Highly Efficient Delivery of Functional Cargoes by a Novel Cell-Penetrating Peptide Derived from SP140-Like Protein

Beyond Transduction: Anti-Inflammatory Effects of Cell Penetrating Peptides

One of the bottlenecks to bringing new therapies to the clinic has been a lack of vectors for delivering novel therapeutics in a targeted manner. Cell penetrating peptides (CPPs) have received a lot of attention and have been the subject of numerous developments since their identification nearly three decades ago. Known for their transduction abilities, they have generally been considered inert vectors. In this review, we present a schema for their classification, highlight what is known about their mechanism of transduction, and outline the existing literature as well as our own experience, vis a vis the intrinsic anti-inflammatory properties that certain CPPs exhibit. Given the inflammatory responses associated with viral vectors, CPPs represent a viable alternative to such vectors; furthermore, the anti-inflammatory properties of CPPs, mostly through inhibition of the NF-κB pathway, are encouraging. Much more work in relevant animal models, toxicity studies in large animal models, and ultimately human trials are needed before their potential is fully realized.

Uptake pathways of cell-penetrating peptides in the context of drug delivery, gene therapy, and vaccine development

Cell-penetrating peptides have been extensively utilized for the purpose of facilitating the intracellular delivery of cargo that is impermeable to the cell membrane. The researchers have exhibited proficient delivery capabilities for oligonucleotides, thereby establishing cell-penetrating peptides as a potent instrument in the field of gene therapy. Furthermore, they have demonstrated a high level of efficiency in delivering several additional payloads. Cell penetrating peptides (CPPs) possess the capability to efficiently transport therapeutic molecules to specific cells, hence offering potential remedies for many illnesses. Hence, their utilization is imperative for the improvement of therapeutic vaccines. In contemporary studies, a plethora of cell-penetrating peptides have been unveiled, each characterized by its own distinct structural attributes and associated mechanisms. Although it is widely acknowledged that there are multiple pathways through which particles might be internalized, a comprehensive understanding of the specific mechanisms by which these particles enter cells has to be fully elucidated. The absorption of cell-penetrating peptides can occur through either direct translocation or endocytosis. However, it is worth noting that categories of cell-penetrating peptides are not commonly linked to specific entrance mechanisms. Furthermore, research has demonstrated that cell-penetrating peptides (CPPs) possess the capacity to enhance antigen uptake by cells and facilitate the traversal of various biological barriers. The primary objective of this work is to examine the mechanisms by which cell-penetrating peptides are internalized by cells and their significance in facilitating the administration of drugs, particularly in the context of gene therapy and vaccine development. The current study investigates the immunostimulatory properties of numerous vaccine components administered using different cell-penetrating peptides (CPPs). This study encompassed a comprehensive discussion on various topics, including the uptake pathways and mechanisms of cell-penetrating peptides (CPPs), the utilization of CPPs as innovative vectors for gene therapy, the role of CPPs in vaccine development, and the potential of CPPs for antigen delivery in the context of vaccine development.

Emerging Landscape of Supercharged Proteins and Peptides for Drug Delivery

Although groundbreaking biotechnological techniques such as gene editing have significantly progressed, the effective and targeted transport of therapeutic agents into host cells remains a major obstacle to the development of biotherapeutics. Confronting the unique challenge posed by large macromolecules such as proteins, peptides, and nucleic acids adds complexity to this issue. Recent findings reveal that the supercharging of proteins and peptides not only enables control over critical properties, such as temperature resistance and catalytic activity, but also holds promise as a viable strategy for their use in drug delivery. This review provides a concise summary of the attributes of supercharged proteins and peptides, encompassing both their natural occurrence and engineered variants. Furthermore, it sheds light on the present status and future possibilities of supercharged proteins and peptides as carriers for significant biomolecules in the realms of medical research and therapeutic applications.

