Effects of valproic acid on the placental barrier in the pregnant mouse: Optical imaging and transporter expression studies.

Our aim was to evaluate the effects of valproic acid (VPA) on the function of the placental barrier in vivo, in pregnant mice. Studies were conducted on gestational days 12.5 (mid-gestation) or 17.5 (late gestation), following intraperitoneal treatment with 200 mg/kg VPA or the vehicle. Indocyanine green (ICG; 0.167 mg, i.v.) was used as a marker for the placental barrier permeability. Transporter expression was evaluated by quantitative -PCR. VPA treatment was associated with a 40% increase (p < 0.05) in accumulation of ICG in maternal liver in mid-pregnancy and a decrease by one fifth (p < 0.05) in late pregnancy. Ex vivo, VPA treatment led to a 20% increase (p < 0.05) in fetal ICG emission in mid-pregnancy. Also in mid-pregnancy, the placental expression of the L-type amino acid transporter, the organic anion-transporting polypeptide (Oatp)4a1 (thyroid hormone transporter), and the reduced folate carrier was lower in VPA-treated mice (p < 0.05). In late pregnancy, hepatic Oatp4a1 levels were 40% less than in controls (p > 0.05). The observed changes in placental transporter expression and function support further research into the potential role of the placenta in the adverse pregnancy outcomes of VPA. Near-infrared imaging provides a noninvasive, nonradioactive tool for future studies on the effects of epilepsy and antiepileptic drugs on tissue transport functions.

Tracking inflammation in the epileptic rat brain by bi-functional fluorescent and magnetic nanoparticles.

Correct localization of epileptic foci can improve surgical outcome in patients with drug-resistant seizures. Our aim was to demonstrate that systemically injected nanoparticles identify activated immune cells, which have been reported to accumulate in epileptogenic brain tissue. Fluorescent and magnetite-labeled nanoparticles were injected intravenously to rats with lithium-pilocarpine-induced chronic epilepsy. Cerebral uptake was studied ex vivo by confocal microscopy and MRI. Cellular uptake and biological effects were characterized in vitro in murine monocytes and microglia cell lines. Microscopy confirmed that the nanoparticles selectively accumulate within myeloid cells in the hippocampus, in association with inflammation. The nanoparticle signal was also detectable by MRI. The in vitro studies demonstrate rapid nanoparticle uptake and good cellular tolerability. We show that nanoparticles can target myeloid cells in epileptogenic brain tissue. This system can contribute to pre-surgical and intra-surgical localization of epileptic foci, and assist in detecting immune system involvement in epilepsy.

Indocyanine Green Liposomes for Diagnosis and Therapeutic Monitoring of Cerebral Malaria.

Cerebral malaria (CM) is a major cause of death of Plasmodium falciparum infection. Misdiagnosis of CM often leads to treatment delay and mortality. Conventional brain imaging technologies are rarely applicable in endemic areas. Here we address the unmet need for a simple, non-invasive imaging methodology for early diagnosis of CM. This study presents the diagnostic and therapeutic monitoring using liposomes containing the FDA-approved fluorescent dye indocyanine green (ICG) in a CM murine model. Increased emission intensity of liposomal ICG was demonstrated in comparison with free ICG. The Liposomal ICG's emission was greater in the brains of the infected mice compared to naïve mice and drug treated mice (where CM was prevented). Histological analyses suggest that the accumulation of liposomal ICG in the cerebral vasculature is due to extensive uptake mediated by activated phagocytes. Overall, liposomal ICG offers a valuable diagnostic tool and a biomarker for effectiveness of CM treatment, as well as other diseases that involve inflammation and blood vessel occlusion.

Near Infrared Imaging of Indocyanine Green Distribution in Pregnant Mice and Effects of Concomitant Medications.

The transfer of indocyanine green (ICG) across the placenta is considered to be very low based on measurements in fetal blood. The goal of this study was to evaluate in mice ICG's distribution within fetuses themselves and effects of concomitant medications on fetal exposure. Mid-gestational (day 12.5) and late-gestational (day 17.5) age mice were imaged after administration of ICG (0.167 mg), in the presence and the absence of the organic anion transporting polypeptide (OATP) inhibitor rifampin (10 mg/kg, n = 11, or 20 mg/kg, n = 1) or the P-glycoprotein inhibitor valspodar (12.5 mg/kg). In vivo ICG emission intensity was followed by ex vivo analysis of blood and tissue emission. Both valspodar and rifampin increased ICG's emission intensity within maternal tissues. In addition, valspodar enhanced the ex vivo signal in mid-pregnancy placentae (2.1-fold; p < 0.01) and fetuses (2.4-fold; p < 0.01), and reduced late-pregnancy placenta:blood and fetus:blood ratios. Rifampin increased placental (1.4-fold, p < 0.05, and 2.3-fold, p < 0.01, in mid- and late-pregnancy, respectively) and fetal (2.2-fold, p < 0.01, and 3.2-fold, p < 0.01, in mid- and late-pregnancy) ICG signal. Similarly to valspodar, late-pregnancy placenta:blood and fetus:blood ratios were reduced by rifampin. Both inhibitors enhanced ICG's emission in fetal leg, liver, and brain. In conclusion, ICG distribution into the mouse fetus can be enhanced when used concomitantly with OATP or P-glycoprotein inhibitors. The greater distribution within individual fetal tissues is likely related to ICG's greater transplacental transfer. Until further data are available on ICG's safety when combined with medications that affect its maternal handling, such combinations should be used with caution.