The structure and configuration changes of multifunctional peptide vectors enhance gene delivery efficiency

Multifunctional gene delivery vectors containing different liver-targeting fragments for specifically transfecting hepatocellular carcinoma (HCC) cells

Gene therapy is a promising strategy for HCC treatment, but it commonly faces the problem of low specificity in gene transfection. In this study, we designed and synthesized a series of peptide-based gene delivery vectors (H-01 to H-18) containing varied HCC cell-targeting fragments for specifically binding different receptors highly expressed on HCC cell membranes. The physicochemical properties of peptide vectors or peptide/DNA complexes were characterized, and the gene delivery abilities of peptide vectors were evaluated in HepG2 cell lines. The results showed that peptide vectors H-02 and H-09, which contained targeted fragments for ACE2 and c-Met receptors, respectively, could specifically transfect HCC cells in a highly -efficient manner in vitro. Furthermore, the liver-targeting function in vivo of Cy5.5 labeled H-02 (H-17) and H-09 (H-18) was investigated by fluorescence imaging.

Overcoming the challenge: cell-penetrating peptides and membrane permeability

<p>Cell-penetrating peptides (CPPs) have emerged as a promising strategy for enhancing the membrane permeability of bioactive molecules, particularly in the treatment of central nervous system diseases. CPPs possess the ability to deliver a diverse array of bioactive molecules into cells using either covalent or non-covalent approaches, with a preference for non-covalent methods to preserve the biological activity of the transported molecules. By effectively traversing various physiological barriers, CPPs have exhibited significant potential in preclinical and clinical drug development. The discovery of CPPs represents a valuable solution to the challenge of limited membrane permeability of bioactive molecules and will continue to exert a crucial influence on the field of biomedical science.</p>

Transferrin receptor targeting segment T7 containing peptide gene delivery vectors for efficient transfection of brain tumor cells

Successful gene therapy for brain tumors are often limited by two important factors, the existence of blood brain barrier (BBB) and inefficient transfection of brain tumor cells. In this study, we designed a series of peptide-based gene delivery vectors decorated with T7 segment for binding the transferrin (Tf) receptors which were highly expressed on brain tumor cells, and evaluated their ability of gene delivery. The physicochemical properties of peptide vectors or peptide/DNA complexes were studied as well. The in vitro transfection efficiency was investigated in normal and glioma cell lines. Among these complexes, PT-02/DNA complexes showed the highest transfection efficiency in glioma cells and low cytotoxicity in normal cell lines, and it could transport DNA across the BBB model in vitro. Furthermore, PT-02/DNA could deliver pIRES2-EGFP into the brain site of zebrafish in vivo. The designed peptide vectors offered a promising way for glioma gene therapy.

Application of Peptides in Construction of Nonviral Vectors for Gene Delivery

Gene therapy, which aims to cure diseases by knocking out, editing, correcting or compensating abnormal genes, provides new strategies for the treatment of tumors, genetic diseases and other diseases that are closely related to human gene abnormalities. In order to deliver genes efficiently to abnormal sites in vivo to achieve therapeutic effects, a variety of gene vectors have been designed. Among them, peptide-based vectors show superior advantages because of their ease of design, perfect biocompatibility and safety. Rationally designed peptides can carry nucleic acids into cells to perform therapeutic effects by overcoming a series of biological barriers including cellular uptake, endosomal escape, nuclear entrance and so on. Moreover, peptides can also be incorporated into other delivery systems as functional segments. In this review, we referred to the biological barriers for gene delivery in vivo and discussed several kinds of peptide-based nonviral gene vectors developed for overcoming these barriers. These vectors can deliver different types of genetic materials into targeted cells/tissues individually or in combination by having specific structure-function relationships. Based on the general review of peptide-based gene delivery systems, the current challenges and future perspectives in development of peptidic nonviral vectors for clinical applications were also put forward, with the aim of providing guidance towards the rational design and development of such systems.

