Live dynamic analysis of cardiac development and congenital defects in mouse embryos
Congenital cardiovascular (CV) defects are very common, occurring in 1% of live births. While it’s well recognized that mechanotransduction plays major role in cardiogenesis, there are no methods for live high-resolution imaging and dynamic analysis of mammalian heart at early developmental stages. We recently developed highly innovative methods based on Optical Coherence Tomography (OCT) in combination with live embryo culture protocols, which allow visualization of the entire live mouse embryo with single cell resolution, which is currently not possible with any other imaging technique. We can visualize beating embryonic hearts volumetrically at the rate of 100 volumes per second, which provide both quantitative and qualitative information about the heart tube dynamics and allow rapid identification of mutant embryo physiology. There is a number of projects going in the lab based on these methods, which are aimed at understanding mechanism of cardiogenesis and mutant phenotype analysis.
Live imaging of mammalian pre-implantation events
Mammalian ovulation, fertilization, estrous cycle and pre-implantation pregnancy are very fundamental processes with long history of research studies and tremendous progress in understanding molecular and genetic mechanisms regulating these events. However, because mammalian reproduction takes place deep inside the body, majority of what we know about dynamics of fertilization and pre-implantation embryo transfer is assumed based on histological analysis of extracted organs, low-resolution visualizations, and studies in more primitive animal models. We are developing an in vivo 3D imaging method for visualizing the mouse oviduct and reproductive events with micro-scale spatial resolution. These measurements are currently not possible with any other methods and provide unique opportunity to explore reproductive processes from a new dynamic perspective, adding to the development of fertility treatments and contraception. The next step is using these methods in vivo longitudinally to understand dynamic aspects of ovulation, fertilization, preimplantation development, and hormonal regulation of these processes.
In vivo micro-scale tomography of ciliary behavior
Motile cilia in the mammalian oviduct play a key role in reproduction, such as transporting fertilized oocytes to the uterus for implantation. Due to their small size (~5-10 μm in length and ~300 nm in diameter), live visualization of cilia and their activity in the lumen of the oviduct through tissue layers represents a major challenge not yet overcome. We developed a functional low-coherence optical imaging technique that allows in vivo depth-resolved mapping of the cilia location and cilia beat frequency (CBF) in the intact mouse oviduct with micro-scale spatial resolution. We validated our approach with widely-used microscopic imaging methods, presented the first in vivo mapping of the oviduct CBF in its native context, demonstrated the ability of this approach to differentiate CBF in different locations of the oviduct at different post-conception stages, and now using these methods to understand patterns of ciliary behavior. We are planning to combine tracking velocimetry approach with our fOCT technique in the mouse oviduct to study the transport of the oocytes and the cumulus cells through the oviduct in correlation with cilia function in vivo, investigate the fluid dynamics, and further understand the interplay between cilia function and biomechanical environment.