Isolation and gene modification of amniotic fluid derived progenitor cells / 生物工程学报

We established methods to isolate human amniotic fluid-derived progenitor cells (hAFPCs), and analyze the ability of hAFPCs to secrete human coagulation factor IX (hFIX) after gene modification. The hAFPCs were manually isolated by selection for attachment to gelatin coated culture dish. hFIX cDNA was transfected into hAPFCs by using a lentiviral vector. The hFIX protein concentration and activity produced from hAFPCs were determined by enzyme-linked immunosorbent assay (ELISA) and clotting assay. The isolated spindle-shaped cells showed fibroblastoid morphology after three culture passages. The doubling time in culture was 39.05 hours. Immunocytochemistry staining of the fibroblast-like cells from amniotic fluid detected expression of stem cell markers such as SSEA4 and TRA1-60. Quantitative PCR analysis demonstrated the expression of NANOG, OCT4 and SOX2 mRNAs. Transfected hAFPCs could produce and secrete hFIX into the culture medium. The observed concentration of secreted hFIX was 20.37% +/- 2.77% two days after passage, with clotting activity of 16.42% +/- 1.78%. The amount of hFIX:Ag reached a plateau of 50.35% +/- 5.42%, with clotting activity 45.34% +/- 4.67%. In conclusion, this study established method to isolate and culture amniotic fluid progenitor cells. Transfected hAFPCs can produce hFIX at stable levels in vitro, and clotting activity increases with higher hFIX concentration. Genetically engineered hAFPC are a potential method for prenatal treatment of hemophilia B.

An Expedient Reliable Double Fluorescent Reporter System for φC31 Integrase Function Evaluation / 生物化学与生物物理进展

A reporter system for φC31 integrase was developed in NIH3T3 cells. The reporter plasmid coding green fluorescent protein (GFP) coupled with red fluorescent protein (RFP) was eo-transfected with the plasmid coding φC31 integrase, to show the activity of integrase in the cells. Fluorescence activated cell sorter (FACS) was used to measure the proportion of the cells containing red and green fluorescence. The increment of green cells was positively related to the increase in the transfection with plasmid coding φC31 integrase. Approximately 90% of green cells were observed under a ratio of [plasmid-φC31-integrase]/[reporter plasmid] at 10 : 1. This suggests that the φC31 integrase reporter system provides a probe for the function of φC31 integrase in cells.

Establishment and application of flow cytometry in detecting human cells in human/goat chimera models / 中华检验医学杂志

Objective To establish the methodology of flow cytometry for detecting human cells in human/goat chimerisra.Methods Human hemopoietic stem/progenitor cells (CD+34 cells) or MIG-tranadueed-GFP CD+34 cells were transplanted into the peritoneal cavity of fetal goats in utero to obtain human/goat chimera modeL The peripheral blood cells from the chimeras were labeled with multiple mouse anti-human antibodies and the monoelonal antibodies that were specific for human but had not or only minimal cross-reaction with goat were screened as the primary antibodies for routine analysis in flow cytometry.Human cord blood was proportionally (25% ,50% ,75%,100%) added into the blood of the untransplanted goats and the cells were labeled with CD+34 monoclonal antibody.The region and size of the "gate" were chosen based on to the distribution of CD+34 cells or human cord blood.One human/goat chimera marked with GFP (MIG goat) was sacrificed and the substantial liver cells from its perfused liver were analyzed for the GFP+cells percentage and DNA contents by flow cytometry.Results CD7,CD15,CD38,CD45CD20CD34CD14and GPA monoclonal antibodies were chosen as the primary antibodies in rou tine detection by flow cytometry.The size and area of the "gate" were also defined.29.1% (29100/100 000 ) of the substantial liver cells from the MIG goat expressed GFP.DNA content analysis showed that the GFP+ cells obtained from the liver of MIG goat mainly manifested two peaks that were correspond to those of human.Conclusions Flow cytometry is rapid,simple and effective for the investigation of differentiation,homing and biological characteristics of stem cells in vivo.The selections of suitable surface antibodies and the "gate" are very important for detecting human cells accurately in the human/goat chimerism.

An Expedient Reliable Double Fluorescent Reporter System for ?C31 Integrase Function Evaluation / 生物化学与生物物理进展

A reporter system for ?C31 integrase was developed in NIH3T3 cells.The reporter plasmid coding green fluorescent protein(GFP) coupled with red fluorescent protein(RFP) was co-transfected with the plasmid coding ?C31 integrase, to show the activity of integrase in the cells.Fluorescence activated cell sorter(FACS) was used to measure the proportion of the cells containing red and green fluorescence.The increment of green cells was positively related to the increase in the transfection with plasmid coding ?C31 integrase.Approximately 90% of green cells were observed under a ratio of plasmid-?C31-integrase/reporter plasmid at 10∶1.This suggests that the ?C31 integrase reporter system provides a probe for the function of ?C31 integrase in cells.

Analysis of the status of mouse fetal transgenic cells existed in the maternal peripheral blood / 中华检验医学杂志

Objective To study the status of mouse fetal transgenic cells existed in the maternal blood in peri-natal period and provide the information for gene diagnosis using fetal cells circulated in the maternal blood.Methods Mating the female normal mice with male transgenic mice integrated with GFP reporter gene driven by ?-globin promoter and HS2-HS3 elements of LCR. Around the offspring were born, maternal blood was collected and GFP expression level was determined with FACS analysis. Meanwhile, DNA extracted from the tails of the mothers and their offspring as well as the maternal blood were analyzed by PCR.Results GFP positive fetal cells were not found in maternal blood before offspring were born. 1-3 weeks later, GFP positive fetal cells were detected and this population in maternal peripheral blood reached the peak. 4-5 weeks later, they disappeared gradually. PCR results showed no GFP positive band in the mothers. However, a positive fragment of GFP gene was amplified in maternal blood samples after their offspring were born. This result was in accordance with FACS analysis.Conclusion Transgene cells may be useful markers for the study of status of fetal cells existed in the maternal circulating blood. The results would be beneficial for the gene diagnosis using maternal blood as an alternative resource of fetal cells.