Accelerated gene transfer through a polysorbitol-based transporter mechanism

Sugar alcohol-modified polyester nanoparticles for gene delivery via selective caveolae-mediated endocytosis

Nucleic acid-based drugs are changing the scope of emerging medicine in preventing and treating diseases. Nanoparticle systems based on lipids and polymers developed to navigate tissue-level and cellular-level barriers are now emerging as vector systems that can be translated to clinical settings. A class of polymers, poly(β-amino esters) (PBAEs) known for their chemical flexibility and biodegradability, has been explored for gene delivery. These polymers are sensitive to changes in the monomer composition affecting transfection efficiency. Hence to add functionality to these polymers, we partially substituted ligands to an identified effective polymer chemistry. We report here a new series of statistical copolymers based on PBAEs where the backbone is modified with sugar alcohols to selectively facilitate the caveolae-mediated endocytosis pathway of cellular transport. These ligands are grafted at the polymer's backbone, thereby establishing a new strategy of modification in PBAEs. We demonstrate that these polymers form nanoparticles with DNA, show effective complexation and cargo release, enter the cell via selective caveolae-mediated endocytosis, exhibit low cytotoxicity, and increase transfection in neuronal cells.

Vimentin Targeted Nano-gene Carrier for Treatment of Renal Diseases

BACKGROUND

Chronic kidney disease (CKD) is a global health problem, and there is no permanent treatment for reversing kidney failure; thus, early diagnosis and effective treatment are required. Gene therapy has outstanding potential; however, the lack of safe gene delivery vectors, a reasonable transfection rate, and kidney targeting ability limit its application. Nanoparticles can offer innovative ways to diagnose and treat kidney diseases as they facilitate targetability and therapeutic efficacy.

METHODS

Herein, we developed a proximal renal tubule-targeting gene delivery system based on alternative copolymer (PS) of sorbitol and polyethyleneimine (PEI), modified with vimentin-specific chitobionic acid (CA), producing PS-conjugated CA (PSC) for targeting toward vimentin-expressing cells in the kidneys. In vitro studies were used to determine cell viability, transfection efficiency, serum influence, and specific uptake in the human proximal renal tubular epithelial cell line (HK-2). Finally, the targeting efficiency of the prepared PSC gene carriers was checked in a murine model of Alport syndrome.

RESULTS

Our results suggested that the prepared polyplex showed low cytotoxicity, enhanced transfection efficiency, specific uptake toward HK-2 cells, and excellent targeting efficiency toward the kidneys.

CONCLUSION

Collectively, from these results it can be inferred that the PSC can be further evaluated as a potential gene carrier for the kidney-targeted delivery of therapeutic genes for treating diseases.

Highly Osmotic Oxidized Sucrose-Crosslinked Polyethylenimine for Gene Delivery Systems

In this work, highly osmotic oxidized sucrose-crosslinked polyethylenimine (SP2K) polymers were developed for gene delivery systems, and the transfection mechanism is examined. First, periodate-oxidized sucrose and polyethylenimine 2K (PEI2K) were crosslinked with various feed ratios via reductive amination. The synthesis was confirmed by ¹H NMR and FTIR. The synthesized SP2K polymers could form positively charged (~40 mV zeta-potential) and nano-sized (150–200 nm) spherical polyplexes with plasmid DNA (pDNA). They showed lower cytotoxicity than PEI25K but concentration-dependent cytotoxicity. Among them, SP2K7 and SP2K10 showed higher transfection efficiency than PEI25K in both serum and serum-free conditions, revealing the good serum stability. It was found that SP2K polymers possessed high osmolality and endosome buffering capacity. The transfection experiments with cellular uptake inhibitors suggest that the transfection of SP2K polymers would progress by multiple pathways, including caveolae-mediated endocytosis. It was also thought that caveolae-mediated endocytosis of SP2K polyplexes would be facilitated through cyclooxygenase-2 (COX-2) expression induced by high osmotic pressure of SP2K polymers. Confocal microscopy results also supported that SP2K polyplexes would be internalized into cells via multiple pathways and escape endosomes efficiently via high osmolality and endosome buffering capacity. These results demonstrate the potential of SP2K polymers for gene delivery systems.

