Objective: To create engineered cartilage through an injectable medium that could be used as a minimally invasive implant material.
Methods: Human nasal septal chondrocytes, carried in an alginate polymer, were injected and molded percutaneously into nude mice and developed in vivo. The cartilage was harvested from 14 to 38 weeks and analyzed through gross, histological, immunohistochemical, and biochemical analysis.
Results: Of the 15 explants, 14 (93%) resembled native cartilage on gross analysis. The injections maintained their overall appearance with some loss of definition. On histological analysis, 6 of the explants (40%) appeared similar to native cartilage throughout the sample. Eight of the explants (53%) resembled native cartilage; however, there were some areas of fibrous tissue differentiation. The neocartilage stained positive for type II collagen. Explants harvested at week 26 or later and the samples that histologically resembled native cartilage had similar hydroxyproline content to native septal cartilage.
Conclusions: Injectable, autologous cartilage may be the answer to the long search for the ideal implant in facial plastic surgery. Alginate and human chondrocytes can be used to create an injection that may be molded and maintains its overall size and shape, with some loss of definition, for at least 38 weeks after injection.