Folate-modified poly(2-ethyl-2-oxazoline) as hydrophilic corona in polymeric micelles for enhanced intracellular doxorubicin delivery

The transmembrane transport of drug loaded micelles to intracellular compartment is quite crucial for efficient drug delivery. In the current study, we investigated the cellular internalization and anticancer activity of doxorubicin loaded micelles with folate modified stealthy PEOz corona. Folate-decorated micelles incorporating doxorubicin were characterized for particle size, degree of folate decoration, drug loading content and encapsulation efficiency, morphology, and surface charge. The targeting capability and cell viability were assessed using HeLa, KB, A549 and MCF-7/ADR cell lines. In vitro study clearly illustrated the folate receptor (FR) mediated targeting of FA modified micelles to FR-positive human HeLa, KB and MCF-7/ADR cells, while specific delivery to FR-negative A549 cells was not apparently increased at the same experimental conditions. Cytotoxicity assay showed 60% and 58% decrease in IC₅₀ values for HeLa and KB cells, while only a slight decrease for A549 cells, following treatment with folate modified formulations. The enhanced intracellular delivery of FA modified micelles in MCF-7/ADR cells was also observed. In vivo antitumor tests revealed DOX entrapped FA-PEOz-PCL micelles effectively inhibited the tumor growth and reduced the toxicity to mice compared with free DOX. The current study showed that the targeted nano-vector improved cytotoxicity of DOX and suggested that this novel PEOz endowed stealthy micelle system held great promise in tumor targeted therapy.     

Efficient serum-resistant lipopolyplexes targeted to the folate receptor

In this work, we have developed and evaluated a new targeted lipopolyplex (LPP), by combining polyethylenimine (PEI), 1,2-dioleoyl-3-(trimethylammonium) propane (DOTAP)/Chol liposomes, the plasmids pCMVLuc/pCMVIL-12, and the ligand folic acid (FA), able to transfect HeLa and B16-F10 cells in the presence of very high concentration of serum (60% FBS). These complexes (Fol-LPP) have a net positive surface charge. The combination of folic acid with lipopolyplexes also enhanced significantly the transfection activity of the therapeutic gene interleukin-12 (IL-12), without any significant cytotoxicity. The specificity of the folate receptor (FR)-mediated gene transfer was corroborated by employing a folate receptor deficient cell line (HepG2). This formulation improved gene delivery showed by conventional lipoplexes or polyplexes resulting an efficient, simple, and nontoxic method for gene delivery of therapeutic genes in vitro and very probably in vivo.     

Targeted drug delivery via the folate receptor

The folate receptor is a highly selective tumor marker overexpressed in greater than 90% of ovarian carcinomas. Two general strategies have been developed for the targeted delivery of drugs to folate receptor-positive tumor cells: by coupling to a monoclonal antibody against the receptor and by coupling to a high affinity ligand, folic acid. First, antibodies against the folate receptor, including their fragments and derivatives, have been evaluated for tumor imaging and immunotherapy clinically and have shown significant targeting efficacy in ovarian cancer patients. Folic acid, a high affinity ligand of the folate receptor, retains its receptor binding properties when derivatized via its gamma-carboxyl. Folate conjugation, therefore, presents an alternative method of targeting the folate receptor. This second strategy has been successfully applied in vitro for the receptor-specific delivery of protein toxins, anti-T-cell receptor antibodies, interleukin-2, chemotherapy agents, gamma-emitting radiopharmaceuticals, magnetic resonance imaging contrast agents, liposomal drug carriers, and gene transfer vectors. Low molecular weight radiopharmaceuticals based on folate conjugates showed much more favorable pharmacokinetic properties than radiolabeled antibodies and greater tumor selectivity in folate receptor-positive animal tumor models. The small size, convenient availability, simple conjugation chemistry, and presumed lack of immunogenicity of folic acid make it an ideal ligand for targeted delivery to tumors.     

