoted. Nanoparticulated systems produced with chitosan demonstrated small size ranges and suitable properties for the encapsulation of plasmidic DNA. Additionally, transfection of eukaryotic neoplastic cells revealed the suitability of the nanocarrier as a novel delivery system of p53 expression vectors to cancer.
- Chitosan/arginine–chitosan polymer blends for assembly of nanofibrous membranes for wound regenerationPublication . Antunes, Bernardo Paiva; Moreira, André; Gaspar, Vítor Manuel Abreu; Correia, Ilídio Joaquim SobreiraFrequently, skin is subjected to damaging events, such as deep cuts, burns or ulcers, which may compromise the integrity of this organ. To overcome such lesions, different strategies have been employed. Among them, wound dressings aimed to re-establish skin native properties and decreased patient pain have been pursued for a long time. Herein, an electrospun membrane comprised by deacetylated/arginine modified chitosan (CH-A) was produced to be used as a wound dressing. The obtained results showed that the membrane has a highly hydrophilic and porous three-dimensional nanofibrous network similar to that found in human native extracellular matrix. In vitro data indicate that human fibroblasts adhere and proliferate in contact with membranes, thus corroborating their biocompatibility. This nanofiber-based biomaterial also demonstrated bactericidal activity for two bacterial strains. In vivo application of CH-A nanofibers in full thickness wounds resulted in an improved tissue regeneration and faster wound closure, when compared to non-modified membranes. Such findings support the suitability of using this membrane as a wound dressing in a near future.
- The biological performance of purified supercoiled p53 plasmid DNA in different cancer cell linesPublication . Valente, J. F. A.; Sousa, A.; Gaspar, V. M.; Queiroz, João; Fani, SousaTumor suppressor p53 remains one of the most interesting therapeutic targets in cancer gene therapy due to itsconsistent mutation in numerous cancers. Thus, the reinstatement of the p53 expression and function can be seenas an effective alternative for cancer treatment, motivating research in thisfield. In this study,L-methioninematrix was used to purify the supercoiled topoisoform of a plasmid DNA encoding the p53 protein. This purebiopharmaceutical was conjugated with liposomes to comprehensively analyze itsin vitroperformance andtherapeutic potential in different cancer cell lines, including the lung and cervix models. A different profile ofcellular responses was attained after the transfection of these cancer cell lines with the p53-pDNA. Actually, thein vitrotransfection with pure sc p53-pDNA resulted in a higher expression of the tumor suppressor protein incancer cells when compared with the native pDNA samples (oc + sc topoisoforms). Also, wild-type p53 ex-pression following transfection was significantly higher in HeLa cervix cancer cells compared to that obtained inA549 lung cancer cells. Overall, ourfindings emphasize the potential of sc pDNA gene-based therapy, alsoraising awareness of the need to adjust the therapeutics, considering the feature of high heterogeneity of cancer cells.
- Preparation of end-capped pH-sensitive mesoporous silica nanocarriers for on-demand drug deliveryPublication . Moreira, André; Gaspar, Vítor Manuel Abreu; Costa, Elisabete C.; Diogo, Duarte Miguel de Melo; Machado, Paulo Filipe Brito; Paquete, Catarina; Correia, Ilídio Joaquim SobreiraNanocarriers with a pH responsive behavior are receiving an ever growing attention due to their potential for promoting on-demand drug release and thus increase the therapeutic effectiveness of anti-tumoral pharmaceutics. However, the majority of these systems require costly, time-consuming and complex chemical modifications of materials or drugs to synthesize nanoparticles with pH triggered release. Herein, the development of dual drug loaded pH-responsive mesoporous silica nanoparticles (MSNs) with a calcium carbonate-based coating is presented as an effective alternative. This innovative approach allowed the loading of a non-steroidal anti-inflammatory drug (Ibuprofen) and Doxorubicin, with high efficiency. The resulting dual drug loaded MSNs have spherical morphology and a mean size of 171 nm. Our results indicate that under acidic conditions the coating disassembles and the drugs are rapidly released, whereas at physiologic pH the release is slower and gradually increases with time. Furthermore, an improved cytotoxic effect was obtained for Doxorubicin–Ibuprofen MSNs coated with CaCO3 in comparison with non-coated particles. The cytotoxic effect of dual loaded carbonate coated particles, was similar to that of Doxorubicin + Ibuprofen free drug administration at 72 h, even with the delivery of a significantly lower amount of drug by MSNs-CaCO3. These results suggest that the carbonate coating of MSNs is a promising approach to create a pH-sensitive template for a delivery system with application in cancer therapy.
