Cell-penetrating peptides in protein mimicry and cancer therapeutics

Cell-penetrating peptides in protein mimicry and cancer therapeutics.

Bioconjugate Supramolecular Pd2+ Metallacages Penetrate the Blood Brain Barrier In Vitro and In Vivo.

ConspectusBiomolecules such as peptides, proteins, and nucleic acids generally cannot cross a cell membrane by passive diffusion. Nevertheless, cell-penetrating peptides (CPPs), bacterial protein toxins, certain eukaryotic proteins, viruses, and many synthetic drug delivery vehicles have been shown to enter the cytosol of eukaryotic cells with varying efficiencies. They generally enter the cell by one or more of the endocytic mechanisms and are initially localized inside the endosomes. But how they cross the endosomal membrane to reach the cytosol (i.e., endosomal escape) has been a mystery for decades, and this knowledge gap has been a major bottleneck for the development of efficient drug delivery systems. In addition, many bacterial and eukaryotic proteins are transported across the plasma membrane in their native states into the periplasmic/extracellular space through the twin-arginine translocation (TAT) and unconventional protein secretion (UPS) systems, respectively. Again, the mechanisms underpinning these protein export systems remain unclear.In this Account, I introduce a previously unrecognized, fundamental membrane translocation mechanism which we have termed the vesicle budding-and-collapse (VBC) mechanism. Through VBC, biomolecules of diverse sizes and physicochemical properties autonomously translocate across cell membranes topologically (i.e., from one side to the other side of the membrane) but not physically (i.e., without going through the membrane). We have demonstrated that CPPs and bacterial protein toxins escape the endosome by the VBC mechanism in giant unilamellar vesicles as well as live mammalian cells. This advance resulted from studies in which we labeled the biomolecules with a pH-sensitive, red-colored dye (pHAb) and phosphatidylserine with a pH-insensitive green dye (TopFluor) and monitored the intracellular trafficking of the biomolecules in real time by confocal microscopy. In addition, by enlarging the endosomes with a kinase inhibitor, we were able to visualize the structural changes of the endosomes (i.e., endosomal escape intermediates) as they went through the VBC process. I postulate that bacterial/viral/eukaryotic proteins, nonenveloped viruses, and synthetic drug delivery vehicles (e.g., polyplexes, lipoplexes, and lipid nanoparticles) may also escape the endosome by inducing VBC. Furthermore, I propose that VBC may be the mechanism that drives the bacterial TAT and eukaryotic UPS systems. Our findings fill a long-standing gap in cell biology and provide guiding principles for designing more efficient drug delivery vehicles.

How Do Biomolecules Cross the Cell Membrane?

In the most recent 25-30 years, multiple novel mechanisms and applications of cell-penetrating peptides (CPP) have been demonstrated, leading to novel drug delivery systems. In this review, I present a brief introduction to the CPP area with selected recent achievements. This is followed by a nostalgic journey into the research in my own laboratories, which lead to multiple CPPs, starting from transportan and paving a way to CPP-based therapeutic developments in the delivery of bio-functional materials, such as peptides, proteins, vaccines, oligonucleotides and small molecules, etc.

https://www.mdpi.com/1999-4923/13/7/987/pdf

Cell-Penetrating Peptides and Transportan.

In this review, recent developments and applications with cell-penetrating peptides (CPP) are discussed. CPPs are widely used tools for the delivery of various macromolecular therapeutics, such as ...

https://www.tandfonline.com/doi/pdf/10.1080/14712598.2021.1823368

Status update in the use of cell-penetrating peptides for the delivery of macromolecular therapeutics.

Therapeutic proteins are currently at the apex of innovation in pharmaceutical medicine. However, their industrial production is technically challenging and improved methods for transient transfection of mammalian cell cultures are necessary. We aimed to find a fast, microliter-scale transfection assay that allows the prediction of protein expression in the transient production settings. We used an array of lipid, polymeric and cell-penetrating peptide transfection reagents, and compared their performance in various high throughput transfection assays to their performance in protein (antibody) expression in professional protein-producer cell lines. First, we show that some of the most frequently used microliter-scale transfection efficacy assays fail to predict performance in the protein production in milliliter and liter scale settings. We found that CHO suspension culture post-transfection EGFP(+) population and SEAP quantitation correlate with large-scale protein production, whereas the adhesion culture assays and transfection of pLuc are non-predictive. Second, we demonstrated that cell-penetrating peptide-based transfection achieves significantly higher protein yields compared to PEI and lipoplex methods in both CHO and HEK293 producer cell lines. In this work we demonstrate a CPP-based transient protein expression approach that significantly outperformed the current industry standard workhorse method of PEI.

/pdf/predicting-transiently-expressed-protein-yields-comparison-1efwelj5.pdf

Predicting Transiently Expressed Protein Yields: Comparison of Transfection Methods in CHO and HEK293

Therapeutic proteins are currently at the hotspot of innovation in the pharmaceutical medicine. However, their industrial production is technically challenging and improved methods for transcriptional manipulation of mammalian industrial cell cultures are needed. In this work we show that some of the most frequently used lab scale transfection efficacy assays fail to predict performance in the protein production settings. We compare the efficacies of a number of transfection reagents using adherent and suspension mammalian cell cultures and assessment based on several assays that utilize reporter protein quantitation, transfected cell population and post-transfection viability of cells. We validate reporter assays for assessing transfection methods in the lab that predict protein production in industrial settings. We also demonstrate that cell penetrating peptide-based transfection achieve significantly higher protein yields compared to PEI and lipoplex methods in both CHO and HEK293 producer cell lines. Availability of fast lab scale screening methods allows future development of improved transfection methods for protein production. One such potentially effective transient transfection method is the CPP-based approach presented currently.

Expressed therapeutic protein yields are predicted by transiently transfected mammalian cell population

Development of nucleic acid delivery systems requires the use of adequate tissue analysis methods, especially when aiming tissue-targeted drug delivery. In this chapter, a protocol is presented for analyzing a reporter signal from the lung tissue. Because lung is an important target tissue from the clinical point of view, yet represents a challenge from the histological point of view, this protocol can be used in any lung-targeting drug delivery project.

Birgit Vunk

Papers

Status update in the use of cell-penetrating peptides for the delivery of macromolecular therapeutics.

Predicting Transiently Expressed Protein Yields: Comparison of Transfection Methods in CHO and HEK293

Expressed therapeutic protein yields are predicted by transiently transfected mammalian cell population

Tissue Analysis of Lung-Targeted Delivery of siRNA and Plasmid DNA.