Multifunctional polyplex micelles for efficient microRNA delivery and accelerated osteogenesis

MicroRNAs (miRNAs) are emerging as a novel class of molecular targets and therapeutics to control gene expression for tissue repair and regeneration. However, a safe and effective transfection of miRNAs to cells has been a major barrier to their applications. In this work, a multifunctional polyplex micelle named PPP-RGI was developed as a non-viral gene vector for the efficient transfection of miR-218 (an osteogenic miRNA regulator) to bone marrow-derived mesenchymal stem cells (BMSCs) for accelerated osteogenic differentiation. PPP-RGI was designed and synthesized via conjugation of a multifunctional R₉-G₄-IKVAVW (RGI) peptide onto an amphiphilic poly(lactide-co-glycolide)-g-polyethylenimine-b-polyethylene glycol (PPP) copolymer. PPP-RGI self-assembled into polyplex micelles and strongly condensed miR-218 to prevent its RNase degradation. When the PPP-RGI/miR-218 complex was brought into contact with BMSCs, it exhibited high internalization efficiency and a fast escape from endo/lysosomes of the BMSCs. Subsequently, miR-218 released from the PPP-RGI/miR-218 complex regulated gene expressions and significantly enhanced the osteogenic differentiation of BMSCs. The multifunctional peptide conjugated nanocarrier serves as an effective miRNA delivery vector to promote osteogenesis.

Substance P containing peptide gene delivery vectors for specifically transfecting glioma cells mediated by a neurokinin-1 receptor

Gene therapy provides a promising treatment for glioblastoma multiforme, which mainly depends on two key aspects, crossing the blood brain barrier (BBB) effectively and transfecting target cells selectively. In this work, we reported a series of peptide-based vectors for transfecting glioma cells specifically consisting of several functional segments including a cell-penetrating peptide, targeting segment substance P (SP), an endosomal escape segment, a PEG linker and a stearyl moiety. The conformations and DNA-loading capacities of peptide vectors and the self-assembly behaviors of peptide/pGL3 complexes were characterized. The in vitro gene transfection was evaluated in U87, 293T-NK1R, and normal 293T cell lines. The transfection efficiency ratio of P-02 (SP-PEG₄-K(C₁₈)-(LLHH)₃-R₉) to Lipo2000 in the U87 cell line was about 36% higher than that in the 293T cell line. The neurokinin-1 receptor (NK1R) in U87 cells mediated the transfection process via interactions with the ligand SP in peptide vectors. The mechanism of NK1R mediated transfection was demonstrated by the use of gene-modified 293T cells expressing NK1R, as well as the gene transfection in the presence of free SP. Besides, P-02 could promote the pGL3 plasmids to cross the BBB model in vitro and achieved the EGFP gene transfection in the brain of zebrafish successfully. The designed peptide vectors, owing to their specific transfection capacity in glioma cells, provide a potential approach for glioblastoma multiforme gene therapy.

The rational design of cell-penetrating peptides for application in delivery systems

Cell penetrating peptides (CPPs) play a crucial role in the transportation of bioactive molecules. Although CPPs have been used widely in various delivery systems, further applications of CPPs are hampered by several drawbacks, such as high toxicity, low delivery efficiency, proteolytic instability and poor specificity. To design CPPs with great cell-penetrating ability, physicochemical properties and safety, researchers have tried to develop new methods to overcome the defects of CPPs. Briefly, (1) the side chain of arginine containing the guanidinium group is essential for the facilitation of cellular uptake; (2) the hydrophobic counterion complex around the guanidinium-rich backbone can "coat" the highly cationic structure with lipophilic moieties and act as an activator; (3) the conformation-constrained strategy was pursued to shield the peptide, thereby impeding access of the proteolytic enzyme; (4) targeting strategies can increase cell-type specificity of CPPs. In this review, the above four aspects were discussed in detail.

Peptide-based gene delivery vectors

Gene therapy as a strategy for disease treatment requires safe and efficient gene delivery systems that encapsulate nucleic acids and deliver them to effective sites in the cell.