Comparative study of cytotoxicity and genotoxicity of commercial Jeffamines® and polyethylenimine in CHO-K1 cells

Jeffamines^® are a family of polymers containing primary amine groups attached to the extremities of polyether backbone which can be used as biomaterials. They have been used in combination with polyethylenimine (PEI) to improve biocompatibility in drug and gene delivery systems. Despite these facts, very few studies have been done on cytotoxicity and genotoxicity of pure Jeffamines^® or compared with PEI. The present study aimed to evaluate and compare the cytotoxic and genotoxic effects of Jeffamines^® and PEI in CHO-K1 cells. Specifically, polypropylene oxide 2000 (PPO 2000, Jeffamine^® D series), polyethylene oxide 1900 (PEO 1900, Jeffamine^® ED series), branched 25 kDa PEI, and linear 20 kDa PEI were evaluated at different concentrations. Cell viability and proliferation were assessed by 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) and 5-bromo-2'-deoxyuridine (BrdU) assays, respectively. Genotoxicity was evaluated using single cell gel electrophoresis assay and the cytokinesis-blocked micronucleus assay. PPO 2000 was the most cytotoxic Jeffamine^® , whereas PEO 1900 did not caused significant cell death at any tested concentration. Branched PEI was more cytotoxic than linear PEI (LPEI) and both were more cytotoxic than Jeffamines^® . Only PPO 2000 induced DNA damage when evaluated in comet assay probably due to its cytotoxicity. PPO 2000, PEO 1900, and PEI did not increase the frequency of micronuclei when tested at sub-cytotoxic concentrations. This work provides new insights about biocompatibility of Jeffamines^® and PEI and suggests the genotoxicological safety for further investigations of PEO 1900 in drug and gene delivery systems. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 742-750, 2018.

Nanosponge-Mediated Drug Delivery Lowers Intraocular Pressure

PURPOSE

We examined the efficacy of an extended-release drug delivery system, nanosponge (NS) encapsulated compounds, administered intravitreally to lower intraocular pressure (IOP) in mice.

METHODS

Bilateral ocular hypertension was induced in mice by injecting microbeads into the anterior chamber. Hypertensive mice received NS loaded with ocular hypotensive drugs via intravitreal injection and IOP was monitored. Retinal deposition and retinal ganglion cell (RGC) uptake of Neuro-DiO were examined following intravitreal injection of Neuro-DiO-NS using confocal microscopy.

RESULTS

Brimonidine-loaded NS lowered IOP 12% to 30% for up to 6 days (P < 0.02), whereas travoprost-NS lowered IOP 19% to 29% for up to 4 days (P < 0.02) compared to saline injection. Three bimatoprost NS were tested: a 400-nm NS and two 700-nm NS with amorphous (A-NS) or amorphous/crystalline (AC-NS) crosslinkers. A single injection of 400 nm NS lowered IOP 24% to 33% for up to 17 days compared to saline, while A-NS and AC-NS lowered IOP 22% to 32% and 18% to 26%, respectively, for up to 32 days (P < 0.046). Over time retinal deposition of Neuro-DiO increased from 19% to 71%; Neuro-DiO released from NS was internalized by RGCs.

CONCLUSIONS

A single injection of NS can effectively deliver ocular hypotensive drugs in a linear and continuous manner for up to 32 days. Also, NS may be effective at targeting RGCs, the neurons that degenerate in glaucoma.

TRANSLATIONAL RELEVANCE

Patient compliance is a major issue in glaucoma. The use of NS to deliver a controlled, sustained release of therapeutics could drastically reduce the number of patients that progress to vision loss in this disease.

Glutathione-triggered disassembly of isothermally responsive polymer nanoparticles obtained by nanoprecipitation of hydrophilic polymers

Nanoparticles obtained by the nanoprecipitation of responsive polymers are shown to specifically and rapidly disassemble into hydrophilic polymer chains in the presence of intracellular concentrations of glutathione.

In situ forming biodegradable electroactive hydrogels

In situ forming biodegradable electroactive hydrogels based on gelatin-graft-polyaniline enhanced the adhesion and proliferation of C2C12 myoblast cells.