Folate-linked lipid-based nanoparticle for targeted gene delivery

Cancer gene therapy has been intensively developed using non-viral vectors, among which cationic liposomes and nanoparticles are the most thoroughly investigated. For targeted delivery to tumors, vitamin folic acid has been utilized for folate receptor (FR)-mediated drug delivery, since FR is frequently overexpressed on many types of human tumors. Liposomes conjugated to folate ligand have been used as carriers of chemotherapeutic agents and DNA to receptor-bearing tumor cells in vitro. As an alternative treatment for prostate cancer, suicide gene therapy by local injection using an adenoviral vector has been reported, but not that using non-viral vectors. The folate-linked, lipid-based nanoparticles which we developed could deliver genes extensively to FR-negative LNCaP and PC-3 cells, as well as FR-positive KB and Hela cells. In this review, we outline folate-linked liposomes and nanoparticles, and show the effectiveness of folate-linked, lipid-based nanoparticles as a vector for DNA transfection and for suicide gene therapy, to treat human nasopharyngeal and prostate tumors.     

Targeted liposomes to deliver DNA to cells expressing 5-HT receptors

Cell targeted delivery of drugs, including nucleic acids, is known to enhance the therapeutic potential of free drugs. We used serotonin (5-HT) as the targeting ligand to deliver plasmid DNA to cells specifically expressing 5-HT receptor. Our liposomal formulation includes the 5-HT conjugated targeting lipid, a cationic lipid and cholesterol. DNA-binding studies indicate that the targeting 5-HT-lipid binds DNA efficiently. The formulation was tested and found to efficiently deliver DNA into CHO cells stably expressing the human serotonin(1A) receptor (CHO-5-HT(1A)R) compared to control CHO cells. Liposomes without the 5-HT moiety were less efficient in both cell lines. Similar enhancement in transfection efficiency was also observed in human neuroblastoma IMR32 and hepatocellular carcinoma (HepG2) cells. Cell uptake studies using CHO-5-HT(1A)R cells by flow cytometry and confocal microscopy clearly indicated that the targeting liposomes through 5-HT moiety may have a direct role in increasing the cellular uptake of DNA-lipid complexes. To our knowledge this is the first report that demonstrates receptor-targeted nucleic acid delivery into cells expressing 5-HT receptor.     

Multifunctional nanomedicine platform for cancer specific delivery of siRNA by superparamagnetic iron oxide nanoparticles-dendrimer complexes

The ability of Superparamagnetic Iron Oxide (SPIO) nanoparticles and Poly(Propyleneimine) generation 5 dendrimers (PPI G5) to cooperatively provoke siRNA complexation was investigated in order to develop a targeted, multifunctional siRNA delivery system for cancer therapy. Poly(ethylene glycol) (PEG) coating and cancer specific targeting moiety (LHRH peptide) have been incorporated into SPIO-PPI G5-siRNA complexes to enhance serum stability and selective internalization by cancer cells. Such a modification of siRNA nanoparticles enhanced its internalization into cancer cells and increased the efficiency of targeted gene suppression in vitro. Moreover, the developed siRNA delivery system was capable of sufficiently enhancing in vivo antitumor activity of an anticancer drug (Cisplatin). The proposed approach demonstrates potential for the creation of targeted multifunctional nanomedicine platforms with the ability to deliver therapeutic siRNA specifically to cancer cells in order to prevent severe adverse side effects on healthy tissues and in situ monitoring of the therapeutic outcome using clinically relevant imaging techniques.     

Receptor-targeted gene delivery viafolate-conjugated polyethylenimine

A novel synthetic gene transfer vector was evaluated for tumor cell-specific targeted gene delivery. The folate receptor is a tumor marker overexpressed in more than 90% of ovarian carcinomas and large percentages of other human tumors. Folic acid is a high affinity ligand for the folate receptor that retains its binding affinity upon derivatization via its gamma carboxyl. Folate conjugation, therefore, presents a potential strategy for tumor-selective targeted gene delivery. In the current study, we investigated a series of folate conjugates of the cationic polymer polyethylenimine (PEI) for potential use in gene delivery. A plasmid containing a luciferase reporter gene (pCMV-Luc) and the folate receptor expressing human oral cancer KB cells were used to monitor gene transfer efficiency in vitro. Transfection activity of polyplexes containing unmodified polyethylenimine was highly dependent on the positive to negative charge (or the N/P) ratio. Folate directly attached to PEI did not significantly alter the transfection activity of its DNA complexes compared to unmodified PEI. Modification of PEI by polyethyleneglycol (PEG) led to a partial inhibition of gene delivery compared to unmodified PEI. Attaching folates to the distal termini of PEG-modified PEI greatly enhanced the transfection activity of the corresponding DNA complexes over the polyplexes containing PEG-modified PEI. The enhancements were observed at all N/P ratios tested and could be blocked partially by co-incubation with 200 μM free folic acid, which suggested the involvement of folate receptor in gene transfer. Targeted vectors based on the folate-PEG-PEI conjugate are potentially useful as simple tumor-specific vehicles of therapeutic genes.     

