N-(2-羟丙基)甲基丙烯酰胺聚合物-5-氟尿嘧啶接合物的体外释药规律、体内分布及抗肿瘤活性研究

考察本实验室合成的N-(2-羟丙基)甲基丙烯酰胺[N-(2-hydroxypropyl)methacrylamide,HPMA]聚合物-5-氟尿嘧啶(5-flurouracil,5-FU)接合物(P-FU)的体外释药、体内分布及抗肿瘤活性。以小鼠血浆为介质,考察P-FU中5-FU的释放规律;以小鼠H22肝癌实体瘤模型(皮下型)为肿瘤模型,考察接合物在荷瘤小鼠体内的分布情况、药代动力学规律及抑瘤活性。结果表明,37℃时P-FU在小鼠血浆中具有一定的稳定性,半衰期(t1/2)为32.4 h。与5-FU相比,P-FU在荷瘤小鼠体内的循环时间明显延长(血浆中t1/2为原药的166倍),在肿瘤中的沉积量(AUC为5-FU的3.3倍)及滞留时间(t1/2为5-FU的2.3倍)均有明显增加。体内药效学研究表明,P-FU组对荷瘤小鼠的肿瘤生长抑制率(69.09%)显著高于5-FU组(56.49%,P<0.05),瘤块组织病理学观察结果也显示P-FU组小鼠肿瘤组织中细胞凋亡程度大于5-FU组。HPMA聚合物可被用于为5-FU构建一种新型实体瘤高分子给药系统。     

Gamma Scintigraphy of the Biodistribution of 123I-Labelled N-(2-Hydroxypropyl)methacrylamide Copolymer-Doxorubicin Conjugates in Mice with Transplanted Melanoma and Mammary Carcinoma

Abstract

An N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer-doxorubicin conjugate is currently under clinical evaluation as a new antitumour agent. It has been shown previously that such conjugates exhibit selective tumour accumulation. In this study HPMA copolymer doxorubicin conjugates of low (LMW) or high (HMW) molecular weight were synthesised (which had a weight average molecular weight (Mw) of 25,000 and 94,000 respectively) and additionally contained a small amount (1 mol%) of the comonomer methacryloyltyrosinamide to permit labelling with [¹²³I or ¹²⁵I]iodide. Gamma camera imaging using the I-labelled probes was used to follow time-dependent biodistribution after intraperitoneal (i.p.) or intravenous (i.v.) administration to mice bearing subcutaneously either B16F10 melanoma or a mammary carcinoma. Imaging showed more rapid clearance of LMW conjugate from the peritoneal cavity than HMW conjugate. The images of mice given the LMW conjugate revealed rapid urinary excretion of radioactivity after both i.p. and i.v. injection with an early high concentration of tracer in the bladder, and subsequently a very high concentration in the kidneys, which came to dominate the views. Dissection analysis 2 days after administration of the LMW conjugate revealed a kidney level of radioactivity corresponding to 25-40 %dose/g tissue in mice bearing the two tumour models. Following administration of the HMW conjugate kidney accumulation at 2 days was less due to retention of the higher molecular weight polymer molecules in the circulation, and spleen and liver displayed the highest concentrations of radioactivity. The tumour accumulation of LMW and HMW conjugates was; mammary carcinoma 3.18 and 5.29 % dose/g respectively; B16F10 melanoma 3.23 and 8.82 %dose/g although these levels of tracer enabled visualisation in the images of the mammary carcinoma with HMW conjugate at later time points. The smaller size of the B16F10 tumour masses did not permit clear visualisation.     

