ABSTRACT
BACKGROUND: Our research team has confirmed that compared to the adenoviral vector, transfection by lentiviral vector to rabbit bone marrow mesenchymal stem cells (BMSCs) is more effective that the expression of enhanced green fluorescent protein (EGFP)/bone morphogenetic protein 2 (BMP-2) can be persistent for a longer term. But further investigations are needed to explore whether BMSCs transfected with hBMP-2 through lentivirus combined with demineralized bone matrix (DBM) can promote bone defect repair. OBJECTIVE: To evaluate the effect of lentivirus-mediated hBMP-2/BMSCs/DBM (LV-hBMP-2/BMSCs/DBM) on the repair of large-segmental femoral defects and to explore the new treatments for large-segmental femoral defects. METHODS: Large-segmental bone defect models were made in the right femur of 48 New Zealand white rabbits by cutting the middle femoral bone and steel plate fixation. Then, animal models were randomly divided into four groups (n=12 per group) and implanted with nothing (control), DBM, hBMP-2/DBM, and LV-hBMP-2/BMSCs/DBM. Three rabbits from each group were sacrificed at 2, 4, 8 and 12 weeks after surgery to evaluate the repairing effect of femoral defects through hematoxylin-eosin staining, biomechanical analysis and radiological examination. RESULTS AND CONCLUSION: X-ray results revealed that osteotylus formed in all the four groups to different extents, and Lane - Sandhu X-ray scores were ranked as follows: control group < DBM group < hBMP-2/DBM group < LV-hBMP-2/BMSCs/DBM group (P < 0.05). Findings from the three-point bending test showed that the maximum load of the LV-hBMP-2/BMSCs/DBM group was significantly higher than that of the hBMP-2/DBM group, but is still lower than that of the normal femur at 8 and 12 weeks after modeling (P < 0.05). Hematoxylin-eosin staining results revealed that a few trabecular bones arranged disorderedly and a large amount of fibrous tissues in the control group; the DBM scaffold was basically degraded in the DBM group presenting with partially disordered trabecular bones and a large amount of fibrous tissues; the trabecular bones in the bone defect area were basically connected into line to start the shaping of the cortical bone, and recanalization of the medullary cavity was insignificant in the hBMP-2/DBM group; new cortical bone formed in the bone defect area and the medullary cavity was recanalized in the LV-hBMP-2/BMSCs/DBM group. These findings indicate that LV-hBMP-2/BMSCs/DBM can produce a large amount of calluses, promote formation of new cortical bone, and promote bone conduction, bone induction and osteogenesis after implantation into the bone defect; and this material has good repairing effect on large-segmental femoral defects of rabbits.
ABSTRACT
<p><b>OBJECTIVE</b>To investigate the effects of sinusoidal magnetic field on isolated sarcoplasmic reticulum (SR) calcium release channel (RyR1) function.</p><p><b>METHODS</b>With the Ca2+ dynamic spectrum and isotope labeled methods, the Ca2+ release and [(3)H]-Ryanodine binding, the initial rates of NADH oxidation and the production of superoxide of SR exposed to 50 Hz sinusoidal magnetic field (MF) were investigated respectively.</p><p><b>RESULTS</b>0.4 mT, 50 Hz sinusoidal MF exposure for 30 min increased SR Ca2+ release initial rate about 35% from (10.82 +/- 0.89) pmol.mg(-1) pro.s(-1) to (14.69 +/- 1.21) pmol.mg(-1) pro.s(-1); and the [(3)H]-Ryanodine binding by about 15% from (2.13 +/- 0.05) pmol/mg pro to (2.45 +/- 0.07) pmol/mg pro, which regulated by 1 mmol/L NADH with 1 mmol/L NAD+. Meanwhile MF upregulated the rate of NADH oxidation by about 22% from (0.88 +/- 0.11) x 10(-4) FI/s to (1.07 +/- 0.13) x 10(-4) FI/s and upregulated the production of superoxide by about 32% from (0.99 +/- 0.09) x 10(-5) FI/s to (1.31 +/- 0.06) x 10(-5) FI/s.</p><p><b>CONCLUSION</b>0.4 mT sinusoidal MF increases the activity of RyR1 within the low redox potential environment, and promotes NADH oxidase activity and superoxide production.</p>
Subject(s)
Animals , Rabbits , Calcium , Metabolism , Magnetic Fields , Ryanodine Receptor Calcium Release Channel , Metabolism , Sarcoplasmic Reticulum , Metabolism , Radiation EffectsABSTRACT
<p><b>OBJECTIVE</b>To investigate the effects of power frequency magnetic field on the Ca2+ transport dynamics of isolated sarcoplasmic reticulum vesicles.</p><p><b>METHODS</b>The assays of Ca2+ uptake time course and the Ca2+-ATPase activity of sarcoplasmic reticulum vesicles were investigated by using dynamic mode of spectrometry with a Ca2+ dye; Ca2+ release channel activation was examined by 3H-ryanodine binding and Ca2+ release assays; membrane fluidity of sarcoplasmic reticulum vesicles was examined by fluorescence polarization, without or with exposure to the vesicles at a 0.4 mT, 50 Hz sinusoidal magnetic field.</p><p><b>RESULTS</b>0.4 mT, 50 Hz sinusoidal magnetic field exposure caused about a 16% decline of the initial Ca2+ uptake rate from a (29.18 +/- 3.90) pmol.mg(-1).s(-1) to a (24.60 +/- 3.81) pmol.mg(-1).s(-1) and a 26% decline of the Ca2+-ATPase activity from (0.93 +/- 0.05) micromol.mg(-1).min(-1) to (0.69 +/- 0.07) micromol.mg(-1).min(-1) of sarcoplasmic reticulum vesicles, whereas caused a 15% increase of the initial Ca2+ release rate from (4.83 +/- 0.82) pmol.mg(-1).s(-1) to (5.65 +/- 0.43) pmol.mg(-1).s(-1) and a 5% increase in 3H-ryanodine binding to the receptor from (1.10 +/- 0.12) pmol/mg to (1.16 +/- 0.13) pmol/mg, respectively.</p><p><b>CONCLUSION</b>The decline of Ca2+-ATPase activity and the increase of Ca2+ release channel activity should result in a down-regulation of Ca2+ dynamic uptake and an up-regulation of Ca2+ release induced by exposing the sarcoplasmic reticulum to a 0.4 mT, 50 Hz power frequency magnetic field.</p>