Clostridium botulinum C3bot mediated effects on cytokine-induced psoriasis-like phenotype in full-thickness skin model

Clostridium botulinum C3 exoenzyme (C3bot) exclusively inhibits RhoA, B and C by ADP-ribosylation and is therefore used as a cell-permeable tool for investigating the cellular role of these Rho-GTPases. Rho-GTPases represent a molecular switch integrating different receptor signalling to downstream cascades including transcriptional cascades that regulate various cellular processes, such as regulation of actin cytoskeleton and cell proliferation. C3bot-induced inhibition of RhoA leads to reorganization of the actin cytoskeleton, morphological changes, and inhibition of cell proliferation as well as modulation of inflammatory response. In this study, we characterized the C3bot-mediated effects on a full-thickness skin model exhibiting a psoriasis-like phenotype through the addition of cytokines. Indeed, after the addition of cytokines, a decrease in epidermal thickness, parakeratosis, and induction of IL-6 was detected. In the next step, it was studied whether C3bot caused a reduction in the cytokine-induced psoriasis-like phenotypes. Basal addition of C3bot after cytokine induction of the full-thickness skin models caused less epidermal thinning and reduced IL-6 abundance. Simultaneous basal incubation with cytokines and C3bot, IL-6 abundance was inhibited, but epidermal thickness was only moderately affected. When C3bot was added apically to the skin model, IL-6 abundance was reduced, but no further effects on the psoriasis-like phenotype of the epidermis were observed. In summary, C3bot inhibits the cytokine-induced expression of IL-6 and thus may have an impact on the pro-inflammatory immune response in the psoriasis-like phenotype.

Delivery of Oleanolic Acid with Improved Antifibrosis Efficacy by a Cell Penetrating Peptide P10

Oleanolic acid (OA), a common pentacyclic triterpenoid found in plants, has several therapeutic uses, including the treatment of hepatopathy disorders. However, due to OA's weak permeability and limited bioavailability, its therapeutic advantages are limited. Here, we showed that a short peptide known as p10 not only binds to OA but also rapidly enhances OA delivery into cultured hepatic stellate cells (HSCs), lowers their synthesis of fibrogenic proteins, and further reduces the HSC migration capacity. Our findings show that noncovalently conjugating short peptides to OA improves its pharmacological efficacy and permeability.

Emerging Landscape of Cell-Penetrating Peptide-Mediated Organelle Restoration and Replacement

Organelles are specialized subunits within a cell membrane that perform specific roles or functions, and their dysfunction can lead to a variety of pathophysiologies including developmental defects, aging, and diseases (cancer, cardiovascular and neurodegenerative diseases). Recent studies have shown that cell-penetrating peptide (CPP)-based pharmacological therapies delivered to organelles or even directly resulting in organelle replacement can restore cell function and improve or prevent disease. In this review, we summarized the current developments in the precise delivery of exogenous cargoes via CPPs at the organelle level, CPP-mediated organelle delivery, and discuss their feasibility as next-generation targeting strategies for the diagnosis and treatment of diseases at the organelle level.

Cell-Permeable PROTAC Degraders against KEAP1 Efficiently Suppress Hepatic Stellate Cell Activation through the Antioxidant and Anti-Inflammatory Pathway

Accumulating evidence indicates that oxidative stress and inflammation are involved in the physiopathology of liver fibrogenesis. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key transcription factor, which regulates the expression of redox regulators to establish cellular redox homeostasis. The Nrf2 modulator can serve as a primary cellular defense against the cytotoxic effects of oxidative stress. We designed a chimeric Keap1-Keap1 peptide (KKP1) based on the proteolysis-targeting chimera technology. The KKP1 peptide not only can efficiently penetrate into the rat hepatic stellate cell line (HSC-T6) cells but also can induce Keap1 protein degradation by the ubiquitination-proteasome degradation pathway, which releases Nrf2 and promotes the transcriptional activity of the Nrf2/antioxidant response element pathway. It then activates the protein expression of the downstream antioxidant factors, the glutamate-cysteine ligase catalytic subunit and heme oxygenase-1 (HO-1). Finally, Keap1 protein degradation inhibits the nuclear factor-kappaB inflammatory signal pathway, the downstream inflammatory factor tumor necrosis factor alpha, and the interleukin-1beta protein expression and further inhibits the expression of the fibrosis biomarker gene. The current research suggests that our designed KKP1 may provide a new avenue for the future treatment of liver fibrosis.

