A bioengineered array of 3D microvessels for vascular permeability assay

Blood vessels exhibit highly regulated barrier function allowing selective passage of macromolecules. Abnormal vascular permeability caused by disorder in barrier function is often associated with various pathological states such as tumor progression or pulmonary fibrosis. There are no realistic in vitro models for measuring vascular permeability as most models are limited to mimicking anatomical structural properties of in vivo vessel barriers. This paper presents a reliable microfluidic-based chip for measuring permeability by engineering tubular perfusable microvessels. This platform is compatible with high resolution, live-cell time-lapse imaging and high throughput permeability measurements. The microvessels were formed by natural angiogenic process and thus exhibit reliable barrier properties with permeability coefficient of 1.55×10(-6)cm/s (for 70kDa FITC-dextran). The bioengineered microvessels showed properties similar to in vivo vessels in terms of cell-cell junction expression (ZO-1, Claudin-5 and VE-cadherin) and response to agonists such as histamine and TNF-α. We showed that hyperpermeability of the tumor microvessel could be normalized with anti-VEGF (bevacizumab) treatment, consistent with the mechanism of action for bevacizumab. The method developed here provides a relatively simple, robust technique for assessing drug effects on permeability of microvessels with a number of potential applications in fundamental vascular biology as well as drug screening.

Changes of early post-traumatic osteoarthritis in an ovine model of simulated ACL reconstruction are associated with transient acute post-injury synovial inflammation and tissue catabolism

The study described here tested the hypothesis that early intra-articular inflammation is associated with the development of post-traumatic osteoarthritis (PTOA) in a sheep model. We extended previously published work in which we investigated joint gross morphology and synovial mRNA expression of inflammatory and catabolic molecules 2 weeks after anatomic Anterior cruciate ligament (ACL) autograft reconstructive surgery (ACL-R). The same variables have been analyzed at 20 weeks post surgery together with new experimental variables at both time points. Animals were sacrificed at 20 weeks post ACL-R surgery and their joints graded for signs of PTOA. Synovial samples were harvested for histological grading plus mRNA and protein analysis for a panel of inflammatory and catabolic molecules. The mRNA expression levels for this panel plus connective tissue matrix turnover molecules were also investigated in cartilage samples. Results of gross morphological assessments at 20 weeks post surgery showed some changes consistent with early OA, but indicated little progression of damage from the 2 week time point. While significant alterations in mRNA levels for synovial inflammatory and catabolic molecules were detected at 2 weeks, values had normalized by 20 weeks. Similarly, all mRNA expression levels for inflammatory and catabolic molecules in articular cartilage had returned to normal levels by 20 weeks post ACL-R surgery. We conclude that synovial inflammatory processes are initiated very early after ACL-R surgery and may instigate events that lead to the gross cartilage and joint abnormalities observed as early as 2 weeks. However, the absence of sustained inflammation and joint instability may prevent OA progression.

Pressurized H2 RF cavities in ionizing beams and magnetic fields

A major technological challenge in building a muon cooling channel is operating rf cavities in multitesla external magnetic fields. We report the first proof-of-principle experiment of a high pressure gas-filled rf cavity for use with intense ionizing beams and strong external magnetic fields. rf power consumption by beam-induced plasma is investigated with hydrogen and deuterium gases with pressures between 20 and 100 atm and peak rf gradients between 5 and 50 MV/m. The low pressure case agrees well with an analytical model based on electron and ion mobilities. Varying concentrations of oxygen gas are investigated to remove free electrons from the cavity and reduce the rf power consumption. Measurements of the electron attachment time to oxygen and rate of ion-ion recombination are also made. Additionally, we demonstrate the operation of the gas-filled rf cavity in a solenoidal field of up to 3 T, finding no major magnetic field dependence. All these results indicate that a high pressure gas-filled cavity is a viable technology for muon ionization cooling.

