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Objective To optimize conditions for hypothermic preservation of rat hepatocyte spheroids without freezing in order to facilitate the application of biological artificial liver. Methods Rat hepatic cells were isolated by a two-step perfusion method, and hepatocyte spheroids formed after 48 hours of rocking culture in serum free medium (SFM). Spheroids were then maintained in rocking culture at 37℃ (control condition), or cold stored at 4℃ for 24 or 48 hours in four different cold storage solutions: SFM alone; SFM+1mmol/L deferoxamine (Def ); SFM+1μmol/L cyclosporin A (CsA); and SFM+1mmol/L Def+1μmol/L CsA. After culturing for another 4 or 5 days, survival rate, changes in ultrastructure, and the production of albumin and urea were observed. Results Cold-induced injury could be reduced significantly by the addition of the iron chelators Def and CsA. The function and structure of hepatocyte spheroids stored in SFM+Def+CsA or SFM+Def for 24 hours were similar to those in control conditions. But the function was significantly reduced after hypothermic preservation in SFM alone. After cold storage for 48 hours, the ultrastructure of hepatocyte spheroids obviously changed and the number of dead cells increased. The survival rate of hepatocyte spheroids stored in SFM+Def+CsA or SFM+Def was significantly higher than that stored in SFM or SFM+CsA(P0.05). Conclusions Hepatocyte spheroids tolerate 24 hours of cold storage with stable viability and function. Hypothermic preservation increases the availability of cell-based therapy for liver diseases. DOI: 10.11855/j.issn.0577-7402.2014.12.02

Liver failure is a life-threatened serious disease with many complications and high mortality rate. Stem cells have been applied to replacement therapy, gene therapy and tissue engineering for its capacity of self-renewal and multi-lineage differentiation. To investigate the bioactivity of the peripheral blood hematopoietic stem cells (PBHSC) in patients with acute-on-chronic liver failure, we isolated CD34+ cells from peripheral blood of patients with acute-on-chronic liver failure and healthy controls. After cultured it in serum-free medium (SFEM), we studied the bioactivity of CD34+ cells by observing the morphology, recording growth curve, detecting cell cycle and cell apoptosis. CD34+ cells and culture solution were collected at the time points of 3, 5, 7, 10, 12 and 14 days, and the levels of hepatocyte growth factor (HGF), matrix metalloproteinase-9 (MMP-9), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in culture solution were detected by ELISA. Also, the expressions of pyruvate kinase muscle isoenzyme 2 (PKM2), integrin-β1 and liver-type pyruvate kinase (LPK) were detected by RT-PCR and immunofluorescence. Our results showed the bioactivity of CD34+ cells from patients with acute-on-chronic liver failure was identified to be similar with that from healthy controls. HGF, MMP-9, TNF-α and IL-6 were found in cell culture medium. RT-PCR and immunofluorescence results indicated that PKM2, Integrin-β1 expressed on CD34+ cells from patients with acute-on-chronic liver failure. In conclusion, bioactivity of CD34+ cells of patients with acute-on-chronic liver failure was demonstrated to be normal, which could secrete HGF, MMP-9, TNF-α and IL-6, promote the growth of hepatocytes, and differentiate along a direction to hepatocyte lineage.