Tissue Engineering Strategies for the Reconstruction of a Functional Larynx
Abstract
Laryngeal cancer affects tens of thousands worldwide every year. The standard of care of surgical resection, chemotherapy, and/or radiation therapy results in significant quality of life deficits including reliance on tracheostomy tubes, loss of voice, and inability to swallow. There are no therapeutic options that restore a functional larynx so that patients can live a more normal life. Laryngeal reconstruction using tissue engineering strategies offers the potential to solve this problem. Laryngeal anatomy is complex with multiple tissue types and therefore engineering approaches require consideration of a multi-layer, interfacial tissue design. Our strategy to overcome these challenges involves the use of advanced bio fabrication techniques where type I oligomeric collagen alone or in the presence of autologous stem cells is used to custom-make the cartilage, skeletal muscle, and mucosal layer of the larynx. This doctoral research project begins by describing the development of the tissue engineered skeletal muscle with aligned collagen matrix and autologous muscle progenitor cells induced to express motor endplates. Next, using this engineered muscle plus the cartilage layer deve loped by a colleague; we implanted the myochondral engineered construct in a rat hemilaryngectomy model. In this study we saw hostimplant integration with no inflammatory foreign body response, neo cartilage and muscle formation, and some return of laryngeal function on the reconstructed side. Next, we worked to scale-up these technologies for use in a porcine model. The pig larynx is more similar in size and function to the human larynx and allows for a full thickness defect to be created. Using confined compression, we created 4-mm thick acellular and cellular cartilage constructs, as well as a 0.5- mm thick acellular mucosal layer. A 1-cm diameter muscle layer containing autologous muscle progenitor cells was created using flow alignment and cultured to induce expression of motor endplates before implantation. Tissue constructs were subjected to mechanical property analyses as well as PCR analysis to describe the differential gene expression by component cells within muscle and cartilage constructs. Each layer was individually sutured into a pig hemilaryngectomy model. The pigs recovered well from the surgery, were eating, had no difficulty breathing, and no aspiration events. At 2 months, respiratory epithelium had completely healed over the implant and was vascularized and had areas of submucosal gland growth. The motor endplate expressing muscle implants showed new, organized muscle ingrowth while the acellular implants showed a relative paucity of new, disorganized muscle. This work represents a significant advancement in the field of laryngeal reconstruction and is a first of its kind to use scalable tissue engineering technologies designed to specifically meet each layer’s functional criteria.
Degree
Ph.D.
Advisors
Harbin, Purdue University.
Subject Area
Biomedical engineering|Cellular biology|Design|Endocrinology|Management|Materials science|Medicine|Morphology|Nuclear physics|Oncology|Pharmaceutical sciences|Physics|Polymer chemistry|Surgery|Therapy
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