Objective To construct HEK 293T cells that express tardigrade Dsup protein fused with green fluorescent protein copGFP in order to study the effect of Dsup protein on proliferation of HEK 293T cells.Methods The CRISPR/Cas9 gene knock-in system was constructed.The target gene fragments of Dsup,copGFP,EF1α and puromycin were amplified by PCR and inserted into pAAVS1-SFFV to construct the fusion vector of Dsup and copGFP,which was known as pAAVS1-SFFV-Dsup-copGFP-EF1α-Puro.pAAVS1-SFFV-Dsup-copGFP-EF1 α-Puro and pAAVS1-CRISPR-Cas9 vector were co-transfected into HEK 293T cells before Dsup gene was inserted into the AAVS1 region of HEK 293T cells via homologous recombination.The HEK 293T cells expressing Dsup gene were obtained following puromycin selection,flow cytometry sorting and genome identification.The expression of Dsup at mRNA and protein levels and proliferation-related genes(MCM2,MCM4,PCNA,Ki-67)were examined to investigate the effects of Dsup gene on the proliferation of HEK 293T-Dsup-copGFP cells.Results The pAAVS1-SFFV-Dsup-copGFP-EF1α-Puro recombinant vector was constructed,and the HEK 293T-Dsup-copGFP cells with Dsup gene inserted in the AAVS1 region were obtained,where both Dsup mRNA and protein were expressed.The cell proliferation rate of HEK 293T-Dsup-copGFP was higher than that of HEK 293T-Control-copGFP(P＜0.001).Further investigation revealed that the expressions of Ki-67 and MCM4 protein in HEK 293T-Dsup-copGFP were significantly higher than in the control group,indicating that the knock in of Dsup gene might enhance the proliferation ability of human cells by promoting the expression of Ki-67 and MCM4 protein.Conclusion A gene editing vector is constructed,and stable cell line HEK 293T-Dsup-copGFP for Dsup fusion expression with copGFP is established.The expression of Dsup gene in HEK 293T cells can promote cell proliferation,possibly by upregulating the expressions of Ki-67 and MCM4 protein.

OBJECTIVETo build a protocol of separation and induction of megakaryocytes derived from cord blood mononuclear cells.

METHODSRed blood cells were precipitated by hydroxyethyl starch (HES). Mononuclear cells were obtained by density gradient centrifugation with Ficoll. The inducing efficiencies of megakaryocytes by using of different cytokine cocktails and culture media were analyzed.

RESULTSThe best choice for erythrocyte sedimentation and high efficiency of nucleated cells retrieving were obtained by using of 1.5% HES. The isolated cord blood mononuclear cells were cultured with domestic serum-free medium supplemented with 116t (IL-11, IL-6, TPO), st36(SCF, TPO, IL-3, IL-6), pt36 (PDGF,TPO,IL-3,IL-6) or pst36 for 7 days. St36 group (50 ng/ml SCF, 50 ng/ml TPO, 20 ng/ml IL-3 and 50 ng/ml IL-6) yielded the most CD41/CD61 positive [(6.79±1.97)×10⁴]. The cell viability [(82.85 ± 0.64)%] of st36 group by using of imported serum-free medium was better than [(60.90±6.93)%] that in domestic medium on day 7 after induction, and CD41/CD61 positive cells count [(18.60±1.97)×10⁴] were more than domestic serum-free medium group. Therefore, we chose imported serum-free medium containing st36 to induce cord blood mononuclear cells. After a prolonged culture, the total cell numbers increased accompanied with an elevated percentage of CD41/CD61 positive cells, which reached (54.27 ± 6.31)% on day 14. Wright-Giemsa staining showed that different phase cells, such as megakaryoblast, promegakaryocyte and granular megakaryocyte, occurred after 10 days'culture. Clone forming unit-megakarocytes (CFU-MK) assay showed that the colonies count increased with the prolonged incubation. CFU-MK colonies were [1 236.0±32.9] on day 14, which was higher than that in medium without induction (P<0.01). Platelets from megakaryocytes showed agglutination function after 10 days'culture.

CONCLUSION1.5% HES was the best solution to precipitate erythrocytes. The combination of an imported serum-free medium with IL-3, IL-6, SCF and TPO showed better induction efficiency than domestic medium or other cytokine cocktails. Meanwhile, induced megakaryocytes produced functional platelets.

Cell Culture Techniques ; Cell Differentiation ; Cell Division ; Cell Separation ; methods ; Cells, Cultured ; Culture Media, Serum-Free ; Fetal Blood ; cytology ; Humans ; Megakaryocyte Progenitor Cells ; cytology