Measurement of transmission efficiency for 400 MeV proton beam through collimator at Fermilab MuCool Test Area using Chromox-6 scintillation screen

The MuCool Test Area (MTA) at Fermilab is a facility to develop the technology required for ionization cooling for a future Muon Collider and∕or Neutrino Factory. As part of this research program, feasibility studies of various types of RF cavities in a high magnetic field environment are in progress. As a unique approach, we have tested a RF cavity filled with a high pressure hydrogen gas with a 400 MeV proton beam in an external magnetic field (B = 3 T). Quantitative information about the number of protons passing through this cavity is an essential requirement of the beam test. The MTA is a flammable gas (hydrogen) hazard zone. Due to safety reasons, no active (energized) beam diagnostic instrument can be used. Moreover, when the magnetic field is on, current transformers (toroids) used for beam intensity measurements do not work due to the saturation of the ferrite material of the transformer. Based on these requirements, we have developed a passive beam diagnostic instrumentation using a combination of a Chromox-6 scintillation screen and CCD camera. This paper describes details of the beam profile and position obtained from the CCD image with B = 0 T and B = 3 T, and for high and low intensity proton beams. A comparison is made with beam size obtained from multi-wires detector. Beam transmission efficiency through a collimator with a 4 mm diameter hole is measured by the toroids and CCD image of the scintillation screen. Results show that the transmission efficiency estimated from the CCD image is consistent with the toroid measurement, which enables us to monitor the beam transmission efficiency even in a high magnetic field environment.

Engineering of functional, perfusable 3D microvascular networks on a chip

Generating perfusable 3D microvessels in vitro is an important goal for tissue engineering, as well as for reliable modelling of blood vessel function. To date, in vitro blood vessel models have not been able to accurately reproduce the dynamics and responses of endothelial cells to grow perfusable and functional 3D vascular networks. Here we describe a microfluidic-based platform whereby we model natural cellular programs found during normal development and angiogenesis to form perfusable networks of intact 3D microvessels as well as tumor vasculatures based on the spatially controlled co-culture of endothelial cells with stromal fibroblasts, pericytes or cancer cells. The microvessels possess the characteristic morphological and biochemical markers of in vivo blood vessels, and exhibit strong barrier function and long-term stability. An open, unobstructed microvasculature allows the delivery of nutrients, chemical compounds, biomolecules and cell suspensions, as well as flow-induced mechanical stimuli into the luminal space of the endothelium, and exhibits faithful responses to physiological shear stress as demonstrated by cytoskeleton rearrangement and increased nitric oxide synthesis. This simple and versatile platform provides a wide range of applications in vascular physiology studies as well as in developing vascularized organ-on-a-chip and human disease models for pharmaceutical screening.

Assessment and mitigation of diagnostic-generated electromagnetic interference at the National Ignition Facility

Electromagnetic interference (EMI) is an ever-present challenge at laser facilities such as the National Ignition Facility (NIF). The major source of EMI at such facilities is laser-target interaction that can generate intense electromagnetic fields within, and outside of, the laser target chamber. In addition, the diagnostics themselves can be a source of EMI, even interfering with themselves. In this paper we describe EMI generated by ARIANE and DIXI, present measurements, and discuss effects of the diagnostic-generated EMI on ARIANE's CCD and on a PMT nearby DIXI. Finally we present some of the efforts we have made to mitigate the effects of diagnostic-generated EMI on NIF diagnostics.

In vitro formation and characterization of a perfusable three-dimensional tubular capillary network in microfluidic devices

This paper describes the in vitro formation and characterization of perfusable capillary networks made of human umbilical vein endothelial cells (HUVECs) in microfluidic devices (MFDs). Using this platform, an array of three-dimensional (3D) tubular capillaries of various dimensions (50-150 μm in diameter and 100-1600 μm in length) can be formed reproducibly. To generate connected blood vessels, MFDs were completely filled with fibrin gel and subsequently processed to selectively leave behind gel structures inside the bridge channels. Following gel solidification, HUVECs were coated along the gel walls, on opposite ends of the patterned 3D fibrin gel. After 3-4 days, HUVECs migrating into the fibrin gel from opposite ends fused with each other, spontaneously forming a connected vessel that expressed tight junction proteins (e.g., ZO-1), which are characteristic of post-capillary venules. With ready access to a perfusable capillary network, we demonstrated perfusion of the vessels and imaged red blood cells (RBCs) and beads flowing through them. The results were reproducible (∼50% successful perfusable capillaries), consistent, and could be performed in a parallel manner (9 devices per well plate). Additionally, compatibility with high resolution live-cell microscopy and the possibility of incorporating other cell types makes this a unique experimental platform for investigating basic and applied aspects of angiogenesis, anastomosis, and vascular biology.

