Enhanced Peptide Delivery into Cells by Using the Synergistic Effects of a Cell-Penetrating Peptide and a Chemical Drug to Alter Cell Permeability

Covalent conjugation and non-covalent complexation strategies for intracellular delivery of proteins using cell-penetrating peptides

Therapeutic proteins provided new opportunities for patients and high sales volumes. However, they are formulated for extracellular targets. The lipophilic barrier of the plasma membrane renders the vast array of intracellular targets out of reach. Peptide-based delivery systems, namely cell-penetrating peptides (CPPs), have few safety concerns, and low immunogenicity, with control over administered doses. This study investigates CPP-based protein delivery systems by classifying them into CPP-protein "covalent conjugation" and CPP: protein "non-covalent complexation" categories. Covalent conjugates ensure the proximity of the CPP to the cargo, which can improve cellular uptake and endosomal escape. We will discuss various aspects of covalent conjugates through non-cleavable (stable) or cleavable bonds. Non-cleavable CPP-protein conjugates are produced by recombinant DNA technology to express the complete fusion protein in a host cell or by chemical ligation of CPP and protein, which ensures stability during the delivery process. CPP-protein cleavable bonds are classified into pH-sensitive and redox-sensitive bonds, enzyme-cleavable bonds, and physical stimuli cleavable linkers (light radiation, ultrasonic waves, and thermo-responsive). We have highlighted the key characteristics of non-covalent complexes through electrostatic and hydrophobic interactions to preserve the conformational integrity of the CPP and cargo. CPP-mediated protein delivery by non-covalent complexation, such as zippers, CPP adaptor methods, and avidin-biotin technology, are featured. Conclusively, non-covalent complexation methods are appropriate when a high number of CPP or protein samples are to be screened. In contrast, when the high biological activity of the protein is critical in the intracellular compartment, conjugation protocols are preferred.

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.

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.

Emerging trends of receptor-mediated tumor targeting peptides: A review with perspective from molecular imaging modalities

Natural peptides extracted from natural components such are known to have a relatively short in-vivo half-life and can readily metabolize by endo- and exo-peptidases. Fortunately, synthetic peptides can be easily manipulated to increase in-vivo stability, membrane permeability and target specificity with some well-known natural families. Many natural as well as synthetic peptides target to their endogenous receptors for diagnosis and therapeutic applications. In order to detect these peptides externally, they must be modified with radionuclides compatible with single photon emission computed tomography (SPECT) or positron emission tomography (PET). Although, these techniques mainly rely on physiological changes and have profound diagnostic strength over anatomical modalities such as MRI and CT. However, both SPECT and PET observed to possess lack of anatomical reference frame which is a key weakness of these techniques, and unfortunately, cannot be available freely in most clinical centres especially in under-developing countries. Hence, it is need of the time to design and develop economic, patient friendly and versatile strategies to grapple with existing problems without any hazardous side effects. Optical molecular imaging (OMI) has emerged as a novel technique in field of medical science using fluorescent probes as imaging modality and has ability to couple with organic drugs, small molecules, chemotherapeutics, DNA, RNA, anticancer peptide and protein without adding chelators as necessary for radionuclides. Furthermore, this review focuses on difference in imaging modalities and provides ample knowledge about reliable, economic and patient friendly optical imaging technique rather radionuclide-based imaging techniques.

Cell-penetrating peptides in oncologic pharmacotherapy: A review

Cancer is the second leading cause of death in the world and its treatment is extremely challenging, mainly due to its complexity. Cell-Penetrating Peptides (CPPs) are peptides that can transport into the cell a wide variety of biologically active conjugates (or cargoes), and are, therefore, promising in the treatment and in the diagnosis of several types of cancer. Some notable examples are TAT and Penetratin, capable of penetrating the central nervous system (CNS) and, therefore, acting in cancers of this system, such as Glioblastoma Multiforme (GBM). These above-mentioned peptides, conjugated with traditional chemotherapeutic such as Doxorubicin (DOX) and Paclitaxel (PTX), have also been shown to induce apoptosis of breast and liver cancer cells, as well as in lung cancer cells, respectively. In other cancers, such as esophageal cancer, the attachment of Magainin 2 (MG2) to Bombesin (MG2B), another CPP, led to pronounced anticancer effects. Other examples are CopA3, that selectively decreased the viability of gastric cancer cells, and the CPP p28. Furthermore, in preclinical tests, the anti-tumor efficacy of this peptide was evaluated on human breast cancer, prostate cancer, ovarian cancer, and melanoma cells in vitro, leading to high expression of p53 and promoting cell cycle arrest. Despite the numerous in vitro and in vivo studies with promising results, and the increasing number of clinical trials using CPPs, few treatments reach the expected clinical efficacy. Usually, their clinical application is limited by its poor aqueous solubility, immunogenicity issues and dose-limiting toxicity. This review describes the most recent advances and innovations in the use of CPPs in several types of cancer, highlighting their crucial importance for various purposes, from therapeutic to diagnosis. Further clinical trials with these peptides are warranted to examine its effects on various types of cancer.

