MR traceable delivery of p53 tumor suppressor gene by PEI-functionalized superparamagnetic iron oxide nanoparticles.

Cancer gene therapy involves the replacement of missing or altered genes with healthy ones. In this paper, we have proposed tumor suppressor gene-carrying superparamagnetic iron oxide nanoparticles (SPIONs) for anti-cancer gene therapy. Thermally crosslinked SPIONs (TCL-SPIONs) were conjugated with branched polyethylenimine (PEI 1800 Da) by EDC-NHS chemistry for p53 plasmid DNA delivery. The morphology of the bPEI conjugated TCL-SPIONs (bPEI-TCL-SPION) and pDNA-loaded bPEI-TCL-SPION nanoparticles was measured using transmission electron microscopy (TEM). The particle sizes of the pDNA-loaded bPEI-TCL-SPION nanoparticles were also confirmed by dynamic light scattering, and ranged from 100 to 130 nm, depending on the molar charge ratio. The fluorescently labeled pDNA was complexed with bPEI-TCL-SPION and its intracellular internalization was investigated using confocal microscopy. The p53 plasmid-loaded bPEI-TCL-SPION nanoparticles achieved significantly higher p53 tumor suppressor gene expression and cellular viability compared to positive controls. The expressed wild-type p53 protein suppressed tumor cell proliferation as compared to the mutant control. When transgene expression of the p53 tumor suppressor gene was evaluated at the mRNA level and quantified using real-time PCR, the results were highly dependent on the molar charge ratio (N/P) as well as the cancer cell type. SPIONs internalized within cancer cells were tracked by magnetic resonance (MR) imaging. It was concluded that bPEI-TCL-SPION could be used as efficient gene delivery carriers that can be tracked by MR imaging.

Acute retinal necrosis: a national population-based study to assess the incidence, methods of diagnosis, treatment strategies and outcomes in the UK.

AIM: To determine the incidence, methods of diagnosis, treatment strategies and outcomes for acute retinal necrosis (ARN) in the UK. METHODS: A 12-month active case ascertainment study was carried out between March 2001 and March 2002 to record cases of ARN presenting to ophthalmologists via the British Ophthalmological Surveillance Unit (BOSU) reporting system. Questionnaires were sent to the reporting consultants, requesting data on patient characteristics, presentation, clinical findings, investigations and treatment. Diagnosis was made using the American Uveitis Society diagnostic criteria. Further questionnaires were sent at 2 weeks and 6 months to assess outcome and therapies. RESULTS: 74 cases of ARN were reported by 58 consultants between March 2001 and March 2002. Questionnaires were returned for 49 cases (66.2%), of which 18 (36.7%) were excluded. Of the 31 cases included, 22 (71.0%) were male and 9 (29.0%) were female. The age range was 13 to 85 years (mean 54.3 years). 28 cases (90.3%) were unilateral, with 3 patients (9.7%) presenting with bilateral ARN. An aqueous or vitreous biopsy was performed in only 18 patients, with one patient having both. Herpes viral DNA analysis was performed on all 19 biopsies, with identification of the viral DNA in 16; results from 3 biopsies were not documented. Varicella zoster virus (VZV) was the commonest cause identified in 10 patients (56%). Of the 31 subjects, 27 (87.1%) were treated for ARN with systemic antiviral treatment: with intravenous antiviral in 23 cases (85.2%) and oral antiviral in 4 cases (14.8%). 21 of these patients went on to receive oral antiviral maintenance therapy. In addition to antiviral treatment, systemic steroids were given to 16 subjects (51.6%). Surgical intervention for retinal detachment was performed on 5 patients. CONCLUSIONS: During the 12-month study period, 31 cases of ARN met the diagnostic criteria set by the American Uveitis Society. The incidence in the UK based on this study is approximately 1 case per 1.6 to 2.0 million population per year. We have ascertained that the management of ARN throughout the UK is variable, suggesting that national guidelines would be of benefit.