Pyridoclax-loaded nanoemulsion for enhanced anticancer effect on ovarian cancer.

BACKGROUND: Pyridoclax is an original lead, recently identified as very promising in treatment of chemoresistant ovarian cancers. To correct the unfavorable intrinsic physico-chemical properties of this BCS II drug, a formulation strategy was implied in the drug discovery step. Pyridoclax-loaded nanoemulsions (NEs) were developed to permit its preclinical evaluation. RESULTS: The resulting nanoemulsions displayed a mean size of about 100 nm and a high encapsulation efficiency (>95%) at a drug loading of 2 wt%, enabling a 1,000-fold increase of the Pyridoclax apparent solubility. NEs have enabled a sustained release of the drug as assayed by a dialysis bag method. In addition, anti-tumor effects of the Pyridoclax-loaded nanoemulsions (PNEs) showed a 2.5-fold higher activity on chemoresistant ovarian cancer cells than free Pyridoclax. This effect was confirmed by a drastic increase of caspase 3/7 activation from 10 µM PNEs, as newly objectified by real time apoptose imaging. The Pyridoclax bioavailability was kept unchanged after encapsulation in nanoemulsions as determined in a mice model after oral administration. CONCLUSION: Thus, NEs should permit valuable Pyridoclax oral administration, and valorization of this promising anticancer drug by maintaining its original anticancer activity, and by reducing the Pyridoclax therapeutic concentration.

Comparison of 2 strategies to enhance pyridoclax solubility: Nanoemulsion delivery system versus salt synthesis.

Pyridoclax is an original oligopyridine lead, very promising in treatment of chemoresistant cancers. However, from solubility measurement and permeability evaluation, it appeared that this compound can be considered as a BCS II drug, with a poor water solubility. To overcome this unfavorable property, two strategies were proposed and compared: pyridoclax di-hydrochloride salt synthesis and formulation of pyridoclax-loaded nanoemulsions (PNEs) efficiently performed by transposing the spontaneous emulsification process previously developed by our team. Whereas the salt improved the thermodynamic solubility of the drug by a factor 4, the apparent solubility of the encapsulated pyridoclax was 1000-fold higher. Their stability was assessed upon dilution in various complex biomimetic media relevant for oral administration (SGF, FaSSIF-V2, FeSSIF-V2) or for the intravenous route (PBS). The solubility of the salt was affected by the nature of the medium, indicating that it could precipitate after administration, negatively impacting its bioavailability and its efficiency in vivo. On the contrary, in all media, PNEs remained stable in terms of granulometric properties (determined by DLS), ζ-potential and encapsulation efficiency (measured by HPLC). Thus, such nanomedicines appear as a valuable option to perform preclinical studies on the promising pyridoclax.

In vivo evaluation of paclitaxel-loaded lipid nanocapsules after intravenous and oral administration on resistant tumor.

AIM & METHODS: The aim of the present work was to encapsulate paclitaxel (Ptx) in various lipid nanocapsules (LNCs) formulations and then to compare their pharmacokinetics and efficacy on a subcutaneous isograft model in rats. RESULTS: Three different Ptx formulations were obtained. Drug payloads ranged from 1.32 to 3.62 mg Ptx/g of formulation. After oral administration the area under concentration-time curve was higher (p < 0.05) if Ptx was encapsulated, (1,2 Distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(PEG)] (DSPE-PEG-NH2)) LNCs displaying the highest area under concentration-time curve (p < 0.05). Efficacy was better than control for standard LNCs after oral administration (p < 0.05) and for (DSPE-PEG-NH2) LNCs after intravenous administration. Despite good absorption, (DSPE-PEG-NH2) LNCs failed to remain efficient after oral route. CONCLUSION: This study highlights the importance of efficacy studies paired to pharmacokinetic studies for nanomedicines.

NF-κB-dependent DNA damage-signaling differentially regulates DNA double-strand break repair mechanisms in immature and mature human hematopoietic cells.