Folate receptor-mediated drug targeting: from therapeutics to diagnostics

Folate targeted drug delivery has emerged as an alternative therapy for the treatment and imaging of many cancers and inflammatory diseases. Due to its small molecular size and high binding affinity for cell surface folate receptors (FR), folate conjugates have the ability to deliver a variety of molecular complexes to pathologic cells without causing harm to normal tissues. Complexes that have been successfully delivered to FR expressing cells, to date, include protein toxins, immune stimulants, chemotherapeutic agents, liposomes, nanoparticles, and imaging agents. This review will summarize the applications of folic acid as a targeting ligand and highlight the various methods being developed for delivery of therapeutic and imaging agents to FR-expressing cells.     

Targeted drug delivery via folate receptors

Targeted delivery via selective cellular markers can potentially increase the efficacy and reduce the toxicity of therapeutic agents. The folate receptor (FR) has two glycosyl phosphatidylinositol (GPI)-anchored isoforms, α and β. FR-α expression is frequently amplified in epithelial cancers, whereas FR-β expression is found in myeloid leukemia and activated macrophages associated with chronic inflammatory diseases. Conjugates of folic acid and anti-FR antibodies can be taken up by cancer cells via receptor-mediated endocytosis, thus providing a mechanism for targeted delivery to FR+ cells. The aim of this article is to provide a brief overview of applications of FR targeting in drug delivery, with an emphasis on the strategy of using folate as a targeting ligand. In order to do this, recent literature is surveyed on targeted delivery via both FR sub-types, as well as new findings on selective receptor upregulation in the targeted cells. A wide variety of molecules and drug carriers, including imaging agents, chemotherapeutic agents, oligonucleotides, proteins, haptens, liposomes, nanoparticles and gene transfer vectors have been conjugated to folate and evaluated for FR-targeted delivery. Substantial targeting efficacy has been found both in vitro and in vivo. In addition, mechanisms and methods for selective FR upregulation have been uncovered, which might enhance the effectiveness of the FR-targeted delivery strategy. FR-α serves as a useful marker for cancer, whereas FR-β serves as a marker for myeloid leukemia and chronic inflammatory diseases. FR-targeted agents have shown promising efficacy in preclinical models and significant potential for future clinical application in a wide range of diseases.     

Selective liposome targeting of folate receptor positive immune cells in inflammatory diseases

Activated macrophages play a key role in the development and maintenance of inflammatory diseases such as atherosclerosis, lupus, psoriasis, rheumatoid arthritis, ulcerative colitis, and many others. These activated macrophages, but not resting or quiescent macrophages highly up-regulate folate receptor beta (FR-β). This differential expression of FR-β provides a mechanism to selectively deliver imaging and therapeutic agents utilizing folate as a targeting molecule. In an effort to determine whether inflammatory diseases can be targeted utilizing a folate-linked nanosize carrier, a PEG-coated liposome was prepared that incorporated a folate conjugated PEG that also could transport imaging or therapeutic cargo. We demonstrate that these folate-liposomes specifically bind to folate receptor positive cells and accumulate at sites of inflammation in mouse models of colitis and atherosclerosis. These two animal models show that folate-targeted liposomes could be successfully utilized to deliver fluorescent molecules and an anti-inflammatory drug (betamethasone) for diagnostic and therapeutic applications.     

N-acetylcysteine amide decreases oxidative stress but not cell death induced by doxorubicin in H9c2 cardiomyocytes

Background

Botulinum neurotoxin (BoNT) is the most potent poison known to mankind. Currently no antidote is available to rescue poisoned synapses. An effective medical countermeasure strategy would require developing a drug that could rescue poisoned neuromuscular synapses and include its efficient delivery specifically to poisoned presynaptic nerve terminals. Here we report a drug delivery strategy that could directly deliver toxin inhibitors into the intoxicated nerve terminal cytosol.