Improved transfer efficiency of supercharged 36 + GFP protein mediate nucleic acid delivery

The potential of nucleic acid therapeutics to treat diseases by targeting specific cells has resulted in its increasing number of uses in clinical settings. However, the major challenge is to deliver bio-macromolecules into target cells and/or subcellular locations of interest ahead in the development of delivery systems. Although, supercharged residues replaced protein 36 + GFP can facilitate itself and cargoes delivery, its efficiency is still limited. Therefore, we combined our recent progress to further improve 36 + GFP based delivery efficiency. We found that the penetration efficacy of 36 + GFP protein was significantly improved by fusion with CPP-Dot1l or treatment with penetration enhancer dimethyl sulfoxide (DMSO) in vitro. After safely packaged with plasmid DNA, we found that the efficacy of in vitro and in vivo transfection mediated by 36 + GFP-Dot1l fusion protein is also significantly improved than 36 + GFP itself. Our findings illustrated that fusion with CPP-Dot1l or incubation with DMSO is an alternative way to synergically promote 36 + GFP mediated plasmid DNA delivery in vitro and in vivo.

Design, Preparation, and Evaluation of Osthol Poly-Butyl-Cyanoacrylate Nanoparticles with Improved In Vitro Anticancer Activity in Neuroblastoma Treatment

Osthol (osthole), known as a neuroprotective drug, has shown potent anticancer activity. However, the potential clinical application of osthol is limited due to its low water solubility and low bioavailability. Polybutyl cyanoacrylate (PBCA) has been widely used to improve the solubility of drugs with poor water solubility. In this study, an orthogonal experimental design (OED) was applied to design the preparation process of PBCA nanoparticles (NPs). Then, nanoparticles were prepared and evaluated in terms of physicochemical properties, in vitro release, and cellular uptake, etc. Further, the anti-cancer activity of osthol-PBCA NPs was demonstrated in SH-SY5Y cells. The pharmacokinetics and area under the curve (AUC) were investigated. The obtained osthol-NPs presented a spherical shape with a particle size of 110 ± 6.7 nm, a polydispersity index (PDI) of 0.126, and a zeta potential of −13 ± 0.32 mV. Compared with the free osthol, the drugs in osthol-NPs presented better stability and sustained release pattern activity. In vitro analysis using SH-SY5Y neuroblastoma cells showed that osthol-loaded nanoparticles displayed a significantly enhanced intracellular absorption process (three times) and cytotoxicity compared with free osthol (p < 0.05, increased 10−20%). The in vivo pharmacokinetic study revealed that the AUC of osthol-NPs was 3.3-fold higher than that of free osthol. In conclusion, osthol-PBCA NPs can enhance the bioactivity of osthol, being proposed as a novel, promising vehicle for drug delivery.

Advanced Peptide Nanomedicines for Bladder Cancer Theranostics

Cancer is still a global public health problem. Although remarkable success has been achieved in cancer diagnosis and treatment, the high recurrence and mortality rates remain severely threatening to human lives and health. In recent years, peptide nanomedicines with precise selectivity and high biocompatibility have attracted intense attention in biomedical applications. In particular, there has been a significant increase in the exploration of peptides and their derivatives for malignant tumor therapy and diagnosis. Herein, we review the applications of peptides and their derivatives in the diagnosis and treatment of bladder cancer, providing new insights for the design and development of novel peptide nanomedicines for the treatment of bladder cancer in the future.

Applying flow cytometry to identify the modes of action of membrane-active peptides in a label-free and high-throughput fashion