Fluorescent RGD-based pro-apoptotic peptide conjugates as mitochondria-targeting probes for enhanced anticancer activities

We have designed 2-domain anticancer peptides with RGD-based KLAK bi-functional short motifs (linear and cyclic analogues). RGD tripeptide acts as tumor blood vessel 'homing' motif while KLAK tetrapeptide internalized in mitochondria and causes cell apoptosis. All three peptides (RGDKLAK; HM, cyclic-RGDKLAK; HMC-1, and RGD-cyclic-KLAK; HMC-2) were conjugated with fluorescein isothiocyanate isomer-I (5-FITC; F) for in-vivo and in-vitro optical imaging studies. These fluorescent-peptide (FL-peptide) analogues were analyzed to possess α_vβ₃-integrin targeting affinity, high uptake in in-vitro cell binding assays followed by in-vivo tumor xenograft mice studies. Pharmacological profile reveals that F-HMC-1 analogue exhibited selectively and specifically higher affinity for α_vβ₃-integrin than other analogues in U87MG cells in comparison with HeLa cells. The subcutaneous U87MG tumor xenograft mice models clearly visualized the uptake of F-HMC-1 in tumor tissue in contrast with normal tissues with tumor-to-normal tissue ratio (T/NT = 15.9 ± 1.1) at 2 h post-injection. These results suggested that F-HMC-1 peptide has potential diagnostic applications for targeting α_vβ₃-integrin assessed by optical imaging study in U87MG tumor xenograft mice models.

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.

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.

Polyhistidine facilitates direct membrane translocation of cell-penetrating peptides into cells

The bovine lactoferricin L6 (RRWQWR) has been previously identified as a novel cell-penetrating peptide (CPP) that is able to efficiently internalize into human cells. L6 interacts with quantum dots (QDs) noncovalently to generate stable L6/QD complexes that enter cells by endocytosis. In this study, we demonstrate a modified L6 (HL6; CHHHHHRRWQWRHHHHHC), in which short polyhistidine peptides are introduced into both flanks of L6, has enhanced cell-penetrating ability in human bronchoalveolar carcinoma A549 cells. The mechanism of cellular uptake of HL6/QD complexes is primarily direct membrane translocation rather than endocytosis. Dimethyl sulfoxide (DMSO), but not pyrenebutyrate (PB), ethanol, oleic acid, or 1,2-benzisothiazol-3(2 H)-one (BIT), slightly enhances HL6-mediated protein transduction efficiency. Neither HL6 nor HL6/QD complexes are cytotoxic to A549 or HeLa cells. These results indicate that HL6 could be a more efficient drug carrier than L6 for biomedical as well as biotechnological applications, and that the function of polyhistidine peptides is critical to CPP-mediated protein transduction.

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.

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.

Efficient therapeutic delivery by a novel cell-permeant peptide derived from KDM4A protein for antitumor and antifibrosis

Cell-penetrating peptide (CPP) based delivery have provided immense potential for the therapeutic applications, however, most of nonhuman originated CPPs carry the risk of possible cytotoxicity and immunogenicity, thus may restricting to be used. Here, we describe a novel human-derived CPP, denoted hPP10, and hPP10 has cell-penetrating properties evaluated by CellPPD web server, as well as In-Vitro and In-Vivo analysis. In vitro studies showed that hPP10-FITC was able to penetrate into various cells including primary cultured cells, likely through an endocytosis pathway. And functionalized macromolecules, such as green fluorescent protein (GFP), tumor-specific apoptosis inducer Apoptin as well as biological active enzyme GCLC (Glutamate-cysteine ligase, catalytic subunit) can be delivered by hPP10 in vitro and in vivo. Collectively, our results suggest that hPP10 provide a novel and versatile tool to deliver exogenous proteins or drugs for clinical applications as well as reprogrammed cell-based therapy.

