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The secondary injury caused by RBC autolysis after intracerebral hemorrhage (ICH) can be reduced by increasing the efficiency of microglia (MG)/macrophages (Mø) phagocytizing red blood cells (RBCs). CD47 is an important regulator of MG/Mø phagocytosis. This study aims to clarify whether anti-CD47 antibody administrated into the cisterna magna after ICH can transfer to the hematoma site, promote MG/Mø gathering to phagocytize RBCs and ultimately reduce cell death.Forty male Wistar rats were divided into sham, ICH, low-dosage (group A, 0.3 μg), medium-dosage (group B, 0.9 μg) and high-dosage (group C, 1.8 μg) anti-CD47 antibody groups. For the rats in group A, B and C, anti-CD47 antibody solution was administrated into the cisterna magna at 10 min after ICH. Brain tissue was harvested 3 days after the operation. Western blotting was performed to detect the expression of Caspase-3 and Bcl-2. Immunofluorescence was performed to detect the CD68 expression. TUNEL was performed to detect the cell death.The hematoma of the ICH rats was located in the basal ganglia, with a good homogeneity of hematoma volume. Low-dosage anti-CD47 antibody in group A had no effects on the perihematomal CD68 (P = 0.338), Caspase-3 (P = 0.769), Bcl-2 (P = 0.176) expression and cell death (P = 0.698), compared with the ICH group. CD68 and Bcl-2 expression increased and Caspase-3 expression decreased significantly in group B (P0.001 for all) and group C (P0.001 for all). The increase of CD68 expression in group C was greater than that in group B (P0.01) by a large margin, while there was no difference for Bcl-2 (P = 0.908) and Caspase-3 (P = 0.913) expression between the 2 groups. Compared with the ICH group, medium-dosage of anti-CD47 antibody in group B significantly reduced the number of TUNEL-positive cells (P0.005), but not for group C (P = 0.311).The results suggested that anti-CD47 antibody administration into the cisterna magna in proper dosage (0.9 μg) can effectively reach the hematoma, induce more MG/Møs to gather around the hematoma, and reduce cell death in perihematomal brain tissue. The results of this study has provided a basic theory for improving the efficiency of MG/Mø phagocytizing RBCs and hematoma clearance after ICH by administrating anti-CD47 antibody via the cisterna magna.

Objective Nuclear factor-κB (NF-κB) is a critical regulator of inflammatory responses after ICH, and different subunits may have different influences on the cell death and prognosis. The aim of the present study is to clarify whether the prognosis can be influenced by inhibiting NF-κB activation and subunits expression using PDTC at different stages after ICH. Methods Rats were divided into sham group, ICH group, early interference group and late interference group. At preset time points after ICH, the ipsilateral striatum and tissue around was obtained for detection of NF-κB activation, cell death, and expression of caspase-3, bcl-2, and NF-κB subunits, to evaluate of the effect of PDTC. Results NF-κB subunit p65 mainly expressed at the early stage after ICH, and c-Rel at the late stage. NF-κB activation can be inhibited at the early stage after ICH by administrating PDTC at 10 min, 1d and 2d after ICH, and at the late stage at 6d,7d and 8d. NF-κB activation inhibition at the early stage was due to p65, and c-Rel at the late stage. Inhibiting p65 expression at the early stage after ICH can reduce the apoptotic factor caspase-3 expression and cell death, and raise the antiapoptotic factor bcl-2. Meanwhile, inhibiting c-Rel expression at the late stage after ICH can lead to the opposite result. Conclusion Measures of inhibiting NF-κB subunits can be performed to influence the secondary brain damage and prognosis of ICH. We can also speculate that early inhibition of p65 expression and late promotion of c-Rel expression may be a more efficient method to improve the prognosis of ICH.