Membrane-active peptides (MAPs) have several potential therapeutic uses, including as antimicrobial drugs. Many traditional methods used to evaluate the membrane interactions of MAPs have limited applicability. Low-throughput methods, such as microscopy, provide detailed information but often rely on fluorophore-labeled MAPs, and high-throughput assays, such as the calcein release assay, cannot assess the mechanism behind the disruption of vesicular-based lipid membranes. Here we present a flow cytometric assay that provides detailed information about the peptide-lipid membrane interactions on single artificial lipid vesicles while being high-throughput (1000-2000 vesicles/s) and based on label-free MAPs. We synthesized and investigated six MAPs with different modes of action to evaluate the versatility of the assay. The assay is based on the flow cytometric readouts from artificial lipid vesicles, including the fluorescence from membrane-anchored and core-encapsulated fluorophores, and the vesicle concentration. From these parameters, we were able to distinguish between MAPs that induce vesicle solubilization, permeation (pores/membrane distortion), and aggregation or fusion. Our flow cytometry findings have been verified by traditional methods, including the calcein release assay, dynamic light scattering, and fluorescence microscopy on giant unilamellar vesicles. We envision that the presented flow cytometric assay can be used for various types of peptide-lipid membrane studies, e.g. to identify new antibiotics. Moreover, the assay can easily be expanded to derive additional valuable information.

Emerging landscape of cell-penetrating peptide-mediated nucleic acid delivery and their utility in imaging, gene-editing, and RNA-sequencing

The safety issues like immunogenicity and unacceptable cancer risk of viral vectors for DNA/mRNA vaccine delivery necessitate the development of non-viral vectors with no toxicity. Among the non-viral strategies, cell-penetrating peptides (CPPs) have been a topic of interest recently because of their ability to cross plasma membranes and facilitate nucleic acids delivery both in vivo and in vitro. In addition to the application in the field of gene vaccine and gene therapy, CPPs based nucleic acids delivery have been proved by its potential application like gene editing, RNA-sequencing, and imaging. Here, we focus on summarizing the recent applications and progress of CPPs-mediated nucleic acids delivery and discuss the current problems and solutions in this field.

In silico identification and experimental validation of cellular uptake by a new cell penetrating peptide P1 derived from MARCKS

Viral vectors for vaccine delivery are challenged by recently reported safety issues like immunogenicity and risk for cancer development, and thus there is a growing need for the development of non-viral vectors. Cell penetrating peptides (CPPs) are non-viral vectors that can enter plasma membranes efficiently and deliver a broad range of cargoes. Our bioinformatic prediction and wet-lab validation data suggested that peptide P1 derived from MARCKS protein phosphorylation site domain is a new potential CPP candidate. We found that peptide P1 can efficiently internalize into various cell lines in a concentration-dependent manner. Receptor-mediated endocytosis pathway is the major mechanism of P1 penetration, although P1 also directly penetrates the plasma membrane. We also found that peptide P1 has low cytotoxicity in cultured cell lines as well as mouse red blood cells. Furthermore, peptide P1 not only can enter into cultured cells itself, but it also can interact with plasmid DNA and mediate the functional delivery of plasmid DNA into cultured cells, even in hard-to-transfect cells. Combined, these findings indicate that P1 may be a promising vector for efficient intracellular delivery of bioactive cargos.

In silico identification and experimental validation of cellular uptake and intracellular labeling by a new cell penetrating peptide derived from CDN1

Bioactive therapeutic molecules are generally impermeable to the cell membrane, hindering their utility and efficacy. A group of peptides called cell-penetrating peptides (CPPs) were found to have the capability of transporting different types of cargo molecules across the cell membrane. Here, we identified a short peptide named P2, which has a higher proportion of basic residues than the CDN1 (cyclin-dependent kinase inhibitor 1) protein it is derived from, and we used bioinformatic analysis and experimental validation to confirm the penetration property of peptide P2. We found that peptide P2 can efficiently enter different cell lines in a concentration-dependent manner. The endocytosis pathway, especially receptor-related endocytosis, may be involved in the process of P2 penetration. Our data also showed that peptide P2 is safe in cultured cell lines and red blood cells. Lastly, peptide P2 can efficiently deliver self-labeling protein HaloTag into cells for imaging. Our study illustrates that peptide P2 is a promising imaging agent delivery vehicle for future applications.