Enhance transgene responses through improving cellular uptake and intracellular trafficking by bio-inspired non-viral vectors

Background

Gene therapy remains a significant challenge due to lots of barriers limiting the genetic manipulation technologies. As for non-viral delivery vectors, they often suffer insufficient performance due to inadequate cellular uptake and gene degradation in endosome or lysosome. The importance of overcoming these conserved intracellular barriers is increasing as the delivery of genetic cargo.

Results

A surface-functionalized non-viral vector involving the biomimetic mannitol moiety is initiated, which can control the cellular uptake and promote the caveolae-mediated pathway and intracellular trafficking, thus avoiding acidic and enzymatic lysosomal degradation of loaded gene internalized by clathrin-mediated pathway. Different degrees of mannitol moiety are anchored onto the surface of the nanoparticles to form bio-inspired non-viral vectors and CaP-MA-40 exhibits remarkably high stability, negligible toxicity, and significantly enhanced transgene expression both in vitro and in vivo.

Conclusions

This strategy highlights a paradigmatic approach to construct vectors that need precise intracellular delivery for innovative applications.

Sugar alcohol-based polymeric gene carriers: Synthesis, properties and gene therapy applications

Advances in the field of nanomedicine have led to the development of various gene carriers with desirable cellular responses. However, unfavorable stability and physicochemical properties have hindered their applications in vivo. Therefore, multifunctional, smart nanocarriers with unique properties to overcome such drawbacks are needed. Among them, sugar alcohol-based nanoparticle with abundant surface chemistry, numerous hydroxyl groups, acceptable biocompatibility and biodegradable property are considered as the recent additions to the growing list of non-viral vectors. In this review, we present some of the major advances in our laboratory in developing sugar-based polymers as non-viral gene delivery vectors to treat various diseases. We also discuss some of the open questions in this field. STATEMENT OF SIGNIFICANCE: Recently, the development of sugar alcohol-based polymers conjugated with polyethylenimine (PEI) has attracted tremendous interest as gene delivery vectors. First, the natural backbone of polymers with their numerous hydroxyl groups display a wide range of hyperosmotic properties and can thereby enhance the cellular uptake of genetic materials via receptor-mediated endocytosis. Second, conjugation of a PEI backbone with sugar alcohols via Michael addition contributes to buffering capacity and thereby the proton sponge effect. Last, sugar alcohol based gene delivery systems improves therapeutic efficacy both in vitro and in vivo.

M cell targeting engineered biomaterials for effective vaccination

Vaccines are one of the greatest medical interventions of all time and have been successful in controlling and eliminating a myriad of diseases over the past two centuries. Among several vaccination strategies, mucosal vaccines have wide clinical applications and attract considerable interest in research, showing potential as innovative and novel therapeutics. In mucosal vaccination, targeting (microfold) M cells is a frontline prerequisite for inducing effective antigen-specific immunostimulatory effects. In this review, we primarily focus on materials engineered for use as vaccine delivery platforms to target M cells. We also describe potential M cell targeting areas, methods to overcome current challenges and limitations of the field. Furthermore, we present the potential of biomaterials engineering as well as various natural and synthetic delivery technologies to overcome the challenges of M cell targeting, all of which are absent in current literature. Finally, we briefly discuss manufacturing and regulatory processes to bring a robust perspective on the feasibility and potential of this next-generation vaccine technology.

Macrocycle-wrapped polyethylenimine for gene delivery with reduced cytotoxicity

Due to its outstanding capability to facilitate DNA condensation, transportation and endosomal escape, polyethylenimine (PEI) has been frequently studied for gene delivery. However, its molecular weight (M.W.) dependent transfection efficiency and cytotoxicity has severely limited its clinical application. To resolve this dilemma, a supramolecular strategy was developed for the first time, in which PEI with large M.W. (branched, 25 kDa) that has a satisfactory transfection efficiency, yet high non-specific cytotoxicity for gene delivery was wrapped with macrocyclic cucurbit[7]uril (CB[7]). The successful wrapping of the PEI by the macrocyclic CB[7] was proved by 1H NMR spectroscopy and supported by isothermal titration calorimetry (ITC). The plasmid DNA (pDNA) condensability of PEI was not affected by the supramolecular coating as evidenced from the agarose gel electrophoresis assay. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) results demonstrated that the particle size, zeta potential, and morphology of the self-assemblies of PEI/pDNA and PEI/CB[7]/pDNA were comparable. As a consequence of the supramolecular wrapping, the cytotoxicity of PEI was significantly constrained as demonstrated by MTT assay, apoptosis assay, and a hemolysis study. In particular, both the cellular uptake and the gene transfection efficiency results suggest that the supramolecular wrapping of PEI by CB[7] exhibits negligible effects on PEI, thus functioning as an effective non-viral gene delivery vector. This novel supramolecular-wrapping strategy provides new insights for facile alleviation of the non-specific toxicity of PEI and potentially other polycationic gene vectors without compromising their transfection efficiency.

