Multistage pH-responsive codelivery liposomal platform for synergistic cancer therapy.

BACKGROUND: Small interfering RNA (siRNA) is utilized as a potent agent for cancer therapy through regulating the expression of genes associated with tumors. While the widely application of siRNAs in cancer treatment is severely limited by their insufficient biological stability and its poor ability to penetrate cell membranes. Targeted delivery systems hold great promise to selectively deliver loaded drug to tumor site and reduce toxic side effect. However, the elevated tumor interstitial fluid pressure and efficient cytoplasmic release are still two significant obstacles to siRNA delivery. Co-delivery of chemotherapeutic drugs and siRNA represents a potential strategy which may achieve synergistic anticancer effect. Herein, we designed and synthesized a dual pH-responsive peptide (DPRP), which includes three units, a cell-penetrating domain (polyarginine), a polyanionic shielding domain (ehG)n, and an imine linkage between them. Based on the DPRP surface modification, we developed a pH-responsive liposomal system for co-delivering polo-like kinase-1 (PLK-1) specific siRNA and anticancer agent docetaxel (DTX), D-Lsi/DTX, to synergistically exhibit anti-tumor effect. RESULTS: In contrast to the results at the physiological pH (7.4), D-Lsi/DTX lead to the enhanced penetration into tumor spheroid, the facilitated cellular uptake, the promoted escape from endosomes/lysosomes, the improved distribution into cytoplasm, and the increased cellular apoptosis under mildly acidic condition (pH 6.5). Moreover, both in vitro and in vivo study indicated that D-Lsi/DTX had a therapeutic advantage over other control liposomes. We provided clear evidence that liposomal system co-delivering siPLK-1 and DTX could significantly downregulate expression of PLK-1 and inhibit tumor growth without detectable toxic side effect, compared with siPLK-1-loaded liposomes, DTX-loaded liposomes, and the combinatorial administration. CONCLUSION: These results demonstrate great potential of the combined chemo/gene therapy based on the multistage pH-responsive codelivery liposomal platform for synergistic tumor treatment.

On the inherent properties of Soluplus and its application in ibuprofen solid dispersions generated by microwave-quench cooling technology.

Polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer, or Soluplus®, is a relatively new copolymer and a promising carrier of amorphous solid dispersions. Knowledge on the inherent properties of Soluplus® (e.g. cloud points, critical micelle concentrations, and viscosity) in different conditions is relatively inadequate, and the application characteristics of Soluplus®-based solid dispersions made by microwave methods still need to be clarified. In the present investigation, the inherent properties of a Soluplus® carrier, including cloud points, critical micelle concentrations, and viscosity, were explored in different media and in altered conditions. Ibuprofen, a BCS class II non-steroidal anti-inflammatory drug, was selected to develop Soluplus®-based amorphous solid dispersions using the microwave-quench cooling (MQC) method. Scanning electronic microscopy (SEM), differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), Raman spectroscopy (RS), and Fourier transform infrared spectroscopy (FT-IR) were adopted to analyze amorphous properties and molecular interactions in ibuprofen/Soluplus® amorphous solid dispersions generated by MQC. Dissolution, dissolution extension, phase solubility, equilibrium solubility, and supersaturated crystallization inhibiting experiments were performed to elucidate the effects of Soluplus® on ibuprofen in solid dispersions. This research provides valuable information on the inherent properties of Soluplus® and presents a basic understanding of Soluplus® as a carrier of amorphous solid dispersions.

The Influence of Cellulosic Polymer's Variables on Dissolution/Solubility of Amorphous Felodipine and Crystallization Inhibition from a Supersaturated State.

The collective impact of cellulosic polymers on the dissolution, solubility, and crystallization inhibition of amorphous active pharmaceutical ingredients (APIs) is still far from being adequately understood. The goal of this research was to explore the influence of cellulosic polymers and incubation conditions on enhancement of solubility and dissolution of amorphous felodipine, while inhibiting crystallization of the drug from a supersaturated state. Variables, including cellulosic polymer type, amount, ionic strength, and viscosity, were evaluated for effects on API dissolution/solubility and crystallization processes. Water-soluble cellulosic polymers, including HPMC E15, HPMC E5, HPMC K100-LV, L-HPC, and MC, were studied. All cellulosic polymers could extend API dissolution and solubility to various extents by delaying crystallization and prolonging supersaturation duration, with their effectiveness ranked from greatest to least as HPMC E15 > HPMC E5 > HPMC K100-LV > L-HPC > MC. Decreased polymer amount, lower ionic strength, or higher polymer viscosity tended to decrease dissolution/solubility and promote crystal growth to accelerate crystallization. HPMC E15 achieved greatest extended API dissolution and maintenance of supersaturation from a supersaturated state; this polymer thus had the greatest potential for maintaining sustainable API absorption within biologically relevant time frames.

