Cell-penetrating peptides (CPPs) are a promising non-viral vector for gene and drug delivery. CPPs exhibit high cell transfection, and are biocompatible. They can be also conjugated with organic and inorganic nanomaterials, such as magnetic nanoparticles (MNPs), graphene oxide (GO), metal-organic frameworks (MOFs), and chitosan. Nanomaterials offered a high specific surface area and provided relatively straightforward methods to be modified with biomolecules including CPPs and oligonucleotides (ONs). Novel nanomaterials conjugates with CPP/ONs complexes are therefore of interest for cell transfection with high efficiency. In this chapter, we described a summary of the non-viral vectors consisting of CPPs and nanomaterials. The book chapter also included a protocol to generate hybrid biomaterials consisting of CPPs and nanoparticles (NPs) for the delivery of oligonucleotides. The conjugation of NPs with CPPs serves as an effective platform for gene therapy with high cell transfection efficiency. The protocol is simple, offers high cell transfection compared to the CPPs-ONs complexes, and can be used for further improvements using external stimuli.

Hierarchical mesoporous carbon (MPC) nanomaterials derived from the carbonized chitosan (CTS) encapsulated zeolitic imidazolate frameworks (ZIF-8) is synthesized and applied for gene delivery. The synthesis of ZIF-8 is achieved at room temperature using water as a solvent in the presence of CTS within 60 min. The synthesis method offered a hierarchical porous structure of ZIF-8. The carbonization of the prepared materials leads to the formation of MPC nanomaterials. MPC materials were applied as a non-viral vectors for gene delivery using two oligonucleotides (ONs) called Luciferase-expressing plasmid (pGL3), and splice correction oligonucleotides (SCO). The materials are biocompatible and showed insignificant toxicity. The transfection using MPC with and without cell-penetrating peptides (CPPs) was reported. MPC improved the transfection efficiency of CPPs (PepFect 14 (PF-14), and PF-221) by 10 fold due to the synergistic effect of MCP and CPPs. The reasonable mechanism for the cell transfection using these new vectors was also highlighted.

Cell-penetrating peptides (CPPs), and metal-organic frameworks (MOFs) are promising as next-generation for the delivery of gene-based therapeutic agents. Oligonucleotide (ON)-mediated assembly of nanostructures composed of hierarchical porous zeolitic imidazolate framework (ZIF-8), and nanoparticles such as graphene oxide (GO), and magnetic nanoparticles (MNPs) for gene therapy are reported. Five different types of non-viral vectors (ZIF-8, RhB@ZIF-8, BSA@ZIF-8, MNPs@ZIF-8, and GO@ZIF-8), and three gene therapeutic agents (plasmid, splice correction oligonucleotides (SCO), and small interfering RNA (siRNA)) were investigated. The polyplexes were characterized and applied for gene transfection. The materials show very low toxicity with high efficiency for luciferase transfection. ZIF-8 enhances the transfection of plasmid, SCO, siRNA of CPPs by 2-8 folds. The mechanism of the cell uptakes was also highlighted. Data reveal cell internalization via scavenger class A (SCARA).

Cell-penetrating peptides (CPPs) are short peptides that are able to efficiently penetrate cellular lipid bilayers. Although CPPs have been used as carriers in conjugation with certain cargos to target specific genes and pathways, how rationally designed CPPs per se affect global gene expression has not been investigated. Therefore, following time course treatments with 4 CPPs-penetratin, PepFect14, mtCPP1 and TP10, HeLa cells were transcriptionally profiled by RNA sequencing. Results from these analyses showed a time-dependent response to different CPPs, with specific sets of genes related to ribosome biogenesis, microtubule dynamics and long-noncoding RNAs being differentially expressed compared to untreated controls. By using an image-based high content phenotypic profiling platform we confirmed that differential gene expression in CPP-treated HeLa cells strongly correlates with changes in cellular phenotypes such as increased nucleolar size and dispersed microtubules, compatible with altered ribosome biogenesis and cell growth. Altogether these results suggest that cells respond to different cell penetrating peptides by alteration of specific sets of genes, which are possibly part of the common response to such stimulus.

Delivery of nucleic acid is a promising approach for genetic diseases/disorders. However, gene therapy using oligonucleotides (ONs) suffers from low transfection efficacy due to negative charges, weak cellular permeability, and enzymatic degradation. Thus, cell-penetrating peptide (CPP), is a short cationic peptide, is used to improve the cell transfection. In this thesis, new strategies for gene transfection using the CPP vectors in complex with ONs without and with nanoparticles, such as magnetic nanoparticles (MNPs, Fe₃O₄), and graphene oxide (GO), are investigated. Furthermore, the possible CPP uptake signalling pathways are also discussed.

