SUMMARY
As clinical trials have high failure rates, in part due to reliance on animal testing that can produce inaccurate
results, accurate in vitro models of human physiology and disease are needed to bridge this gap. Recent
progress in organoid and organ-on-chip systems demonstrates promising potential to do this; however, in vitro
models have their own limitations. Stem cell derived models tend to have immature phenotypes, primary cell
derived models may be difficult to keep functioning for long periods of time, and in vitro models in general do
not recapitulate the full functionality of human organs. In an effort to increase the physiological relevance of
these systems, we have developed a cardiovascular microfluidic organoid chip, the µCV chip, which develops
according to biomimetic morphogen gradients, and can self-assemble into elongated tube-like structures when
the cells are seeded in specific starting geometries with a robotic seeding machine. These pumping tube-like
structures can generate flow autonomously in our microfluidic chips. Although this preliminary data is
compelling, it remains to be tested whether these tube-like structures have cellular spatial organization or
heart-like functionality that is more physiologically accurate than simpler cardiac spheroids. In this proposal, we
aim to systematically compare cardiovascular spheroids and cardiovascular tube-shaped microfluidic
organoids in depth, in order to further understand how the organization and functionality of organoids change
when seeded with different starting geometries and exposed to different flow conditions, and test the
hypothesis that tube-shaped flow-generating cardiovascular organoids have microphysiology more similar to a
simplified human heart. We will further expand the repertoire of our microfluidic organoid chip by teaming up
with colleagues in the Division of Liver Diseases to create hepatic organoids, both iPSC derived and primary
cell derived, in order to similarly evaluate differences in hepatic function when the organoids are created with
spheroid versus tubular geometries and exposed to different flow conditions. Finally, we will combine these two
microfluidic organoid systems into a single microfluidic heart-liver microphysiologic system, the µCV-MPS, and
characterize the two organoids as they co-develop and function within a single circulatory system. As the liver
is responds to flow and beat rate, and the heart responds to factors secreted by the liver, we hypothesize that
we will observe improvements in functionality, viability, and microphysiology by studying heart and liver
organoids while they are connected via paracrine signaling and homeostatic regulatory mechanisms. We will
additionally use the µCV-MPS as a model of Nonalcoholic Fatty Liver Disease, which is known to lead to
cardiovascular disease including left ventricular hypertrophy and diastolic disfunction, pathologies which we
hypothesize to be observable inthe µCV-MPS. Validation of this model system would represent a significant
step forward in the sophistication and capabilities of human MPS models, helping to provide more predictive
alternatives to animal models for next-generation therapeutic development and regulatory approval.