High-Fidelity Tissue Engineering of Patient-Specific Auricles for Reconstruction of Pediatric Microtia and Other Auricular Deformities

Introduction Autologous techniques for the reconstruction of pediatric microtia often result in suboptimal aesthetic outcomes and morbidity at the costal cartilage donor site. We therefore sought to combine digital photogrammetry with CAD/CAM techniques to develop collagen type I hydrogel scaffolds and their respective molds that would precisely mimic the normal anatomy of the patient-specific external ear as well as recapitulate the complex biomechanical properties of native auricular elastic cartilage while avoiding the morbidity of traditional autologous reconstructions. Methods Three-dimensional structures of normal pediatric ears were digitized and converted to virtual solids for mold design. Image-based synthetic reconstructions of these ears were fabricated from collagen type I hydrogels. Half were seeded with bovine auricular chondrocytes. Cellular and acellular constructs were implanted subcutaneously in the dorsa of nude rats and harvested after 1 and 3 months. Results Gross inspection revealed that acellular implants had significantly decreased in size by 1 month. Cellular constructs retained their contour/projection from the animals' dorsa, even after 3 months. Post-harvest weight of cellular constructs was significantly greater than that of acellular constructs after 1 and 3 months. Safranin O-staining revealed that cellular constructs demonstrated evidence of a self-assembled perichondrial layer and copious neocartilage deposition. Verhoeff staining of 1 month cellular constructs revealed de novo elastic cartilage deposition, which was even more extensive and robust after 3 months. The equilibrium modulus and hydraulic permeability of cellular constructs were not significantly different from native bovine auricular cartilage after 3 months. Conclusions We have developed high-fidelity, biocompatible, patient-specific tissue-engineered constructs for auricular reconstruction which largely mimic the native auricle both biomechanically and histologically, even after an extended period of implantation. This strategy holds immense potential for durable patient-specific tissue-engineered anatomically proper auricular reconstructions in the future.

[1]  D. Shepherd,et al.  Skin cell culture on an ear-shaped scaffold created by fused deposition modelling. , 2005, Bio-medical materials and engineering.

[2]  M. Cunningham,et al.  Microtia: Epidemiology and genetics , 2012, American journal of medical genetics. Part A.

[3]  S. Park,et al.  Autogenous tissue-engineered cartilage: evaluation as an implant material. , 1998, Archives of otolaryngology--head & neck surgery.

[4]  Joseph P Vacanti,et al.  The tissue-engineered auricle: past, present, and future. , 2012, Tissue engineering. Part B, Reviews.

[5]  Michael Sittinger,et al.  A tissue-engineering model for the manufacture of auricular-shaped cartilage implants , 2002, European Archives of Oto-Rhino-Laryngology.

[6]  Jonathan Bard,et al.  COLLAGEN SUBSTRATA FOR STUDIES ON CELL BEHAVIOR , 1972, The Journal of cell biology.

[7]  D J Mooney,et al.  Injection molding of chondrocyte/alginate constructs in the shape of facial implants. , 2001, Journal of biomedical materials research.

[8]  J. Wazen,et al.  Reconstruction of Congenital Microtia-Atresia: Outcomes With the Medpor/Bone-Anchored Hearing Aid–Approach , 2009, Annals of plastic surgery.

[9]  Division on Earth.  Guide for the Care and Use of Laboratory Animals , 1996 .

[10]  T. Gill,et al.  Engineering cartilage in a photochemically crosslinked collagen gel. , 2009, The journal of knee surgery.

[11]  Charles A Vacanti,et al.  Tissue Engineering of Autologous Cartilage for Craniofacial Reconstruction by Injection Molding , 2003, Plastic and reconstructive surgery.

[12]  B. S. Aminuddin,et al.  Formation of tissue engineered composite construct of cartilage and skin using high density polyethylene as inner scaffold in the shape of human helix. , 2011, International journal of pediatric otorhinolaryngology.