A fragment quantitative structure-activity relationship (FQSAR) model is applied to predict new effective peptides for plasmid DNA transfection. The best-predicted peptides were able to transfect plasmids with significant enhancement compared to the other peptides. CPPs (PeptFect220 (denoted PF220), PF221, PF222, PF223, PF224) generated from the FQSAR, and standard PF14 were able to form self-assembled complexes with MNPs and GO. The formed new hybrid vectors improved the cell transfection for plasmid (pGL3), splicing correcting oligonucleotides (SCO), and small interfering RNA (siRNA). These vectors showed high cell biocompatibility and offered high transfection efficiency (> 4-fold for MNPs, 10–25-fold for GO) compared to PF14/SCO complex, which was before reported with a higher efficacy compared to the commercial lipid-based transfection vector Lipofectamine™2000. The high transfection efficiency of the novel complexes (CPP/ON/MNPs and CPP/ON/GO) may be due to their low cytotoxicity, and the synergistic effect of MNPs, GO, and CPPs. In vivo gene delivery using PF14/pDNA/MNPs was also reported. The assembly of CPPs/ON with MNPs or GO is promising and may open new venues for potent and selective gene therapy using external stimuli. The uptake signaling pathways using CPPs vectors, the RNA expression profile for PF14, with and without ON were investigated using RNA sequencing and qPCR analysis. Data showed that the signaling pathways are due to the regulation of autophagy-related genes. Our study revealed that the autophagy regulating proteins are concentration-dependent. Confocal microscopy and transmission electron microscopy have demonstrated the autophagy initiation and colocalization of ON with autophagosomes. Results showed that the cellular uptake of CPP-based transfection activates the autophagy signaling pathway. These findings may open new opportunities to use autophagy modifiers in gene therapy.

Genterapi med hjälp av av oligonukleotider (ON) har en enorm potential för behandling av olika genetiska sjukdomar. För att ha terapeutisk effekt måste dock oligonukleotiderna nå in i cellen och detta försvåras på grund av deras negativa laddningar och snabba nedbrytning. Cellpenetrerande peptider (CPP), är korta katjoniska peptider, som kan användas för att förbättra det cellulära upptaget (transfektionen) av oligonukleotider. I denna avhandling undersöks nya strategier för hur CPP tillsammans med magnetiska nanopartiklar, såsom MNP och Fe3O4, eller grafenoxid (GO) nanopartiklar, kan möjliggöra effektivare transfektion av ON.  Vidare studeras även de möjliga cellulära signalvägar som reglerar CPP-medierat upptag.

En så kallad ”fragment quantitative structure-activity relationship” (FQSAR) modell  användes för att förutsäga nya effektiva CPP för leverans av plasmider (ringformade DNA-molekyler med omkring 5000 nukleotidbaspar). De bäst prediktade peptiderna visade en signifikant ökad transfektionsförmåga jämfört med den tidigare använda peptiden PeptFect 14 (PF14). De nya peptiderna PF220, PF221, PF222, PF223 och PF224 som identifierades med FQSAR kunde dessutom bilda självmonterande komplex med MNP eller GO nanopartiklar. I cellulära försök uppvisade dessa nya hybridvektorer (CPP/MNP och CPP/GO) en klart förbättrad transfektionsförmåga av såväl plasmider, som splitsningskorrigerande oligonukleotider (SCO) och små interfererande RNA (siRNA), jämfört med PF14-nanopartikel hybridvektorer, såväl som den kommersiella lipidbaserade transfektionsvektorn Lipofectamine™ 2000. Den höga transfektionseffektiviteten hos dessa nya hybridvektorer beror troligen på deras låga cellulära toxicitet och en möjlig synergistisk effekt vid kombinationen av CPP och MNP/GO nanopartiklar. Förmågan hos en CPP/MNP hybridvektor att levera plasmider in vivo undersöktes också och transfektion av celler i såväl lunga och mjälte i behandlade djur kunde påvisas. Dessa nya hybridvektorer utgör således en ny lovande strategi för leverans av ON vid genterapi.

För att kartlägga de signalvägar som kontrollerar upptaget av CPP-baserade vektorer analyserades  genuttrycket hos celler som transfekterats med PF14 eller PF14-ON, med hjälp av  RNA-sekvensering och qPCR-analys. Resultaten påvisade att en ökning i uttrycket av flera autofagirelaterade gener sker tidigt vid transfektionen. Konfokal- och transmissionselektronmikroskopi demonstrerade vidare en ökad initiering av autofagi och samlokalisering av ON med autofagosomer. Detta visar att CPP-medierad transfektion aktiverar signalvägar som stryr autofagi och öppnar nya möjligheter att använda autofagimodifierare för att förbättra genterapi.

Gene-based therapies, including the delivery of oligonucleotides, offer promising methods for the treatment of cancer cells. However, they have various limitations including low efficiency. Herein, cell-penetrating peptides (CPPs)-conjugated chitosan-modified iron oxide magnetic nanoparticles (CPPs-CTS@MNPs) with high biocompatibility as well as high efficiency were tested for the delivery of oligonucleotides such as plasmid pGL3, splice correction oligonucleotides, and small-interfering RNA. A biocompatible nanocomposite, in which CTS@MNPs was incorporated in non-covalent complex with CPPs-oligonucleotide, is developed. Modifying the surface of magnetic nanoparticles with cationic chitosan-modified iron oxide improved the performance of magnetic nanoparticles-CPPs for oligonucleotide delivery. CPPs-CTS@MNPs complexes enhance oligonucleotide transfection compared to CPPs@MNPs or CPPs. The hydrophilic character of CTS@MNPs improves complexation with plasmid pGL3, splice correction oligonucleotides, and small-interfering RNA payload, which consequently resulted in not only strengthening the colloidal stability of the constructed complex but also improving their biocompatibility. Transfection using PF14-splice correction oligonucleotides-CTS@MNPs showed sixfold increase of the transfection compared to splice correction oligonucleotides-PF14 that showed higher transfection than the commercially available lipid-based vector Lipofectamine™ 2000. Nanoscaled CPPs-CTS@MNPs comprise a new family of biomaterials that can circumvent some of the limitations of CPPs or magnetic nanoparticles.

