Macromolecular organization and fine structure of the human basilar membrane - RELEVANCE for cochlear implantation

Wei Liu, Francesca Atturo, Robair Aldaya, Peter Santi, Sebahattin Cureoglu, Sabrina Obwegeser, Rudolf Glueckert, Kristian Pfaller, Annelies Schrott-Fischer, Helge Rask-Andersen

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

Results: The human BM consisted in four separate layers: (1) epithelial basement membrane positive for laminin-β2 and collagen IV, (2) BM “proper” composed of radial fibers expressing collagen II and XI, (3) layer of collagen IV and (4) tympanic covering layer (TCL) expressing collagen IV, fibronectin and integrin. BM thickness varied both radially and longitudinally (mean 0.55–1.16 μm). BM was thinnest near the OHC region and laterally.

Introduction: Cochlear micromechanics and frequency tuning depend on the macromolecular organization of the basilar membrane (BM), which is still unclear in man. Novel techniques in cochlear implantation (CI) motivate further analyses of the BM.

Materials and methods: Normal cochleae from patients undergoing removal of life-threatening petro-clival meningioma and an autopsy specimen from a normal human were used. Laser-confocal microscopy, high resolution scanning (SEM) and transmission electron microscopy (TEM) were carried out in combination. In addition, one human temporal bone was decellularized and investigated by SEM.

Conclusions: There are several important similarities and differences between the morphology of the BM in humans and animals. Unlike in animals, it does not contain a distinct pars tecta (arcuate) and pectinata. Its width increases and thickness decreases as it travels apically in the cochlea. Findings show that the human BM is thinnest and probably most vibration-sensitive at the outer pillar feet/Deiter cells at the OHCs. The inner pillar and IHCs seem situated on a fairly rigid part of the BM. The gradient design of the BM suggests that its vulnerability increases apical wards when performing hearing preservation CI surgery.

Original languageEnglish (US)
Pages (from-to)245-262
Number of pages18
JournalCell and Tissue Research
Volume360
Issue number2
DOIs
StatePublished - May 1 2015

Bibliographical note

Funding Information:
This study was supported by ALF grants from Uppsala University Hospital and Uppsala University and by the Foundation of “Tysta Skolan”, Swedish Deafness Foundation (HRF). Our research is part of the European Community 7th Framework Programme on Research, Technological Development and Demonstration. Project acronym: NANOCI. Grant agreement no: 281,056 and kind private funds from Börje Runögård. Funding for the decellularized temporal bone was provided by NIDCD grant U24 DC011968.

Publisher Copyright:
© 2015, The Author(s).

Keywords

  • Basilar membrane
  • Cochlear implant
  • Collagen II
  • Human
  • Ultrastructure

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