Basic and practical concepts of radiopharmaceutical purification methods

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Endocytosis and transcytosis

Vesicular coat proteins mediate the formation of nascent vesicles and select the cargo to be incorporated therein. As additional coat proteins are discovered that regulate vesicular traffic along very specific intracellular pathways, the possibility looms of regulating the intracellular trafficking and targeting of therapeutic agents by modulation of the action of vesicular coat proteins. Examples are provided of coat proteins thought to regulate the trafficking of pharmaceutically relevant molecules via clathrin-mediated endocytosis, caveolae-mediated endocytosis, and transcytosis.     

Physical methods of nucleic acid transfer: general concepts and applications

Physical methods of gene (and/or drug) transfer need to combine two effects to deliver the therapeutic material into cells. The physical methods must induce reversible alterations in the plasma membrane to allow the direct passage of the molecules of interest into the cell cytosol. They must also bring the nucleic acids in contact with the permeabilized plasma membrane or facilitate access to the inside of the cell. These two effects can be achieved in one or more steps, depending upon the methods employed. In this review, we describe and compare several physical methods: biolistics, jet injection, hydrodynamic injection, ultrasound, magnetic field and electric pulse mediated gene transfer. We describe the physical mechanisms underlying these approaches and discuss the advantages and limitations of each approach as well as its potential application in research or in preclinical and clinical trials. We also provide conclusions, comparisons, and projections for future developments. While some of these methods are already in use in man, some are still under development or are used only within clinical trials for gene transfer. The possibilities offered by these methods are, however, not restricted to the transfer of genes and the complementary uses of these technologies are also discussed. As these methods of gene transfer may bypass some of the side effects linked to viral or biochemical approaches, they may find their place in specific clinical applications in the future.This article is part of a themed section on Vector Design and Drug Delivery. For a list of all articles in this section see the end of this paper, or visit: http://www3.interscience.wiley.com/journal/121548564/issueyear?year=2009     

Characterisation of cell-penetrating peptide-mediated peptide delivery

Cell-penetrating peptides such as antennapedia, TAT, transportan and polyarginine have been extensively employed for in vitro and in vivo delivery of biologically active peptides. However, little is known of the relative efficacy, toxicity and uptake mechanism of individual protein transduction domain-peptide conjugates, factors that will be critical in determining the most effective sequence. In the present study, we show by FACS analysis that unconjugated antennapedia, TAT, transportan and polyarginine demonstrate similar kinetic uptake profiles, being maximal at 1-3 h and independent of cell type (HeLa, A549 and CHO cell lines). A comparison of the magnitude of uptake of cell-penetrating peptide conjugates demonstrated that polyarginine=transportan>antennapedia>TAT. However, examination of cellular toxicity showed that antennapedia相似文献   

细胞穿膜肽在癌症治疗中的应用

细胞膜有选择渗透性,能阻止大多数外来因子进入细胞。然而许多治疗因子必须穿过细胞膜才能进入细胞内起作用。细胞穿膜肽是一组简短的阳离子序列,它具有很强的穿膜能力。自从1988年发现细胞穿膜肽后,细胞穿膜肽被用于携带各种物质,如小分子、核酸、抗体、纳米粒等进入细胞膜。本文重点介绍了近几年来关于细胞穿膜肽穿膜机制的研究进展,以及细胞穿膜肽作为运载体携带抗癌药物靶向进入肿瘤细胞,从而实现对肿瘤细胞的靶向性,同时可克服肿瘤的多药抗药性等研究进展。     

Endocytosis and retrograde transport of Shiga toxin

Shiga toxin belongs to the group of bacterial and plant toxins that act on cells by binding to cell surface receptors via a binding-moiety, then the toxins are endocytosed and transported retrogradely to the Golgi apparatus and the endoplasmic reticulum (ER) before an enzymatically active moiety enters the cytosol and exerts the toxic effect. In the case of Shiga toxin, similarly to plant toxins such as ricin and viscumin, the toxin removes one adenine from the 28S RNA of the 60S subunit of the ribosome and thereby inhibits protein synthesis. This ribotoxic effect is in some cells followed by apoptosis. In this article we focus on new discoveries concerning endocytosis and retrograde transport of Shiga toxin to the Golgi, the ER and the cytosol.     

