Tyrosol Derived Poly(ester-arylate)s for Sustained Drug Delivery from Microparticles.

New biodegradable polymers are needed for use in drug delivery systems to overcome the high burst release, lack of sustained drug release, and acidic degradation products frequently observed in current formulations. Commercially available poly(lactide-co-glycolide) (PLGA) is often used for particle drug release formulations; however, it is often limited by its large burst release and acidic degradation products. Therefore, a biocompatible and biodegradable tyrosol-derived poly(ester-arylate) library has been used to prepare a microparticle drug delivery system which shows sustained delivery of hydrophobic drugs. Studies were performed using polymers with varying hydrophilicity and thermal properties and compared to PLGA. Various drug solubilizing cosolvents were used to load model drugs curcumin, dexamethasone, nicotinamide, and acyclovir. Hydrophobic drugs curcumin and dexamethasone were successfully loaded up to 50 weight percent (wt %), and a linear correlation between drug wt % loaded and the particle glass transition temperature (Tg) was observed. Both curcumin and dexamethasone were visible on the particle surface at 20 wt % loading and higher. By adjusting the polymer concentration during particle formation, release rates were able to be controlled. Release studies of dexamethasone loaded particles with a lower polymer concentration showed a biphasic release profile and complete release after 47 days. Particles prepared using a higher polymer concentration showed sustained release for up to 77 days. Comparably, PLGA showed a traditional triphasic release profile and complete release after 63 days. This novel tyrosol-derived poly(ester-arylate) library can be used to develop injectable, long-term release formulations capable of providing sustained drug delivery.

In vitro activity of Paclitaxel-loaded polymeric expansile nanoparticles in breast cancer cells.

Through a series of in vitro studies, the essential steps for intracellular drug delivery of paclitaxel using a pH-responsive nanoparticle system have been investigated in breast cancer cells. We successfully encapsulated paclitaxel within polymeric expansile nanoparticles (Pax-eNPs) at 5% loading via a miniemulsion polymerization procedure. Fluorescently tagged eNPs were readily taken up by MDA-MB-231 breast cancer cells grown in culture as confirmed by confocal microscopy and flow cytometry. The ability of the encapsulated paclitaxel to reach the cytoplasm was also observed using confocal microscopy and fluorescently labeled paclitaxel. Pax-eNPs were shown to be efficacious against three in vitro human breast adenocarcinoma cell lines (MDA-MB-231, MCF-7, and SK-BR-3) as well as cells isolated from the pleural effusions of two different breast cancer patients. Lastly, macropinocytosis was identified as the major cellular pathway responsible for eNP uptake, as confirmed using temperature-sensitive metabolic reduction, pharmacologic inhibitors, and fluid-phase marker colocalization.

Cytoreductive surgery and intraoperative administration of paclitaxel-loaded expansile nanoparticles delay tumor recurrence in ovarian carcinoma.

BACKGROUND: Locoregional recurrence significantly impacts survival and quality of life in patients with ovarian carcinoma. We hypothesize that local administration of paclitaxel-loaded expansile nanoparticles (pax-eNP) at the time of cytoreductive surgery decreases local tumor recurrence. METHODS: In vitro cytotoxicity of pax-eNP was assessed against both the OVCAR-3 human ovarian cancer cell line and tumor cells isolated from a malignant pleural effusion from a patient with multidrug-resistant ovarian cancer. A murine xenogenic model involving surgical cytoreduction of established OVCAR-3 intra-abdominal tumor was used to evaluate in vivo efficacy of intraoperative intraperitoneal (IP) injection of 10 mg/kg of paclitaxel either as pax-eNP or paclitaxel in Cremophor EL/ethanol solution (pax-C/E) versus empty eNP controls. Cytoreductive surgery and intraoperative treatment were performed 4 weeks after established tumor. All animals were sacrificed when empty eNP controls displayed extensive evidence of disease progression. RESULTS: Labeled-eNP entered tumor cells in vitro within 4 h and specifically accumulated at sites of tumor in vivo. Pax-eNP exhibited dose-dependent cytotoxicity in both OVCAR-3 and patient tumor cells isolated from a malignant pleural effusion and effectively prevented tumor recurrence following debulking (p = 0.003 vs. empty eNP). Furthermore, pax-eNP-treated animals did not develop severe recurrent carcinomatosis compared with 43 % of the pax-C/E-treated cohort, suggesting that single-dose intracavitary pax-eNP is more effective than an equivalent dose of pax-C/E. CONCLUSIONS: Expansile nanoparticles readily enter human ovarian tumor cells and localize to sites of tumor in vivo with pax-eNP cytotoxicity resulting in superior inhibition of locoregional tumor recurrence following cytoreductive surgery.

