The Tissue-Engineered Auricle: Past, Present, and Future

Abstract

The reconstruction, repair, and regeneration of the external auricular framework continue to be one of the greatest challenges in the field of tissue engineering. To replace like with like, we should emulate the native structure and composition of auricular cartilage by combining a suitable chondrogenic cell source with an appropriate scaffold under optimal in vitro and in vivo conditions. Due to the fact that a suitable and reliable substitute for auricular cartilage has yet to be engineered, hand-carved autologous costal cartilage grafts and ear-shaped porous polyethylene implants are the current treatment modalities for auricular reconstruction. However, over the last decade, significant advances have been made in the field of regenerative medicine and tissue engineering. A variety of scaffolds and innovative approaches have been investigated as alternatives to using autologous carved costal cartilage or porous polyethylene implants. A review of recent developments and the current state of the art and science is presented, focusing on scaffolds, cell sources, seeding densities, and mechanical characteristics of tissue-engineered auricular cartilage.

Novel bilayer bacterial nanocellulose scaffold supports neocartilage formation in vitro and in vivo

“…For such cases, the field of tissue engineering (TE) provides a promising potential alternative therapy to the conventional and complex surgical reconstruction of auricular cartilage by using ear-shaped autologous costal and nasoseptal cartilage [1][2][3]. Bacterial nanocellulose (BNC), a novel biomaterial with excellent biocompatibility and remarkable tissue integration capability [4][5][6][7][8], has been evaluated for several TE strategies and has shown to support adhesion, proliferation and differentiation of different cell types [9][10][11][12][13][14][15].…”

Mechanical evaluation of bacterial nanocellulose as an implant material for ear cartilage replacement

“…Although several groups have investigated engineering ear cartilage (Bichara et al, 2012), few successful outcomes have been reported (Yanaga et al, 2009). Many studies have investigated the potential of biodegradable scaffold materials (Cao et al, 1997;Haisch et al, 2002;Isogai et al, 2004;Kusuhara et al, 2009;Shieh et al, 2004); for example, results reported by Shieh et al (Shieh et al, 2004) in an immuno-competent animal model showed poor shape stability due to an immune response presumably caused by degradation byproducts.…”

Long-Term Morphological and Microarchitectural Stability of Tissue-Engineered, Patient-Specific AuriclesIn Vivo

“…1,2 Current clinical practice utilizes autologous costal cartilage to fabricate auricular facsimiles with longterm stability 3,4 ; however, this method is limited by donor-site morbidity, [3][4][5][6] a complex surgical sculpting process, [3][4][5]7 and differing mechanical properties compared to elastic auricular cartilage. 4,5 Alternatively, alloplastic implants produce predictable shapes and eliminate donor-site surgery, 3,8 but suffer from poor biocompatibility and high rates of infection and extrusion. 3,6 A tissue engineering approach to auricular reconstructions would overcome the limitations of both autologous and alloplastic contemporary treatments.…”

“…However, the degradation of these polymers has been reported to cause inflammatory reactions. 3,4 Natural polymer scaffolds and hydrogels, such as alginate 13 and fibrin, 14 are easily molded and have high biocompatibility, 4 but are limited by low stiffness, making them difficult to handle. 15 Chondrocytes encapsulated in alginate and then implanted also become fibrochondrogenic.…”