Results

A targeted delivery vehicle was developed for intracellular transport of emerging botulinum neurotoxin antagonists. The drug delivery vehicle consisted of the non-toxic recombinant heavy chain of botulinum neurotoxin-A coupled to a 10-kDa amino dextran via the heterobifunctional linker 3-(2-pyridylthio)-propionyl hydrazide. The heavy chain served to target botulinum neurotoxin-sensitive cells and promote internalization of the complex, while the dextran served as a platform to deliver model therapeutic molecules to the targeted neurons. Our results indicated that the drug delivery vehicle entry into neurons was via BoNT-A receptor mediated endocytosis. Once internalized into neurons, the drug carrier component separated from the drug delivery vehicle in a fashion similar to the separation of the BoNT-A light chain from the holotoxin. This drug delivery vehicle could be used to deliver BoNT-A antidotes into BoNT-A intoxicated cultured mouse spinal cord cells.

Conclusion

An effective BoNT-based drug delivery vehicle can be used to directly deliver toxin inhibitors into intoxicated nerve terminal cytosol. This approach can potentially be utilized for targeted drug delivery to treat other neuronal and neuromuscular disorders. This report also provides new knowledge of endocytosis and exocytosis as well as of BoNT trafficking.     

RNAi mediated gene silencing of ITPA using a targeted nanocarrier: Apoptosis induction in SKBR3 cancer cells

A pure nucleotide pool is required for high‐fidelity DNA replication and prevention of carcinogenesis in living cells. Human inosine triphosphatase (ITPase), encoded by the ITPA gene, plays a critical role in maintaining the purity of the cellular nucleotide pool by excluding nucleotides that enhance mutagenesis. ITPase is a nucleoside triphosphate pyrophosphatase that hydrolyzes the non‐canonical nucleotides inosine triphosphate (ITP) and xanthine triphosphate (XTP). The monophosphate products of ITPase reactions are subsequently excluded from the nucleotide pool and the improper substitution of ITP and XTP into DNA and RNA is prevented. Previous studies show that deficiency in ITPA can suppress cellular growth and enhance DNA instability. In this study, we evaluated the influence of effective ITPA down‐regulation on the induction of apoptosis in a human cancer cell line using folate‐single wall nanotubes (SWNT) as a targeted nanocarrier. We assessed whether SWNT enhances IPTA‐siRNA transfection efficiency in cancer cells using folate as a homing device. Since folate receptor is considerably overexpressed in cancer cells, conjugation of SWNTs to folate could enhance their cancer‐specific penetrance. We found that nanocarrier mediated ITPA‐siRNA transfection into SKBR3 cells caused significant reduction of ITPA mRNA expression level and complete down‐regulation of the ITPase protein product. The silencing of ITPA led to promotion of apoptosis in SWNT‐treated SKBR3 cancer cells.     

Targeted drug delivery via folate receptors

Targeted delivery via selective cellular markers can potentially increase the efficacy and reduce the toxicity of therapeutic agents. The folate receptor (FR) has two glycosyl phosphatidylinositol (GPI)-anchored isoforms, alpha and beta. FR-alpha expression is frequently amplified in epithelial cancers, whereas FR-beta expression is found in myeloid leukemia and activated macrophages associated with chronic inflammatory diseases. Conjugates of folic acid and anti-FR antibodies can be taken up by cancer cells via receptor-mediated endocytosis, thus providing a mechanism for targeted delivery to FR+ cells. The aim of this article is to provide a brief overview of applications of FR targeting in drug delivery, with an emphasis on the strategy of using folate as a targeting ligand. In order to do this, recent literature is surveyed on targeted delivery via both FR sub-types, as well as new findings on selective receptor upregulation in the targeted cells. A wide variety of molecules and drug carriers, including imaging agents, chemotherapeutic agents, oligonucleotides, proteins, haptens, liposomes, nanoparticles and gene transfer vectors have been conjugated to folate and evaluated for FR-targeted delivery. Substantial targeting efficacy has been found both in vitro and in vivo. In addition, mechanisms and methods for selective FR upregulation have been uncovered, which might enhance the effectiveness of the FR-targeted delivery strategy. FR-alpha serves as a useful marker for cancer, whereas FR-beta serves as a marker for myeloid leukemia and chronic inflammatory diseases. FR-targeted agents have shown promising efficacy in preclinical models and significant potential for future clinical application in a wide range of diseases.     