Identification of a novel cell-penetrating peptide derived from the capsid protein of chicken anemia virus and its application in gene delivery

Cell membranes are a great obstacle for entrance of gene therapeutic agents. Cell-penetrating peptides (CPPs) have been proven as a promising gene delivery tool. However, the early TAT peptide derived from the HIV transcription activator protein has been proven that the sequence contains Furin protease cleaved motifs which limited the TAT application in delivery of exogenous active molecules. In the present study, through the bioinformatics and experimental approach, we have identified a novel CPP derived from the N terminus of VP1 protein of chicken anemia virus (CAV), designated as CVP1-N2, which is rich in arginine residues and contains α-helical structure. Then, the ability of CVP1-N2 cell penetrating was detected using confocal imaging and flow cytometry. FITC-labeled CVP1-N2 peptide could rapidly internalize into different types of live cells with dose dependence and without cytotoxic effects by MTT assay. Surprisingly, CVP1-N2 with a pattern of nuclear sub-location has shown the higher uptake efficiency than TAT. At 10, 1, and 0.1 μM, the mean relative internalization of CVP1-N2 was respectively 1.08-, 12-, and 75-fold higher than that of CVP1, as well as 1.6-, 56-, and 75-fold higher than that of TAT. Moreover, using endocytic inhibitors along with low-temperature stress validated that the CVP1-N2 internalization route is direct translocation pathway. Finally, the capacity of CVP1-N2 for delivery of gene into cells was determined, where it was able to carry red fluorescent protein (RFP) and apoptin genes into cells respectively and induce the apoptosis. All these data indicate that CVP1-N2 could be used as a novel gene delivery vehicle for gene therapy in the future. KEY POINTS: • 1CVP1-N2 was identified as a novel more efficient cell-penetrating peptide. • 2. CVP1-N2 localized to the nucleus through the direct transduction pathway. • 3. CVP1-N2 was able to deliver the apoptin gene into HCT116 cells and induce apoptosis.

Intracellular Delivery of DNA and Protein by a Novel Cell-Permeable Peptide Derived from DOT1L

Cellular uptake and intracellular release efficiency of biomacromolecules is low because of hurdles in the cell membrane that result in limited access to intra-cellular targets with few functional effects. Cell-penetrating peptides (CPPs) act as cargo delivery vehicles to promote therapeutic molecule translocation. Here, we describe the novel CPP-Dot1l that not only penetrates by itself, but also mediates cargo translocation in cultured cells, as confirmed by fluorescence microscopy and fluorescence spectrophotometry. We conducted cytotoxicity assays and safety evaluations, and determined peptide-membrane interactions to understand the possible pathway for cargo translocation. Additional nucleic acid and covalently conjugated green fluorescence protein (GFP) studies mediated by CPP-Dot1l were conducted to show functional delivery potential. Results indicate that CPP-Dot1l is a novel and effective CPP due to its good penetrating properties in different cell lines and its ability to enter cells in a concentration-dependent manner. Its penetration efficiency can be prompted by DMSO pretreatment. In addition, not only can it mediate plasmid delivery, but CPP-Dot1l can also deliver GFP protein into cytosol. In conclusion, the findings of this study showed CPP-Dot1l is an attractive pharmaceutical and biochemical tool for future drug, regenerative medicine, cell therapy, gene therapy, and gene editing-based therapy development.

Nano-Inspired Technologies for Peptide Delivery

Nano-inspired technologies offer unique opportunities to treat numerous diseases by using therapeutic peptides. Therapeutic peptides have attractive pharmacological profiles and can be manufactured at relatively low costs. The major advantages of using a nanodelivery approach comprises significantly lower required dosages compared to systemic delivery, and thus reduced toxicity and immunogenicity. The combination of therapeutic peptides with delivery peptides and nanoparticles or small molecule drugs offers systemic treatment approaches, instead of aiming for single biological targets or pathways. This review article discusses exemplary state-of-the-art nanosized delivery systems for therapeutic peptides and antibodies, as well as their biochemical and biophysical foundations and emphasizes still remaining challenges. The competition between using different nanoplatforms, such as liposome-, hydrogel-, polymer-, silica nanosphere-, or nanosponge-based delivery systems is still "on" and no clear frontrunner has emerged to date.

