Biofabrication, Biomechanics and Biocompatibility of Nanocellulose-based Scaffolds for Auricular Cartilage Regeneration
Doktorsavhandling, 2015

In about 2:10,000 births the external part of the ear, the auricle, is severely malformed or absent. Furthermore, tumors and trauma can cause defects to the auricle. For patients with dysplasia of the auricle, and especially for children, an inconspicuous outer appearance with life-like auricles is important for their psychological and emotional well being as well as their psycho-social development. Auricular reconstruction remains a great challenge due to the complexity of surgical reconstruction using rib cartilage. Despite the advances in stem cell technology and biomaterials, auricular cartilage tissue engineering (TE) is still in an early stage of development due to critical requirements demanding appropriate mechanical properties and shape stability of the tissue-engineered construct. This thesis has focused on developing patient-specific tissue-engineered auricles for one-step surgery using a novel biomaterial, bacterial nanocellulose (BNC), seeded with human nasoseptal chondrocytes (hNC) and bone marrow mononuclear cells (MNC). Biomechanical properties of human auricle cartilage were measured and used as a benchmark for tuning BNC properties. In order to meet the biomechanical requirements, a scaffold with bilayer architecture composed of a dense BNC support layer and a macroporous structure was designed. Firstly, the biocompatibility of the dense BNC layer was investigated, demonstrating a minimal foreign body response according to standards set forth in ISO 10993. Secondly, different methods to create macroporous BNC scaffolds were studied and the redifferentiation capacity of hNCs was evaluated in vitro; revealing that macroporous BNC scaffolds support cell ingrowth, proliferation and neocartilage formation. The bilayer BNC scaffold was biofabricated and tested for endotoxins and cytotoxicity before evaluating in long-term 3D culture, and subsequently in vivo for eight weeks—in an immunocompromised animal model. The results demonstrated that the non-pyrogenic and non- cytotoxic bilayer BNC scaffold offers a good mechanical stability and maintains a structural integrity, while providing a porous 3D environment that is suitable for hNCs and MNCs to produce neocartilage, in vitro and in vivo. Furthermore, patient-specific auricular BNC scaffolds with bilayer architecture were biofabricated and seeded with autologous rabbit auricular chondrocytes (rAC) for implantation in an immunocompetent rabbit model for six weeks. The results demonstrated the shape stability of the rAC-seeded scaffolds and neocartilage depositions in the immunocompetent autologous grafts. 3D bioprinting was also evaluated for biofabrication of patient-specific, chondrocyte-laden auricular constructs using a bioink composed of nanofibrillated cellulose and alginate. Bioprinted auricular constructs showed an excellent shape and size stability after in vitro culture. Moreover, this bioink supports redifferentiation of hNCs while offering excellent printability, making this a promising approach for auricular cartilage TE. Furthermore, the use of bioreactors is essential for the development of tissue-engineered cartilage in vitro. Thus, a compression bioreactor was utilized to apply dynamic mechanical stimulation to cell-seeded constructs as a means to enhance production of extracellular matrix in vitro. In this work, a potential clinical therapy for auricular reconstruction using tissue-engineered auricles is demonstrated; where BNC is proposed as a promising non-degradable biomaterial with good chemical and mechanical stability for auricular cartilage TE. Although the primary focus of this thesis is on auricular reconstruction, the methods developed are also applicable in the regeneration of other cartilage tissues such as those found in the nose, trachea, spine and articular joints.

Nasoseptal Chondrocytes

Tissue Engineering

Auricular Cartilage

Auricular reconstruction

Bacterial Nanocellulose

Neocartilage

Nanofibrillated Cellulose

Mononuclear Cells

3D Bioprinting

Room KB, Kemigården 4, Göteborg
Opponent: Prof. Marcy Zenobi-Wong, Department of Health Sciences and Technology, ETH Zürich, Switzerland.

Författare

Hector Martinez Avila

Chalmers, Kemi och kemiteknik, Tillämpad kemi, Polymerteknologi

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

Biomaterials,; Vol. 44(2015)p. 122-133

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Mechanical stimulation of fibroblasts in micro-channeled bacterial cellulose scaffolds enhances production of oriented collagen fibers

Journal of Biomedical Materials Research - Part A,; Vol. 100A(2012)p. 948-957

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Biocompatibility evaluation of densified bacterial nanocellulose hydrogel as an implant material for auricular cartilage regeneration

Applied Microbiology and Biotechnology,; Vol. 98(2014)p. 7423-7435

Artikel i vetenskaplig tidskrift

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

Journal of the Mechanical Behavior of Biomedical Materials,; Vol. 22(2013)p. 12-21

Artikel i vetenskaplig tidskrift

In Sweden, in about 2 out of every 10,000 births the external part of the ear, the auricle, is severely malformed or absent. For patients affected with such malformations, and especially for children, an ordinary outer appearance with life-like auricles is important for their psychological and emotional well being. Unfortunately, the auricle has a complex structure that surgeons have a hard time replacing. Héctor Martínez Ávila presents in his doctoral thesis the process development and biofabrication of patient-specific, tissue-engineered auricles using a novel biomaterial, bacterial nanocellulose, seeded with human chondrocytes. The customizable auricular scaffolds are designed based on the mechanical requirements of human auricular cartilage and the porosity requirements for neo-tissue growth. Based on the evidence from multiple studies, we propose bacterial nanocellulose as a promising non-degradable biomaterial for auricular cartilage tissue engineering. Although the primary focus of this thesis has been on auricular reconstruction, the methods developed are also applicable in the regeneration of other cartilage tissues such as those found in the nose, trachea, spine and articular joints. This work is the result of a close collaboration between engineers at Chalmers University of Technology in Sweden and ETH Zürich in Switzerland, cell biologists at Erasmus University Medical Center in The Netherlands and clinicians at Ulm University Medical Center in Germany.

Ämneskategorier

Annan medicinteknik

Biomaterial

Bioprocessteknik

Biomaterialvetenskap

Medicinska material och protesteknik

ISBN

978-91-7597-161-2

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie

Room KB, Kemigården 4, Göteborg

Opponent: Prof. Marcy Zenobi-Wong, Department of Health Sciences and Technology, ETH Zürich, Switzerland.