Biology subjects

Kooiman, K.

Publications and source records attributed to Kooiman, K..

3 recordsLinked to original sources

bioRxiv2024

Early Fibrin Biofilm Development in Cardiovascular Infections

The single most common microbe causing cardiovascular infections is Staphylococcus aureus (S. aureus). S. aureus produces coagulase that converts fibrinogen to fibrin, which is incorporated into biofilms. This process aids in adherence to intravascular structures, defense against the host immune system, and resistance to antimicrobial treatment. Despite its significance, fibrin formation in S. aureus biofilms remains poorly understood. Therefore, this study aimed to elucidate the early development of cardiovascular biofilms. Clinically isolated coagulase-positive S. aureus and coagulase-negative Streptococcus gordonii (S. gordonii) from patients with cardiovascular infections, and a coagulase mutant S. aureus {Delta}coa, were grown in tryptic soy broth (TSB), Iscoves Modified Dulbeccos Medium (IMDM), and pooled human plasma, with or without porcine heart valves. Bacterial growth, metabolic activity, and bacterial fibrinogen utilization were measured over 24 hr at 37 {degrees}C. Time-lapse confocal microscopy was used to visualize and track biofilm development. S. aureus exhibited more growth in TSB and human plasma than S. gordonii and S. aureus {Delta}coa, but showed similar growth as S. aureus {Delta}coa in IMDM. Peak metabolic activity for all isolates was highest in TSB and lowest in human plasma. The presence of porcine valves caused strain-dependent alterations in time to peak metabolic activity. Confocal imaging revealed fibrin-based biofilm development exclusively in the coagulase-producing S. aureus strains. Between 2 and 6 hr of biofilm development, 74.9% (p=0.034) of the fibrinogen from the medium was converted to fibrin. Variations in fibrin network porosity and density were observed among different coagulase-producing S. aureus strains. Fibrin formation is mediated by S. aureus coagulase and first strands occurred within 3 hr for clinical strains after exposure to human plasma. This study stresses the importance of experimental design given the bacterial changes due to different media and substrates and provides insights into the early pathogenesis of S. aureus cardiovascular biofilms. HighlightsO_LIBacterial growth and activity are medium and substrate dependent C_LIO_LICoagulase is necessary for Staphylococcus aureus fibrin biofilm development C_LIO_LIFibrin strands begin forming in Staphylococcus aureus biofilms within 3 hours C_LI

microbiology↗

bioRxiv2024

Ultrasound-activated microbubbles mediate F-actin disruptions and endothelial gap formation during sonoporation

Locally opening up the endothelial barrier in a safe and controlled way is beneficial for drug delivery into the extravascular tissue. Although ultrasound-induced microbubble oscillations can affect endothelial barrier integrity, the mechanism remains unknown. Here we uncover a new role for F-actin in microbubble-mediated endothelial gap formation. Unique simultaneous high-resolution confocal microscopy and ultra-high-speed camera imaging (10 million frames per second) reveal that oscillating microbubbles (radius 1.3-3.8 {micro}m) induce sonoporation in all cells in which F-actin remodeling occurred. F-actin disruption only mainly resulted in tunnel formation (75%) and F-actin stress fiber severing and recoil mainly resulted in cell-cell contact opening within 15 s upon treatment (54%) and tunnel formation (15%). Stress fiber severing occurred when fibers were within reach of the microbubbles maximum radius during oscillation, requiring normal forces of [≥]230 nN. Together, these findings reveal a novel mechanism of microbubble-mediated drug delivery, which associates with the underlying cytoskeletal organization.

bioengineering↗

bioRxiv2024

Characterizing microbubble-mediated permeabilization in a vessel-on-a-chip model

Drug transport from blood to extravascular tissue can locally be achieved by increasing the vascular permeability through ultrasound-activated microbubbles. However, the mechanism remains unknown, including whether short and long cycles of ultrasound induce the same onset rate, spatial distribution, and amount of vascular permeability increase. Accurate models are necessary for insights into the mechanism so a microvessel-on-a-chip is developed with a membrane-free extravascular space. Using these microvessels-on-a-chip, we show distinct differences between 2 MHz ultrasound treatments with 10 or 1000 cycles. The onset rate is slower for 10 than 1000 cycles, while both cycle lengths increase the permeability in spot-wise patterns without affecting cell viability. Significantly less vascular permeability increase and sonoporation are induced for 10 versus 1000 cycles at 750 kPa (i.e., highest studied peak negative acoustic pressure (PNP)). The PNP threshold for vascular permeability increases is 750 versus 550 kPa for 10 versus 1000 cycles, while this is 750 versus 220 kPa for sonoporation. Vascular permeability increases do not correlate with v{beta}3-targeted microbubble behavior, while sonoporation correlates with v{beta}3-targeted microbubble clustering. In conclusion, the further mechanistic unraveling of vascular permeability increase by ultrasound-activated microbubbles in a developed microvessel-on-a-chip model aids safe and efficient development of microbubble-mediated drug transport.

bioengineering↗