Restoration of tumour-growth suppression in vivo via systemic nanoparticle-mediated delivery of PTEN mRNA

PTEN is a well-characterized tumour-suppressor gene that is lost or mutated in about half of metastatic castration-resistant prostate cancers and in many other human cancers. The restoration of functional PTEN as a treatment for prostate cancer has however proven difficult. Here, we show that PTEN mRNA can be reintroduced into PTEN-null prostate cancer cells in vitro and in vivo via its encapsulation in polymer-lipid hybrid nanoparticles coated with a poly(ethylene glycol) shell. The nanoparticles are stable in serum, elicit low toxicity, enable high PTEN mRNA transfection in prostate cancer cells, and lead to significant inhibition of tumour growth when delivered systemically in multiple mouse models of prostate cancer. We also show that the restoration of PTEN function in PTEN-null prostate cancer cells inhibits the PI3K-AKT pathway and enhances apoptosis. Our findings provide proof-of-principle evidence of the restoration of mRNA-based tumour suppression in vivo.

Investigation on vascular cytotoxicity and extravascular transport of cationic polymer nanoparticles using perfusable 3D microvessel model

Vascular networks are the first sites exposed to cationic polymer nanoparticles (NPs) administered intravenously, and thus function as a barrier for NPs reaching the target organ. While cationic polymer NPs have been intensively studied as non-viral delivery systems, their biological effects in human microvessels have been poorly investigated due to a lack of appropriate in vitro systems. Here, we employed a three-dimensional microvessel on a chip, which accurately models in vivo conditions. An open and perfused microvessel surrounded by pericytes was shown to reproduce the important features of living vasculature, including barrier function and biomarkers. Using this microvessel chip, we observed contraction of the microvascular lumen induced by perfused polyethylenimine (PEI)/DNA NPs. We demonstrated that the oxidative stress present when microvessels were exposed to PEI NPs led to rearrangement of microtubules resulting in microvessel contraction. Furthermore, the transcytotic behavior of PEI NPs was analyzed in the microvessel by monitoring the escape of PEI NPs from the microvascular lumen into the perivascular region, which was not possible in two-dimensional culture systems. With our new understanding of the different behaviors of cationic polymer NPs depending on their transcytotic route, we suggest that caveolae-mediated transcytosis is a powerful route for efficient extravascular transport.

STATEMENT OF SIGNIFICANCE

Microvascular networks are not only biological system constituting largest surface area in the body and but also first site exposed to nanoparticle in vivo. While cationic polymer NPs have been intensively studied as non-viral delivery systems, its biological effects in human microvessel have been poorly investigated due to lack of appropriate in vitro systems. Here, we microengineered an open and perfused 3D pericyte incorporated microvessel model which possesses same morphological characteristic of in vivo. Using the microengineered model, this study represents the first report of transcytotic behavior of NPs in 3D microvessel, and its effect on extravasation efficiency. Our study lays the groundwork for the integration of innovative technologies to examine blood vessel-nanoparticle interaction, which a critical but ill-defined phenomenon.

Stimuli-Regulated Smart Polymeric Systems for Gene Therapy

The physiological condition of the human body is a composite of different environments, each with its own parameters that may differ under normal, as well as diseased conditions. These environmental conditions include factors, such as pH, temperature and enzymes that are specific to a type of cell, tissue or organ or a pathological state, such as inflammation, cancer or infection. These conditions can act as specific triggers or stimuli for the efficient release of therapeutics at their destination by overcoming many physiological and biological barriers. The efficacy of conventional treatment modalities can be enhanced, side effects decreased and patient compliance improved by using stimuli-responsive material that respond to these triggers at the target site. These stimuli or triggers can be physical, chemical or biological and can be internal or external in nature. Many smart/intelligent stimuli-responsive therapeutic gene carriers have been developed that can respond to either internal stimuli, which may be normally present, overexpressed or present in decreased levels, owing to a disease, or to stimuli that are applied externally, such as magnetic fields. This review focuses on the effects of various internal stimuli, such as temperature, pH, redox potential, enzymes, osmotic activity and other biomolecules that are present in the body, on modulating gene expression by using stimuli-regulated smart polymeric carriers.