Gamma Scintigraphy of a 123I-Labelled N-(2-Hydroxypropyl)Methacrylamide Copolymer-Doxorubicin Conjugate Containing Galactosamine Following Intravenous Administration to Nude Mice Bearing Hepatic Human Colon Carcinoma

Abstract

Polymer drug conjugates composed of N-(2-Hydroxypropyl)methacrylamide (HPMA) copolymer covalently bound, doxorubicin, and containing additionally galactosamine to facilitate hepatocyte-specific targeting (HPMA copolymer-dox-gal), were synthesised to contain a small amount (～1 mol%) of the monomer methacryloyltyrosinamide to permit radioiodination with [¹²³I]iodide. After intravenous administration to both normal mice and nude mice bearing hepatic human colon carcinoma, the biodistribution of the conjugate was monitored using the gamma camera, and also by dissection analysis. Efficient liver accumulation of HPMA copolymer-dox-gal was seen in the gamma camera images within 20 min, both in normal and rumour-bearing animals. Quantitatively liver uptake was ～40% dose administered/g liver. Images of the tumour-bearing animals showed clearly a much lower accumulation of HPMA copolymer-dox-gal in the colon carcinoma deposits within the liver (3-9% dose/g tumour), and this lack of uptake was verified by ex vivo imaging of the tumour-containing liver and also by dissection analysis. It can be concluded that ¹²³I-labelled HPMA copolymer conjugates offer great potential as effective imaging agents and can be used for future non-invasive clinical studies. This nuclear imaging method will enable optimisation of the dosing schedule by identification of doses of HPMA copolymer-dox-gal that display receptor saturation (and hence diminished targeting efficiency). In addition this conjugate can provide negative images of liver-associated tumour deposits that do not express the asialoglycoprotein receptor.     

Influence of the Structure of Drug Moieties on the in Vitro Efficacy of HPMA Copolymer–Geldanamycin Derivative Conjugates

Purpose To optimize the structure of geldanamycin (GDM) derivative moieties attached to N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers via an enzymatically degradable spacer. Methods HPMA copolymers containing different AR-GDM (AR = 3-aminopropyl (AP), 6-aminohexyl (AH), and 3-amino-2-hydroxy-propyl AP(OH)) were synthesized and characterized. Their cytotoxicity towards the A2780 human ovarian carcinoma cells was evaluated. Results The cytotoxic efficacy of HPMA copolymer-AR-GDM conjugates depended on the structure of AR-GDM. Particularly, HPMA copolymer-bound AH-GDM, which possessed the longest substituent at the 17-position, demonstrated the highest efficacy among the polymer-bound GDM derivatives; however the activity of free AH-GDM was lower than that of the other free AR-GDMs. The relative increase of the activity of macromolecular AH-GDM when compared to AP-GDM or AP(OH)-GDM correlated with the enhanced recognition of AH-GDM terminated oligopeptide side-chains by the active site of the lysosomal enzyme, cathepsin B Drug stability and further stabilization upon binding to HPMA copolymer also contributed to the observed phenomena. Conclusion AH-GDM was found to be a suitable GDM derivative for the design of a drug delivery system based on HPMA copolymers and enzymatically-degradable spacers.     

一种对pH敏感的地塞米松前药的合成、表征及体外特性研究

目的 合成具有pH敏感特性的聚N-(2-羟丙基)甲基丙烯酰胺(HPMA)负载地塞米松(Dex)的前药.方法 以双甘氨肽(Gly-Gly-OH)为连接臂,将Dex与HPMA共价连接,再经聚合反应形成高分子地塞米松前药(P-Dex).考察其水溶性,通过核磁共振表征其结构,酸水解后HPLC法测定Dex的含量.考察P-Dex在pH5、pH7.4的释药特性.结果 合成的P-Dex改善了Dex的水溶性,P-Dex中Dex的含量为4.59％.P-Dex在pH7.4缓冲体系中几乎不释放Dex,在pH5的缓冲体系中,每天约释放0.86％ Dex.结论 合成的P-Dex增强了Dex的水溶性,具有pH敏感释放的特点.     

Poly (Lactide-co-Glycolide) Nanoparticles Containing Coumarin-6 for Suppository Delivery: In Vitro Release Profile and In Vivo Tissue Distribution

A delivery system consisting of the lipophilic fluorescent dye coumarin-6 embedded into polymer nanoparticles in a suppository base was formulated. Particle diameters of 400–1100 nm were produced by a salting-out method and measured by laser diffraction. Nanoparticles reach the systemic circulation via fenestrated capillaries or remain within rectal membranes to release their contents. Dissolution over 168 hr was initially rapid followed by a steady decline, and tissue distribution showed coumarin-6 to be present in liver and lungs for a similar time period while in kidney, small intestines, and blood up to 96 hr. Microscopic observations showed nanoparticles to be present in blood up to 72 hr.     