A new strategy for gene transfection using the nanocarrier of cell penetrating peptides (CPPs; PepFect14 (PF14) or PepFect14 (PF14) (PF221)) in complex with graphene oxide (GO) is reported. GO complexed with CPPs and plasmid (pGL3), splice correction oligonucleotides (SCO) or small interfering RNA (siRNA) are performed. Data show adsorption of CPPs and oligonucleotides on the top of the graphenic lamellar without any observed change of the particle size of GO. GO mitigates the cytotoxicity of CPPs and improves the material biocompatibility. Complexes of GO-pGL3-CPPs (CPPs; PF14 or PF221) offer 2.1–2.5 fold increase of the cell transfection compared to pGL3-CPPs (CPPs; PF14 or PF221). GO-SCO-PF14 assemblies effectively transfect the cells with an increase of > 10–25 fold compared to the transfection using PF14. The concentration of GO plays a significant role in the material nanotoxicity and the transfection efficiency. The results open a new horizon in the gene treatment using CPPs and offer a simple strategy for further investigations.

Cell-penetrating peptide-based transfection systems (PBTS) are a promising group of drug delivery vectors. Cell-penetrating peptides (CPPs) are short cationic peptides that are able of transporting cell non-permeant cargos into different cell types. Some CPPs can be used to form non-covalent complexes with oligonucleotides for gene delivery applications. For the potential use of CPPs as drug delivery tools, it is important to understand the mechanism of uptake. Here, a fragment quantitative structure–activity relationships (FQSAR) model is generated to predict novel peptides based on approved alpha helical conformers and assisted model construction with energy refinement molecular mechanics simulations of former peptides. The modeled peptides were examined for plasmid transfection efficiency and compared with their predicted biological activity. The best predicted peptides were efficient for plasmid transfection with significant enhancement compared to the former group of peptides. Our results confirm that FQSAR model refinement is an efficient method for optimizing PBTS for improved biological activity. Additionally, using RNA sequencing, we demonstrated the involvement of autophagy pathways in PBTS uptake.

Magnetic nanoparticles (MNPs, Fe₃O₄) incorporated into the complexes of cell penetrating peptides (CPPs)-oligonucleotides (ONs) promoted the cell transfection for plasmid transfection, splice correction, and gene silencing efficiencies. Six types of cell penetrating peptides (CPPs; PeptFect220 (denoted PF220), PF221, PF222, PF223, PF224 and PF14) and three types of gene therapeutic agents (plasmid (pGL3), splicing correcting oligonucleotides (SCO), and small interfering RNA (siRNA) were investigated. Magnetic nanoparticles incorporated into the complexes of CPPs-pGL3, CPPs-SCO, and CPPs-siRNA showed high cell biocompatibility and efficiently transfected the investigated cells with pGL3, SCO, and siRNA, respectively. Gene transfer vectors formed among PF14, SCO, and MNPs (PF14-SCO-MNPs) showed a superior transfection efficiency (up to 4-fold) compared to the noncovalent PF14-SCO complex, which was previously reported with a higher efficiency compared to commercial vector called Lipofectamine™2000. The high transfection efficiency of the new complexes (CPPs-SCO-MNPs) may be attributed to the morphology, low cytotoxicity, and the synergistic effect of MNPs and CPPs. PF14-pDNA-MNPs is an efficient complex for in vivo gene delivery upon systemic administration. The conjugation of CPPs-ONs with inorganic magnetic nanoparticles (Fe₃O₄) may open new venues for selective and efficient gene therapy.

Cell-penetrating peptide (CPP) based transfection systems (PBTS) are a promising class of drug delivery vectors. CPPs are short mainly cationic peptides capable of delivering cell non-permeant cargo to the interior of the cell. Some CPPs have the ability to form non-covalent complexes with oligonucleotides for gene therapy applications. In this study, we use quantitative structure–activity relationships (QSAR), a statistical method based on regression data analysis. Here, a fragment QSAR (FQSAR) model is developed to predict new peptides based on standard alpha helical conformers and Assisted Model Building with Energy Refinement molecular mechanics simulations of previous peptides. These new peptides were examined for plasmid transfection efficiency and compared with their predicted biological activity. The best predicted peptides were capable of achieving plasmid transfection with significant improvement compared to the previous generation of peptides. Our results demonstrate that FQSAR model refinement is an efficient method for optimizing PBTS for improved biological activity.