Gene therapy for bone tissue engineering

Gene therapy holds a great promise and has been extensively investigated to improve bone formation and regeneration therapies in bone tissue engineering. A variety of osteogenic genes can be delivered by combining different vectors (viral or non-viral), scaffolds and delivery methodologies. Ex vivo & in vivo gene enhanced tissue engineering approaches have led to successful osteogenic differentiation and bone formation. In this article, we review recent advances of gene therapy-based bone tissue engineering discussing strengths and weaknesses of various strategies as well as general overview of gene therapy.

Efficient gene transfection to liver cells via the cellular regulation of a multifunctional polylactitol-based gene transporter

A new polylactitol-based multifunctional gene carrier has shown low cytotoxicity, a high transfection efficiency, and liver cell targeting bothin vitroandin vivo.

Hyperosmotic polydixylitol for crossing the blood brain barrier and efficient nucleic acid delivery

Here, we introduce a polydixylitol based highly osmotic polymer that not only transmigrates the BBB by intra-arterial infusion of osmotic polyol but also triggers cellular uptake via modulation of caveolae mediated endocytosis.

Suppression of tumor growth in lung cancer xenograft model mice by poly(sorbitol-co-PEI)-mediated delivery of osteopontin siRNA

Small interfering RNA (siRNA)-mediated gene silencing represents a promising strategy for treating diseases such as cancer; however, specific gene silencing requires an effective delivery system to overcome the instability and low transfection efficiency of siRNAs. To address this issue, a polysorbitol-based transporter (PSOT) was prepared by low molecular weight branched polyethylenimine (bPEI) crosslinked with sorbitol diacrylate (SDA). Osteopontin (OPN) gene, which is highly associated with non-small cell lung cancer (NSCLC) was targeted by siRNA therapy using siRNA targeting OPN (siOPN). Characterization study confirmed that PSOT formed compact complexes with siOPN and protected siOPN against degradation by RNase. PSOT/siOPN complexes demonstrated low cytotoxicity and enhanced transfection efficiency in vitro, suggesting that this carrier may be suitable for gene silencing. In the A549 and H460 lung cancer cell lines, PSOT/siOPN complexes demonstrated significant silencing efficiency at both RNA and protein levels. To study in vivo tumor growth suppression, two lung cancer cell-xenograft mouse models were prepared and PSOT/siOPN complexes were delivered into the mice through intravenous injection. The siOPN-treated groups demonstrated significantly reduced OPN expression at both the RNA and protein levels as well as suppression of tumor volume and weight. Taken together, siOPN delivery using PSOT may present an effective and novel therapeutic system for lung cancer treatment.

Diglycidyl Esters Cross-Linked with Low Molecular Weight Polyethyleneimine for Magnetofection

Magnetic polyethyleneimine (PEI) complexes have demonstrated to be simple and efficient vectors for enhancing gene transfection. However, the high cytotoxicity of PEI restricts its further application in vivo. In this study, we synthesized several low cytotoxicity biodegradable cationic polymers derived from PEI (Mw 600) linked with diglycidyl tartrate (DT-PEI) or its analogues (diglycidyl succinate (DS-PEI) and diglycidyl malate (DM-PEI); D-PEIs for all 3 polymers). Moreover, a type of biocompatible magnetic nanoparticles (MNPs) with negative charges was prepared to assemble with D-PEIs/DNA complexes via electrostatic interactions. The magnetic ternary complexes have appropriate sizes of 120–150 nm and zeta potential values of ~20–25 mV. The transfection ability and cell viability of D-PEIs increased as the amount of hydroxyl groups increased in the repeat unit, which indicated that increasing the hydroxyl number in the backbone of D-PEIs can enhance gene expression and decrease cytotoxicity in A549 cells. Magnetofection of DT-PEI showed similar transfection efficiency with 30 min incubation; in contrast, the standard incubation time was 4 h. All three magnetic complexes displayed lower cytotoxicity when compared with those of PEI complexes in COS-7 and A549. These results indicated that these series of magnetic PEI derivatives complexes could be potential nanocarriers for gene delivery.

