Poly(lactic-co-glycolic acid) nanosphere as a vehicle for gene delivery to human cord blood-derived mesenchymal stem cells: comparison with polyethylenimine

Nanoparticles design considerations to co-deliver nucleic acids and anti-cancer drugs for chemoresistance reversal

Chemoresistance and hence the consequent treatment failure is considerably challenging in clinical cancer therapeutics. The understanding of the genetic variations in chemoresistance acquisition encouraged the use of gene modulatory approaches to restore anti-cancer drug efficacy. Many smart nanoparticles are designed and optimized to mediate combinational therapy between nucleic acid and anti-cancer drugs. This review aims to define a rational design of such co-loaded nanocarriers with the aim of chemoresistance reversal at various cellular levels to improve the therapeutic outcome of anticancer treatment. Going through the principles of therapeutics loading, physicochemical characteristics tuning, and different nanocarrier modifications, also looking at combination effectiveness on chemosensitivity restoration. Up to now, these emerging nanocarriers are in development status but are expected to introduce outstanding outcomes.

Construction of an Effective Delivery System for DNA Vaccines Using Biodegradable Polylactic Acid Based Microspheres

Nanotechnology represents a new impetus for biomedical research applications, especially using nanotechnology to formulate microspheres or nanospheres based delivery system for treatment of infectious diseases in animals. In this work, polylactic acid (PLA) microspheres with an average size of 156 nm were prepared by combining emulsion polymerization coupled with emulsion-solvent evaporation. Coating with polyethylenimine (PEI) polymers increased the surface charges of the resulting PLA/PEI microspheres, thus enabled plasmid DNA to adsorb tightly to the microspheres. As expected, the plasmid DNA was successfully transferred into the pig kidney-15 cells with high transfection efficiency. In addition, the protection rate of PLA/PEI microspheres loaded with DNA vaccine against foot-and-mouth disease in guinea pigs reached 87.5%, which was significantly higher than that of the pure DNA vaccine group. These results indicated that PLA/PEI microspheres were expected to be an effective delivery system for DNA vaccines.

PLGA nanoparticles co-delivering MDR1 and BCL2 siRNA for overcoming resistance of paclitaxel and cisplatin in recurrent or advanced ovarian cancer

The inherent or acquired resistance to paclitaxel and cisplatin, which are commonly used chemotherapeutic agents for ovarian cancer treatment, remains an important issue in chemotherapy of multidrug resistant ovarian cancer. Currently, it is still challenging to deal with the recurrent or advanced stage ovarian cancer. When drug efflux and anti-apoptotic pathways are highly interdependent and also involved in developing the resistance of multidrug resistant ovarian cancer, simultaneous inhibition of both pathways represents the potential targets to enhance the efficacy of chemotherapy. Here, we introduce PLGA nanoparticles system as a “dual RNAi delivery system” to contain both MDR1 and BCL2 siRNA, which is designed for simultaneous inhibition of drug efflux and cell death defense pathways. In the present studies, siRNA-loaded PLGA nanoparticles efficiently elicit the simultaneous suppression of both genes, which consequently shows more enhanced drug-sensitivity than sole suppression of drug efflux or anti-apoptosis in the resistant ovarian cancer cells, owing to the interdependence of both pathways. Our siRNA-loaded PLGA nanoparticles for co-delivering MDR1 and BCL2 siRNA provide an efficient combination therapy strategy to overcome the chemoresistance of paclitaxel and cisplatin on the paclitaxel-resistant SKOV3-TR and cisplatin-resistant A2780-CP20 ovarian cancer respectively.

Tripartite polyionic complex (PIC) micelles as non-viral vectors for mesenchymal stem cell siRNA transfection

In the context of regenerative medicine, the use of RNA interference mechanisms has already proven its efficiency in targeting specific gene expression with the aim of enhancing, accelerating or, more generally, directing stem cell differentiation. However, achievement of good transfection levels requires the use of a gene vector. For in vivo applications, synthetic vectors are an interesting option to avoid possible issues associated with viral vectors (safety, production costs, etc.). Herein, we report on the design of tripartite polyionic complex micelles as original non-viral polymeric vectors suited for mesenchymal stem cell transfection with siRNA. Three micelle formulations were designed to exhibit pH-triggered disassembly in an acidic pH range comparable to that of endosomes. One formulation was selected as the most promising with the highest siRNA loading capacity while clearly maintaining pH-triggered disassembly properties. A thorough investigation of the internalization pathway of micelles into cells with tagged siRNA was made before showing an efficient inhibition of Runx2 expression in primary bone marrow-derived stem cells. This work evidenced PIC micelles as promising synthetic vectors that allow efficient MSC transfection and control over their behavior, from the perspective of their clinical use.