[13]  W. Shockley,et al.  Analysis of Human Auricular Cartilage to Guide Tissue-Engineered Nanofiber-Based Chondrogenesis , 2011, Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery.

[14]  Guangdong Zhou,et al.  In vitro engineering of human ear-shaped cartilage assisted with CAD/CAM technology. , 2010, Biomaterials.

[15]  J. Mansour,et al.  Cartilage tissue engineering for laryngotracheal reconstruction: comparison of chondrocytes from three anatomic locations in the rabbit. , 2007, Tissue engineering.

[16]  L. Bonassar,et al.  Dense type I collagen matrices that support cellular remodeling and microfabrication for studies of tumor angiogenesis and vasculogenesis in vitro. , 2010, Biomaterials.

[17]  J. Vacanti,et al.  Tissue engineering auricular reconstruction: in vitro and in vivo studies. , 2004, Biomaterials.

[18]  Nedjeljko Frančula.  The National Academies Press , 2013 .

[19]  L. Bonassar,et al.  Self-assembly of aligned tissue-engineered annulus fibrosus and intervertebral disc composite via collagen gel contraction. , 2010, Tissue engineering. Part A.

[20]  Erik K. Bassett,et al.  Engineering ear constructs with a composite scaffold to maintain dimensions. , 2011, Tissue engineering. Part A.

[21]  Jason P. Gleghorn,et al.  Boundary mode frictional properties of engineered cartilaginous tissues. , 2007, European cells & materials.

[22]  J. Burdick,et al.  Differential behavior of auricular and articular chondrocytes in hyaluronic acid hydrogels. , 2008, Tissue engineering. Part A.

[23]  J. Vacanti,et al.  Synthetic Polymers Seeded with Chondrocytes Provide a Template for New Cartilage Formation , 1991, Plastic and reconstructive surgery.

[24]  Charles A. Vacanti,et al.  Transplantation of Chondrocytes Utilizing a Polymer‐Cell Construct to Produce Tissue‐Engineered Cartilage in the Shape of a Human Ear , 1997, Plastic and reconstructive surgery.

[25]  E. Sanz,et al.  Formation of Cartilage In Vivo with Immobilized Autologous Rabbit Auricular Cultured Chondrocytes in Collagen Matrices , 2007, Plastic and reconstructive surgery.

[26]  L. Bonassar,et al.  Age-related changes in the composition and mechanical properties of human nasal cartilage. , 2002, Archives of biochemistry and biophysics.

[27]  A. Atala,et al.  Engineered cartilage covered ear implants for auricular cartilage reconstruction. , 2011, Biomacromolecules.

[28]  Stephen S. Park,et al.  Characteristics of tissue-engineered cartilage from human auricular chondrocytes. , 2004, Biomaterials.

[29]  T. Taguchi,et al.  Repair of full-thickness articular cartilage defects using injectable type II collagen gel embedded with cultured chondrocytes in a rabbit model , 2008, Journal of orthopaedic science : official journal of the Japanese Orthopaedic Association.

[30]  L. Bonassar,et al.  Analysis of bending behavior of native and engineered, auricular and costal cartilage , 2001, Proceedings of the IEEE 27th Annual Northeast Bioengineering Conference (Cat. No.01CH37201).

[31]  Yoshito Ikada,et al.  Tissue engineering of an auricular cartilage model utilizing cultured chondrocyte-poly(L-lactide-epsilon-caprolactone) scaffolds. , 2004, Tissue engineering.

[32]  I. Kiviranta,et al.  Quantitative evaluation of spontaneously and surgically repaired rabbit articular cartilage using intra-articular ultrasound method in situ. , 2010, Ultrasound in medicine & biology.

[33]  Y. Ikada,et al.  Tissue engineering a model for the human ear: Assessment of size, shape, morphology, and gene expression following seeding of different chondrocytes , 2009, Wound repair and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society.