Intraperitoneal transplantation of microencapsulated xenogeneic hepatocytes in totally hepatectomized rats

Controlled formation of heterotypic hepatic micro-organoids in anisotropic hydrogel microfibers for long-term preservation of liver-specific functions

We have developed a hydrogel-based cell cultivation platform for forming 3D restiform hepatic micro-organoids consisting of primary rat hepatocytes and feeder cells (Swiss 3T3 cells). Sodium alginate solutions containing hepatocytes/3T3 cells were continuously introduced into a microfluidic channel to produce cell-incorporating anisotropic Ba-alginate hydrogel microfibers, where hepatocytes at the center were closely sandwiched by 3T3 cells. Hydrogel fiber-based cultivation under high oxygen tension enabled the formation of heterotypic micro-organoids with a length of up to 1 mm and a diameter of ∼50 μm, mimicking the hepatic cord structures found in the liver, while maintaining a high hepatocyte viability (∼80%) over 30 days. Long-term observation of up to 90 days revealed a significant enhancement of hepatic functions because of heterotypic and homotypic cell-cell interactions, including albumin secretion and urea synthesis as well as expression of hepatocyte-specific genes, compared with conventional monolayer culture and single cultivation in the hydrogel fibers. The encapsulated hepatic constructs were recovered as scaffold-free micro-organoids by enzymatically digesting the hydrogel matrices using alginate lyase. This technique for creating heterotypic micro-organoids with precisely ordered multiple cell types will be useful for the development of a new liver tissue engineering approach and may be applicable to the fabrication of extracorporeal bioartificial liver (BAL) devices and assessment tools for drug development and testing.

Construction of IL-2 gene-modified human hepatocyte and its cultivation with microcarrier

AIM: To construct interleukin-2 gene-modified human hepatocyte line (L-02/IL-2) and investigate the changes of the function of liver cells and IL-2 secretion in culture with microcarrier, laying the foundation for further experimentation on hepatocyte transplantation.

METHODS: hIL-2 gene was transduced into L-02 hepatocytes by recombinant retroviral vector pLNCIL-2, and the changes of morphology and clonogeneicity rate of the transduced cells were observed, the secretion levels of hIL-2 in cultural supernatant were detected by ELISA and NeoR gene was amplified by PCR. The growth of L-02/IL-2, the special biochemistry items and the levels of IL-2 were detected after cultivation with microcarrier.

RESULTS: The clonogeneicity rate of the L-02/IL-2 cells was lower than that of L-02/Neo cells and L-02 cells. The levels of hIL-2 could reach 32000 pg/10⁶ cells per day and kept secreting for more than ten weeks. NeoR gene segment was respectively obtained by PCR from both L-02/IL-2 and L-02/Neo cell’s genomic DNA. At the 6^th day in culture with microcarrier, the matrix-induced liver cell aggregates were formed, the number of alive L-02/IL-2 cell were 16.8 ± 0.53 × 10⁶/flask and the levels of ALB and UREA were 52.54 ± 1.28 mg/L and 5.29 ± 0.17 mmol/L, respectively. These data had not significantly changed as compared with those of L-02 cells (P > 0.05); However, the levels of IL-2 in IL-2/L-02 cells remarkably exceeded that in L-02 cells in the whole culture process (P < 0.001).

CONCLUSION: The IL-2 gene-modified hepatocyte line has been successfully constructed. The L-02/IL-2 cellular aggregates cultured with microcarrier have a high capacity of IL-2 production as well as protein synthesis and amino acid metabolism.

Efficacy of double filtration plasmapheretic cross-circulation using a high permeability membrane between totally hepatectomized dogs and donor pigs

BACKGROUND

Major obstacles to develop a bioartificial liver are xenogeneic immune reactions and viral infection from donor pigs. To solve these problems, we studied the effect of xenogeneic double filtration plasmapheretic cross-circulation (DFPCC) using a high performance semipermeable membrane on totally hepatectomized dogs.

METHODS

Mongrel dogs, weighing 12-15 kg, underwent total hepatectomy in one stage (n=18). One hr after total hepatectomy, the femoral vein and the jugular vein were cannulated in both dogs and pigs by using the blood access catheter tubes that were connected to the DFPCC system. In the DFPCC circuit, filtrated dog plasma and pig plasma counterflowed in a hollow fiber cartilage at a rate of 25 ml/min for 6 hr and met through a semipermeable membrane with 100 kd nominal molecular weight cut-off (n=5). In control dogs, the circuit was not connected to the pig (n=13).

RESULTS

In vitro mass transfer study suggested that very little immunoglobulins crossed the semipermeable membrane. During and after 6 hr of DFPCC, anhepatic dogs had significantly lower blood ammonia and aromatic amino acid levels than did controls. DFPCC-treated dogs demonstrated decreased intracranial pressure and survived significantly longer than control dogs (20.75+/-3.80 hr vs. 14.75+/-1.30 hr, P<0.05). Histology showed no xenogeneic rejection in both dogs and pigs.

CONCLUSIONS

Our DFPCC systems with a high permeability membrane demonstrated detoxification-function and contributed to intracranial decompression and longer animal survivals without adverse immune reaction and the possibility of zoonosis.