叶酸受体介导的负载紫杉醇纳米药物输送系统的体外生物活性的研究

目的:叶酸受体介导的负载紫杉醇纳米药物输送系统的的体外生物活性研究。方法:应用激光共聚焦观察肝素-叶酸-紫杉醇纳米粒进入叶酸受体阳性表达KB细胞和叶酸受体阴性表达A549细胞的情况,考察纳米粒对靶细胞摄取情况;以原药紫杉醇为对照组,应用MTT法检测纳米粒子对叶酸受体阳性表达KB细胞的抗癌抑制活性;应用流式细胞仪对纳米粒子抗癌机制进行分析。结果:细胞摄取实验表明,肝素-叶酸-紫杉醇纳米药物是通过叶酸受体介导的内吞作用实现对靶细胞的特异性;与紫杉醇对比,纳米粒子的针对叶酸受体阳性细胞的抑制效果更好,半数抑制浓度(IC50)为0.06g/mL,MTT实验结果与细胞摄取实验结果一致;流式细胞仪检测表明肝素-叶酸-紫杉醇纳米药物也表现出与紫杉醇相似的抑制作用,即G2/M期均有所增长。结论:体外生物活性检测表明叶酸受体介导的负载紫杉醇的纳米药物输送系统有较好的靶向性,其应用前景值得期待。     

Targeted delivery of antisense oligodeoxynucleotide and small interference RNA into lung cancer cells

Selective gene inhibition by antisense oligodeoxynucleotide (AS-ODN) or by small interference RNA (siRNA) therapeutics promises the treatment of diseases that cannot be cured by conventional drugs. However, antisense therapy is hindered due to poor stability in physiological fluids and limited intracellular uptake. To address these problems, a ligand targeted and sterically stabilized nanoparticle formulation has been developed in our lab. Human lung cancer cells often overexpress the sigma receptor and, thus, can be targeted with a specific ligand such as anisamide. AS-ODN or siRNA against human survivin was mixed with a carrier DNA, calf thymus DNA, before complexing with protamine, a highly positively charged peptide. The resulting particles were coated with cationic liposomes consisting of DOTAP and cholesterol (1:1, molar ratio) to obtain LPD (liposome-polycation-DNA) nanoparticles. Ligand targeting and steric stabilization were then introduced by incubating preformed LPD nanoparticles with DSPE-PEG-anisamide, a PEGylated ligand lipid developed earlier in our lab, by the postinsertion method. Nontargeted nanoparticles coated with DSPE-PEG were also prepared as a control. Antisense activities of nanoparticles were determined by survivin mRNA down-regulation, survivin protein down-regulation, ability to trigger apoptosis in tumor cells, tumor cell growth inhibition, and chemosensitization of the treated tumor cells to anticancer drugs. We found that tumor cell delivery and antisense activity of PEGylated nanoparticles were sequence dependent and rely on the presence of anisamide ligand. The uptake of oligonucleotide in targeted, PEGylated nanoparticles could be competed by excess free ligand. Our results suggest that the ligand targeted and sterically stabilized nanoparticles can provide a selective delivery of AS-ODN and siRNA into lung cancer cells for therapy.     

An updated review of folate-functionalized nanocarriers: A promising ligand in cancer

The uncontrolled release of drugs in conventional drug delivery systems has led to the introduction of new nanotechnology-based drug delivery systems and the use of targeted nanocarriers for cancer treatment. These targeted nanocarriers, which consist of intelligent nanoparticles modified with targeting ligands, can deliver drugs to specified locations at the right time and reduce drug doses to prevent side effects. Folate is a suitable targeting ligand for folate receptors overexpressed on cancer cells and has shown promising results in the diagnosis and treatment of cancer. In this review, we highlight the latest developments on the use of folate-conjugated nanoparticles in cancer diagnosis and treatment. Moreover, the toxicity, biocompatibility and efficacy of these nanocarriers are discussed.     