Prevention of nodal metastases in breast cancer following the lymphatic migration of paclitaxel-loaded expansile nanoparticles.

Although breast cancer patients with localized disease exhibit an excellent long-term prognosis, up to 40% of patients treated with local resection alone may harbor occult nodal metastatic disease leading to increased locoregional recurrence and decreased survival. Given the potential for targeted drug delivery to result in more efficacious locoregional control with less morbidity, the current study assessed the ability of drug-loaded polymeric expansile nanoparticles (eNP) to migrate from the site of tumor to regional lymph nodes, locally deliver a chemotherapeutic payload, and prevent primary tumor growth as well as lymph node metastases. Expansile nanoparticles entered tumor cells and paclitaxel-loaded eNP (Pax-eNP) exhibited dose-dependent cytotoxicity in vitro and significantly decreased tumor doubling time in vivo against human triple negative breast cancer in both microscopic and established murine breast cancer models. Furthermore, migration of Pax-eNP to axillary lymph nodes resulted in higher intranodal paclitaxel concentrations and a significantly lower incidence of lymph node metastases. These findings demonstrate that lymphatic migration of drug-loaded eNP provides regionally targeted delivery of chemotherapy to both decrease local tumor growth and strategically prevent the development of nodal metastases within the regional tumor-draining lymph node basin.

Hydrogels as intracellular depots for drug delivery.

The intracellular activity and drug depot characteristics of micrometer-sized hydrogels are described. The hydrogel structure is formed after cellular uptake of a solid polymeric nanoparticle that swells in response to mildly acidic conditions as it transforms from a hydrophobic to a hydrophilic structure. These nanoparticles are rapidly taken up into A549 human non-small cell lung cancer cells with 88.3 ± 0.8% of cells experiencing uptake in 24 h, undergo expansion to release encapsulated drug and can effectively deliver chemotherapeutics in vitro. The anticancer drug paclitaxel was also shown to have a 3- to 4-fold increased affinity for the expanded nanoparticle state, allowing the expansile nanoparticles to act as intracellular drug depots and concentrate the drug locally.

Paclitaxel-loaded expansile nanoparticles in a multimodal treatment model of malignant mesothelioma.

BACKGROUND: Malignant mesothelioma has a poor prognosis even when treated aggressively with multimodal therapy. Traditional murine tumor models can be used to evaluate drug efficacy and toxicity in malignant mesothelioma, but not to assess the effect of a multimodal approach that includes the surgical resection of tumor. We therefore developed a murine model of multimodal therapy in which we evaluated paclitaxel-loaded expansile nanoparticles (Pax-eNP) for delivering intracavitary chemotherapy in malignant mesothelioma. METHODS: Paclitaxel-loaded expansile nanoparticles (Pax-eNP) of 100 nm, designed to release drug at an endosomal pH below 5, were synthesized. Xenografts of human malignant mesothelioma were established intraperitoneally in nude mice, followed by cytoreductive surgery (CRS) via laparotomy, and with omentectomy and resection of abdominal fat pads done 14 days later. At fascial closure, 10 mg/kg paclitaxel was delivered as traditional paclitaxel/paclitaxel Cremophor-EL (Pax-CE) or Pax-eNP. Morbidity and survival were assessed over a period of 90 days. RESULTS: Cytoreductive surgery in mice was feasible and reproducible, and incurred less than 5% operative mortality. By itself, CRS did not significantly prolong survival; however, the addition of intraoperative Pax-CE or Pax-eNP significantly increased survival as compared with that of mice with untreated disease. In the case of Pax-eNP, the increase in survival was also statistically significant as compared with that following resection alone. CONCLUSIONS: A murine model of CRS for malignant mesothelioma allows the in vivo assessment of multimodal therapy, including nanoparticle delivery. Combination therapy was superior to no treatment or CRS alone in prolonging survival. Treatment with Pax-eNP improved overall survival in the setting of CRS, suggesting that Pax-eNP merits further evaluation for intracavitary drug delivery following the surgical resection of malignant mesothelioma.