Therapeutic Use of 3β-[N-(N',N'-Dimethylaminoethane) Carbamoyl] Cholesterol-Modified PLGA Nanospheres as Gene Delivery Vehicles for Spinal Cord Injury

Gene delivery holds therapeutic promise for the treatment of neurological diseases and spinal cord injury. Although several studies have investigated the use of non-viral vectors, such as polyethylenimine (PEI), their clinical value is limited by their cytotoxicity. Recently, biodegradable poly (lactide-co-glycolide) (PLGA) nanospheres have been explored as non-viral vectors. Here, we show that modification of PLGA nanospheres with 3β-[N-(N′,N′-dimethylaminoethane) carbamoyl] cholesterol (DC-Chol) enhances gene transfection efficiency. PLGA/DC-Chol nanospheres encapsulating DNA were prepared using a double emulsion-solvent evaporation method. PLGA/DC-Chol nanospheres were less cytotoxic than PEI both in vitro and in vivo. DC-Chol modification improved the uptake of nanospheres, thereby increasing their transfection efficiency in mouse neural stem cells in vitro and rat spinal cord in vivo. Also, transgene expression induced by PLGA nanospheres was higher and longer-lasting than that induced by PEI. In a rat model of spinal cord injury, PLGA/DC-Chol nanospheres loaded with vascular endothelial growth factor gene increased angiogenesis at the injury site, improved tissue regeneration, and resulted in better recovery of locomotor function. These results suggest that DC-Chol-modified PLGA nanospheres could serve as therapeutic gene delivery vehicles for spinal cord injury.

Additive nanocomplexes of cationic lipopolymers for improved non-viral gene delivery to mesenchymal stem cells

Additive polyplexes composed of cationic lipopolymers and hyaluronic acid–pDNA combination for implementing gene delivery to mesenchymal stem cells.

Poly(ethyleneimine) functionalized carbon nanotubes as efficient nano-vector for transfecting mesenchymal stem cells

For gene and drug delivery applications, carbon nanotubes (CNTs) have to be functionalized in order to become compatible with aqueous media and bind with genetic materials. In this study, combination of polyethyleneimine (PEI) grafted multi-walled carbon nanotubes (PEI-g-MWCNTs) and chitosan substrate is used as an efficient gene delivery system for transfection of hard-to-transfect bone marrow mesenchymal stem cells (BMSCs) with enhanced green fluorescent protein (EGFP) gene. Fourier transform infrared (FT-IR) spectra, dynamic light scattering (DLS) analysis and zeta potential measurements are used to characterize binding of PEI, particle size distribution and colloidal stability of the functionalized CNTs, respectively. DNA binding affinity, cellular uptake, transfection efficiency and possible cytotoxicity are also tested by agarose gel electrophoresis, flow cytometry, cytochemisty and MTT assay. The results demonstrate that cytotoxic effect of PEI-g-MWCNTs is negligible under optimal transfection condition. In consistency with high cellular uptake (>82%), PEI-g-MWCNTs give higher delivery of EGFP into the BMSCs which results in a more sustained expression of the model gene (EGFP) in short-term culture. These results suggest that PEI-g-MWCNTs in corporation with chitosan substrates would be a promising delivery system for BMSCs, a cell type with relevancy in the regenerative medicine and clinical applications.

Non-viral gene therapy for bone tissue engineering

The possibilities of using gene therapy for bone regeneration have been extensively investigated. Improvements in the design of new transfection agents, combining vectors and delivery/release systems to diminish cytotoxicity and increase transfection efficiencies have led to several successful in vitro, ex vivo and in vivo strategies. These include growth factor or short interfering ribonucleic acid (siRNA) delivery, or even enzyme replacement therapies, and have led to increased osteogenic differentiation and bone formation in vivo. These results provide optimism to consider use in humans with some of these gene-delivery strategies in the near future.

