[Effect on cochlea function by tissue-engineering ossicle prosthesis containing controlled release bone morphogenetic...

To prepare the tissue-engineering ossicle prosthesis which contained controlled release BMP-2 and implant into the acoustic bulla of guinea-pig, and observed the osteogenesis of the prosthesis in the bulla and the effect of the prosthesis on the cochlea.

The acellular bony microtubule filled with collagen containing BMP-2 as tissue-engineering prosthesis was implanted into the acoustic bulla of the guinea-pig through the retroauricular approach. The prosthesis without BMP-2 was implanted into the contralateral bulla as control. ABR of the animals was checked after surgery at different time to observe the variation of the hearing threshold. After 3 months, the osteogenesis of the prosthesis and its effect on the structure of bulla, cochlea and hair cells was observed by histological technique and silver nitrate staining method.

The animals were recovered soon after surgery. The hearing threshold of the animals [(15.5 +/- 2.8) dB SPL] were increased slightly just after the surgery [(28.3 +/- 4.8) dB SPL, P<0.05], and come back completely after 3 month [(16.1 +/- 4.0) dB, P>0.05]. The prosthesis was covered with mucosa finally while the bulla and cochlea were normal in shape. The osteogenesis was occurred at the inner side of the acellular bony tube. There wasn't any abnormal hyperplasia of bone in the bulla and cochlea. The articulation between the stapes and oval window wasn't merged. The shape of the hair cells were normal and there wasn't obvious deletion of the hair cells compared with control group.

The tissue-engineering ossicle prosthesis contained controlled release BMP-2 can induce osteogenesis in the bulla of the animals. This kind of material doesn't affect the shape of the bulla and the hearing threshold of the cochlea, moreover, they doesn't induce the abnormal hyperplasia of bone in the bulla and might be used to reconstruct the defects of ossicles.