Effect Of Low-Frequency Ultrasound-Enhanced Fibrinolysis In Intracerebral Hematoma: A Porcine Model Experiment

Objective To observe the different effect of fibrinolysis, histopathological changes, ultrastructural changes, and the apoptotic cell rate by low-frequency ultrasound (LFUS) united with albumin microbubble(MB) and/or urokinase(UK) in intracerebral hematomas in porcines, and to evaluate its efficacy and safety of enhanced fibrinolysis. To provide experimental and theoretical basis for LFUS therapy of intracerebral hemorrhage(ICH). Methods A total of 24 pigs with intracerebral hematoma by double injection of autologous blood were divided randomly into 4 groups (n=6 in each group). Different treatment were carried out 6 hours after hematoma created. In treatment groupⅠ(TGⅠ): clots were lyseed with LFUS+UK+MB; In treatment groupⅡ(TGⅡ): hematomas were treated with LFUS+UK; In treatment groupⅢ(TGⅢ): hematomas were treated with UK alone; Control group(Con): with saline injection. In all the 4 groups, clots were aspirated after the treatment. pigs were sacrificed at 24 hours after the establishment of the model, and brains were fixed by formaldehyde. The residual hematoma volumes were determined on coronal sections using computer-assisted morphometry. Histopathological and ultrastructural changes of perihematoma were observed under light microscope and electron microscope. Terminal-deoxynucleotidyl transferase mediated d-UTP nick end labeling(TUNEL) staining was used to examine the apoptotic cell rate in perihematomal brain tissure. Results The residual hematoma volumes of the treatment groups were decreased significantly than that of the control group(P<0.01).The residual hematoma volumes of treatment groupⅠand Ⅱwere decreased significantly than that of the treatment groupⅢ(P<0.05). but there was no difference between the former two groups(P>0.05). Light microscopic examination demonstrated that the degree of perihematoma edema is similar. Under the electron microscope, no significant difference of ultrastructural changes of perihematoma were found among 4 groups. It's found that mitochondrion swelling and endoplasmic reticulum swelling were main pathological manifestantons of perihematoma; the structure of myelinated nerve fiber and blood-brain barrier were normal. The apoptotic cell rates of perihematoma were (30.21±2.83)%, (28.60±3.26)%, (27.86±2.62)% and (27.12±3.14)% in TGⅠ, TGⅡ, TGⅢ and Con respectively, and there were no difference among 4 groups. Conclusion (1)LFUS could enhance enzymatic fibrinolysis through the skull, and quicken intracerebral hematoma to liquidize in porcines. (2)MB have no significant effect on enzymatic fibrinolysis united with LFUS, but have a trend of fragmentating hematoma and enhancing fibrinolysis.(3)LFUS(2.0W/cm2)have no side-effect according to the result from histopathological changes, ultrastructural changes and the apoptotic cell rate. So it is an effective and safe method for the treatmentof intracerebral hemorrhage.