Postnatal meningeal CSF transport is primarily mediated by the arachnoid and pia maters and is not altered after intraventricular hemorrhage-posthemorrhagic hydrocephalus.

BACKGROUND: CSF has long been accepted to circulate throughout the subarachnoid space, which lies between the arachnoid and pia maters of the meninges. How the CSF interacts with the cellular components of the developing postnatal meninges including the dura, arachnoid, and pia of both the meninges at the surface of the brain and the intracranial meninges, prior to its eventual efflux from the cranium and spine, is less understood. Here, we characterize small and large CSF solute distribution patterns along the intracranial and surface meninges in neonatal rodents and compare our findings to meningeal CSF solute distribution in a rodent model of intraventricular hemorrhage-posthemorrhagic hydrocephalus. We also examine CSF solute interactions with the tela choroidea and its pial invaginations into the choroid plexuses of the lateral, third, and fourth ventricles. METHODS: 1.9-nm gold nanoparticles, 15-nm gold nanoparticles, or 3 kDa Red Dextran Tetramethylrhodamine constituted in aCSF were infused into the right lateral ventricle of P7 rats to track CSF circulation. 10 min post-1.9-nm gold nanoparticle and Red Dextran Tetramethylrhodamine injection and 4 h post-15-nm gold nanoparticle injection, animals were sacrificed and brains harvested for histologic analysis to identify CSF tracer localization in the cranial and spine meninges and choroid plexus. Spinal dura and leptomeninges (arachnoid and pia) wholemounts were also evaluated. RESULTS: There was significantly less CSF tracer distribution in the dura compared to the arachnoid and pia maters in neonatal rodents. Both small and large CSF tracers were transported intracranially to the arachnoid and pia mater of the perimesencephalic cisterns and tela choroidea, but not the falx cerebri. CSF tracers followed a similar distribution pattern in the spinal meninges. In the choroid plexus, there was large CSF tracer distribution in the apical surface of epithelial cells, and small CSF tracer along the basolateral surface. There were no significant differences in tracer intensity in the intracranial meninges of control vs. intraventricular hemorrhage-posthemorrhagic hydrocephalus (PHH) rodents, indicating preserved meningeal transport in the setting of PHH. CONCLUSIONS: Differential CSF tracer handling by the meninges suggests that there are distinct roles for CSF handling between the arachnoid-pia and dura maters in the developing brain. Similarly, differences in apical vs. luminal choroid plexus CSF handling may provide insight into particle-size dependent CSF transport at the CSF-choroid plexus border.

Meningeal CSF transport is primarily mediated by the arachnoid and pia maters during development.

Background: The recent characterization of the glymphatic system and meningeal lymphatics has re-emphasized the role of the meninges in facilitating CSF transport and clearance. Here, we characterize small and large CSF solute distribution patterns along the intracranial and surface meninges in neonatal rodents and compare our findings to a rodent model of intraventricular hemorrhage-posthemorrhagic hydrocephalus. We also examine CSF interactions with the tela choroidea and its pial invaginations into the choroid plexuses of the lateral, third, and fourth ventricles. Methods: 1.9-nm gold nanoparticles, 15-nm gold nanoparticles, or 3 kDa Red Dextran Tetramethylrhodamine constituted in aCSF were infused into the right lateral ventricle of P7 rats to track CSF circulation. 10 minutes post-1.9-nm gold nanoparticle and Red Dextran Tetramethylrhodamine injection and 4 hours post-15-nm gold nanoparticle injection, animals were sacrificed and brains harvested for histologic analysis to identify CSF tracer localization in the cranial and spine meninges and choroid plexus. Spinal dura and leptomeninges (arachnoid and pia) wholemounts were also performed. Results: There was significantly less CSF tracer distribution in the dura compared to the arachnoid and pia maters in neonatal rodents. Both small and large CSF tracers were transported intracranially to the arachnoid and pia mater of the perimesencephalic cisterns and tela choroidea, but not the dura mater of the falx cerebri. CSF tracers followed a similar distribution pattern in the spinal meninges. In the choroid plexus, there was large CSF tracer distribution in the apical surface of epithelial cells, and small CSF tracer along the basolateral surface. There were no significant differences in tracer intensity in the intracranial meninges of control vs. intraventricular hemorrhage-posthemorrhagic hydrocephalus (PHH) rodents, indicating preserved meningeal transport in the setting of PHH. Conclusions: Differential CSF tracer handling by the leptomeninges suggests that there are distinct roles for CSF handling between the arachnoid-pia and dura maters in the developing brain. Similarly, differences in apical vs. luminal choroid plexus CSF handling may provide insight into particle-size dependent CSF transport at the CSF-choroid plexus border.

