Treatment of adhesions after Achilles tendon injury using focused ultrasound with targeted bFGF plasmid-loaded cationic microbubbles

Abstract

Nonviral targeting technology has become promising as a form of gene therapy for diseases and injuries, such as Achilles tendon injuries. In this study, we used avidin–biotin bridge and positive–negative charge attractions to load the intercellular adhesion molecule-1 (ICAM-1) antibody and the basic fibroblast growth factor (bFGF) plasmid onto the surface of the microbubbles. The saturated loading capacity for 1.1 × 108 microbubble was 6.55 ± 0.53 µg. We established the ICAM-1 antigen microenvironment using tumor necrosis factor-alpha-stimulated human umbilical vein endothelial cells and found the targeting ability of the prepared microbubbles in vitro. In vivo, we also found that the injected targeted bFGF gene microbubbles expressed the bFGF gene better when compared with that of the control group. Furthermore, we evaluated adhesions after Achilles tendon injuries in rabbits using hematoxylin and eosin and immunohistochemical (IHC) staining methods. The collagen fibers were properly arranged in the tendon, and there was greater cellularity inside the tendon sheath and a clearer boundary between the internal and external tendon sheath than that of the control group. IHC staining showed greater ICAM-1 expression inside the tendon sheath when compared with outside the tendon sheath. In conclusion, targeted microbubbles can be a useful carrier of genes to provide gene therapy for the prevention of adhesions after tendon injury.

Keywords

• microbubbles
• icam-1
• bfgf
• tendon adhesion
• gene therapy