Fabrication of oxygen carrying microparticles functionalized with liver
ECM-proteins to improve phenotypic three-dimensional in vitro liver
assembly, function, and responses
Abstract
Oxygen and extracellular matrix (ECM)-derived biopolymers play vital
roles in regulating many cellular functions in both the healthy and
diseased liver. This study reveals the importance of synergistically
tuning the internal microenvironment to enhance oxygen availability
alongside phenotypic ECM ligand presentation to promote native metabolic
functions of human liver three-dimensional (3D) cell aggregates. First,
fluorinated (PFC) chitosan microparticles (MPs) were generated with a
microfluidic chip, then their oxygen transport properties were studied
using a custom ruthenium-based oxygen sensing approach. Next, to allow
for integrin engagements the surfaces of these MPs were functionalized
using liver ECM proteins including fibronectin, laminin-111,
laminin-511, and laminin-521. These MPs were used to assemble
heterogeneous composite spheroids composed of human hepatocytes and
human hepatic stellate cells. After in vitro culture,
liver-specific functions and cell adhesion patterns were compared
between groups and cells showed enhanced liver phenotypic responses in
response to laminin-511 and 521 as evidenced via enhanced E-cadherin and
vinculin expression as well as albumin and urea secretion. Furthermore,
hepatocytes and stellate cells arranged in more phenotypic arrangements
when cocultured with laminin-511 and 521 modified MPs providing clear
evidence that specific ECM proteins have distinctive roles in the
phenotypic regulation of liver cells in engineering 3D spheroids. This
study advances efforts to create more physiologically relevant organ
models allowing for well-defined conditions and phenotypic cell
signaling which together improve the relevance of 3D spheroid and
organoid models.