ObjectiveBased on the rat in situ perfusion system, to explore the effect of up-regulating Chemokine (C-X-C motif) receptor 4 (CXCR4) expression on bone marrow neutrophils in modulating its ECC-related rapid release. MethodsTwelve SD rats were randomly divided into fucoidan perfusion group (F, n=6) and control group (C, n=6) after in situ perfusion system establishment. Rats in F group received perfusion of fucoidan solution (total volume 6 ml, 1 h) and C group received buffer only. Femurs from two groups were dissected after one-hour perfusion and bone marrow tissues were collected. The neutrophil CXCR4 expression in two groups were compared using flowcytometry. Eighteen SD rats were randomly divided into fucoidan perfusion group (F', n=6), fucoidan and AMD-3100 perfusion group (F+AMD3100, n=6) and control group (C', n=6) after in situ perfusion system establishment. Rats received desired interventions before stimulation from ECC plasma. After that, 40-min perfusions of buffer were added and total counts of neutrophil in perfusates were compared. ResultsThe percentages of CXCR4 (+) cell and CXCR4 expression fluorescence in F group were 4.71%±0.21% and 161.3±7.8 respectively while the values were 1.11%±0.11% and 58.4±6.5 respectively in C group. Values in F group were both significantly higher than those in C group (P<0.05). The total counts of neutrophil in perfusates from F' group, F+AMD3100 and C' group were 261 393.7±12 470.6, 872 635.2±10 430.6 and 818 675.2±10 708.8, respectively. Statistically differences were observed between each other (P<0.05). ConclusionBone marrow neutrophil CXCR4 expression of SD rat could be effectively up-regulated by perfusion of fucoidan within the in situ perfusion system. ECC-plasma-stimulated bone marrow neutrophil release in rat could be inhibited by fucoidan induced up-regulation of neutrophil CXCR4 expression, and this inhibition effect could be canceled by AMD-3100 intervention.
ObjectiveTo evaluate the efficacy and reversible effect of anti-VCAM-1 ultrasound-targeted microbubbles on extracorporeal circulation (ECC) related bone marrow neutrophil releasing. MethodsThirty-six male SD rats were randomly divided into 6 groups with 6 rats in each group, including an antibody group (group A), antibody with ultrasound group (group AU), targeted microbubble group (group T), targeted microbubble rupture group (group TU), post-ECC plasma simulation group (group MC) and control group (group C) after in situ perfusion model establishment. Rats in group C received buffer perfusion for 4 cycles, and rats in other groups received perfusion for 5 cycles. After buffer perfusion for the first cycle, post-ECC plasma was infused to each group from the second cycle to the fifth cycle in group MC, A, AU, T and TU. Rats in group A and AU received injection with anti-VCAM-1 antibodies, while rats in group T and TU were given anti-VCAM-1 targeted microbubbles after the second perfusion cycle. Same ultrasound radiation was given to group AU and TU in the third perfusion cycle. Neutrophil counts from perfusate were compared among the 6 groups. ResultsUnder simulated inflammatory condition after ECC, compared with group MC, significant reduction of neutrophil count released from bone marrow was found in group A and T, especially in group T (P < 0.05). After ultrasonic radiation, neutrophil mobilization recovered in group TU and its neutrophil count was significantly higher than that of group T (P < 0.05). There was no significant difference in neutrophil count between group A and AU in each perfusion cycle (P > 0.05). ConclusionsAnti-VCAM-1 targeted microbubbles can block the binding of VCAM-1 and its ligand, and form a barrier on the surface of bone marrow sinusoids endothelium to inhibit neutrophils migrating and releasing. The binding of VCAM-1 and its ligand on microbubbles is separated by cavitation of disrupting microbubbles with ultrasound, and neutrophils recover the ability to cross the sinusoidal endothelium of bone marrow in inflammatory conditions to achieve the controllability of neutrophil releasing.