Major progress in tumor accumulation and penetration of nanomedicine / 药学学报

Nanomedicine has great potential in cancer therapy, but the complex tumor microenvironment greatly prevents nanomedicine from being effectively delivered into tumor in vivo. It has been widely accepted that the encapsulated drugs in the nanoparticles have to go through five major cascading steps, including blood circulation, accumulation in tumor, penetration into the depth of tumor tissue, internalization by tumor cells and then intracellular drug release, before they can exert the anti-tumor efficacy. Among the five steps, drug accumulation in tumor and penetration in the depth of tumor have been the two major issues undermines the antitumor efficacy of nanomedicine. This paper summarizes the new major progress in improving the tumor accumulation and penetration of nanomedicine, especially the technologies that appeared or developed in the last five years.

Preparation of disulfiram naonosuspensions and their anti-tumor efficacy in vitro and in vivo / 药学学报

Disulfiram (DSF) is a traditional anti-alcohol drug, but it was recently found that DSF has strong inhibitory effect on the growth of a variety of cancer cells. However, its clinical application is greatly limited due to its poor solubility, instability in gastrointestinal tract and short plasma half-life. In this study, DSF is fabricated into nanosuspensions with the aim of trying to solve these problems. DSF nanosuspensions (DSF-NSps) were prepared by the anti-solvent precipitation method under ultrasonication, and the suitable stabilizer was screened according to the size, polydispersity index (PDI), and zeta potential of the resultant nanosuspensions, along with their particle size change during the storage at room temperature. The particle size, PDI, and zeta potential of DSF-NSps were determined using dynamic light scattering method, while the morphology of DSF-NSps was observed by transmission electronic microscope (TEM). The stability of DSF-NSps in media was examined according to their particle size change in different physiological media. The concentration of DSF was measured by HPLC assay. The in vitro drug release was evaluated on basis of dialysis. MTT assay was employed to evaluate the in vitro cytotoxicity of DSF-NSps against cancer cell lines. The 4T1 tumor-bearing mouse model was used to evaluate the in vivo therapeutic efficacy of DSF-NSps. All the animal experiments were acquired according to the Regulations for Animal Experiments and Guidelines for Ethical as defined by Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College. As a result, the combinational use of soyabean lecithin (SPC) and D-alpha tocopherol acid polyethyene glycol succinate (TPGS) was determined to best stabilize DSF-NSps when the ratio of DSF-SPC-TPGS was 24∶20∶4 (weight ratio), with small particle size and good storage stability. The resultant DSF-NSps showed a regular spherical morphology and drug loading content of (45.36 ± 2.09) %, with average particle size of 175.00 ± 0.75 nm, PDI of 0.24 ± 0.07 and zeta potential of -14.3 mV. DSF-NSps displayed good particle size stability in a variety of biological media including phosphate buffer saline, normal saline, 5% glucose, artificial gastric fluid, artificial intestinal fluid and plasma, which would meet the demand of both intravenous and oral administration. The in vitro study demonstrated that nano-encapsulation greatly increased the stability of DSF in aqueous media, DSF-NSps exhibited sustained release of the encapsulated drug and significantly inhibited 4T1 cells compared to free DSF (IC50, 1.07 vs 5.53 μg·mL-1, P<0.01). DSF-NSps showed a good dose-response relationship on the 4T1 tumor-bearing mice with the tumor inhibition rates at the three doses being 80.22%, 75.14% and 66.10%, all higher than that of paclitaxel injections (55.01%, P<0.05). The in vivo biodistribution study displayed that DSF-NSps were mainly distributed into liver, spleen and tumor. In sum, disulfiram nanoparticles could be expected to provide an effective anti-cancer drug for the treatment of breast cancer.

Preparation of annonaceous acetogenins nanosuspensions using poloxamer 188 as a stabilizer and their in vitro and in vivo investigation / 药学学报

