BACKGROUND: The precartilaginous stern cells are limited regarding in vitro proliferative capacity, but the immortalized cell lines can provide a large number of stable immortalized cells, and simian virus 40 large T antigen gene (SV40Tag) is one of gene fragments which are commonly used and effective in vitro immortalized ceils. OBJECTIVE: To construct human immortalized precartilaginous stem cells (IPSCs) using human precartilaginous stem calls induced by SV40LTAg gane. METHODS: The human immortalized precartilaginous stem calls were isolated from aborted fetus and purified with enzyme digestion and immunomagnetic beads screening method. By using liposome-mediated gene transfection technology, plasmid pCMVSV40T/PUR containing SV40Tag was transfected in primary embryonic precartilaginous stem cells, while non-transfected cells sewed as negative controls. Positive clones were cultured to observe the cell morphology and the passage recovery, to calculate cell survival rata and population doubling time, to drew call growth curve. Immunofluorescence cytochemistry was used to detect the expression of IPSCs fibroblast growth factor receptor 3, the expressions of SV40Tag and fibroblast growth factor receptor 3 in the human precartilaginous stem cells were determined by RT-PCR. RESULTS AND CONCLUSION: Morphology of human IPSCs seemed coincidence with primary human precartilaginous stem cells. The survival rate of human IPSCs was not influenced by subculture, freezing and recovery, but the survival rate was descended in the human precartilaginous stem cells at the 6~(th) and 10~(th) passages (P < 0.01). Compared with cells at the 6~(th) and 10~(th) passages, the proliferation of human IPSCs was greater, with short population doubling time and high growth rate (P < 0.01). The immunofluorescence showed that fibroblast growth factor receptor 3 was positive in human IPSCs at the second passage, and the RT-PCR results of fibroblast growth factor receptor 3 revealed a specific amplification band at 400 bp,.while that of SV40Tag revealed at 560 bp. No band was seen in the primary cells. It is indicated that SV40Tag human IPSCs can be constructed successfully using immunomagnatic bead screening technology and liposome transfection technique.

Objective To study the biological effects of pulsed electromagnetic fields (PEMFs) on the pro-liferation of immunomagnetically separated human precartilaginous stem cells (PSCs) in vitro. Methods The cells from an aborted fetus's metaphysis were digested using collagenase. The PSCs were isolated by magnetic cell sorting (MACS), then subcultured and amplified. Flow cytometry, immunohistochemistry, immunofluorescence and RT-PCR analysis were performed to identify the purified PSCs. The PSCs were stimulated by PEMFs at 50 Hz frequency and 1 mT intensity. Cell proliferation was measured at different time points using methyl thiazolyl tetrazolium ( MTT), and the cell growth curve was plotted. Flow cytometry was applied to measure the cell cycle and apoptosis. Results The PSCs were successfully cultured. There was fibroblast growth factor receptor-3 (FGFR-3) on their sur-face. Cell proliferation was promoted after 4 and 6 days of PEMF stimulation. The percentage of cells at the S phase was higher than in a control group. Early, late and total rates of apoptosis in the experimental group decreased signifi-cantly. Conclusion PEMFs can enhance the proliferation and inhibit the apoptosis of human PSCs, and it is possi-ble to cultivate the high density human PSCs in vitro.

BACKGROUND:For the patients with proximal humeral fractures or serious complications, internal fixation is the effective method that cannot influence the activity of the shoulder with few trauma. OBJECTIVE:To investigate the biomechanical characteristics of percutaneous plate combined with anatomical locking plate fixation for the treatment of proximal humeral fractures. METHODS:Seventy-five patients with proximal humeral fractures were selected from Department of Orthopedics, the Third Affiliated Hospital of Guangzhou Medical University between March 2007 and December 2011. The healing after the locking plate fixation and the shoulder joint score after internal fixation were observed. The biomechanical advantages of locking plate fixation in the treatment of proximal humeral fractures were analyzed. RESUTLS AND CONCLUSION:Al the 75 patients were fol owed up for 6-24 months, average 13.3 months. The X-ray film after treatment showed al the screws were in correct position with satisfactory fracture reduction, and the fractures were healed without neurovascular injury and humeral head necrosis;one case had infection and healed after treatment, 72 cases had no shoulder pain, while three cases had occasional shoulder pain. The Neer score was excel ent in 57 cases, good in 11 cases, moderate in seven cases and poor in none, and the excel ent and good rate was 90.7%. Compared with other fixation implants, the locking plate fixation in the treatment of proximal humeral fractures has the advantages of high fixation strength and satisfactory effect, becoming the first choice for the clinical treatment of proximal humeral fractures.

Animals ; B7-H1 Antigen ; immunology ; Cell Line, Tumor ; Gene Expression Regulation, Neoplastic ; immunology ; Humans ; Interferons ; immunology ; Mice ; Neoplasm Proteins ; immunology ; Neoplasms ; immunology ; Up-Regulation ; immunology