OBJECTIVETo study the changes in the biological behavior of bone marrow mesenchymal stem cells (BMSCs) transfected with red fluorescent protein by lentivirus (RFP-BMSCs) seeded on in poly-D, L-lactide acid (PDLLA) scaffolds with bioactive modification by ammonia plasma and Gly-Arg-Gly-Asp-Ser (GRGDS) in vitro.

METHODSCircular sheets of PDLLA scaffolds (8 mm in diameter and 1 mm in thickness) were prepared and aminated with PDLLA (group A) or modified with the peptide conjugate A/PDLLA (group PA), with untreated PDLLA as the control (group P). The RFP-BMSCs were seeded on the scaffold materials and their proliferation and metabolic activity were detected using CyQuant NF and Alamar blue staining. The mineralization on the scaffolds was observed using calcein fluorescent dye under a fluorescent microscope. The adhesion and proliferation of RFP-BMSCs were observed by fluorescent microscope, and scanning electron microscope (SEM) was used to confirm the observed adhesion of the seed cells.

RESULTSThe RFP-BMSCs seeded on the 3 scaffolds all showed proliferative activity at different time points after cell seeding, and the cell numbers decreased significantly in the order of PA>A>P (P<0.001). The cell number was significantly greater in group PA than in group A at all the time points except for days 10 (P=0.077) and 12 (P=0.491), and gradually became similar with the passage of time. The metabolic changes of the cells follow a similar pattern of cell proliferation. RFP-BMSCs showed more active proliferation in group A and group PA than in group P. On days 14 and 21, the intensity of green fluorescence decreased in the order of group PA, A and P. The RFP-BMSCs showed better adhesion in group PA than in group A, and the cells in group P appeared more scattered under scanning electron microscope.

CONCLUSIONBioactive modification of PDLLA by ammonia treatment and conjugation with GRGDS peptides may promotes the adhesion, proliferation, metabolism and mineralization of RFP-BMSCs seeded on PDLLA scaffolds.