Gold nanoparticle-enhanced X-ray microtomography of the rodent reveals region-specific cerebrospinal fluid circulation in the brain.

Cerebrospinal fluid (CSF) is essential for the development and function of the central nervous system (CNS). However, the brain and its interstitium have largely been thought of as a single entity through which CSF circulates, and it is not known whether specific cell populations within the CNS preferentially interact with the CSF. Here, we develop a technique for CSF tracking, gold nanoparticle-enhanced X-ray microtomography, to achieve micrometer-scale resolution visualization of CSF circulation patterns during development. Using this method and subsequent histological analysis in rodents, we identify previously uncharacterized CSF pathways from the subarachnoid space (particularly the basal cisterns) that mediate CSF-parenchymal interactions involving 24 functional-anatomic cell groupings in the brain and spinal cord. CSF distribution to these areas is largely restricted to early development and is altered in posthemorrhagic hydrocephalus. Our study also presents particle size-dependent CSF circulation patterns through the CNS including interaction between neurons and small CSF tracers, but not large CSF tracers. These findings have implications for understanding the biological basis of normal brain development and the pathogenesis of a broad range of disease states, including hydrocephalus.

Auryon Laser in Peripheral Arterial Interventions: A Single-Center Experience (Auryon-SCE).

BACKGROUND: The Auryon 355-nm laser atherectomy system (AngioDynamics, Inc) showed a low rate of target-lesion revascularization (TLR) at 6-month follow-up in the investigational device exemption study. At present, real-world data are not available. In this study, we analyze major adverse events and 6-month outcomes with the Auryon laser system in treating infrainguinal arterial disease in all comers at a single center. METHODS: Consecutive patients treated with the Auryon laser between September 2017 and March 2021 were retrospectively reviewed from a single operator at a single center. Demographic, procedural, angiographic, and outcome data were extracted from patients' medical records. Descriptive and survival analyses were performed. The study's primary endpoint was the assessment of freedom from TLR at 6-month follow-up. Secondary endpoints included acute procedural results, distal embolization, bailout stenting (dissection type D or higher by National Heart, Lung, and Blood Institute [NHLBI] classification, and/or residual narrowing >30%), unplanned major amputation, death, or vascular complications. RESULTS: A total of 56 patients (65 procedures, 70 lesions) were enrolled. The mean age was 70.9 ± 10 years, 66.1% were males, 48.2% were diabetics, and 25% had limb ischemia. Of the 70 lesions, 31.4% had severe calcification, 38.6% were chronic total occlusions, and 48.6% were de novo disease (in-stent restenosis in 28.6%). The majority of treated vessels were femoropopliteal (88.6%) and 29.2% had 2 or more prior interventions. Mean stenosis was 91.3 ± 9.7% at baseline, 56.0 ± 17.3% post laser, and 11.4 ± 11.2% post final treatment. Lesion length was 117.1 ± 101.2 mm and treated length was 174.0 ± 116.0 mm. Bailout stenting occurred in 11/70 lesions (15.7%). There were no NHLBI type D dissections post laser and 1 type D dissection post laser + percutaneous transluminal angioplasty. A total of 47.1% received Lutonix drug-coated balloons (BD/Bard), 27.1% received In.Pact drug-coated balloons (Boston Scientific), and 1.4% received both. The probability of freedom from TLR per procedure was 95.6% at 6 months. CONCLUSION: In a real-world cohort of patients with complex disease, the Auryon laser had excellent freedom from TLR at 6 months, although these findings need to be replicated in a randomized trial.