- Optimization of liquid overlay technique to formulate heterogenic 3D co‐cultures modelsPublication . Costa, Elisabete C.; Gaspar, Vítor Manuel Abreu; Coutinho, Paula; Correia, Ilídio Joaquim SobreiraThree‐dimensional (3D) cell culture models of solid tumors are currently having a tremendous impact in the in vitro screening of candidate anti‐tumoral therapies. These 3D models provide more reliable results than those provided by standard 2D in vitro cell cultures. However, 3D manufacturing techniques need to be further optimized in order to increase the robustness of these models and provide data that can be properly correlated with the in vivo situation. Therefore, in the present study the parameters used for producing multicellular tumor spheroids (MCTS) by liquid overlay technique (LOT) were optimized in order to produce heterogeneous cellular agglomerates comprised of cancer cells and stromal cells, during long periods. Spheroids were produced under highly controlled conditions, namely: (i) agarose coatings; (ii) horizontal stirring, and (iii) a known initial cell number. The simultaneous optimization of these parameters promoted the assembly of 3D characteristic cellular organization similar to that found in the in vivo solid tumors. Such improvements in the LOT technique promoted the assembly of highly reproducible, individual 3D spheroids, with a low cost of production and that can be used for future in vitro drug screening assays.
- Poly(2-ethyl-2-oxazoline)–PLA-g–PEI amphiphilic triblock micelles for co-delivery of minicircle DNA and chemotherapeuticsPublication . Gaspar, Vítor Manuel Abreu; Gonçalves, Cristine; Diogo, Duarte Miguel de Melo; Costa, Elisabete C.; Queiroz, João; Pichon, Chantal; Sousa, Fani; Correia, Ilídio Joaquim SobreiraThe design of nanocarriers for the delivery of drugs and nucleic-acids remains a very challenging goal due to their physicochemical differences. In addition, the reported accelerated clearance and immune response of pegylated nanomedicines highlight the necessity to develop carriers using new materials. Herein, we describe the synthesis of amphiphilic triblock poly(2-ethyl-2-oxazoline)–PLA-g–PEI (PEOz–PLA-g–PEI) micelles for the delivery of minicircle DNA (mcDNA) vectors. In this copolymer the generally used PEG moieties are replaced by the biocompatible PEOz polymer backbone that assembles the hydrophilic shell. The obtained results show that amphiphilic micelles have low critical micellar concentration, are hemocompatible and exhibit stability upon incubation in serum. The uptake in MCF-7 cells was efficient and the nanocarriers achieved 2.7 fold higher expression than control particles. Moreover, mcDNA-loaded micelleplexes penetrated into 3D multicellular spheroids and promoted widespread gene expression. Additionally, to prove the concept of co-delivery, mcDNA and doxorubicin (Dox) were simultaneously encapsulated in PEOz–PLA-g–PEI carriers, with high efficiency. Dox–mcDNA micelleplexes exhibited extensive cellular uptake and demonstrated anti-tumoral activity. These findings led us to conclude that this system has a potential not only for the delivery of novel mcDNA vectors, but also for the co-delivery of drug–mcDNA combinations without PEG functionalization.
- Combinatorial delivery of Crizotinib–Palbociclib–Sildenafil using TPGS-PLA micelles for improved cancer treatmentPublication . Diogo, Duarte Miguel de Melo; Gaspar, Vítor Manuel Abreu; Costa, Elisabete C.; Moreira, André; Oppolzer, David; Gallardo, Eugenia; Correia, Ilídio Joaquim SobreiraThe co-delivery of multiple chemotherapeutics by micellar delivery systems is a valuable approach to improve cancer treatment since various disease hallmarks can be targeted simultaneously. However, the delivery of multiple drugs requires a nanocarrier structure that can encapsulate various bioactive molecules. In this study, we evaluate the simultaneous encapsulation of a novel triple drug combination in D-α-tocopheryl polyethylene glycol 1000 succinate-poly(lactic acid) (TPGS-PLA) amphiphilic micelles for cancer therapy. The drug mixture involves two anti-tumoral drugs, Crizotinib and Palbociclib combined with Sildenafil, a compound that is capable of increasing drug accumulation in the intracellular compartment. Such combination aims to achieve an enhanced cytotoxic effect in cancer cells. Our results demonstrated that TPGS-PLA copolymers self-assembled into stable nanosized micelles (158.3 nm) capable of co-encapsulating the three drugs with high loading efficiency. Triple drug loaded TPGS-PLA micelles were internalized in A549 non-small lung cancer cells and exhibited an improved cytotoxic effect in comparison with single (Crizotinib) or dual (Crizotinib–Palbociclib) drug loaded micelles, indicating the therapeutic potential of the triple co-delivery strategy. These findings demonstrate that TPGS-PLA micelles are suitable carriers for multiple drug delivery and also that this particular drug combination may have potential to improve cancer treatment.
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