Event Abstract

Stabilization of electrospun collagen scaffold for tympanic membrane perforations

  • 1 The University of Western Ontario, Biomedical Engineering Graduate Program, Canada
  • 2 The University of Western Ontario, Department of Chemical and Biochemical Engineering, Canada

Introduction: Tympanic membrane (TM) perforations or ruptured eardrum due to diseases and accidents are common and often require surgical treatment[1]. Current treatment using grafts suffer various limitations and none of these grafts has the microanatomy of the native TM to produce sound quality in the native eardrum. A normal TM includes two layers of orthogonally organized collagen nanofibers which play an essential role in sound transmission[2]. Thus, it is desirable to fabricate collagen-based scaffolds that can replicate the complex microanatomy to reproduce sound quality in the native TM. Among scaffold fabrication techniques, electrospinning allows fabrication of fibers with sub-micron diameter and possible alignments and assemblies of the fibers can mimic the local structure of native TM. The purpose of this study is to use the electrospinning technique to develop a collagen scaffold that mimics the natural tissue's microanatomy to guide new matrix deposition.

Materials and Methods: Electrospinning was carried out in a controlled environment chamber. Experimental parameters such as needle to collector distance, supplied voltage, and solution flow rate were adjusted to obtain fibers with desired morphology and sizes. Collagen solution was prepared by dissolving lyophilized collagen in 40v/v% acetic acid. Random fibers were collected on a stationary electrode while organized fibers were collected on rotating mandrel. Fibers were exposed to 365nm Ultra-violet (UV) light and 520nm green LED at various intensity and time interval for crosslinking. Genipin crosslinking was also carried out as previously established[3]. Aqueous stability of the fibers after crosslinking was tested by placing the samples in distilled water for various amount of time. Two layers of perpendicularly aligned fibers were collected using rotating mandrel to mimic the fiber orientation in TM.

Results and Discussion: By placing the as-spun fibers in water for 5 seconds, fibrous scaffold immediately gelled and lost fiber morphology (Fig. 1a). Whereas UV crosslinking, green LED crosslinking and genipin crosslinking enhanced the aqueous stability of the fibers (Fig. 1b-d).

Two-dimensional fast Fourier transform (2D FFT) was used to compare the degree of fiber alignment to the rat TM (Fig. 2a and 2b). Two distinct peaks offset by 90 degree indicate the orthogonal relationship between the two layers and these peaks match the fiber organization of the TM (Fig. 2c).

Conclusion: UV and green LED crosslinking, which include no chemical crosslinking reagents, demonstrate improved aqueous stability of fibers as genipin crosslinking. Two layered aligned fibers shows a close mimicry to the fiber organization in the native TM. With similar structure to the original TM, this scaffold can potentially direct cells to not only restore the integrity but also improve the sound quality recovered for TM perforation patients. 

Western Nanofabrication Facility, the University of Western Ontario; University Machine Services Shop, the University of Western Ontario; Western Physics and Astronomy Machine Shop, the University of Western Ontario; Ontario Research Fund; Ontario Graduate Scholarship; Canada Foundation for Innovation; Axcelon Biopolymers Corporation

References:
[1] O’Connor, K.N.; Tam, M.; Blevins, N.H.; Puria, S. Tympanic membrane collagen fibers: a key to high-frequency sound conduction. Laryngoscope. 2008, 118, 483–490
[2] Liu, J.; Ladak, H.M.; Agrawal, S.K.; Wan, W.K. Fiber arrangement in the rat tympanic membrane. In 36 th Annual Abstract Book of Association for Research in Otolaryngolog Annual Meeting Abstract. 2013, 36, 215-216
[3] Mekhail, M.; Wong, K.K.H.; Padavan, D.T.; Wu, Y.; O'Gorman, D.B.; Wan, W.K. Genipin-cross-linked electrospun collagen fibers. Journal of Biomaterials Science. 2010, 22, 2241-2259

Keywords: Tissue Engineering, Scaffold, Biocompatibility, Biodegradable material

Conference: 10th World Biomaterials Congress, Montréal, Canada, 17 May - 22 May, 2016.

Presentation Type: New Frontier Oral

Topic: Biomimetic materials

Citation: Li Y, Liu J and Wan W (2016). Stabilization of electrospun collagen scaffold for tympanic membrane perforations. Front. Bioeng. Biotechnol. Conference Abstract: 10th World Biomaterials Congress. doi: 10.3389/conf.FBIOE.2016.01.00332

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Received: 27 Mar 2016; Published Online: 30 Mar 2016.