An agarose-based microfluidic platform with a gradient buffer for 3D chemotaxis studies

The current state-of-art in 3D microfluidic chemotaxis device (μFCD) is limited by the inherent coupling of the fluid flow and chemical concentration gradients. Here, we present an agarose-based 3D μFCD that decouples these two important parameters, in that the flow control channels are separated from the cell compartment by an agarose gel wall. This decoupling is enabled by the transport property of the agarose gel, which—in contrast to the conventional microfabrication material such as polydimethylsiloxane (PDMS)—provides an adequate physical barrier for convective fluid flow while at the same time readily allowing protein diffusion. We demonstrate that in this device, a gradient can be pre-established in an agarose layer above the cell compartment (a gradient buffer) before adding the 3D cell-containing matrix, and the dextran (10 kDa) concentration gradients can be re-established within 10 min across the cell-containing matrix and remain stable indefinitely. We successfully quantified the chemotactic response of murine dendritic cells to a gradient of CCL19, an 8.8 kDa lymphoid chemokine, within a type I collagen matrix. This model system is easy to set up, highly reproducible, and will benefit research on 3D chemoinvasion studies, for example with cancer cells or immune cells. Because of its gradient buffering capacity, it is particularly suitable for studying rapidly migrating cells like mature dendritic cells and neutrophils. Electronic Supplementary Material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Ulrike Haessler and Yevgeniy Kalinin have equal contribution.     

Purulent Pericarditis Caused by Haemophilus parainfluenzae

Bacterial pericarditis is a rare disease in the era of antibiotics. Purulent pericarditis is most often caused by Staphylococcus aureus, Streptococcus pneumoniae, or Haemophilus influenzae. The number of H. parainfluenzae infections has been increasing; in rare cases, it has caused endocarditis. We report a case of purulent pericarditis caused by H. parainfluenzae in a 62-year-old woman who reported a recent upper respiratory tract infection. The patient presented with signs and symptoms of pericardial tamponade. Urgent pericardiocentesis restored her hemodynamic stability. However, within 24 hours, fluid reaccumulation led to recurrent pericardial tamponade and necessitated the creation of a pericardial window. Cultures of the first pericardial fluid grew H. parainfluenzae. Levofloxacin therapy was started, and the patient recovered. Haemophilus parainfluenzae should be considered in a patient who has signs and symptoms of purulent pericarditis. Prompt diagnosis, treatment, and antibiotic therapy are necessary for the patient''s survival. To our knowledge, this is the first report of purulent pericarditis caused by H. parainfluenzae.Key words: Endocarditis, bacterial/diagnosis/microbiology/pathology; haemophilus/isolation & purification; haemophilus infections/diagnosis/drug therapy; haemophilus parainfluenzae; pericarditis/complications/diagnosis/etiology/microbiology/therapy; suppuration/diagnosis; treatment outcomePurulent pericarditis is a disease process that is usually described as a secondary infection from a primary site in the respiratory tract. The condition has been associated with respiratory disease processes such as pneumonia or empyema, but it can be a sequela of endocarditis, chest trauma, chest surgery, or the hematogenous spread of infection from elsewhere in the body.¹ Haemophilus influenzae has been suspected as a cause of purulent pericarditis; however, H. parainfluenzae has not previously been reported as a cause. Haemophilus parainfluenzae organisms are considered to be normal respiratory flora with low pathogenicity. However, H. parainfluenzae is being more frequently implicated in a variety of infections.^2,3 We present what we think is the first report of purulent pericarditis caused by H. parainfluenzae.     

A quantitative, randomized study evaluating three methods of mesenchymal stem cell delivery following myocardial infarction.

AIMS: Mesenchymal stem cells (MSCs), rare bone marrow-derived stem cell precursors of non-haematopoietic tissues, have shown promise in potentially repairing infarcted myocardium. These and similar cell types are being tested clinically, but understanding of delivery and subsequent biodistribution is lacking. This study was designed to quantitatively compare MSC engraftment rates after intravenous (IV), intracoronary (IC), or endocardial (EC) delivery in a porcine myocardial infarction (MI) model. METHODS AND RESULTS: Allogeneic, male MSCs were cultured from porcine bone marrow aspirates. Iridium nanoparticles were added during culturing and internalized by the MSCs. An MI was induced in female swine (27-40 kg in size) by prolonged balloon occlusion of the mid-left anterior descending artery. Animals (n = 6 per group) were randomized to one of three delivery methods. Cellular engraftment was determined 14+/-3 days post-delivery by measuring ex-vivo the iridium nanoparticle concentration in the infarct. Confirmation of cellular engraftment utilized both DiI and fluorescence in situ hybridization (FISH) labelling techniques. During MSC infusion, no adverse events were noted. However, following IC infusion, half of the pigs exhibited decreased blood flow distal to the infusion site. At 14 days, the mean number of engrafted cells within the infarct zone was significantly greater (P< or =0.01) following IC infusion than either EC injection or IV infusion and EC engraftment was greater than IV engraftment (P< or =0.01). There was less systemic delivery to the lungs following [EC vs. IV (P = 0.02), EC vs. IC (P = 0.06)]. Both DiI and FISH labelling demonstrated the presence of engrafted male MSCs within the female infarcted tissue. CONCLUSION: IC and EC injection of MSCs post-MI resulted in increased engraftment within infarcted tissue when compared with IV infusion, and IC was more efficient than EC. However, IC delivery was also associated with a higher incidence of decreased coronary blood flow. EC delivery into acutely infarcted myocardial tissue was safe and well tolerated and was associated with decreased remote organ engraftment with compared with IC and IV deliveries.     

Proton magnetic resonance spectroscopy study of dyskinesia patients.

Oral dyskinesias may occur spontaneously or be induced by medications such as antipsychotics and antidepressants. In this study, single voxel proton magnetic resonance spectroscopy was used to compare metabolite levels in the striatum for (1) 12 patients with drug-induced tardive dyskinesia (TD), (2) 12 patients with spontaneous oral dyskinesia (SOD), (3) 8 antidepressant-treated patients without TD, and (4) 8 control subjects. Statistically significant reductions in the choline/creatine (Cho/Cr) ratio were measured for the drug-treated patients with TD (-13%, P = 0.020) and SOD patients (-12%, P = 0.034) relative to control subjects. In comparison with antidepressant-treated patients without TD, drug-treated patients with TD showed a non statistically significant reduction in Cho/Cr (-11%, P = 0.079). All other metabolite ratios (N-acetylaspartate (NAA)/Cr, myo-inositol (mI)/Cr, glutamine + glutamate (Glx)/Cr, macromolecule + lipid (MM+Lip)/Cr, NAA/Cho) were unaffected by either type of dyskinesia. The observed Cho/Cr reduction in dyskinesia patients suggests decreased membrane phosphatidylcholine turnover, which provides free choline as precursor of molecules responsible for cellular signal transduction.