Endocytosis of adenovirus and adenovirus capsid proteins

Key proteins of the icosahedral-shaped adenovirus (Ad) capsid mediate infection, and interact with cellular proteins to coordinate stepwise events of cell entry that produce successful gene transfer. Infection is mediated predominantly by the penton and fiber capsid proteins. The fiber initiates cell binding while the penton binds integrin coreceptors, triggering integrin-mediated endocytosis. Penton integrin signaling precedes viral escape from the endosomal vesicle. After cell binding, the virus undergoes stepwise disassembly of the capsid, shedding proteins during cell entry. Intracellular trafficking of the remaining capsid shell is mediated by the interaction of naked particles with the cytoskeleton. The capsid translocates toward the nucleus, with the majority of capsid proteins accumulating at the nuclear periphery, while viral DNA and associated protein VII are extruded through the nuclear pore. This discussion will encompass the current knowledge on Ad cell entry and trafficking, with an emphasis on the contribution of Ad capsid proteins to these processes. A greater understanding of the highly effective Ad cell entry pathway may lend itself to the development of safer drug and gene delivery alternatives utilizing similar pathways.     

穿膜肽的研究进展

穿膜肽是一些具有细胞膜穿透能力的小分子多肽,可有效携带比其分子质量大100倍的外源性疏水大分子进入细胞,并对宿主细胞没有显著毒副作用.穿膜肽存在多种穿膜机制,诸如直接渗透到细胞膜,通过易位形成的一个暂时性的结构和内吞作用介导入膜等.具体的穿膜机制还不清楚,但普遍认为穿膜肽与细胞表面负电荷物质的直接接触是必不可少的.由于穿膜肽的穿膜性质,其在分子生物学、药学、细胞生物学、疫苗学甚至影像学上有广泛的应用前景.本文对近年来穿膜肽的结构、穿膜机制和应用方面的研究进展进行了综述.     

Preparation and characterization of photo-responsive cell-penetrating peptide-mediated nanostructured lipid carrier

Abstract

Tumor-oriented nanocarrier drug delivery approaches with photo-sensitivity have been drawing considerable attention over the years. Here we described a nanostructured lipid carrier (NLC) modified with photo-responsive cell-penetrating peptides (pCPP-NLC). The conventional cell penetrating peptide (CPP)-mediated intracellular drug delivery system sometimes seemed limited due to the lack of target selectivity of the cell penetrating activity. In this study, pCPP (CKRRMK^NvocWK^Nvo0cK^Nvoc), a photo-responsive CPP originated from the CPP (CKRRMKWKK), was endowed photo-responsiveness after masking of lysines in the sequence of CPP with photolabile-protective groups, and was introduced onto the surface of NLC. Accordingly, upon reaching the tumor tissues, pCPP-NLC enhance specific cancer cellular uptake after rapidly cleaving the photolabile-protective group, in this case, illumination in the presence of UV-light. In contrast, in circulation, the penetration was shielded. The pCPP-NLC carrying paclitaxel (PTX) prepared in this work possessed suitable physiochemical properties such as small particle size, high drug encapsulation efficiency, and good stability. The strong cellular uptake and cytotoxic activity of pCPP-NLC in HT-1080 cells verified the correlation with illumination. The remarkable penetration into HT-1080 multicellular tumor spheroids confirmed that the temporary mask of the photolabile-protective group in pCPP does not disturb the penetration ability of CPP in the tumor microenvironment with illumination. Furthermore, the triggered activation exhibited higher antitumor efficacy with the tumor spheroids compared with the non-modified NLC (N-NLC) and Taxol®. In conclusion, the application of pCPP modifications may be an approach for the selectively targeted delivery of anti-tumor agents.     

凝胶电泳法及荧光光度法测定siRNA阳离子脂质体的含量和包封率

建立siRNA含量测定方法,用于阳离子脂质体中siRNA的含量和包封率测定。利用荧光染料SYBR Gold和Ribogreen与siRNA结合后能发出强烈荧光的原理,分别采用电泳法和荧光分光光度法测定脂质体中的siRNA含量, 计算阳离子脂质体的包封率。SYBR Gold电泳法的检测线性范围为0.2～2.0 μmol·L^-1 (R=0.993 0), 高、中、低3个浓度的回收率分别为96.35%、96.92%和100.74% (n = 3); 日内日间精密度的RSD均小于5% (n = 5)。Ribogreen荧光分光光度法的检测线性范围为10～50 nmol·L^-1 (R = 0.997 1), 高、中、低3个浓度的回收率分别为98.22%、99.88%和99.64% (n = 3);日内日间精密度的RSD均小于5% (n = 5)。利用这两种方法所测得3批阳离子脂质体中siRNA平均含量分别为98.52%和97.85%,平均包封率分别为99.20%和96.45%,经方差分析, 两种方法无显著性差异。两种方法准确可靠、稳定性高和方便实用,均可用于阳离子脂质体中siRNA的含量和包封率测定。

     

Binding of cationic porphyrin to human serum albumin studied using comprehensive spectroscopic methods