Cell penetrating peptides: the potent multi-cargo intracellular carriers

Introduction: Cell penetrating peptides (CPPs) known as protein translocation domains (PTD), membrane translocating sequences (MTS), or Trojan peptides (TP) are able to cross biological membranes without clear toxicity using different mechanisms, and facilitate the intracellular delivery of a variety of bioactive cargos. CPPs could overcome some limitations of drug delivery and combat resistant strains against a broad range of diseases. Despite delivery of different therapeutic molecules by CPPs, they lack cell specificity and have a short duration of action. These limitations led to design of combined cargo delivery systems and subsequently improvement of their clinical applications. Areas covered: This review covers all our studies and other researchers in different aspects of CPPs such as classification, uptake mechanisms, and biomedical applications. Expert opinion: Due to low cytotoxicity of CPPs as compared to other carriers and final degradation to amino acids, they are suitable for preclinical and clinical studies. Generally, the efficiency of CPPs was suitable to penetrate the cell membrane and deliver different cargos to specific intracellular sites. However, no CPP-based therapeutic approach has approved by FDA, yet; because there are some disadvantages for CPPs including short half-life in blood, and nonspecific CPP-mediated delivery to normal tissue. Thus, some methods were used to develop the functions of CPPs in vitro and in vivo including the augmentation of cell specificity by activatable CPPs, specific transport into cell organelles by insertion of corresponding localization sequences, incorporation of CPPs into multifunctional dendrimeric or liposomal nanocarriers to improve selectivity and efficiency especially in tumor cells.

Intracellular delivery of nucleic acid by cell-permeable hPP10 peptide

Although gene therapy offers hope against incurable diseases, nonreplicating transduction vectors remain lacking. We have previously characterized a cell-penetrating peptide hPP10 for the delivery of various cargoes; however, whether hPP10 can mediate nucleic acid delivery is still unknown. Here, examining via different ways, we demonstrate that hPP10 stably complexes with plasmid DNA (pDNA) and safely mediates nucleic acid transfection. hPP10 can mediate GFP-, dsRed-, and luciferase-expressing plasmids into cells with nearly the same efficiency as commercial transfection reagents Turbofectin or Lipofect. Furthermore, hPP10 can mediate Cre fusion protein delivery and pDNA transfection simultaneously in the Cre/loxp system in vitro. In addition, hPP10 fused with an RNA-binding domain can mediate delivery of small interfering RNA into cells to silence the reporter gene expression. Collectively, our results suggest that hPP10 is an option for nucleic acid delivery with efficiencies similar to that of commercial reagents.

Efficient penetration of Scp01-b and its DNA transfer abilities into cells

The in vivo application potential of viral-based gene delivery approaches is hindered by a risk of insertional oncogenesis. Of the many delivery methods, cell-penetrating peptides (CPP)-based delivery has good biocompatibility and biodegradability. However, low efficiency is still the disadvantage of CPPs-based nucleic acid transfection, and delivery efficiency may vary from different CPPs. Here, we describe Scp01-b, as a new CPP, which can enter cultured cell lines and primary cultured cells examined by fluorescence microscopy and quantitative assay, the internalization process is a concentration, temperature, and incubation time-dependent manner. Scp01-b does not insert into the membrane directly and its uptake is mediated through endocytosis pathway. Moreover, Scp01-b could mediate the uptake of plasmid DNA into the Caski and HSC-T6 cells, and we noted that Scp01-b-mediated transfection efficiency was nearly the same with traditional liposome (TurboFectin)-mediated transfection. These findings suggest that Scp01-b can act as a useful tool for non-viral-based delivery in further application such as reprogramming and gene editing.

Designing and enhancing the antifungal activity of corneal specific cell penetrating peptide using gelatin hydrogel delivery system

Background

Fungal keratitis is a major cause of corneal blindness accounting for more than one-third of microbiologically proven cases. The management of fungal keratitis is through topical or systemic antifungal medications alone or in combination with surgical treatment. Topical medications such as natamycin and voriconazole pose major challenges due to poor penetration across the corneal epithelium. To address the issue various carrier molecules like nanoparticles, lipid vesicles, and cell penetrating peptides were explored. But the major drawback such as non-specificity and lack of bioavailability remains.

Purpose

In this study, we have attempted to design corneal specific cell penetrating peptide using subtractive proteomic approach from the published literature and tried to improve its bioavailability through gelatin hydrogel delivery system.