Sequential targeted delivery of paclitaxel and camptothecin using a cross-linked "nanosponge" network for lung cancer chemotherapy

The applicability of a HVGGSSV peptide targeted "nanosponge" drug delivery system for sequential administration of a microtubule inhibitor (paclitaxel) and topoisomerase I inhibitor (camptothecin) was investigated in a lung cancer model. Schedule-dependent combination treatment with nanoparticle paclitaxel (NP PTX) and camptothecin (NP CPT) was studied in vitro using flow cytometry and confocal imaging to analyze changes in cell cycle, microtubule morphology, apoptosis, and cell proliferation. Results showed significant G2/M phase cell cycle arrest, changes in microtubule dynamics that produced increased apoptotic cell death and decreased proliferation with initial exposure to NP PTX, followed by NP CPT in lung cancer cells. In vivo molecular imaging and TEM studies validated HVGGSSV-NP tumor binding at 24 h and confirmed the presence of Nanogold labeled HVGGSSV-NPs in tumor microvascular endothelial cells. Therapeutic efficacy studies conducted with sequential HVGGSSV targeted NP PTX and NP CPT showed 2-fold greater tumor growth delay in combination versus monotherapy treated groups, and 4-fold greater delay compared to untargeted and systemic drug controls. Analytical HPLC/MS methods were used to quantify drug content in tumor tissues at various time points, with significant paclitaxel and camptothecin levels in tumors 2 days postinjection and continued presence of both drugs up to 23 days postinjection. The efficacy of the NP delivery system in sequential treatments was corroborated in both in vitro and in vivo lung cancer models showing increased G2/M phase arrest and microtubule disruption, resulting in enhanced apoptotic cell death, decreased cell proliferation and vascular density.

Trans-meningeal drug delivery to optic nerve ganglion cell axons using a nanoparticle drug delivery system

The purpose of this study was to investigate if neuroprotective drugs can cross the optic nerve sheath in vitro. Four optic nerves were used for this study. Two porcine nerves were harvested at the time of euthanasia and two human nerves were obtained at the time of therapeutic globe enucleation. The optic nerve sheaths were dissected and placed as a membrane in a two chamber diffusion cell to test meningeal penetration by both brimonidine alone and brimonidine encapsulated in nanoparticle (NP-brimonidine). Brimonidine concentration was assayed by UV-vis spectrometer measurement of absorbance at 389 nm. Increasing concentration of brimonidine on the receiver side of the chamber was measured in both the brimonidine alone and the brimonidine encapsulated experiments. The human data were fitted with a two parameter exponential regression analysis (brimonidine alone donor r(2) = 0.87 and receiver r(2) = 0.80, NP-brimonidine donor r(2) = 0.79 and receiver r(2) = 0.84). Time constant (τ) was 10.2 h (donor) and 13.1 h (receiver) in the brimonidine study, and 24.0 h (donor) and 15.9 h (receiver) in the NP-brimonidine study. Encapsulated brimonidine had a longer time to reach equilibrium. Passage of brimonidine through the optic nerve sheath was demonstrated in the experiments. Increase in time constants when comparing the NP-brimonidine with the brimonidine curves in the human studiesindicates that diffusion is delayed by the initial parameter of drug being loaded in NP. Direct treatment of injured optic nerve axons may be possible by trans-meningeal drug diffusion.

Nanosponge formation from organocatalytically-synthesized poly(carbonate) copoplymers

Advanced organocatalytic synthesis methods were employed to prepare linear poly(carbonate)s with control over functional group incorporation and molecular weight. Pendant allyl or epoxide groups served as reaction partners in thiol-ene click or epoxide-amine reactions with ethylene oxide-containing crosslinking groups to form a panel of six novel poly(carbonate) nanosponges with crosslinking densities ranging from 5%, 10% and 20% via an intermolecular chain-crosslinking approach.

Targeted nanoparticles that deliver a sustained, specific release of Paclitaxel to irradiated tumors

To capitalize on the response of tumor cells to XRT, we developed a controlled-release nanoparticle drug delivery system using a targeting peptide that recognizes a radiation-induced cell surface receptor. Phage display biopanning identified Gly-Ile-Arg-Leu-Arg-Gly (GIRLRG) as a peptide that selectively recognizes tumors responding to XRT. Membrane protein extracts of irradiated glioma cells identified glucose-regulated protein GRP78 as the receptor target for GIRLRG. Antibodies to GRP78 blocked the binding of GIRLRG in vitro and in vivo. Conjugation of GIRLRG to a sustained-release nanoparticle drug delivery system yielded increased paclitaxel concentration and apoptosis in irradiated breast carcinomas for up to 3 weeks. Compared with controls, a single administration of the GIRLRG-targeted nanoparticle drug delivery system to irradiated tumors delayed the in vivo tumor tripling time by 55 days (P = 0.0001) in MDA-MB-231 and 12 days in GL261 (P < 0.005). This targeting agent combines a novel recombinant peptide with a paclitaxel-encapsulating nanoparticle that specifically targets irradiated tumors, increasing apoptosis and tumor growth delay in a manner superior to known chemotherapy approaches.