The interaction between cationic porphyrin, a potential valuable anti-tumor and antibiotic drug, and human serum albumin (HSA) was investigated using spectroscopy methods. The binding constants were obtained using fluorescence quenching method (K(SV) = (3.24 +/- 0.29) x 10(4) M(-1)) and surface plasmon resonance (SPR) spectroscopy (K(A) = (6.287 +/- 0.407) x 10(4) M(-1)). The association rate constant (k(a) = 1622 +/- 72.9 M(-1) s(-1)) and dissociation rate constant (K(d) = 0.02589 +/- 0.0024 s(-1)) of the binding process were also calculated. Compared with the two results, it was known that one of the binding sites was near the tryptophan residue and also there existed other binding sites. The Fourier transform infrared (FT-IR) spectroscopy and circular dichroism (CD) spectroscopy indicated that the confirmation of HSA was nearly not affected with the addition of porphyrin.     

Methods to follow intracellular trafficking of cell-penetrating peptides

Cell-penetrating peptides (CPPs) are efficient vehicles to transport bioactive molecules into the cells. Despite numerous studies the exact mechanism by which CPPs facilitate delivery of cargo to its intracellular target is still debated. The current work presents methods that can be used for tracking CPP/pDNA complexes through endosomal transport and show the role of endosomal transport in the delivery of cargo. Separation of endosomal vesicles by differential centrifugation enables to pinpoint the localization of delivered cargo without labeling it and gives important quantitative information about pDNA trafficing in certain endosomal compartments. Single particle tracking (SPT) allows following individual CPP/cargo complex through endosomal path in live cells, using fluoresently labled cargo and green fluoresent protein expressing cells. These two different methods show similar results about tested NickFect/pDNA complexes intracellular trafficing. NF51 facilitates rapid internalization of complexes into the cells, prolongs their stay in early endosomes and promotes release to cytosol. NF1 is less capable to induce endosomal release and higher amount of complexes are routed to lysosomes for degradation. Our findings offer potential delivery vector for in vivo applications, NF51, where endosomal entrapment has been allayed. Furthermore, these methods are valuable tools to study other CPP-based delivery systems.     

The use of cell-penetrating peptides for drug delivery

In the past decade, several peptides that can translocate cell membranes have been identified. Some of these peptides, which can be divided into different families, have short amino acid sequences (10-27 residues in length) and enter the cell by a receptor-independent mechanism. Furthermore, these peptides are capable of internalizing hydrophilic cargoes. Although the detailed mechanism by which these molecules enter cells is poorly understood, their ability to traverse the membrane into the cytoplasm has provided a new and powerful biological tool for transporting drugs across cell membranes.     

细胞促渗肽在透皮给药中的应用

细胞促渗肽（CPP）最早于细胞研究中发现,此后被引入透皮制剂领域,相关透皮机制尚未阐明。CPP在透皮制剂领域中应用广泛,对小分子药物、多肽、蛋白质、核酸和胶粒载体均有皮肤促渗作用。本文综述CPP在透皮领域中的应用。     

Advancement of cell-penetrating peptides in combating triple-negative breast cancer

Extensive research efforts have been made and are still ongoing in the search for an ideal anti-cancer therapy. Almost all chemotherapeutics require a carrier or vehicle, a drug delivery system that can transport the drug specifically to the targeted cancer cells, sparing normal cells. Cell-penetrating peptides (CPPs) provide an effective and efficient pathway for the intra-cellular transportation of various bioactive molecules in several biomedical therapies. They are now well-recognized as facilitators of intracellular cargo delivery and have excellent potential for targeted anti-cancer therapy. In this review, we explain CPPs, recent progress in the development of new CPPs, and their utilization to transport cargoes such as imaging agents, chemotherapeutics, and short-interfering RNAs (siRNA) into tumor cells, contributing to the advancement of novel tumor-specific delivery systems.     

细胞穿膜肽作为药物载体的研究进展

生物大分子在许多疾病的治疗中发挥着重要的作用, 但由于细胞膜的天然屏障作用, 只有分子质量小于600 Da的分子才能穿透细胞膜进入细胞内。这使得一些有治疗价值但无细胞膜穿透性的分子在细胞生物学、药学等领域的应用受到极大的限制。近年来发现的一些具有细胞穿透功能的短肽 (少于30个氨基酸) 即细胞穿膜肽 (CPPs), 能够有效地将蛋白质、多肽、核酸片段等以多种方式导入多种哺乳动物细胞, 其转导效率高且不会造成细胞损伤。CPPs的发现为生物大分子在细胞生物学、基因治疗、药物体内转运、临床药效评价以及细胞免疫学等研究领域等均具有良好的应用前景。本文就CPPs的种类特点、内化机制、应用及其存在的问题进行讨论和评述。