A Preliminary Study On Acoustic Characteristics Of L-Selectin Guide Target Microbubbles

Objective:To explore the feasibility of L-Selectin guide targeted liposome contrast agents in the purpose of enhaning ultrasoud imaging of lymph node for detecting lymph metastatic as well as for its further use in clinic.Methods:1) Rabbit specific polyclonal antibody L-Selectin were attached on the surface of liposome microbubbles by the methods of electrostatic attraction,thus,the targeted liposome microbubbles of contrast agent were prepared.The combination of L-Selectin with liposome microbubble was confirmed by the immunofluorescent assay; And the combining rate of targeted microbubble were detected by using flow cytometric;The gray scales of B mode ultrasonogram in the group of saline, normal liposome contrast agent and L-selectin targeted liposome contrast agent were recorded and compared after experiment.2) Animal model of vulva carcinoma metastatic lymph nodes were established with five rabbits.L-selectin targeted liposome contrast agent and normal liposome contrast agent were injected into the rabbits model alternately after a interval for thirty minutes.The effects of TUCA enhancing lymph nodes visualization on ultrasonography were evaluated by using gray scale imaging mode and gray-scale video analysis.Results:1) L-S were combined on the surface of liposome microbubbles with electrostatic attraction and were confirmed by immunofluorescent assay.The average combination rate of TUCA in different concentration of antibody of 5ug/ml, 15ug/ml and 35ug/ml were 9.88±1.49%,29.59±2.23% and 86.66±4.71% respectively (P<0.01). The average gray scales in the group of saline,ultrasound contrast agent (UCA) and L-Selectin targeted ultrasound contrast agent (TUCA) were 16.64±3.86 dB,75.77±7.08dB and 73.72±8.19dB respectively(P<0.01).2)The contrast imaging of vulvar cancers inguinal lymph node metastasis of the five rabbits were analysed by video quantitative analysis.The average peak-gray scales of the lymph node in the group of targeted microbubble contrast agent were first injected was 97.18±8.38dB and was 83.12±2.81dB in that group of liposome contrast agent were next injected (P＜0.05). Well then the average peak-gray scales of the lymph node in the group of liposome contrast contrast agent were first injected was 80.27±3.56dB and was 92.36±9.45dB in that group of targeted microbubble contrast agent were next injected(P<0.05).Conclusion:High rate of L-Selectin targeted microbubbles were successfully prepared by the method of Electrostatic attraction.The combination rate was concerned with the concentration of antibodies.The L-Selectin targeted liposome contrast agent was observed have the ability of enhancing ultrasound imaging of the metastatic lymph nodes in rabbits and this showed TUCA possesse good characteristics of targeting and ultrasonograph for lymph nodes.