According to an article published in the May 7, 2015 edition of IOP Science’s journal Biofabrication, a team of researchers from several universities in Europe have created tiny, complex scaffolds that replicate the intricate network of collagen fibers that form the human eardrum. The researchers hope that these scaffolds can be used to replace eardrums when they become severely damaged, reducing the need for patients to have their own tissue used in reconstruction surgery.
As explained in the article, the eardrum, or tympanic membrane (TM), is a thin, flexible membrane that separates the external ear from the middle ear. The eardrum is composed of collagen fibers that are precisely aligned in a complex network to enable sound waves to be transmitted to the ear ossicles — three tiny bones in the ear.
It is quite common for the eardrum to become perforated through infection or physical damage, which can lead to temporary hearing loss. Most minor damage to the eardrum can heal on its own; however, more severe damage requires a type of surgery to repair the eardrum known as myringoplasty.
Over the years, researchers have investigated several different techniques to repair or replace the eardrum using a patient’s own tissue (an autograft) or tissue taken from a donor (a homograft), but the optimal replacement has yet to be found, say the study authors. In this study, the researchers explored a tissue engineering approach whereby they created polymer scaffolds on which cells could be grown. The scaffolds were reportedly composed of two copolymers that are FDA-approved for biomedical use.
The eardrum scaffolds were built using two different approaches. According to the article, for the first approach the scaffolds were created by electrospinning (ES) in which fine fibers of polylactic-co-glycolic acid (PLGA) were drawn out from a liquid using an electrical charge to create a one dimensional structure. For the second approach, ES was combined with 3D printing to manufacture 2D and 3D structures from polyethylene oxide terephthalate/polybutylene terephthalate (PEOT/PBT) with radial and circular patterns.
The sizes of the scaffolds created were comparable to that of a human eardrum. Once created, a preliminary biological study was conducted by culturing human mesenchymal stromal cells (MSCs) onto the scaffolds to test how cells could grow and then survive on the structures. According to the study authors, the cells were viable when grown on all of the scaffolds, with particularly good results seen on the 3D scaffold.
“Since the eardrum is a unique tissue in the human body, traditional replacements are usually autografts that have come from other tissues which do not have specific structural similarity with the eardrum,” said study co-author Serena Danti, PhD, from the University of Pisa. “Consequently, their acoustic performances are not optimal. The eardrum has a complex structure with collagen fibers arranged precisely to interact with sound waves. We have replicated this structure in our scaffolds by combining electrospinning with 3D fiber deposition, and we believe this will eventually allow for replacements that are anatomically and acoustically similar to the [natural] eardrum.”
Source: IOP Publishing / IOP Science
Journal Reference: Carlos Mota, Serena Danti, Delfo D’Alessandro, Luisa Trombi, Claudio Ricci, Dario Puppi, Dinuccio Dinucci, Mario Milazzo, Cesare Stefanini, Federica Chiellini, Lorenzo Moroni, Stefano Berrettini. Multiscale fabrication of biomimetic scaffolds for tympanic membrane tissue engineering. Biofabrication, 2015; 7 (2): 025005 DOI: 10.1088/1758-5090/7/2/025005