Physical non-viral gene delivery methods for tissue engineering

The integration of gene therapy into tissue engineering to control differentiation and direct tissue formation is not a new concept; however, successful delivery of nucleic acids into primary cells, progenitor cells, and stem cells has proven exceptionally challenging. Viral vectors are generally highly effective at delivering nucleic acids to a variety of cell populations, both dividing and non-dividing, yet these viral vectors are marred by significant safety concerns. Non-viral vectors are preferred for gene therapy, despite lower transfection efficiencies, and possess many customizable attributes that are desirable for tissue engineering applications. However, there is no single non-viral gene delivery strategy that "fits-all" cell types and tissues. Thus, there is a compelling opportunity to examine different non-viral vectors, especially physical vectors, and compare their relative degrees of success. This review examines the advantages and disadvantages of physical non-viral methods (i.e., microinjection, ballistic gene delivery, electroporation, sonoporation, laser irradiation, magnetofection, and electric field-induced molecular vibration), with particular attention given to electroporation because of its versatility, with further special emphasis on Nucleofection™. In addition, attributes of cellular character that can be used to improve differentiation strategies are examined for tissue engineering applications. Ultimately, electroporation exhibits a high transfection efficiency in many cell types, which is highly desirable for tissue engineering applications, but electroporation and other physical non-viral gene delivery methods are still limited by poor cell viability. Overcoming the challenge of poor cell viability in highly efficient physical non-viral techniques is the key to using gene delivery to enhance tissue engineering applications.

PLGA nanoparticles codeliver paclitaxel and Stat3 siRNA to overcome cellular resistance in lung cancer cells

BACKGROUND

Effective cancer chemotherapy remains an important issue in cancer treatment, and signal transducer and activator of transcription-3 (Stat3) activation leads to cellular resistance of anticancer agents. Polymers are ideal vectors to carry both chemotherapeutics and small interfering ribonucleic acid (siRNA) to enhance antitumor efficacy. In this paper, poly(lactic-co-glycolic acid) (PLGA) nanoparticles loaded with paclitaxel and Stat3 siRNA were successfully synthesized, and their applications in cancer cells were investigated.

METHODS

Firstly, paclitaxel was enclosed by PLGA nanoparticles through solvent evaporation. They were then coated with cationic polyethylenimine polymer (PLGA-PEI-TAX), enabling it to carry Stat3 siRNA on its surface through electrostatic interactions (PLGA-PEI-TAX-S3SI). The size, zeta potential, deliver efficacy, and release profile of the PLGA nanocomplexes were characterized in vitro. The cellular uptake, intracellular nanoparticle trajectory, and subsequent cellular events were evaluated after treatment with various PLGA nanocomplexes in human lung cancer A549 cells and A549-derived paclitaxel-resistant A549/T12 cell lines with α-tubulin mutation.

RESULTS

A549 and A549/T12 cells contain constitutively activated Stat3, and silencing Stat3 by siRNA made both cancer cells more sensitive to paclitaxel. Therefore, PLGA-PEI-TAX-S3SI was synthesized to test its therapeutic role in A549 and A549/T12 cells. Transmission electron microscopy showed the size of PLGA-PEI-TAX-S3SI to be around 250 nm. PLGA-PEI nanoparticles were nontoxic. PLGA-PEI-TAX was taken up by A549 and A549/T12 cells more than free paclitaxel, and they induced more condensed microtubule bundles and had higher cytotoxicity in these cancer cells. Moreover, the yellowish fluorescence observed in the cytoplasm of the cancer cells indicates that the PLGA-PEI nanoparticles were still simultaneously delivering Oregon Green paclitaxel and cyanine-5-labeled Stat3 siRNA 3 hours after treatment. Furthermore, after the cancer cells were incubated with the synthesized PLGA nanocomplexes, PLGA-PEI-TAX-S3SI suppressed Stat3 expression and induced more cellular apoptosis in A549 and A549/T12 cells compared with PLGA-PEI-TAX.

CONCLUSION

The PLGA-PEI-TAX-S3SI complex provides a new therapeutic strategy to control cancer cell growth.

