Production of recombinant human dipeptidyl peptidase IV from SF9 cells in microbial fermenters

The human dipeptidyl peptidase IV (hDPPIV/CD26) is expressed as an immune response in some cancer cells as well as intestine and incretin metabolism, and deficiency of the enzyme leads to metabolic disorders. In the present study, recombinant hDPPIV/CD26 genes were expressed in baculovirus–insect cell systems in a 5-L stirred-tank fermenter. Because of the shear sensitivity of the insect cell line, production from insect cells should be performed in new-generation type bioreactors, which are commonly more expensive than microbial fermenters. To optimize the process, hydrodynamic parameters and oxygen consumption of Sf9 cells at 1.5 L and 3 L were monitored, and a certain amount of serum was added to the production medium to decrease shear and stabilize the growth of insect cells that normally do not need serum addition. In this study, dimensionless numbers and some hydrodynamic parameters were calculated in 1.5 L, and predictions were made for 3 L fermenter volumes. Agitation rates of 60 rpm were determined to protect insect cells against damaging shear stress. Regarding the agitation rate, oxygen mass transfer coefficient (k L a) was 0.0129 min –1 for 1.5 L and was kept constant for 3 L (0.0133 min –1 ). The maximum enzyme activity from microbial fermenters was 2.37-fold higher than activity from T-flask in our previous work. The infection efficiency of transfected cells was 78%–81% in the 1.5-L and 3-L fermenters. © TÜBİTAK

Isolation and in vitro cultivation of human urine-derived cells: An alternative stem cell source

Objective: For in vitro tissue engineering in urology, stem cells are commonly isolated from tissue specimens obtained during open or endoscopic surgery. Within the context of the present study our aim was to isolate cells from human urine by an alternative and safe technique rather than using the indicated method. Material and methods: After human urine samples had been collected from young and healthy donors via urethral catheterization, cells were precipitated by centrifugation and cultured. Following this isolation procedure, cells were characterized by immunocytochemical method using specific antibodies. Results: When these cells were characterized by immunocytochemical methods using specific antibodies some of them were positive for mesenchymal stem cell marker CD90 while the others were labelled with urothelial marker cytokeratin 7. When all these results were taken into consideration, urothelial cells together with stem cells were observed in the urine- derived cell population. Conclusion: According to the results obtained from this study human urine may be preferred as an alternative stem cell and urothelial cell source in that this method is and easily reproducible non-invasive method. © 2017 by Turkish Association of Urology