Factors affecting hepatocyte viability and CYPIA1 activity during encapsulation

Area of Science:

• Biomaterials Science
• Hepatology
• Cell Encapsulation Technology

Background:

• Alginate-poly-1-lysine-alginate (APA) encapsulation is crucial for hepatocyte transplantation and bioartificial liver support systems.
• Significant loss of hepatocyte viability (20-30%) occurs during APA encapsulation, with limited data on its impact on cytochrome CYP450 activity.

Purpose of the Study:

• To investigate the detrimental effects of APA encapsulation on hepatocyte viability and CYP1A1 activity.
• To identify methods for mitigating these negative influences using specific reagents in the encapsulation solution.

Main Methods:

• Hepatocytes were encapsulated using alginate-poly-1-lysine-alginate (APA) with varying calcium chloride (CaCl2) and calcium lactate (CaLa) concentrations and temperatures.
• The impact of nifedipine, glutathione, taurine, Dulbecco's modified Eagle's medium, and fructose on cell viability and CYP1A1 activity was assessed.
• Cell death mechanisms (necrosis vs. apoptosis) were analyzed.

Main Results:

• Extracellular calcium toxicity, not mechanical damage, was the primary cause of reduced hepatocyte viability and CYP1A1 activity.
• Using 10 mM CaCl2 improved CYP1A1 activity but not viability or microcapsule quality compared to 100 mM.
• CaCl2 resulted in higher hepatocyte viability than CaLa, with lower temperatures benefiting CaLa more.
• Nifedipine, glutathione, and taurine demonstrated protective effects on hepatocyte survival and CYP1A1 activity in 100 mM CaCl2 solutions.

Conclusions:

• CaCl2 is preferable to CaLa for optimizing calcium use in APA encapsulation.
• Incorporating nifedipine, glutathione, or taurine into 100 mM CaCl2 solutions is recommended to enhance hepatocyte viability and CYP1A1 activity.