Delivering siRNA and Chemotherapeutic Molecules Across BBB and BTB for Intracranial Glioblastoma Therapy.

For aggressive brain glioblastoma, the therapy is significantly impaired by blood-brain barrier (BBB) and blood-tumor barrier (BTB). Choosing more than one target from the pool of tumor-stroma interactions is profoundly beneficial to therapeutic approaches. Thus, a multifunctional liposomal system based on anchoring two receptor-specific and penetrable peptides was designed for the combination delivery of BBB-impermeable siRNA and chemotherapeutic docetaxel to brain glioblastoma. Both macroscopic and microscopic specific distributions and targeting effect of the liposomes in the intracranial glioblastoma were confirmed. Superiority in therapeutic efficacies of the siRNA and DTX combination delivery system was revealed from encouraged VEGF gene silencing, tumor cell apoptosis, prolonged survival time, subdued glioblastoma cells in intracranial glioblastoma, and negligible system toxicities after systemic application. Furthermore, the liposomes made better modulation of glioblastoma microenvironment such as the down-regulation of CD31-positive tumor vessels and HIF-1α expression. The transport mechanism of the liposomes delivering the cargos across BBB via receptor-mediated transcytosis without destroying the integrity of BBB has been evaluated from in vitro and in vivo. Therefore, the dual peptides-modified liposomal system provides a safe and noninvasive approach for the delivery of siRNA and chemotherapeutic molecules across the BBB and BTB to target therapy of brain glioblastoma.

Neuroprotective Effects of a Standardized Flavonoid Extract from Safflower against a Rotenone-Induced Rat Model of Parkinson's Disease.

Parkinson's disease (PD) is a major age-related neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra par compacta (SNpc). Rotenone is a neurotoxin that is routinely used to model PD to aid in understanding the mechanisms of neuronal death. Safflower (Carthamus tinctorius. L.) has long been used to treat cerebrovascular diseases in China. This plant contains flavonoids, which have been reported to be effective in models of neurodegenerative disease. We previously reported that kaempferol derivatives from safflower could bind DJ-1, a protein associated with PD, and that a flavonoid extract from safflower exhibited neuroprotective effects in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced mouse model of PD. In this study, a standardized safflower flavonoid extract (SAFE) was isolated from safflower and found to primarily contain flavonoids. The aim of the current study was to confirm the neuroprotective effects of SAFE in rotenone-induced Parkinson rats. The results showed that SAFE treatment increased body weight and improved rearing behavior and grip strength. SAFE (35 or 70 mg/kg/day) treatment reversed the decreased protein expression of tyrosine hydroxylase, dopamine transporter and DJ-1 and increased the levels of dopamine and its metabolite. In contrast, acetylcholine levels were decreased. SAFE treatment also led to partial inhibition of PD-associated changes in extracellular space diffusion parameters. These changes were detected using a magnetic resonance imaging (MRI) tracer-based method, which provides novel information regarding neuronal loss and astrocyte activation. Thus, our results indicate that SAFE represents a potential therapeutic herbal treatment for PD.

[Rules and characteristics of crystallization inhibition of cellulose polymers against drugs in supersaturated states].

This study aims to explore the characteristics of crystallization inhibition by cellulose polymers at the supersaturated states of drugs. The study was performed by simulating supersaturated process and preparing supersaturated drug solid, and was carried out by measuring the content of drugs at different time points using dissolution apparatus. The types, amounts, ionic intensity and viscosity of cellulose polymers were examined to assess the crystallization inhibition effect on BCS II class drug indomethacin. HPMC E15 exhibited the strongest crystallization inhibition effect. The more added, more obvious crystallization suppression was observed against indomethacin. The decrease in viscosity and increase in ionic intensity led to an enhanced inhibition. The research provides a scientific guide for the crystallization inhibition of supersaturated drug by cellulose polymers.

[Activatable cell-penetrating peptides: a potential activatable modality for diseases diagnosis and therapy].

Cell-penetrating peptides are composed of positively-charged amino acids that can mediate molecules or nano-carriers across cell membranes. However, most of the known cell-penetrating peptides have no cell- or tissue-specificity, with affinity to almost all types of cells in internalization. The non-specificity of cell-penetrating peptides is a significant obstacle in the application to targeted delivery of imaging probes and therapeutic agents. Accordingly, many studies focused on selective switching of systemically-delivered inert cell-penetrating peptides into active forms in diseased tissues. Tsien groups introduced the concept of activatable cell-penetrating peptides in 2004. Subsequently, a growing number of similar delivery systems(molecular or nano-sized) have been documented, and the sensitive factors have included enzyme, lower p H, light and exogenous component. In this paper, we make an overview of the development of activatable delivery system in recent years.