Material and Methods

Using subtractive proteomic approach two peptides VRF005 and VRF007 were identified on the basis of solubility, cell permeability and amphipathicity. The peptides were modeled for three-dimensional structure and simulated for membrane penetration. The peptides were characterized using circular dichroism spectroscopy, dynamic light scattering and native polyacrylamide gel electrophoresis. Further uptake studies were performed on primary corneal epithelial cells and the stability was analyzed in corneal epithelial tissue lysates. Insilico prediction of peptides showed it to have antifungal activity which was further validated using colony forming assay and time killing kinetics. The duration of antifungal activity of peptide was improved using gelatin hydrogel through sustained delivery.

Results

VRF005 and VRF007 showed α-helical structure and was within the allowed region of Ramachandran plot. The simulation study showed their membrane penetration. The peptide uptake was found to be specific to corneal epithelial cells and also showed intracellular localization in Candida albicans and Fusarium solani. Peptides were found to be stable up to 2 hours when incubated with corneal epithelial tissue lysate. Dynamic light scattering, and native polyacrylamide gel electrophoresis revealed aggregation of peptides. VRF007 showed antifungal activity up to 24 hour whereas VRF005 showed activity up to 4 hours. Hence gelatin hydrogel-based delivery system was used to improve the activity. Actin staining of corneal epithelial cells showed that the cells were attached on gelatin hydrogel.

Conclusion

We have designed corneal specific cell penetrating peptides using subtractive proteomic approach. Bioavailability and delivery of peptide was enhanced using gelatin hydrogel system.

1988-2018: Thirty years of drug smuggling at the nano scale. Challenges and opportunities of cell-penetrating peptides in biomedical research

In 1988, two unrelated papers reported the discovery of peptide vectors with innate cell translocation properties, setting the ground for a new area of research that over the years has grown into considerable therapeutic potential. The vectors, named cell-penetrating peptides (CPPs), constitute a now large and diversified family, sharing the extraordinary ability to diffuse unaltered across cell membranes while ferrying diverse associated cargos. Such properties have made CPPs ideal tools for delivery of nucleic acids, proteins and other therapeutic/diagnostic molecules to cells and tissues via covalent conjugation or complexation. This year 2018 marks the 30^th anniversary of a peptide research landmark opening new perspectives in drug delivery. Given its vastness, exhaustive coverage of the main features and accomplishments in the CPP field is virtually impossible. Hence this manuscript, after saluting the above 30^th jubilee, focuses by necessity on the most recent contributions, providing a comprehensive list of recognized CPPs and their latest-reported applications over the last two years. In addition, it thoroughly reviews three areas of peptide vector research of particular interest to us, namely (i) efficient transport of low-bioavailability drugs into the brain; (ii) CPP-delivered disruptors of G protein-coupled receptor (GPCRs) heteromers related to several disorders, and (iii) CPP-mediated delivery of useful but poorly internalized drugs into parasites.

Mitochondrial-targeted penetrating peptide delivery for cancer therapy

INTRODUCTION

Mitochondria are promising targeting organelles for anticancer strategies; however, mitochondria are difficult for antineoplastic drugs to recognize and bind. Mitochondria-penetrating peptides (MPPs) are unique tools to gain access to the cell interior and deliver a bioactive cargo into mitochondria. MPPs have combined or delivered a variety of antitumor cargoes and obviously inhibited the tumor growth in vivo and in vitro. MPPs create new opportunities to develop new treatments for cancer.

AREAS COVERED

We review the target sites of mitochondria and the target-penetration mechanism of MPPs, different strategies, and various additional strategies decorated MPPs for tumor cell mitochondria targeting, the decorating mattes including metabolism molecules, RNA, DNA, and protein, which exploited considered as therapeutic combined with MPPs and target in human cancer treatment.

EXPERT OPINION/COMMENTARY

Therapeutic selectivity that preferentially targets the mitochondrial abnormalities in cancer cells without toxic impact on normal cells still need to be deepen. Moreover, it needs appropriate study designs for a correct evaluation of the target delivery outcome and the degradation rate of the drug in the cell. Generally, it is optimistic that the advances in mitochondrial targeting drug delivery by MPPs plasticity outlined here will ultimately help to the discovery of new approaches for the prevention and treatment of cancers.