Paclitaxel-loaded expansile nanoparticles delay local recurrence in a heterotopic murine non-small cell lung cancer model.

BACKGROUND: Surgical resection remains the most effective treatment option for patients with early stage non-small cell lung cancer; however, comorbidities and poor pulmonary reserve often limit the extent of resection. Limited resections are associated with a twofold to threefold increase in locoregional recurrence, suggesting that microscopic disease remains near the resection margin. We hypothesized that local delivery of paclitaxel through 100-nm expansile polymer nanoparticles (pax-eNP) immediately after tumor resection could prevent local recurrence. METHODS: Primary tumors, initiated on the dorsum of C57BL/6J mice through subcutaneous injection of 750,000 Lewis lung carcinoma cells, were excised when tumor volume reached 300 mm(3). After resection, animals were randomized to receive 300 µg paclitaxel intravenously or as pax-eNP locally at the tumor resection site versus unloaded eNP or saline controls. RESULTS: In all mice receiving saline, unloaded eNP, or paclitaxel intravenously, visible local tumor recurrence developed at a median of 6 days. In contrast, tumor recurrence after pax-eNP was delayed to 10 days (pax-eNP versus all other groups, Kaplan-Meier, p < 0.05). Delay in local recurrence was associated with increased survival in the pax-eNP group (16 days) versus all other groups (11 and 12 days, p < 0.05). CONCLUSIONS: The pax-eNP placed at the time of surgical resection delayed local tumor recurrence and modestly prolonged survival in a murine Lewis lung carcinoma recurrence model.

The performance of expansile nanoparticles in a murine model of peritoneal carcinomatosis.

Carcinomatosis from peritoneal surface malignancies, such as mesothelioma, appendiceal carcinoma or ovarian metastases, significantly decreases survival and quality of life. Given a 60-80% locoregional recurrence rate after surgical debulking for mesothelioma, the current study explores the use of polymeric nanoparticles, specifically engineered to expand and locally deliver chemotherapeutic agents at endosomal pH, for the prevention of progressive carcinomatosis. Anti-tumor efficacy of paclitaxel-loaded pH-responsive expansile nanoparticles (Pax-eNP) was evaluated in vitro and in in vivo murine models of malignant peritoneal mesothelioma. Pax-eNP inhibited mesothelioma growth in vitro, markedly decreased tumor growth and disease severity in vivo, prevented initial intraperitoneal tumor implants, and significantly prolonged survival compared to other intraperitoneal drug delivery methods. These outcomes suggest that the mechanism of pH-triggered drug delivery and tumor affinity associated with eNP may effectively improve the local control of residual microscopic disease following surgical debulking of locoregionally aggressive malignancies.

Synthetic fibers as an indicator of land application of sludge.

Synthetic fabric fibers have been proposed as indicators of past spreading of wastewater sludge. Synthetic fiber detectability was examined in sludges (dewatered, pelletized, composted, alkaline-stabilized) and in soils from experimental columns and field sites applied with those sludge products. Fibers (isolated by water extraction and examined using polarized light microscopy) were detectable in sludge products and in soil columns over 5 years after application, retaining characteristics observed in the applied sludge. Concentrations mirrored (within a factor of 2) predictions based on soil dilution. Fibers were detectable in field site soils up to 15 years after application, again retaining the characteristics seen in sludge products. Concentrations correlated with residual sludge metal concentration gradients in a well-characterized field site. Fibers found along preferential flow paths and/or in horizons largely below the mixed layer suggest some potential for translocation. Synthetic fibers were shown to be rapid and semi-quantitative indicators of past sludge application.