Hematopoietic stem and progenitor cells (HSPC), that is, the cell population giving rise not only to all mature hematopoietic lineages but also the presumed target for leukemic transformation, can transmit (adverse) genetic events, such as are acquired from chemotherapy or ionizing radiation. Data on the repair of DNA double-strand-breaks (DSB) and its accuracy in HSPC are scarce, in part contradictory, and mostly obtained in murine models. We explored the activity, quality and molecular components of DSB repair in human HSPC as compared with mature peripheral blood lymphocytes (PBL). To consider chemotherapy/radiation-induced compensatory proliferation, we established cycling HSPC cultures. Comparison of pathway-specific repair activities using reporter systems revealed that HSPC were severely compromised in non-homologous end joining and homologous recombination but not microhomology-mediated end joining. We observed a more pronounced radiation-induced accumulation of nuclear 53BP1 in HSPC relative to PBL, despite evidence for comparable DSB formation from cytogenetic analysis and γH2AX signal quantification, supporting differential pathway usage. Functional screening excluded a major influence of phosphatidylinositol-3-OH-kinase (ATM/ATR/DNA-PK)- and p53-signaling as well as chromatin remodeling. We identified diminished NF-κB signaling as the molecular component underlying the observed differences between HSPC and PBL, limiting the expression of DSB repair genes and bearing the risk of an inaccurate repair.

Association of hue discrimination loss and diabetic retinopathy.

The results of Farnsworth-Munsell 100-hue, visual acuity, and visual field testing were compared with the severity of retinopathy in a group of 90 diabetic patients. The patients showed significantly higher than expected Farnsworth-Munsell 100-hue scores, with a tritanlike axis, compared with published age norms for nondiabetic individuals. The magnitude of the acquired blue-yellow hue discrimination defect correlated significantly and to a similar extent with both the severity of overall diabetic retinopathy and the severity of macular edema and hard exudate formation. Visual acuity loss correlated somewhat more significantly with macular edema than with overall retinopathy, whereas the converse was true for visual fields. For all visual function tests, the correlations were more significant for fluorescein leakage in the macula than for capillary nonperfusion in the macula. Abnormal hue discrimination was found in 65% (32/49) of eyes with proliferative diabetic retinopathy, suggesting a potential role for this test in screening for proliferative diabetic retinopathy in primary care facilities. Also, because the ability of diabetic patients with color vision deficiency to perform color-dependent tests for urinary and blood glucose may be impaired, such patients should be made aware of this potential problem.

Urinary glucose testing inaccuracies among diabetic patients. Effect of acquired color vision deficiency caused by diabetic retinopathy.

The performance of two urinary glucose tests (Clinitest and Diastix) and several color vision and lightness discrimination tests was assessed in 43 diabetic patients and 43 age-matched controls. Most of the diabetics had proliferative diabetic retinopathy, with normal or mildly reduced visual acuity. The diabetics made significantly more errors on color interpretation of the urinary test results than did controls. The extent of errors for both diabetics and controls correlated with the severity of color vision deficiency but not with lightness discrimination deficiency. The diabetics' performance of the Clinitest test and, to a lesser extent, of the Diastix test was significantly better in bright light than in dimmer light. The type of color vision deficiency among most of the diabetics was characteristic of the acquired blue-yellow defect associated with diabetes mellitus. All of the color vision tests enabled identification of patients likely to make a large number of urine-testing errors with high sensitivity and fairly high specificity.

Electroretinographic oscillatory potentials predict progression of diabetic retinopathy. Preliminary report.

The oscillatory potential (OP) amplitudes of the electroretinogram (ERG) were determined in a group of 85 diabetic patients entering the Early Treatment Diabetic Retinopathy Study (ETDRS). The rate of progression among nonphotocoagulated eyes to the Diabetic Retinopathy Study high-risk characteristics (DRS-HRC) during a ten- to 40-month follow-up period was determined. Progression occurred in 19 of 85 eyes at risk. Those eyes with abnormal OP amplitudes (less than or equal to 75 microV) at study entry had a tenfold higher rate of progression to DRS-HRC than did eyes with normal amplitudes (greater than 75 microV). Although the level of retinopathic severity at study entry was a significant factor in the rate of subsequent progression, the amplitudes of the OPs remained a significant risk factor even after correcting the initial retinopathic level. The ERG seems to be a useful clinical tool in predicting the rate of progression of diabetic retinopathy. The reduction in OP amplitudes probably is a quantitative measure of the degree of overall inner layer retinal ischemia.

Abnormalities of the foveal avascular zone in diabetic retinopathy.

The dimensions of the foveal avascular zone (FAZ) were measured in fluorescein angiograms from 36 diabetic patients and 20 nondiabetic controls. The median values for longest diameter, mean diameter, and circumference were significantly greater in the diabetic group than in the control group. Longest diameters greater than 1.0 mm were found almost exclusively in eyes with proliferative diabetic retinopathy. The FAZ dimensions were strongly positively correlated with the severity of capillary nonperfusion in the posterior retina, but not with fluorescein leakage. The presence of proliferative diabetic retinopathy was also strongly correlated with capillary nonperfusion. Retinal capillary occlusion as the cause of FAZ enlargement in diabetic retinopathy is supported by these findings.