小干扰RNA的靶向运送体系

靶向运送是小干扰RNA(siRNA)药物进入临床应用最关键的环节。研究人员利用配体、抗体和适配子构建了非常有效的靶向特异性细胞组织的siRNA运送体系。制备运送体系分3步:先使脂质体或多聚物与siRNA自发结合形成微粒,利用聚乙二醇等作为桥接分子包被在微粒外层,最后将配体、抗体或适配子等靶向性分子与桥接分子连接。     

PLGA-TPGS 负载α-TIF-siRNA 纳米粒对疱疹病毒1的抑制作用

目的：研究以 PLGA-TPGS 生物可降解材料为载体包载α-TIF-siRNA 的纳米粒对 HSV1的抑制作用。方法以 PLGA-TPGS 为载体,采用双乳蒸发法制备包载α-TIF-siRNA 的 PLGA-TPGS 纳米粒（命名为 PLGA-TPGS/α-TIF-siRNA NPs）,并对其进行表征,包括粒径大小、zeta 电位、包封率和释放率,用 MTT 法检测纳米粒对上皮细胞和HeLa 细胞的细胞毒作用,免疫荧光观察纳米粒在细胞内的释放,用空斑实验研究体外研究纳米粒对 HSV1病毒的抑制作用。结果 PLGA-TPGS/α-TIF-siRNA NPs 的粒径大小为（257±2.94）nm,zeta 电位为（-31.25±1.70）mV,siRNA的包封率为（56.23±3.68）％,纳米释放 siRNA 呈双相,即在96 h 释放达到50％,之后呈缓慢释放,用 MTT 法分析 PL-GA-TPGS/α-TIF-siRNA NPs 对原代角质形成细胞和 HeLa 细胞几乎无细胞毒性。荧光显微镜能观察纳米粒 siRNA 细胞内释放。PLGA-TPGS/α-TIF-siRNA NPs 能明显延长抑制感染 HeLa 细胞的 HSV1。结论 PLGA-TPGS 纳米粒可以作 siRNA 的载体。PLGA-TPGS/α-TIF-siRNA NPs 在体外对 HSV1病毒具有明显的抑制作用,可以成为治疗 HSV1-诱导的角膜炎在内的相关疾病的候选药物。     

The human fatty acid synthase: a new therapeutic target for coxsackievirus B3-induced diseases?

Coxsackievirus is linked to a large variety of severe human and animal diseases such as myocarditis. The interplay between host factors and virus components is crucial for the fate of the infected cells. However, host proteins which may play a role in coxsackievirus-induced diseases are ill-defined. Two-dimensional gel electrophoresis of protein extracts obtained from coxsackievirus B3 (CVB3)-infected and uninfected HeLa or HepG2 cells combined with spot analysis revealed several proteins which are exclusively up-regulated in infected cells. One of these proteins was identified as the fatty acid synthase (FAS). By using cerulenin and C75, two known inhibitors of FAS we were able to significantly block CVB3 replication. FAS appears to be directly involved in CVB3-caused pathology and is therefore suitable as a therapeutic target in CVB3-induced diseases.     

叶酸靶向的PGA联合N-苯乙酰化阿霉素的抗肿瘤活性

目的考察叶酸靶向的青霉素酰化酶G(PGA)联合前药N-苯乙酰化阿霉素(DOXP)对叶酸受体阳性肿瘤细胞的活性。方法通过双功能偶联剂EDC将叶酸与PGA偶联，荧光显微镜观察HeLa和SKOV3细胞对叶酸-PGA的摄取，MTT法检测DOXP联合叶酸-PGA对HeLa和SKOV3细胞的毒性。结果叶酸-PGA能被HeLa和SKOV3细胞选择性摄取；DOXP在叶酸-PGA的作用下对HeLa和SKOV3细胞的IC₅₀分别为0.72和0.75 μmol·L^-1，均低于阿霉素。结论叶酸-PGA的特异性靶向作用提高了阿霉素对HeLa和SKOV3细胞的敏感性。