Optimization of yeast autolysis under solid-state fermentation conditions / 生物工程学报

Yeast autolysis under solid-state fermentation can effectively promote the release of various active substances, thereby improving the quality of yeast products. The optimal process for yeast autolysis under solid-state fermentation was obtained by optimizing the autolysis temperature, autolysis time and the zinc ion concentration. We analyzed the indexes of free amino acid, soluble protein and α-amino nitrogen in the fermentation material, as well as A₂₆₀/A₂₈₀ ratio to determine yeast autolysis process conditions in the solid-state fermentation. On the basis of the obtained data, L₉ (3³) orthogonal test was designed to optimize the solid-state fermentation parameters for yeast autolysis: temperature at 40, 50 and 55 °C; time 12, 18 and 24 h; zinc ion concentration 2, 4 and 8 mg/kg. The optimum process conditions for yeast autolysis were: autolysis temperature 55 °C, time 18 h, zinc ion concentration 2 mg/kg, and soluble protein content reached 9.31 mg/g, free amino acid 14.36 mg/g, α-amino nitrogen 10.16 μg/g and A₂₆₀/A₂₈₀ 1.73. After optimization of the process, the soluble protein, free amino acid and α-amino nitrogen contents of the yeast autolysis production can be significantly increased, thereby obviously improving the quality of the composite culture.

Co-culture of adipose-derived stem cells and osteoblasts under different conditions / 中国组织工程研究

BACKGROUND:After co-culture with osteoblasts, bone marrow stem cells can be induced to differentiate into osteoblasts. Whether adipose-derived stem cells co-cultured with osteoblasts can differentiate into osteoblasts or not? OBJECTIVE:To observe whether adipose-derived stem cells co-cultured with osteoblasts can differentiate into osteoblasts. METHODS:Adipose-derived stem cells and osteoblasts were isolated from New Zealand white rabbits. Then, passage 3 adipose-derived stem cells were co-cultured with passage 2 osteoblasts in 10%or 5%fetal bovine serum for 14 days. RESULTS AND CONCLUSION:After 7 days of co-culture, some adipose-derived stem cells became round in the two groups. After 14 days of co-culture, adipose-derived stem cells highly differentiated and differentiated cells were similar to mature osteoblasts that were positive for alkaline phosphatase staining and alizarin red staining. The mRNA expression of type I col agen and osteocalcin increased in both two group, especial y in the 10%fetal bovine serum group. These findings indicate that adipose-derived stem cells co-cultured with osteoblasts can differentiate into osteoblasts induced by high-concentration serum culture.

Calcitonin gene-related peptide induces the osteogenic differentiation of adipose derived stem cells combined with calcium alginate gel / 中国组织工程研究

BACKGROUND:Calcitonin gene-related peptide has been confirmed to induce osteogenic differentiation, but whether it can induce the osteogenic differentiation of adipose-derived stem cells under three-dimensional culture to construct tissue-engineered bone is rarely reported. OBJECTIVE:To investigate the feasibility of exogenous calcitonin gene-related peptide to induce osteogenic differentiation of adipose-derived stem cells combined with calcium alginate gel in three-dimensional condition. METHODS:Adipose-derived stem cells were gained by col agenase I digestion of the subcutaneous adipose tissue of both inguinal regions of New Zealand rabbits. Passage 3 cells were mixed with sodium alginate to prepare calcium alginate gel, and then the cells were assigned into two groups and cultured in 24-wel plates. Adipose-derived stem cells in the control group were cultured in Dulbecco’s modified Eagle’s medium/Ham’s nutrient mixture F-12 supplemented with 10-2 mol/Lβ-glycerophosphate sodium, 10-7 mol/L dexamethasone, 50 mg/L ascorbic acid, 10%fetal bovine serum. While, adipose-derived stem cells in the experimental group were incubated with the same medium as above, but 1.5 μg/L calcitonin gene-related peptide was added. The cells proliferation and the mRNA expressions of col agen I and osteocalcin were detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and reverse transcription-PCR respectively, and alkaline phosphatase and calcium concentration were detected at different induction time. RESULTS AND CONCLUSION:The cellproliferation curves were S shaped. The absorbance values of the experimental group were higher than those of the control group at1, 3, 5, 7, 14, 21 days after osteogenic induction (P<0.05). Alkaline phosphatase and alizarin red staining of adipose-derived stem cells was al positive, but golden round nodes became more and bigger in the experimental group compared with the control group after 2 weeks. At 7 and 14 days, col agen I and osteocalcin mRNA expressions were higher in the experimental group than in the control group. Alkaline phosphatase activity and calcium concentration of the experimental group were higher than those of the control group at 1, 2, 3, 4 weeks after osteogenic induction (P<0.05). Results showed that the calcitonin gene-related peptide can induce the osteogenic differentiation of adipose-derived stem cells combined with calcium alginate gel.