N-(2-羟丙基)甲基丙烯酰胺聚合物-5-氟尿嘧啶接合物的体外释药规律、体内分布及抗肿瘤活性研究

考察本实验室合成的N-(2-羟丙基)甲基丙烯酰胺［N-(2-hydroxypropyl) methacrylamide，HPMA］聚合物-5-氟尿嘧啶(5-flurouracil，5-FU)接合物(P-FU)的体外释药、体内分布及抗肿瘤活性。以小鼠血浆为介质，考察P-FU中5-FU的释放规律；以小鼠H22肝癌实体瘤模型(皮下型)为肿瘤模型，考察接合物在荷瘤小鼠体内的分布情况、药代动力学规律及抑瘤活性。结果表明，37 ℃时P-FU在小鼠血浆中具有一定的稳定性，半衰期(t_1/2)为32.4 h。与5-FU相比，P-FU在荷瘤小鼠体内的循环时间明显延长(血浆中t_1/2为原药的166倍)，在肿瘤中的沉积量(AUC为5-FU的3.3倍)及滞留时间(t_1/2为5-FU的2.3倍)均有明显增加。体内药效学研究表明，P-FU组对荷瘤小鼠的肿瘤生长抑制率(69.09%)显著高于5-FU组(56.49%，P<0.05)，瘤块组织病理学观察结果也显示P-FU组小鼠肿瘤组织中细胞凋亡程度大于5-FU组。HPMA聚合物可被用于为5-FU构建一种新型实体瘤高分子给药系统。     

LYG-202, a Newly Synthesized Flavonoid,Exhibits Potent Anti-angiogenic Activity In Vitro and In Vivo

LYG-202 (C₂₅H₃₀N₂O₅) is a newly synthesized flavonoid that has been confirmed to possess an antitumor effect, but the mechanism is unclear. Our present study was performed to identify the anti-angiogenic activity of this novel compound in vitro and in vivo. LYG-202 inhibited vascular endothelial growth factor (VEGF) stimulated migration and tube formation of human umbilical vein endothelial cells and arrested microvessel outgrowth from rat aortic rings in vitro. Meanwhile, LYG-202 suppressed the neovascularization of Chicken Chorioallantoic Membrane in vivo. Mechanistic studies revealed that LYG-202 suppressed the VEGF-induced tyrosine phosphorylation of KDR/Flk-1 (VEGFR-2) as well as its downstream protein kinases activation, by decreasing phosphorylated forms of serine/threonine kinase Akt, extracellular signal-regulated kinase, and p38 mitogen-activated protein kinase. LYG-202 exerts anti-angiogenic activity both in vitro and in vivo, and these results suggest that it deserves further investigation as a promising anti–tumor angiogenesis compound.     

Silk Reservoirs for Local Delivery of Cisplatin for Neuroblastoma Treatment: In Vitro and In Vivo Evaluations

Neuroblastoma is the most common extracranial childhood tumor, and current treatment requires surgical resection and multidrug chemotherapy. Local, perioperative delivery of chemotherapeutics is a promising treatment method for solid tumors that require surgical removal. In this study, we have aimed to develop a controlled-release implant system to deliver cisplatin in tumor or tumor resection area. Silk fibroin, a biodegradable, nonimmunogenic biopolymer was used to encapsulate different doses of cisplatin in a reservoir system. The physical integrity of the reservoirs was characterized by evaluating the crystalline structure of silk secondary structure using FTIR spectroscopy. The in vitro release of cisplatin was evaluated in phosphate-buffered saline at 37°C, and the reservoirs were able to release the drug up to 30 days. The cytotoxicity of cisplatin and cisplatin reservoirs were tested on KELLY cells. Cytotoxicity data showed 3.2 μg/mL cisplatin was required to kill 50% of the cell population, and the released cisplatin from the silk reservoirs showed significant cytotoxicity up to 21 days. Intratumoral implantation of silk reservoirs into an orthotopic neuroblastoma mouse model decreased tumor growth significantly when compared with control subjects. These results suggest that silk reservoirs are promising carriers for cisplatin delivery to the tumor site.     

