Modular assembly-based approach of loosely packing co-cultured hepatic tissue elements with endothelialization for liver tissue engineering.

ABSTRACT:

Background

In liver tissue engineering, co-culturing hepatocytes with typical non-parenchymal hepatic cells to form cell aggregates is available to mimic the in vivo microenvironment and promote cell biological functions. With a modular assembly approach, endothelialized hepatic cell aggregates can be packed for perfusion culture, which enables the construction of large-scale liver tissues. Since tightly packed aggregates tend to fuse with each other and block perfusion flows, a loosely packed mode was introduced in our study.

Methods

Using an oxygen-permeable polydimethylsiloxane (PDMS)-based microwell device, highly dense endothelialized hepatic cell aggregates were generated as hepatic tissue elements by co-culturing hepatocellular carcinoma (HepG2) cells, Swiss 3T3 cells, and human umbilical vein endothelial cells (HUVECs). The co-cultured aggregates were then harvested and applied in a PDMS-fabricated bioreactor for 10 days of perfusion culture. To maintain appropriate interstitial spaces for stable perfusion, biodegradable poly-L-lactic acid (PLLA) scaffold fibers were used and mixed with the aggregates, forming a loosely packed mode.

Results

In a microwell co-culture, Swiss 3T3 cells significantly contributed to the formation of hepatic cell aggregates. HUVECs developed a peripheral distribution in aggregates for endothelialization. In the perfusion culture, compared with pure HepG2 aggregates, HepG2/Swiss 3T3/HUVECs co-cultured aggregates exhibited a higher level of cell proliferation and liver-specific function expression (i.e., glucose consumption and albumin secretion). Under the loosely packed mode, co-cultured aggregates showed a characteristic histological morphology with cell migration and adhesion to fibers. The assembled hepatic tissue elements were obtained with 32% of in vivo cell density.

Conclusions

In a co-culture of HepG2, Swiss 3T3, and HUVECs, Swiss 3T3 cells were observed to be beneficial for the formation of endothelialized hepatic cell aggregates. Loosely packed aggregates enabled long-term perfusion culture with high viability and biological function. This study will guide us in constructing large-scale liver tissue models by way of aggregate-based modular assembly.

SUBMITTER: He J 

PROVIDER: S-EPMC7723527 | biostudies-literature | 2020 Nov

REPOSITORIES: biostudies-literature