Effect of local environment, fibrin, and basic fibroblast growth factor incorporation on a canine autologous model of bioengineered cartilage tissue.

We developed a technique to form a bioabsorbable synthetic polymer (polyglycolic acid, PGA) combined with a natural polymer (fibrin) to serve as a scaffold to help retain seeded cells and improve the seeding efficiency of chondrocytes in an implantable construct. This approach was evaluated in a canine autologous implant model of bioengineered cartilage. The implantation site (subcutaneous or intrafascial) and the use of basic fibroblast growth factor (b-FGF) were also evaluated with this system. The intrafascial implantation site yielded optimal results, especially when used in conjunction with fibrin and a b-FGF sustained-release system incorporated into the complex. A thicker, more sustained cartilagenous layer was formed, with a more vascularized outer fibrous supporting tissue layer. This combined approach of implant environment selection, natural polymer for cell retention, and growth factor supplementation offers a more optimized method for generating bioengineered auricular cartilage.

Design and assessment of a tissue-engineered model of human phalanges and a small joint.

OBJECTIVES: To develop models of human phalanges and small joints by suturing different cell-polymer constructs that are then implanted in athymic (nude) mice. DESIGN: Models consisted of bovine periosteum, cartilage, and/or tendon cells seeded onto biodegradable polymer scaffolds of either polyglycolic acid (PGA) or copolymers of PGA and poly-L-lactic acid (PLLA) or poly-epsilon-caprolactone (PCL) and PLLA. Constructs were fabricated to produce a distal phalanx, middle phalanx, or distal interphalangeal joint. SETTING AND SAMPLE POPULATION: Studies of more than 250 harvested implants were conducted at the Northeastern Ohio Universities College of Medicine. EXPERIMENTAL VARIABLE: Polymer scaffold, cell type, and implantation time were examined. OUTCOME MEASURE: Tissue-engineered specimens were characterized by histology, transmission electron microscopy, in situ hybridization, laser capture microdissection and qualitative and quantitative polymerase chain reaction analysis, magnetic resonance microscopy, and X-ray microtomography. RESULTS: Over periods to 60 weeks of implantation, constructs developed through vascularity from host mice; formed new cartilage, bone, and/or tendon; expressed characteristic genes of bovine origin, including type I, II and X collagen, osteopontin, aggrecan, biglycan, and bone sialoprotein; secreted corresponding proteins; responded to applied mechanical stimuli; and maintained shapes of human phalanges with small joints. CONCLUSION: Results give insight into construct processes of tissue regeneration and development and suggest more complete tissue-engineered cartilage, bone, and tendon models. These should have significant future scientific and clinical applications in medicine, including their use in plastic surgery, orthopaedics, craniofacial reconstruction, and teratology.