Fabrication and Characterization of Surface Engineered Rifampicin Loaded Lipid Nanoparticulate Systems for the Potential Treatment of Tuberculosis: An In Vitro and In Vivo Evaluation

The main aim of the present investigation highlights the development of mannose appended rifampicin containing solid lipid nanoparticles (Mn-RIF-SLNs) for the management of pulmonary TB. The developed Mn-RIF-SLNs showed particle size of Mn-RIF-SLNs (479 ± 13 nm) which was found to be greater than that of unconjugated SLNs (456 ± 11 nm), with marginal reduction in percentage entrapment efficiency (79.41 ± 2.42%). The in vitro dissolution studies depicted an initial burst release followed by sustained release profile indicating biphasic release pattern, close-fitting Weibull model having least F-value. The cytotoxicity studies using J774A.1 cell line represented that the developed SLNs were non-toxic and safe as compared to free drug. Fluorescence imaging and flow cytometric (FACS) analysis depicted significant (1.79-folds) intracellular uptake of coumarin-6 (fluorescent marker) loaded Mn–C6-SLNs. The in vivo pharmacokinetic studies in sprague-dawley rats were performed and Mn-RIF-SLNs showed remarkable enhancement in terms of relative bioavailability (~17-folds) as compared to its drug solution via oral administration. The biodistribution studies revealed higher lung accumulation (1.8-folds) of Mn-RIF-SLNs as compared to the Un-RIF-SLNs. In conclusion, the developed Mn-RIF-SLNs could serve as a promising tool for delivering the drug cargo to the site of infection (lungs) in the treatment of TB.     

In vitro cytotoxicity, in vivo biodistribution and antitumor activity of HPMA copolymer–5-fluorouracil conjugates

5-Fluorouracil (5-FU) is an antimetabolite with a broad-spectrum activity against solid tumors. However, its very short half-life in plasma circulation greatly limited the in vivo antitumor efficacy and clinical application. The current work aimed to solve this problem as well as to increase 5-FU biodistribution to tumor by covalently conjugating 5-FU to a biocompatible, non-toxic and non-immunogenic drug carrier – N-(2-hydroxypropyl) methacrylamide (HPMA) copolymer. The in vitro cytotoxicity, in vivo biodistribution and therapeutic efficacy of HPMA copolymer–5-FU conjugates (P-FU) were reported. Cytotoxicity was evaluated by using a serial of tumor cells (A549, CT-26, Hela, HepG₂ cells and 5-FU resistant HepG₂ cells). In vivo biodistribution and therapeutic efficacy were investigated in Kunming mice-bearing hepatoma 22 (H₂₂). Results indicated that P-FU could increase the cytotoxicity of 5-FU in Hela, HepG₂ and 5-FU resistant HepG₂ cells, while it decreases the cytotoxicity of 5-FU in A549 and CT-26. Both in vitro release profile in plasma and biodistribution study showed that P-FU significantly prolonged the drug plasma circulation time. P-FU also showed an over 3-fold larger area under the concentration–time curve (AUC) in tumor when compared with free drug. Therapeutic evaluation also demonstrated that the treatment with P-FU displayed stronger inhibition of the tumor growth when compared with that of control group (physiologic saline) or 5-FU group at the same dose. All the results suggested that P-FU could increase cytotoxicity of 5-FU in certain cancer cell lines, prolong 5-FU circulation time in vivo, enhance 5-FU distribution to tumor and improve therapeutic efficacy. Therefore, HPMA copolymer is a potential carrier for 5-FU for the effective treatment of cancer.     