Annonaceous acetogenins (ACGs) are effective part extracted and separated from Annona squamosa seeds, they have good antitumor activity against a variety of tumor cells. However, the solubility of ACGs is poor with serious toxic and side effects, which greatly limits their application in clinical practice. In this study poloxamer 188 (P188) was selected as a drug carrier or a stabilizer to prepare ACGs nanosuspensions (ACGs-NSps) using anti-solvent precipitation. The nanosuspensions were examined via dynamic light scattering (DLS) method to examine size of the nanosuspensions. Transmission electron microscopy was used to observe their morphology. HPLC assay was used to measure their drug loading content and the in vitro drug release. The stability of ACGs-NSps at room temperature, in various physiological media and plasma, and the hemolytic test and lyophilization were all investigated. MTT assay was performed to study the cytotoxocity of ACGs-NSps against four tumor cell lines. 4T1 bearing tumor model was used to assess their in vivo antitumor therapeutic efficacy. The obtained ACGs-NSps were spherical, the average particle size was 169.4±1.25 nm, the polydispersity index (PDI) value was 0.130±0.020, the zeta potential was -19.8 mV and the drug loading content was 48.18%. ACGs-NSps were stable at room temperature for at least 15 days. They could be lyophilized in the presence of 0.5% glucose and 2.0% P188. ACGs-NSps showed sustained in vitro drug release, and the cumulative drug release reached 80.82% within 144 hours. ACGs-NSps maintained their particle size in various physiological media, and plasma with no hemolysis and then met demands of both oral and intravenous administration. In contrast to free ACGs, ACGs-NSps displayed significantly higher cytotoxicity against 4T1 (IC50, 0.892±0.124 μg·mL-1 vs 2.495±0.108 μg·mL-1, P 50, 0.747±0.051 μg·mL-1 vs 2.204±0.064 μg·mL-1, P 50, 2.265±0.081 μg·mL-1 vs 4.159±0.071 μg·mL-1, P 50, 0.473±0.024 μg·mL-1 vs 1.196±0.022 μg·mL-1, P in vivo study demonstrated that the daily oral administration of ACGs-NSps (3 mg·kg-1) resulted in higher tumor inhibition rate compared to ACGs/oil solution (67.23% vs 53.11%), comparable to the intravenous injection of 0.5 mg·kg-1 ACGs-NSps every other day (70.34%). Nanosuspensions effectively solved the problem of ACGs insolubility and difficulty in drug delivery. Using P188, a pharmaceutic adjuvant approved by FDA for iv injection, the resultant ACGs-NSps appear promising as an anti-tumor drug that can be used in clinic.

Preparation of gambogic acid naonosuspensions and their anti-tumor efficacy / 药学学报

Gambogic acid (GA), the main active ingredient in gamboge, has been reported to have good anti-tumor activity with excellent selectivity. However, its clinical application is limited by the poor water solubility. GA nanosuspensions were designed in this study in order to solve this problem. GA nanosuspensions were prepared by microprecipitation method based on pH adjustment. Suitable stabilizer was screened according to the size and polydispersity index (PDI) of the resultant nanosuspensions. Dynamic light scattering method was used to measure the particle size and transmission electron microscopy was used to observe the morphology. The stability was studied in different medium. The drug release was evaluated using a dialysis method. MTT assay was used to assess their cytotoxicity in vitro against cancer cell line. Anti-tumor effect in vivo was investigated on H22-bearing mice. In result, Poloxamer (P188) was found to be a good stabilizer. The resultant GA nanosuspensions (GA-NSps) were 135.9 ±5.1 nm in diameter, with PDI value being 0.26 ±0.01 and the zeta potential being −35.1 ±1.36) mV. GA-NSps were nearly spherical. They were quite stable in various physiological media. GA-NSps exhibited a sustained drug release pattern, with the cumulative release reaching 90.26% within 312 h. In MTT assay, GA-NSps had a stronger cytotoxicity against HepG2 cells than the free drug (IC50, 0.851 8 μg·mL−1 vs 2.104 μg·mL−1, P vs 66.80%, P < 0.01). In summary, we prepared GA-NSps with high drug loading capacity, small particle size and good stability, and provided a solid basis for the effective dosage form of gambogic acid.

Honokiol nanosuspensions:preparation, in vitro and in vivo evaluation / 药学学报

Honokiol (HK) have extensive pharmacological activities, but its poor solubility and instability restricted its clinical application and efficacy exertion. HK nanosuspensions (HK-NSps) were designed in this study in order to solve the problems. HK-NSps were prepared by antisolvent precipitation method, using poly-vinylpyrrolidone (PVP) and bovine serum albumin (BSA) as a combined stabilizer. The particle size was measured using dynamic light scattering method, the morphology was observed by transmission electron microscopy. The size change and drug content of HK-NSps in various physiological media during the storage at ambient temperature was examined to evaluate their storage stability. Dialysis method was used to study their drug release in vitro. MTT assay was used to assess their in vitro cytotoxicity against 4T1 breast cancer cell line. Anti-tumor effect in vivo was also investigated in 4T1 tumor-bearing mice. HK-NSps were prepared with high drug loading content of 48.62%, nearly spherical shape and good storage stability. The average particle size was (83.40 ±1.042) nm, the polydispersity index (PDI) value was 0.223 ±0.011, the zeta potential was (-42.2 ±1.2) mV. HK-NSps showed sustained in vitro drug release and enhanced cytotoxicity in contrast to free HK against 4T1 cells (IC50, 8.36 μg·mL-1 vs 37.58 μg·mL-1, Pin vivo study on 4T1 tumor-bearing mice demonstrated that HK-NSps showed good dose-dependent tumor inhibition rate (TIR). In contrast to 4 mg·kg-1 of PTX injection (TIR, 47.9%), medium and high dose of HK-NSps displayed improved therapeutic efficacy (TIR, 55.67% for 40 mg·kg-1, 67.28% for 60 mg·kg-1, P-1) had TIR of only 54.13% even administrated every day. In conclusion, HK-NSps were prepared with small size, high drug-loading capacity, and good stability. The improved in vitro and in vivo antitumor efficacy demonstrated that HK can be a promising antitumor drug in combination with nanosuspensions technology.