Hyperosmotic treatment synergistically boost efficiency of cell-permeable peptides

Therapeutics delivery into cells has been hurdled due to the barrier of cytoplasmic membrane. Although cell penetrating peptide (CPP) can potentially serve as an intracellular drug delivery vehicle, the application of CPP-based delivery is limited because the unsatisfactory delivery efficiency of CPP conjugated potent cargos is challenging their applications in present. Thus, the development of strategies for enhancing the penetrating efficiency of CPP would therefore urgent need to be explored to increase the scope of potential applications. We report here the effects of glucose, sucrose and manntiol (abbreviated as GSM) combination facilitating the penetration efficiency of CPP peptide alone or CPP-GFP (green fluorescence protein) conjugation in cultured cell lines or primary cells. Moreover, osmoprotectants glycerol and glycine supplementation help cells cope with the stress from GSM combination. Thus, our present study suggests that GSM combination in the presence of osmoprotectant can work as a new strategy for CPP penetration enhancement.

Tumor-penetrating peptide fused to a pro-apoptotic peptide facilitates effective gastric cancer therapy

KLA (sequence, KLAKLAKKLAKLAK) is a peptide which leads to programmed cell death by disrupting the mitochondrial membrane. However, low penetration in tumors greatly limits its application and efficacy. To develop a KLA-based cancer therapy, KLA-iRGD, a recombinant protein was constructed. It consists of the KLA peptide and iRGD (CRGDKGPDC), a tumor-homing peptide with high penetration into tumor tissue and cells. The conjugated KLA exhibits pro-apoptotic activity to prevent the growth of a tumor once it is inside the cell. Once KLA-iRGD is internalized in cultured tumor cells, via the activation of the receptor neuropilin-1, it spreads extensively throughout the mass of the tumor. The recombinant KLA-iRGD protein showed antitumor activity in vivo in mice and in vitro in tumor cell lines. Repeated treatment with KLA-iRGD greatly prevented tumor growth, resulting in a considerable reduction in tumor volume. According to our data, KLA-iRGD may serve as a potential anticancer agent with limited systemic toxicity and high selectivity for the treatment of MKN45 gastric cancer, which may lead to the enhancement of new targeted anticancer agents.

In vitro and in vivo delivery of therapeutic proteins using cell penetrating peptides

The failure of proteins to penetrate mammalian cells or target tumor cells restricts their value as therapeutic tools in a variety of diseases such as cancers. Recently, protein transduction domains (PTDs) or cell penetrating peptides (CPPs) have been shown to promote the delivery of therapeutic proteins or peptides into live cells. The successful delivery of proteins mainly depends on their physicochemical properties. Although, linear cell penetrating peptides are one of the most effective delivery vehicles; but currently, cyclic CPPs has been developed to potently transport bioactive full-length proteins into cells. Up to now, several small protein transduction domains from viral proteins including Tat or VP22 could be fused to other peptides or proteins to entry them in various cell types at a dose-dependent approach. A major disadvantage of PTD-fusion proteins is primary uptake into endosomal vesicles leading to inefficient release of the fusion proteins into the cytosol. Recently, non-covalent complex formation (Chariot) between proteins and CPPs has attracted a special interest to overcome some delivery limitations (e.g., toxicity). Many preclinical and clinical trials of CPP-based delivery are currently under evaluation. Generally, development of more efficient protein transduction domains would significantly increase the potency of protein therapeutics. Moreover, the synergistic or combined effects of CPPs with other delivery systems for protein/peptide drug delivery would promote their therapeutic effects in cancer and other diseases. In this review, we will describe the functions and implications of CPPs for delivering the therapeutic proteins or peptides in preclinical and clinical studies.

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

Cell-penetrating peptides (CPPs) have been successfully applied to deliver various functional macromolecules into cells in recent times. Here, we describe a novel CPP designated as hPP3 (KPKRKRRKKKGHGWSR), which were derived from human nuclear body protein SP140-like protein. The location of hPP3-FITC in cells was investigated using the fluorescence microscopy, and the internalization of hPP3 was quantitatively measured using a fluorescence spectrophotometer. The results showed that hPP3-FITC could enter into culturing cells, following a concentration-, incubation time-, serum-, and temperature-dependent manner. Uptake of hPP3-FITC into cells was significantly enhanced by DMSO pretreatment, and inhibited by heparin and the endocytosis inhibitors (chlorpromazine and sodium azide), while the potent lysosomotropic agent, chloroquine, showed small positive effects on hPP3-FITC penetrating. Moreover, hPP3 could mediate functional GFP, KLA, or NBD penetration. The findings of this study showed that human origin peptide hPP3 has the potential to act as a macromolecular carrier penetrating cellular membranes and promising delivery peptide as drug delivery vectors.