Interaction of poly-l-lysine coating and heparan sulfate proteoglycan on magnetic nanoparticle uptake by tumor cells

Background

Poly-l-lysine (PLL) enhances nanoparticle (NP) uptake, but the molecular mechanism remains unresolved. We asked whether PLL may interact with negatively charged glycoconjugates on the cell surface and facilitate uptake of magnetic NPs (MNPs) by tumor cells.

Methods

PLL-coated MNPs (PLL-MNPs) with positive and negative ζ-potential were prepared and characterized. Confocal and transmission electron microscopy was used to analyze cellular internalization of MNPs. A colorimetric iron assay was used to quantitate cell-associated MNPs (MNP_cell).

Results

Coadministration of PLL and dextran-coated MNPs in culture enhanced cellular internalization of MNPs, with increased vesicle size and numbers/cell. MNP_cell was increased by eight- to 12-fold in response to PLL in a concentration-dependent manner in human glioma and HeLa cells. However, the application of a magnetic field attenuated PLL-induced increase in MNP_cell. PLL-coating increased MNP_cell regardless of ζ-potential of PLL-MNPs, whereas magnetic force did not enhance MNP_cell. In contrast, epigallocatechin gallate and magnetic force synergistically enhanced PLL-MNP uptake. In addition, heparin, but not sialic acid, greatly reduced the enhancement effects of PLL; however, removal of heparan sulfate from heparan sulfate proteoglycans of the cell surface by heparinase III significantly reduced MNP_cell.

Conclusion

Our results suggest that PLL-heparan sulfate proteoglycan interaction may be the first step mediating PLL-MNP internalization by tumor cells. Given these results, PLL may facilitate NP interaction with tumor cells via a molecular mechanism shared by infection machinery of certain viruses.

Transduction Methods for Cytosolic Delivery of Proteins and Bioconjugates into Living Cells

The human organism and its constituting cells rely on interplay between multiple proteins exerting specific functions. Progress in molecular biotechnologies has facilitated the production of recombinant proteins. When administrated to patients, recombinant proteins can provide important healthcare benefits. To date, most therapeutic proteins must act from the extracellular environment, with their targets being secreted modulators or extracellular receptors. This is because proteins cannot passively diffuse across the plasma membrane into the cytosol. To expand the scope of action of proteins for cytosolic targets (representing more than 40% of the genome) effective methods assisting protein cytosolic entry are being developed. To date, direct protein delivery is extremely tedious and inefficient in cultured cells, even more so in animal models of pathology. Novel techniques are changing this limitation, as recently developed in vitro methods can robustly convey large amount of proteins into cell cultures. Moreover, advances in protein formulation or protein conjugates are slowly, but surely demonstrating efficiency for targeted cytosolic entry of functional protein in vivo in tumor xenograft models. In this review, various methods and recently developed techniques for protein transport into cells are summarized. They are put into perspective to address the challenges encountered during delivery.

Novel peptide MT23 for potent penetrating and selective targeting in mouse melanoma cancer cells

Cell-penetrating peptides (CPPs) have a great potential for intracellular delivery of cell-impermeable biological macromolecules in clinical therapy. However, their lack of cell and tissue specificity remains the primary limitation for their clinical development as drug delivery vehicles. In this study, based on phage display and an in silico approach, we found a novel CPP-MT23 with mouse melanoma cell specificity, it can only enter B16 melanoma cancer cells and without any cytotoxicity, Moreover, MT23 showed higher penetration efficiency based on fluorescence microcopy and quantitative assay, and it has capability for mediating functional Apoptin into cells in vitro or in vivo. Moreover, MT23-Apoptin can significantly inhibit tumor growth and induce the cell apoptosis in B16 tumor bearing mice. To sum up, all the results implicated that MT23 has the potential to deliver exogenous therapeutic proteins for further use and it also expected to lay the foundation for developing human melanoma cancer cell specific CPP.