Designing a tissue-engineered tracheal scaffold for preclinical evaluation

Abstract

Objective Recent efforts to tissue engineer long-segment tracheal grafts have been complicated by stenosis and malacia. It has been proposed that both the mechanical characteristics and cell seeding capacity of TETG scaffolds are integral to graft performance. Our aim was to design a tracheal construct that approximates the biomechanical properties of native sheep trachea and optimizes seeding with bone marrow derived mononuclear cells prior to preclinical evaluation in an ovine model. Methods A solution of 8% polyethylene terephthalate (PET) and 3% polyurethane (PU) was prepared at a ratio of either 8:2 or 2:8 and electrospun onto a custom stainless steel mandrel designed to match the dimensional measurements of the juvenile sheep trachea. 3D-printed porous or solid polycarbonate C-shaped rings were embedded within the scaffolds during electrospinning. The scaffolds underwent compression testing in the anterior-posterior and lateral-medial axes and the biomechanical profiles compared to that of a juvenile ovine trachea. The most biomimetic constructs then underwent vacuum seeding with ovine bone marrow derived mononuclear cells. Fluorometric DNA assay was used to quantify scaffold seeding. Results Both porous and solid rings approximated the biomechanics of the native ovine trachea, but the porous rings were most biomimetic. The load-displacement curve of scaffolds fabricated from a ratio of 2:8 PET:PU most closely mimicked that of native trachea in the anterior-posterior and medial-lateral axes. Solid C-ringed scaffolds had a greater cell seeding efficiency when compared to porous ringed scaffolds (Solid: 19 × 104 vs. Porous: 9.6 × 104 cells/mm3, p = 0.0098). Conclusion A long segment tracheal graft composed of 2:8 PET:PU with solid C-rings approximates the biomechanics of the native ovine trachea and demonstrates superior cell seeding capacity of the two prototypes tested. Further preclinical studies using this graft design in vivo would inform the rational design of an optimal TETG scaffold.

Biomedical grafts for tracheal tissue repairing and regeneration “Tracheal tissue engineering: an overview”

“…Similarly, to enhance the biochemical strength of bioengineered PET–PU electrospun, fiber‐coated polycarbonate rings hollow tubular tracheal graft was designed. Graft was seeded with bone marrow‐derived mononuclear cells under vacuum condition and preclinical tested in sheep model (Best et al, ). Janke et al () also designed spiral collagen ring tubular graft to enhance the mechanical strength of the bioengineered tracheal transplant.…”

Seeding and Implantation of a Biosynthetic Tissue-engineered Tracheal Graft in a Mouse Model

“…Other animal models that have been utilized in studying TETGs include New Zealand white rabbits, dogs, rats, pigs, and sheep 8,9,10,11 ; many of which can be cost prohibitive and lack comprehensive quantification methods (i.e., ELISAs, Immunohistochemistry antibodies, PCR primers, etc.) and/or transgenic options.…”

The History of Engineered Tracheal Replacements: Interpreting the Past and Guiding the Future

“…A number of groups are addressing challenges seen in the clinic through focused and well-controlled preclinical work. Recent advancements in tracheal grafts are broadly focused on preventing adverse host response, [73][74][75] capturing complex native mechanical behavior, [76][77][78][79][80][81] and improving functional integration upon implantation. 76,[82][83][84][85] The Cho group of South Korea has developed a polymeric tracheal replacement graft designed with a ''bellows'' configuration, comprising polycaprolactone, to attempt to capture native-like structure and mechanical behavior.…”