HPMA copolymers: Origins, early developments, present, and future

The overview covers the discovery of N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers, initial studies on their synthesis, evaluation of biological properties, and explorations of their potential as carriers of biologically active compounds in general and anticancer drugs in particular. The focus is on the research in the authors' laboratory — the development of macromolecular therapeutics for the treatment of cancer and musculoskeletal diseases. In addition, the evaluation of HPMA (co)polymers as building blocks of modified and new biomaterials is presented: the utilization of semitelechelic poly(HPMA) and HPMA copolymers for the modification of biomaterial and protein surfaces and the design of hybrid block and graft HPMA copolymers that self-assemble into smart hydrogels. Finally, suggestions for the design of second-generation macromolecular therapeutics are portrayed.     

Noninvasive Visualization of Pharmacokinetics,Biodistribution and Tumor Targeting of Poly[<Emphasis Type="BoldItalic">N</Emphasis>-(2-hydroxypropyl)methacrylamide] in Mice Using Contrast Enhanced MRI

Purpose To study a non-invasive method of using contrast enhanced magnetic resonance imaging (MRI) to visualize the real-time pharmacokinetics, biodistribution and tumor accumulation of paramagnetically labeled poly[N-(2-hydroxypropyl)methacrylamide] (PHPMA) copolymer conjugates with different molecular weights and spacers in tumor-bearing mice. Materials and Methods Paramagnetically labeled HPMA copolymer conjugates were synthesized by free radical copolymerization of HPMA with monomers containing a chelating ligand, followed by complexation with Gd(OAc)₃. A stable paramagnetic chelate, Gd-DO3A, was conjugated to the copolymers via a degradable spacer GlyPheLeuGly and a non-degradable spacer GlyGly, respectively. The conjugates with molecular weights of 28, 60 and 121 kDa and narrow molecular weight distributions were prepared by fractionation with size exclusion chromatography. The conjugates were injected into athymic nude mice bearing MDA-MB-231 human breast carcinoma xenografts via a tail vein. MR images were acquired before and at various time points after the injection with a 3D FLASH sequence and a 2D spin-echo sequence at 3T. Pharmacokinetics, biodistribution and tumor accumulation of the conjugates were visualized based on the contrast enhancement in the blood, major organs and tumor tissue at various time points. The size effect of the conjugates was analyzed among the conjugates. Results Contrast enhanced MRI resulted in a real-time, three-dimensional visualization of blood circulation, pharmacokinetics, biodistribution and tumor accumulation of the conjugates, and the size effect on these pharmaceutical properties. HPMA copolymer conjugates with high molecular weight had a prolonged blood circulation time and high passive tumor targeting efficiency. Non-biodegradable HPMA copolymers with molecular weights higher than the threshold of renal filtration demonstrated higher efficiency for tumor drug delivery than biodegradable poly(L-glutamic acid). Conclusions Contrast enhanced MRI is an effective method for non-invasive visualization of in vivo properties of the paramagnetically labeled polymer conjugates in preclinical studies.     

Biodegradable Nanocapsules Containing a Lipophilic Immunomodulator: Drug Retention and Tolerance Towards Macrophages In Vitro

Abstract

Nanocapsules (250 nm diameter) were prepared from poly (D,L-lactide) containing a lipophilic immunomodulator: MDP-L-alanyl cholesterol (MTP-Chol). High encapsulation rates were obtained at 37°C in culture medium or in buffers imitating phagosomes and lysosomes. The tolerance of these particles by rat alveolar macrophages in vitro was tested. A slight toxicity was observed which was the result of two factors: the capacity of the immunomodulator to stimulate the generation of nitrite oxide by the L-arginine-dependent pathway and the polymer itself. The latter toxicity seemed to be mediated by a different mechanism.     