Environmental parameters influence non-viral transfection of human mesenchymal stem cells for tissue engineering applications

Non-viral transfection is a promising technique that could be used to increase the therapeutic potential of stem cells. The purpose of this study was to explore practical culture parameters of relevance in potential human mesenchymal stem cell (hMSC) clinical and tissue engineering applications, including type of polycationic transfection reagent, N/P ratio and dose of polycation/pDNA polyplexes, cell passage number, cell density and cell proliferation. The non-viral transfection efficiency was significantly influenced by N/P ratio, polyplex dose, cell density and cell passage number. hMSC culture conditions that inhibited cell division also decreased transfection efficiency, suggesting that strategies to promote hMSC proliferation may be useful to enhance transfection efficiency in future tissue engineering studies. Non-viral transfection treatments influenced hMSC phenotype, including the expression level of the hMSC marker CD105 and the ability of hMSCs to differentiate down the osteogenic and adipogenic lineages. The parameters found here to promote hMSC transfection efficiency, minimize toxicity and influence hMSC phenotype may be instructive in future non-viral transfection studies and tissue engineering applications.

Incorporation of tripolyphosphate nanoparticles into fibrous poly(lactide-co-glycolide) scaffolds for tissue engineering

Poly(lactide-co-glycolide) (PLGA) has been widely used for scaffolding materials in tissue engineering. It degrades mainly via hydrolysis of the ester bonds into lactic acid and glycolic acid leading to the decrease in pH of the surrounding microenvironment. The current study was designed to quickly neutralize the acidic degradation products of PLGA fibrous scaffolds by incorporating tripolyphosphate (TPP) nanoparticles into PLGA fibers. A homogeneous mixture of PLGA and TPP was first obtained by water-in-oil emulsion-dispersion followed by freeze-drying. The dried blend was melt-spun to yield fibers which were processed into scaffolds and subsequently immersed into phosphate-buffered saline (PBS) to verify the degradation properties. The pH of the saline was monitored for a duration of 80 days. The amount of TPP was optimized to obtain a PLGA based scaffolds without acidic degradation problems. Cellular compatibility of the modified and pristine scaffolds was evaluated using rabbit adipose-derived stem cells (rASCs). It was shown that TPP particles within the fibers were roughly 100nm in diameter and mainly located inside fibers instead of on the superficial layer. The acidic degradation of PT-16 and PT-64 (PT-X is termed when the monomer molar ratio of TPP to PLGA was 1:X) was significantly improved as the pH values of their respective solutions were maintained in a well neutralized state during the degradation. PT-64 and PT-16 scaffolds could well support the attachment and proliferation of rASCs. Hence, the incorporation of TPP nanoparticles via an emulsion-dispersion method could be an effective strategy to improve/adjust the acidic degradation of PLGA and further pave the way for clinical applications of such polyesters.

Polymeric nanoparticles for siRNA delivery and gene silencing

Gene silencing using small interfering RNA (siRNA) has several potential therapeutic applications. In the present study, we investigated nanoparticles formulated using the biodegradable polymer, poly(d,l-lactide-co-glycolide) (PLGA) for siRNA delivery. A cationic polymer, polyethylenimine (PEI), was incorporated in the PLGA matrix to improve siRNA encapsulation in PLGA nanoparticles. PLGA-PEI nanoparticles were formulated using double emulsion-solvent evaporation technique and characterized for siRNA encapsulation and in vitro release. The effectiveness of siRNA-loaded PLGA-PEI nanoparticles in silencing a model gene, fire-fly luciferase, was investigated in cell culture. Presence of PEI in PLGA nanoparticle matrix increased siRNA encapsulation by about 2-fold and also improved the siRNA release profile. PLGA-PEI nanoparticles carrying luciferase-targeted siRNA enabled effective silencing of the gene in cells stably expressing luciferase as well as in cells that could be induced to overexpress the gene. Quantitative studies indicated that presence of PEI in PLGA nanoparticles resulted in 2-fold higher cellular uptake of nanoparticles while fluorescence microscopy studies showed that PLGA-PEI nanoparticles delivered the encapsulated siRNA in the cellular cytoplasm; both higher uptake and greater cytosolic delivery could have contributed to the gene silencing effectiveness of PLGA-PEI nanoparticles. Serum stability and lack of cytotoxicity further add to the potential of PLGA-PEI nanoparticles in gene silencing-based therapeutic applications.