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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.