Formation of Phalanges and Small Joints by Tissue-Engineering*†

Abstract

Background: This report describes the formation of small phalanges and whole joints from three types of bovine-cell sources transplanted onto biodegradable polymer matrices. The resulting structures had the shape and composition of human phalanges with joints.Methods: Fresh bovine periosteum was wrapped around a copolymer of polyglycolic and poly-L-lactic acid. Separate sheets of polyglycolic acid polymer were then seeded with chondrocytes and tenocytes isolated from the shoulders of freshly killed calves. The gross form of a composite tissue structure was constituted in vitro by assembling the parts and suturing them to create models of a distal phalanx, a middle phalanx, and a distal interphalangeal joint.Results: Subcutaneous implantation of the sutured composite tissues into athymic mice resulted in the formation, after twenty weeks, of new tissue with the shape and dimensions of human phalanges with joints. Histological examination revealed mature articular cartilage and subchondral bone with a tenocapsule that had a structure similar to that of human phalanges and joints. There was continuous cell differentiation at the ectopic site even after extended periods.Conclusions: These findings suggest that the formation of phalanges and small joints is possible with the selective placement of periosteum, chondrocytes, and tenocytes into a biodegradable synthetic polymer scaffold.Clinical Relevance: The formation of a joint construct of this nature is an example of a growing list of tissue-engineering techniques that, in general, offer alternatives to obtaining autogenous tissue for reconstructive operations in humans. Tissue-engineering holds promise for the treatment of loss of tissue or organ function as well as congenital malformations. Difficult reconstructions in symphalangism, arthrogryposis multiplex congenita, brachydactyly, or traumatically fixed joint contractures may someday be performed with this approach.