Cellularized biosynthetic microhydrogel polymers for intravascular liver tissue regeneration therapy.

INTRODUCTION

The liver is the natural microenvironment for hepatocytes transplantation but unfortunately engraftment efficiency is low. Cell-laden microhydrogels made of fibrinogen attached to poly(ethylene glycol) (PEG)-diacrylate side chains, were used as a cell carrier, for intravascular transplantation. This approach may reduce shear stress and immediate immunological pressure after intravascular transplantation and provide biomatrix for environmental support.

AIMS

In vitro assessment of HuH-7 viability and function after polymerization within PEGylated fibrinogen-hydrogel. In vivo assessment of intraportal transplantation of cell-laden microhydrogels with rat adult parenchymal cells.

METHODS

(1) In vitro assessment of HuH-7 cell viability and function, after cell-laden hydrogel (hydrogel volume 30 μL) fabrication, by propidium iodide (PI)/fluorescein diacetate (FDA), and MTT assays, albumin concentration and CYP1A activity. (2) Fabrication of cell-laden microhydrogels and their intraportal transplantion. Engraftment efficiency in vivo was evaluated by real-time qPCR of Y chromosome (SRY gene) and histology.

RESULTS

The viability of cells in hydrogels in culture was comparable to viability of not embedded cells during the first 48 h. However, the viability of cells in hydrogels was reduced after 72 h compared with not embedded cells. Activity of CYP1A in hydrogel was comparable to that of not embedded cells (4.33±1 pmole/μg DNA/4 h vs. 5.13±1 pmole/μg DNA/4 h, respectively). Albumin concentration increased at day 3 in hydrogels to 1.4±0.6 μg/10(4)/24 h and was greater to that of free cells, 0.3±0.1 μg/10(4)/24 h. Cell-laden microhydrogels at a size of 150-150-600 μm (6×10(6) cells/rat) showed better engraftment efficiency at 21 days post-transplantation, compared with isolated cell transplantation (54.6%±5% vs. 1.8%±1.2%, p<0.001).

CONCLUSIONS

The in vitro HuH-7 viability and function after polymerization in PEGylated fibrinogen hydrogel was comparable to cells without the hydrogel. Long-term survival and engraftment efficiency of intravascular transplanted adult hepatocytes is much better in within cell-laden microhydrogels compared with isolated cells. The overall efficiency of the procedure needs to be improved.