In vitro promotion of SDF-1α on the migration and proliferation of C-kit+ cardiac stem cells in neonatal mice.

The aim of this study was to explore the In Vitro effects of stromal-derived factor-1α (SDF-1α) on the migration and proliferation of c-kit+ cardiac stem cells. The lentivirus containing SDF-1α (LV-SDF-1α) was constructed. Primary myocardial fibroblasts were transfected by LV-SDF-1α, followed by primary culture of cardiac tissue cells and separation of c-kit+ cardiac stem cells with a flow cytometer, in order to investigate the effects of SDF-1α on the migration and proliferation of c-kit+ cardiac stem cells using cell co-culture, immunofluorescence and EdU tracing technologies. The results showed that myocardial fibroblasts could secrete SDF-1α after the transfection with LV-SDF-1α. High-purity c-kit+ cardiac stem cells were obtained through flow cytometry sorting and the positive rate was about 40%. The c-kit+ cardiac stem cells cultured In Vitro could be differentiated into cTnT positive cardiomyocyte-like cells. After co-culture of myocardial fibroblasts and c-kit+ cardiac stem cells transfected with lentivirus, SDF-1α might increase the migration of c-kit+ cardiac stem cells, but SDF-1α did not promote the proliferation of c-kit+ cardiac stem cells. In conclusion, the myocardial fibroblasts transfected with lentivirus can highly express SDF-1α, c-kit+ cardiac stem cells can be differentiated into cTnT positive cardiomyocyte-like cells and SDF-1α can effectively enhance the migration of c-kit+ cardiac stem cells but fails to stimulate the proliferation.

Identification of a peptide that crosses the blood-cerebrospinal fluid barrier by phage display technology.

Treatments of brain diseases are heavily limited by the existence of the blood-brain barrier (BBB), which precludes efficient drug delivery to the brain. Compared with the BBB, drugs may have a better likelihood of reaching the brain via the cerebrospinal fluid (CSF) because of the lack of a barrier between the CSF and the brain. In this study, phage display technology was effectively applied to screen novel peptides as targeting motifs to transport drugs across the blood-cerebrospinal fluid barrier (BCSFB). We applied a phage seven-mer cyclic peptide library (Ph.D.-C7C™) intravenously to rats and later recovered phages from the CSF. After several rounds of screening, the candidate phages that could cross the BCSFB were enriched. Several bacteriophage clones from the final round were randomly selected and sequenced. A peptide sequence denoted as PMK, which was demonstrated to be able to cross the BCSFB via in vivo optical imaging analysis, could be used in the future for the construction of targeted drug delivery systems.

A lactate-induced Snail/STAT3 pathway drives GPR81 expression in lung cancer cells.

Highly expressed G protein-coupled receptor 81 (GPR81), a receptor for lactate, is emerging as a critical regulator of tumor growth and metastasis. However, the mechanistic basis for its highly expression in cancer cells remains elusive. Here we report that tumor-derived lactate transcriptionally regulates GPR81 expression. We demonstrated that the transcriptional response of GPR81 to lactate is mediated by Signal transducer and activator of transcription 3 (STAT3). Mechanistically, lactate upregulates transcriptional factor Snail and induces the assembly of Snail/EZH2/STAT3 complex. Within this ternary complex, STAT3 activity is strongly enhanced. Consequently, the activated STAT3 by lactate directly binds GPR81promoter and activates its expression. These findings shed light on the transcriptional mechanism by which GPR81 expression is regulated in cancer cells, and provides mechanistic insight into how aberrant signaling and continually high lactate levels due to metabolic switch may yield a feed-forward/self-enabling loop to promote tumor progression.

SDF-1α promotes repair of myocardial ischemic necrosis zones in rats.

OBJECTIVE: To explore the repair effect of stromal cell-derived factor-1α (SDF-1α) on myocardial ischemic necrosis zones. METHODS: Lentivirus (LV-SDF-1α-GFP) containing SDF-1α target gene was established, the separated and cultured neonatal rat cardiac fibroblasts were transfected, and caudal intravenous injection of isoproterenol was conducted to prepare a rat model of myocardial ischemia. Small animal ultrasound was used to evaluate the effect on cardiac functions. Morphology and immunofluorescence were used to observe the change of ischemic necrosis zones and expressions of stem cellular markers c-kit, CD34, nkx2.5, and nanog, and a quantitative analysis was performed. RESULTS: The established LV-SDF-1α-GFP was used to transfect myocardial fibroblasts which presented GFP green fluorescent expression and could secrete SDF-1α. The small animal ultrasound system showed that rat cardiac functions of the lentivirus group and cell group were improved to different degrees, myocardial ischemic necrosis zones of lentivirus group and cell group were reduced, and differences had statistical significances (P<0.05). Immunofluorescence showed that expressions of stem cellular markers c-kit, CD34, nkx2.5 and nanog in myocardial tissue ischemic zones in both the lentivirus group and cell group increased, and differences through inter-group comparison had statistical significances (P<0.05). CONCLUSION: SDF-1α can promote migration and proliferation of stem cells into the myocardial ischemic necrosis zone, participate in repair of the myocardial necrosis zone, and improve cardiac function.