Formulation of glutathione responsive anti-proliferative nanoparticles from thiolated Akt1 siRNA and disulfide-crosslinked PEI for efficient anti-cancer gene therapy

In this study, thiol-modified siRNA (SH-siRNA) was delivered by bioreducible polyethylenimine (ssPEI), to enhance physicochemical properties of polyplexes and function of siRNA through disulfide bonding between SH-siRNA and ssPEI. The ssPEI was utilized to deliver Akt1 SH-siRNA for suppression of Akt1 mRNA and blockage of Akt1 protein translation, resulting in reduced cellular proliferation and the induction of apoptosis. Disulfide bondings between the ssPEI and SH-siRNA through thiol groups in both were confirmed by DTT treatment. Complexation between ssPEI and Akt1SH-siRNA was enhanced and reduced surface charge of ssPEI/Akt1SH-siRNA complexes with smaller average particle sizes even at lower N/P ratios was obtained compared with PEI/Akt1siRNA ones. Cellular uptake of ssPEI/Akt1SH-siRNA complexes in CT-26 mouse colon cancer cells was also enhanced. The ssPEI/Akt1SH-siRNA complexes reduced proliferation and increased apoptosis of mouse colon cancer cells in vitro. In an in vivo mouse tumor model, the complexes reduced tumor proliferation and downregulation of Akt1 compared to controls.

Induction of long-term immunity against respiratory syncytial virus glycoprotein by an osmotic polymeric nanocarrier

Respiratory syncytial virus (RSV) is one of the most common causes of viral deaths in infants worldwide, yet no effective vaccines are available. Here, we report an osmotically active polysaccharide-based polysorbitol transporter (PST) prepared from sorbitol diacrylate and low-molecular-weight polyethylenimine (PEI) showing a potent, yet safe, adjuvant activity and acting as an effective delivery tool for RSV glycoprotein (RGp) antigen. PST showed no toxicity in vitro or in vivo, unlike PEI and the well-known experimental mucosal adjuvant cholera toxin (CT). PST formed nano-sized complexes with RGp by simple mixing, without affecting antigenic stability. The complexes exhibited negative surface charges that made them highly efficient in the selective activation of phagocytic cells and enhancement of phagocytic uptake. This resulted in an improved cytokine production and in the significant augmentation of RGp-specific antibody production, which persisted for over 200 days. Interestingly, PST/RGp enhanced phagocytic uptake owing to the osmotic property of PST and its negative zeta potential, suggesting that PST could selectively stimulate phagocytic cells, thereby facilitating a long-lived antigen-specific immune response, which was presumably further enhanced by the polysaccharide properties of PST.

MicroRNA delivery with osmotic polysorbitol-based transporter suppresses breast cancer cell proliferation

MicroRNAs (miRNA) are short oligonucleotides of endogenous origin involved in post-transcriptional regulation and are altered in disease, making them potential therapeutic targets. miRNA replacement is necessary in cells with downregulated miRNAs levels in response to disease. miRNA 145 is a novel tumor suppressor gene involved in cell suppression, invasion and migration of cancer cells; it is downregulated in most cancers. Delivery of therapeutic miRNA using nanoparticles enhances the chances of successful delivery and expression of genes at the target site. We evaluated polysorbitol-mediated transporter (PSMT) in the cellular delivery of miRNA 145. The polysorbitol backbone possesses osmotic properties and leads to enhanced cellular uptake. PSMT delivers genes into cells by a caveolae-mediated endocytic pathway. Caveolae expression is usually altered in transformed cancer cells. Physicochemical characterization, and the transfection efficiency and transgene expression capability of PSMT/reporter plasmid DNA nanoparticles, were determined. GFP-tagged miRNA 145 delivery with PSMT was confirmed by confocal microscopy and Western blotting. The functional effects of miRNA 145 delivered with PSMT were analyzed by confocal microscopy, as well as in apoptosis, proliferation and wound healing assays. Finally, the expression of an miRNA 145 target protein, c-myc, was determined by Western blotting after intracellular delivery of PSMT/miRNA 145 nanoparticle (NP).

