DNA nanoscale coordination polymers promote the activity of bone marrow stem cells / 肿瘤

Objective:A DNA coordination polymer(Ca-pHis-Apt1 9S)was synthesized and its effect on the activity of bone marrow stem cells(BMSCs)was investigated. Methods:BMSCs were extracted from the epiphysis of the femoral shaft of mice by adherence screening method and identified by the expression of surface antigens through flow cytometry.Cell penetrating peptide pHis was covalently linked with the BMSCs aptamer Aptl9S,and a DNA coordination polymer(Ca-pHis-Aptl 9S),which was expected to improve the viability of BMSCs,was prepared through coordination assembly with calcium ions.BMSCs were treated with different concentrations of Ca-pHis-Apt1 9S,and the effects of Ca-pHis-Apt1 9S on the biological activities and the phenotype of BMSCs were evaluated by CCK-8 assay,live/dead cell staining assay and flow cytometry assay.The targeting ability of Ca-pHis-Apt1 9S toward BMSCs was observed using a fluorescence confocal microscope.Meanwhile,CCK-8 assay was used to study the main components of Ca-pHis-Aptl 9S that could promote the viability of BMSCs. Results:Spherical Ca-pHis-Apt1 9S with the particle size of 50-120 nm was successfully synthesized.The synthesized Ca-pHis-Apt1 9S could significantly promote the viability of BMSCs(P＜0.05)without affecting the apoptosis or the expression of surface antigens(CD29,CD44 and CD34).Confocal microscopy analysis showed that the BMSCs aptamer Apt19S could further enhance the cellular uptake of Ca-pHis-Apt1 9S by BMSCs.The results of CCK-8 assay revealed that pHis in Ca-pHis-Apt1 9S was the main component that could promote the viability of BMSCs,and this promotional effect was dose-dependent(P＜0.05). Conclusion:Ca-pHis-Aptl 9S can target BMSCs in vitro and significantly promote their biological activity without affecting their phenotype,providing a new method for the in vitro culture of BMSCs.

Model flavoproteins : Interaction of ribofIavin-5'-monophosphate with poly-( α –L-lysine) and poly-( α -L-histidine).

The interactions of flavin mononucleotide (riboflavin-5'-monophosphate) with two polypeptides, poly-(α-L-lysine) and poly-(α-L-histidine) in water and 0.05 Μ phosphate buffer were studied by measuring circular dichroism in the pH range 3 to 11. The interation of flavin mononucleotide with the two polypeptides was due to hydrophobic as well as ionic associations and was further influenced by the involvement of the ribityl side chain. The results of the present study have shown that small changes in the environmental conditions of the interacting molecules could modify their mode of interaction considerably.