Phase I dose-finding study of epirubicin, oxaliplatin, and S-1 (EOS) in patients with previously untreated advanced gastric cancer (AGC)

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Background: To determine the recommended dose (RD) and dose-limiting toxicity (DLT) of EOS combination in patients with previously untreated AGC.

Methods: Previously untreated patients with histologically proven metastatic or recurrent AGC and ECOG performance status 0-2 were enrolled. Fixed dose of epirubicin (50 mg/m2) and oxaliplatin (130 mg/m2) was administered i.v. on day 1. The dose of S-1 was escalated as following schedule: Level I: 30 mg/m2, Level II: 40 mg/m2, Level III: 45 mg/m2, Level IV: 50 mg/m2. S-1 was administered orally twice a day on days 1-14. Each cycle was repeated every 21 days. DLTs were evaluated during the first two cycles of treatment.

Results: Nineteen patients were enrolled: 13 patients in dose-escalation phase and 6 patients in the extension at the RD. Median age was 53 years (range, 40-71 years). At dose level II, 1 DLT (grade 4 neutropenia lasting more than 5 days) was found among 6 patients while at dose level III, 2 DLTs (grade 3 diarrhea and nausea) were observed among 4 patients. Therefore, the dose level II was determined as RD. Cumulative (all cycles) grade 3/4 toxicity included neuropenia (58%), leucopenia (32%), thrombocytopenia (11%), diarrhea (11%), and nausea (5%). Of 13 patients with measurable lesions, 8 achieved partial response and 3 showed stable diseases, and the objective response rate was 62% (95% CI, 36-88%). The median progression-free survival was 6.5 months (95% CI, 4.7-8.2 months).

Conclusions: The RD of the EOS regimen in patients with previously untreated AGC was epirubicin 50 mg/m2 and oxaliplatin 130 mg/m2 on day 1 and S-1 40 mg/m2 twice a day on days 1-14 of every 21-day cycle. This regimen seems to have promising preliminary activity.

No significant financial relationships to disclose.

Prognostic impact of immunohistochemical expression of Ki-67 in patients with advanced gastric cancer who underwent curative resection

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Background: Ki-67, tumor proliferation marker, is an important prognostic factor in a variety of cancers. In the present study, we investigated the prognostic value of immunoexpression of Ki-67 in patient with gastric cancer who underwent curative resection.

Methods: We retrospectively analyzed 241 patients who had undergone curative gastrectomy at Gachon University Gil Hospital between January 2008 and July 2009. Ki-67 proliferation index (PI) by immunohistochemistry on formalin-fixed, paraffin-embedded material and the other clinicopathologic variables were evaluated by univariate and mulvariate analysis.

Results: The median follow-up from surgery was 12 months (range, 0.5-26.7 months) and mean recurrence-free survival was 23 months (95% confidence interval, 21.8-24.1 months). The mean Ki-67 PI was 40% (range, 5-90%). No significant correlation was found between Ki-67 PI and other clinicopathologic variables including histologic grade and pathologic TNM (pTNM) stage. Univariate analysis revealed that significant prognostic factors of recurrence-free survival included age, preoperative serum albumin, pre-operative hemoglobin, surgery type, pTNM, histologic grade, lymphatic vessel invasion, peri-neural invasion, and Ki-67 PI. In the multivariate analysis besides pTNM (p=0.046), lymphatic vessel invasion (p=0.024), and surgery type (p=0.047), Ki-67 PI (p=0.005) also remained as an independent prognostic factor of recurrence, whereas the other factors lost its prognostic value.

Conclusions: Our results suggest that high Ki-67 PI is independent, poor prognostic factor of recurrence in patient with gastric cancer who underwent curative resection.

No significant financial relationships to disclose.