Selective transfection with osmotically active sorbitol modified PEI nanoparticles for enhanced anti-cancer gene therapy

Polysorbitol-mediated transporter (PSMT) has been previously shown to achieve high transfection efficiency with minimal cytotoxicity. Polysorbitol backbone possesses osmotic properties and leads to enhanced cellular uptake. The PSMT/pDNA nanoparticles were prepared and the particle size, surface charge of the nanoparticles was determined for the study. PSMT delivers genes into cells by the caveolae mediated endocytic pathway. Caveolae expression is usually altered in transformed cancer cells. Transfection through the caveolae may help PSMT to selectively transfect cancer cells rather than normal cells. Transfection of the luciferase gene by PSMT was tested in various cell types including cancer cell lines, primary cells, and immortalized cells. Luciferase transgene expression mediated by PSMT was remarkably increased in HeLa cells compared to expression using the control carrier Lipofectamine. Moreover, the toxicity of PSMT was comparable to the control carrier (Lipofectamine) in the same cells. Selective transfection of cancer cells using PSMT was further confirmed by co-culture of cancer and normal cells, which showed that transgene expression was pre-dominantly achieved in cancer cells. A functional p53 gene was also delivered into HeLa cells using PSMT and the selective transgene expression of p53 protein in cancer cells was analyzed through western blotting and confocal microscopy. HeLa cells transfected with PSMT/p53 plasmid nanoparticles showed cellular damage and apoptosis, which was confirmed through propidium iodide staining.

The effect of RNAi silencing of p62 using an osmotic polysorbitol transporter on autophagy and tumorigenesis in lungs of K-rasLA1 mice

Treating cancer patients by conventional chemotherapy to achieve prolonged survival still remains complicated. Autophagy is a topic of considerable interest in recent times, as it may contribute greatly to tumor suppression. Recent studies indicate that autophagy-deficient cells accumulate high levels of p62, an ubiquitin-binding scaffold protein, involved greatly in tumorigenesis. Here, we synthesized an osmotically active polysorbitol-mediated transporter (PSMT) to downregulate p62 using an RNAi strategy and described the mechanism of how p62 silencing using PSMT/siRNA p62 system activates autophagy and contributes to tumor suppression in the lungs of K-ras(LA1) mice. Downregulation of p62 by PSMT/siRNA p62 activated autophagy confirmed by the formation of autophagosomes and swelling of Golgi apparatus with a decreasing level of GM130, a cis-Golgi matrix protein. Activation of osmotic PSMT-mediated autophagy remarkably reduced the size and number of tumors by suppressing proliferative cell nuclear antigen, cluster of differentiation 31, and vascular endothelial growth factor levels. Furthermore, an increase in apoptosis was observed in the lungs of PSMT/siRNA p62-delivered K-ras(LA1) mice.

Ternary nanoparticles composed of cationic solid lipid nanoparticles, protamine, and DNA for gene delivery

Background

The objective of this research was to design an effective gene delivery system composed of cationic solid lipid nanoparticles (SLNs), protamine, and Deoxyribonucleic acid DNA.

Methods

Cationic SLNs were prepared using an aqueous solvent diffusion method with octadecylamine as the cationic lipid material. First, protamine was combined with DNA to form binary protamine/DNA nanoparticles, and the ternary nanoparticle gene delivery system was then obtained by combining binary protamine/DNA nanoparticles with cationic SLNs. The size, zeta potential, and ability of the binary and ternary nanoparticles to compact and protect DNA were characterized. The effect of octadecylamine content in SLNs and the SLNS/DNA ratios on transfection efficiency, cellular uptake and cytotoxicity of the ternary nanoparticles were also assessed using HEK293 cells.

