Postdoctoral Scholars of the Siebel Stem Cell Institute

Siebel Postdocs

Verena Charwat
Organ-on-a-chip systems are miniaturized in vitro cell culture models that recapitulate 3D tissue organization and function. I work with cardiac tissue models derived from human induced pluripotent stem cells. These microphysiological systems represent a structural and functional replicate of heart muscle tissue. Integrated sensors and genetically encoded reporters allow for in situ assessment of electrophysiology and biomechanics. I will use our cardiac microphysiological systems to investigate the pathological processes occurring during myocardial infarction (MI). In an initial phase (ischemia) of MI, cardiac muscle tissue is cut off from blood supply. Once the blood supply is re-established, further tissue damage occurs due to extensive oxidative stress (reperfusion). I aim to mimic the different aspects of ischemia-reperfusion injury and evaluate the contribution of each factor to overall tissue damage.

Hsin-Jung (Tiffany) Chou
Adult stem cells (SCs) play critical roles in tissue maintenance and regeneration following injury. Using mouse olfactory epithelium as a model, the Ngai lab has recently shown that upon severe injury, the normally quiescent neural SCs transition en masse into an activated state prior to self-renewal and differentiation. The transition is rapid and accompanied by dramatic changes in gene expression. My research aims to study the epigenetic regulatory mechanisms underlying the SC activation using deep sequencing techniques. Specifically, I will focus on mapping chromatin accessibility, histone modifications, and chromatin interactions in the SCs, in order to understand how chromatin structure and cis-regulatory elements contribute to the activation of adult SCs.

Johannes Schöneberg
I work at the exciting interface between stem cells, data science and advanced imaging. Together with the Drubin, Hockemeyer and Betzig labs, I differentiate stem cells into 3D organoids of brain and intestinal tissue, image them with the lattice light-sheet microscope and develop algorithms to segment the data.

Vlad Senatorov
Aging involves a decline in brain function that progresses slowly and eventually leads to cognitive impairment and disease. While the hallmarks of the aging brain are well known, the underlying biological mechanisms that trigger this transition from a “young-and-healthy” to “aged-and-dysfunctional” brain remain elusive. My work investigates dysfunction of the blood-brain barrier – the highly regulated interface between blood and the brain – as an early trigger of age-related pathology. By understanding the molecular and cellular changes that occur at the neurovascular unit, I seek to develop novel therapeutic approaches for age-related disease.

Bonnie Danqing Zhu
Adult neural stem cells (NSC) are an important class of therapeutically relevant cells that reside in a constantly dynamic microenvironment composed of diverse extrinsic signals. These external inputs can exert profound effects on cell behaviors including signaling, differentiation, and tissue function. Using optogenetics and micromirror device microscopy, I aim to investigate how NSC commitment to different lineages can be precisely controlled by spatiotemporal activation of Wnt/β-catenin signaling, particularly the effects of varying duration and subcellular location. These approaches can expand our knowledge in the proposed pathway, as well as other important signaling pathways (such as Rho GTPases, Notch, TGF-β, etc.) in other types of stem cells. The insights gained into stem cell biology and engineering tools will have significant implications for future stem cell-based therapies