Preliminary study on synthesis of novel amphiphilic molecules and their application as drug vectors / 中国中药杂志

<p><b>OBJECTIVE</b>To synthesize three amphiphilic molecules (TEG-R1, TEG-R2, TEG-R3), with branched oligo polyethylene glycol as hydrophilic fractions and aliphatic chains (containing six, eight and twelve carbon atoms respectively) as hydrophobic fractions, and study them as insoluble drug vectors.</p><p><b>METHOD</b>Three compounds were successfully through acylation, substitution reaction, reduction reaction and esterification. Their structures were verified by NMR analysis; and the critical micelle concentrations (CMC) of TEG-R1, TEG-R2, TEG-R3 were determined by pyrene fluorescence probe spectrometry. Transmission electronic microscopy (TEM) photos displayed the state of the aqueous solution. The self-assembly solution evaporation method was adopted to prepare drug loading podophyllotoxin micelles, and characterize their grain size, in order to detect the hemolysis of the three amphiphilic molecules.</p><p><b>RESULT</b>Nuclear magnetism showed the successful synthesis of three amphiphilic molecules, with critical micelle concentrations of TEG-R1, TEG-R2, TEG-R3 of 50, 50, 10 mg x L(1), respectively. Transmission electronic microscopy (TEM) photos displayed a spherical-like state, with diameter of 20-50 nm. All of the three amphiphilic molecules could be prepared into drug-loading micelles, with the range of grain sizes between 100-200 nm. Hemdytic experiment showed that, among the amphiphilic molecules of the graft six-carbon aliphatic chain, TEG-R1 could not cause hemolysis.</p><p><b>CONCLUSION</b>All of the three amphiphilic molecules are micellized in water solution, and can be used as insoluble drug vectors. Among them, TEG-R1 could not cause hemolysis, and is expected to become a new-type drug vector.</p>

Study on the hepatocytic cell targetability of liposomes / 药学学报

<p><b>AIM</b>To target for hepatocytic cell, liposomes was modified by special ligand.</p><p><b>METHODS</b>Sterically stabilized liposomes (SSL) was conjugated with asialofeticin (AF), the ligand of asialoglycoprotein receptor (ASGP-R) of hepatocyte. ASGP-R-BLM is the ASGP-R reconstructed on bilayer lipid membrane (BLM). The recognition reaction between AF-SSL and ASGP-R-BLM can be monitored by the varieties of membrane electrical parameters. The targetability of AF-SSL mediated to hepatocyte was detected by radioisotopic labeled in vitro and in vivo. The therapeutic effect of antihepatocarcinoma was observed also.</p><p><b>RESULTS</b>The lifetime of ASGP-R-BLM decreased with the added amount of AF-SSL. It was demonstrated that there was recognition reaction between AF-SSL and ASGP-R-BLM. The combination of AF-SSL with hepatocyte was significantly higher than that of SSL without AF-modified in vitro and in vivo. The survival time of rat for AF-SSL carriered ADM (adriamycin) group was much longer and the toxicities on heart, kidney and lung were lower than those SSL carried ADM group.</p><p><b>CONCLUSION</b>It is possible to actively target the cell with specific receptor by ligand modified liposomes. The result prvide scientific basis of hepatocyte targeted liposomes.</p>

Preparation of thrombus-targeted urokinase liposomes and its thrombolytic effect in model rats / 药学学报

<p><b>AIM</b>To prepare thrombus-targeted urokinase liposomes and observe its improved thrombolytic efficacy on thrombus model rats.</p><p><b>METHODS</b>The ligand H-Arg-Gly-Asp-Ser-OH (RGDS) which has specific affinity to thrombus was synthesized by liquid phase method and anchored on the surface of liposomes by incorporating its conjugate with DSPE-PEG3,500-COOH into liposomal lipid bilayers, thus thrombus-targeted liposomes were produced. Urokinase (UK) liposomes were prepared at room temperature through method modification using hydrogenated soy phosphatidylcholine (HSPC); the in vivo thrombolysis of the obtained thrombus-targeted UK liposomes and its comparison with TBS (Tris-HCl buffered solution) control, free UK and UK liposomes were assessed on common carotid artery model rats.</p><p><b>RESULTS</b>The obtained liposomes were characteristic of high UK entrapment efficiency, small mean diameter and good storage stability. At the same dose (60,000 U.kg-1), compared to the wet thrombi weights of TBS control group, those of free UK group and UK liposome group showed no statistical difference, while those of targeted UK liposomes group were significantly decreased (P < 0.001); when evaluated in term of dry thrombi weights the result was slightly different. Compared to UK liposomes of the same dose, the targeted UK liposomes showed significantly improved thrombolytic efficacy (P < 0.01 in wet weights decrease and P < 0.05 in dry weights decrease respectively).</p><p><b>CONCLUSION</b>The targeted UK liposomes displayed good targeted thrombolytic effect.</p>