Results

When the weight ratio of protamine to DNA reached 1.5:1, the plasmid DNA could be effectively compacted and protected. The average hydrodynamic diameter of the ternary nanoparticles when combined with protamine increased from 188.50 ± 0.26 nm to 259.33 ± 3.44 nm, and the zeta potential increased from 25.50 ± 3.30 mV to 33.40 ± 2.80 mV when the weight ratio of SLNs to DNA increased from 16/3 to 80/3. The ternary nanoparticles showed high gene transfection efficiency compared with Lipofectamine™ 2000/DNA nanoparticles. Several factors that might affect gene transfection efficiency, such as content and composition of SLNs, post-transfection time, and serum were examined. The ternary nanoparticles composed of SLNs with 15 wt% octadecylamine (50/3 weight ratio of SLNs to DNA) showed the best transfection efficiency (26.13% ± 5.22%) in the presence of serum. It was also found that cellular uptake of the ternary nanoparticles was better than that of the SLN/DNA and binary protamine/DNA nanoparticle systems, and DNA could be transported to the nucleus.

Conclusion

SLNs enhanced entry of binary protamine/DNA nanoparticles into the cell, and protamine protected DNA from enzyme degradation and transported DNA into the nucleus. Compared with Lipofectamine 2000/DNA nanoparticles, these cationic ternary nanoparticles showed relatively durable and stable gene transfection in the presence of serum.

Design and Development of Degradable Polyethylenimines for Delivery of DNA and Small Interfering RNA: An Updated Review

Polyethylenimine (PEI), considered as the most potent and promising alternative carrier to viral vectors, has been studied as the “state of the art” among various polymers for nonviral gene delivery applications for many years. Although PEI-based carrier minimizes the bottlenecks associated with viral vectors such as unwanted immunogenicity and production problems, the toxic side effects of PEI prevent its rapid advancements due to nondegradable nature. In this regard, various degradable cross-linking and/or grafting agents have been linked to synthesize degradable PEIs in order to minimize the toxicity and improve the efficacy of PEI-mediated gene carriers. This paper describes an update on various cross-linkers and grafting agents in the design and development of degradable PEI derivatives and their potential applications for effective delivery of DNA in vitro and in vivo. The molecular weight (MW) of PEI and the structural relationship to its cellular toxicity and transfection ability were also discussed. Finally, the potential applications of various degradable PEIs for small interfering RNA (siRNA)-mediated gene silencing were also covered.

Selective stimulation of caveolae-mediated endocytosis by an osmotic polymannitol-based gene transporter

Controlling the cellular uptake mechanism and consequent intracellular route of polyplexes is important to improve the transfection efficiency of the non-viral gene delivery. Here, we report a new non-viral vector, polymannitol-based gene transporter (PMT), generated by crosslinking low molecular weight polyethylenimine with mannitol diacrylate, which has low cytotoxicity and good transfection efficiency. Interestingly, the uptake pathway of PMT/DNA complexes was shifted into caveolae-mediated endocytosis, avoiding lysosomal degradation. The mechanism of increased caveolae-mediated endocytosis of PMT/DNA complexes was found to be correlated with mechanosensing signal transduction by the hyperosmotic polymannitol part. Our results suggested that PMT, polymannitol-based gene transporter, is a safe and efficient gene delivery system with a well-modulated uptake pathway and intracellular route for gene therapy.

High gene transfer by the osmotic polysorbitol-mediated transporter through the selective caveolae endocytic pathway

Cationic polymers have been the subject of intense research as nonviral gene delivery systems due to several advantages in comparison with viral vectors. However, the nonsimultaneous combination of high transfection efficiency and low cytotoxicity of nonviral vectors for gene delivery has long been an issue for scientists looking into ways to deliver genes into cells. Toward this goal, we designed, synthesized, and evaluated a safe and accelerated gene transfer system through polysorbitol-mediated transporter (PSMT) based on sorbitol diacrylate (SDA) and low molecular weight polyethylenimine (LMW PEI). The PSMT formed stable complexes with plasmid DNA in serum. The nano sizes and spherical shapes of PSMT/DNA complexes are not toxic, even at a high concentration of PSMT. The higher transfection efficiency of PSMT compared to PEI 25K was observed both in vitro, despite the existence of many hydroxyl groups, and in vivo. These improvements presumably stem from the osmotic property of polysorbitol and endosomal buffer capacity of PEI in PSMT. Most importantly, we confirmed that the selective cavaeolae endocytic pathway played a role in high transfection efficiency by osmotic PSMT-mediated gene delivery. We propose that PSMT is a promising nonviral carrier for the effective gene delivery to cancer cells via synergistic effects derived from rapid cellular uptake through the caveolae endocytic pathway and a high endosomal buffering capacity.