DOXO-EMCH (INNO-206): the first albumin-binding prodrug of doxorubicin to enter clinical trials

The (6-maleimidocaproyl)hydrazone derivative of doxorubicin (DOXO-EMCH) is an albumin-binding prodrug of doxorubicin with acid-sensitive properties that demonstrates superior antitumor efficacy in murine tumor models and a favorable toxicity profile in mice, rats and dogs, including significantly reduced cardiotoxicity. After intravenous administration, DOXO-EMCH binds rapidly to the Cys-34 position of circulating albumin and accumulates in solid tumors due to passive targeting. In a clinical Phase I study, the dose of doxorubicin could be increased by a factor of 4.5 – 340 mg/m² when 75 mg/m² of free doxorubicin is considered to be the dose that can be administered as a single agent concomitant with the typical spectrum of side effects (i.e., myelotoxicity and mucositis). DOXO-EMCH was able to induce tumor regressions in anthracycline-sensitive tumors (i.e., breast cancer, small cell lung cancer and sarcoma). Phase II studies will be initiated at the beginning of 2007.     

In Vitro and in Vivo Evaluation of Mucoadhesive Microspheres Prepared for the Gastrointestinal Tract Using Polyglycerol Esters of Fatty Acids and a Poly(acrylic acid) Derivative

Two types of polyglycerol ester of fatty acid (PGEF)-based microspheres were prepared: Carbopol 934P (CP)-coated microspheres (CPC-microspheres) and CP-dispersion microspheres (CPD-microspheres). Comparative studies on mucoadhesion were done with these microspheres and PGEF-based microspheres without CP (PGEF-microspheres). In an in vitro adhesion test, the CPD-microspheres adhered strongly to mucosa prepared from rat stomach and small intestine because each CP particle in the CPD-microsphere was hydrated and swelled with part of it remaining within the microsphere and part extending to the surface serving to anchor the microsphere to the mucus layer. The gastrointestinal transit patterns after administration of the CPD-microspheres and PGEF-microspheres to fasted rats were fitted to a model in which the microspheres are emptied from the stomach monoexponentially with a lag time and then transit through the small intestine at zero-order. Parameters obtained by curve fitting confirmed that the gastrointestinal transit time of the CPD-microspheres was prolonged compared with that of the PGEF-microspheres. MRT in the gastrointestinal tract was also prolonged after administration of the CPD-microspheres compared with that following the administration of the PGEF-microspheres.     

The Antipsychotics Olanzapine, Risperidone, Clozapine, and Haloperidol Are D2-Selective Ex Vivo but Not In Vitro

In a recent human [¹¹C]-(+)-PHNO positron emission tomography study, olanzapine, clozapine, and risperidone occupied D2 receptors in striatum (STR), but, despite their similar in vitro D2 and D3 affinities, failed to occupy D3 receptors in globus pallidus. This study had two aims: (1) to characterize the regional D2/D3 pharmacology of in vitro and ex vivo [³H]-(+)-PHNO binding sites in rat brain and (2) to compare, using [³H]-(+)-PHNO autoradiography, the ex vivo and in vitro pharmacology of olanzapine, clozapine, risperidone, and haloperidol. Using the D3-selective drug SB277011, we found that ex vivo and in vitro [³H]-(+)-PHNO binding in STR is exclusively due to D2, whereas that in cerebellar lobes 9 and 10 is exclusively due to D3. Surprisingly, the D3 contribution to [³H]-(+)-PHNO binding in the islands of Calleja, ventral pallidum, substantia nigra, and nucleus accumbens was greater ex vivo than in vitro. Ex vivo, systemically administered olanzapine, risperidone, and haloperidol, at doses occupying ∼80% D2, did not occupy D3 receptors. Clozapine, which also occupied ∼80% of D2 receptors ex vivo, occupied a smaller percentage of D3 receptors than predicted by its in vitro pharmacology. Across brain regions, ex vivo occupancy by antipsychotics was inversely related to the D3 contribution to [³H]-(+)-PHNO binding. In contrast, in vitro occupancy was similar across brain regions, independent of the regional D3 contribution. These data indicate that at clinically relevant doses, olanzapine, clozapine, risperidone, and haloperidol are D2-selective ex vivo. This unforeseen finding suggests that their clinical effects cannot be attributed to D3 receptor blockade.