Enhance Cancer Cell Recognition and Overcome Drug Resistance Using Hyaluronic Acid and α-Tocopheryl Succinate Based Multifunctional Nanoparticles.

Multidrug resistance (MDR) presents a clinical obstacle to cancer chemotherapy. The main purpose of this study was to evaluate the potential of a hyaluronic acid (HA) and α-tocopheryl succinate (α-TOS) based nanoparticle to enhance cancer cell recognition and overcome MDR, and to explore the underlying mechanisms. A multifunctional nanoparticle, HTTP-50 NP, consisted of HA-α-TOS (HT) conjugate and d-α-tocopheryl polyethylene glycol succinate (TPGS) with docetaxel loaded in its hydrophobic core. The promoted tumor cell recognition and accumulation, cytotoxicity, and mitochondria-specific apoptotic pathways for the HTTP-50 NP were confirmed in MCF-7/Adr cells (P-gp-overexpressing cancer model), indicating that the formulated DTX and the conjugated α-TOS in the HTTP-50 NP could synergistically circumvent the acquired and intrinsic MDR in MCF-7/Adr cells. In vivo investigation on the MCF-7/Adr xenografted nude mice models confirmed that HTTP-50 NP possessed much higher tumor tissue accumulation and exhibited pronouncedly enhanced antiresistance tumor efficacy with reduced systemic toxicity compared with HTTP-0 NP and Taxotere. The mechanisms of the multifunctional HTTP-50 NP to overcome MDR and enhance antiresistance efficacy may be contributed by CD44 receptor-targeted delivery and P-gp efflux inhibition, and meanwhile to maximize antitumor efficacy by synergism of DTX and mitocan of α-TOS killing tumor cells.

[The application of enzyme-sensitive activatable cell-penetrating peptides to targeted delivery system].

Cell-penetrating peptides (CPPs) offer a non-selective and receptor-independent mode to promote cellular uptake. Although the non-specificity of CPP-mediated internalization allows this approach applicable to a wide range of tumor types potentially, their universality is a significant obstacle to their clinical utility for targeted delivery of cancer therapeutics and imaging agents. Accordingly, many reports have focused on selective switching of systemically delivered inert CPPs into their active form in lesions (tumor). In this review, our attention is mainly confined to such an enzyme-sensitive domain incorporated delivery system with activatable CPPs (ACPPs), which have displayed the exciting strength in balancing the CPPs' pros and cons, and potential in the treatment and diagnosis of some diseases.

Cancer-associated fibroblasts barrier breaking via TGF-ß blockade paved way for docetaxel micelles delivery to treat pancreatic cancer.

TGF-ß is a crucial regulator in tumor microenvironment (TME), especially for myofibroblastic cancer-associated fibroblasts (myCAFs). The myCAFs can be motivated by TGF-ß signaling to erect pro-tumor TME, meanwhile, myCAFs overexpress TGF-ß to mediate the crosstalk between tumor and stromal cells. The blockade of TGF-ß can break cancer-associated fibroblasts barrier, consequently opening the access for drugs into tumor. The TGF-ß is a promising target in anti-tumor therapy. Herein, we introduced a two-stage combination therapy (TC-Therapy), including TGF-ß receptor I inhibitor SB525334 (SB) and cytotoxicity agent docetaxel micelle (DTX-M). We found that SB and DTX-M synergistically inhibited myCAFs proliferation and elevated p53 protein expression in BxPC-3/3T3 mixed cells. Gene and protein tests demonstrated that SB cut off TGF-ß signaling via receptor blockade and it did not arouse TGF-ß legend compensated internal autocrine. On the contrary, two agents combined decreased TGF-ß secretion and inhibited myCAFs viability marked by α-SMA and FAPα. TC-Therapy was applied in BxPc-3/3T3 mixed tumor-bearing mice model. After TC-Therapy, the α-SMA+/ FAPα+ myCAFs faded increasingly and collagenous fibers mainly secreted by myCAFs decreased dramatically as well. More than that, the myCAFs barrier breaking helped to normalize micro-vessels and paved way for micelle penetration. The TGF-ß protein level of TC-Therapy in TME was much lower than that of simplex DTX-M, which might account for TME restoration. In conclusion, TGF-ß inhibitor acted as the pioneer before nano chemotherapeutic agents. The TC-Therapy of TGF-ß signaling inhibition and anti-tumor agent DTX-M is a promising regimen without arising metastasis risk to treat pancreatic cancer. The therapeutic regimen focused on TGF-ß related myCAFs reminds clinicians to have a comprehensive understanding of pancreatic cancer.