Exploring microrheological properties of in-vivo blood flow with holographic optical tweezers

Flow characteristics of blood play a prominent role in microcirculation and thus proper tissue perfusion. An alteration of these properties leads to different diseases like hereditary hemorrhagic telangiectasia (HHT) or coronary heart disease. The underlying mechanisms are still not fully comprehended. We use zebrafish embryos, a popular in vivo model organism which offers particular advantages for studies of flow patterns in different blood vessels. Mutants with a degenerated blood flow caused by vessel caliber modifications are particularly investigated. The classification of this alteration is important to get a deeper understanding of HHT. Holographic Optical Tweezers (HOT) enable the three dimensional manipulation of microscopic objects like red blood cells. In vivo measurements mark an important milestone for this exciting biophotonic tool that still has to be managed. We extend the standard HOT setup by an active laser driving system. The combined system offers new possibilities and can be used to measure local viscoelasticity in media, a determining rheological factor of blood flow.