Background/purpose: This study was aimed at applying fetal tissue engineering to chest wall reconstruction.

Methods: Fetal lambs underwent harvest of elastic and hyaline cartilage specimens. Once expanded in vitro, fetal chondrocytes were seeded onto synthetic scaffolds, which then were placed in a bioreactor. After birth, fetal cartilage constructs (n = 10) were implanted in autologous fashion into the ribs of all lambs (n = 6) along with identical, but acellular scaffolds, as controls (n = 6). Engineered and acellular specimens were harvested for analysis at 4 to 12 weeks postimplantation. Standard histology and matrix-specific staining were performed both before implantation and after harvest on all constructs.

Results: Regardless of the source of chondrocytes, all fetal constructs resembled hyaline cartilage, both grossly and histologically, in vitro. In vivo, engineered implants retained hyaline characteristics for up to 10 weeks after implantation but remodeled into fibrocartilage by 12 weeks postoperatively. Mononuclear inflammatory infiltrates surrounding residual PGA/PLLA polymer fibers were noted in all specimens but most prominently in the acellular controls.

Conclusions: Engineered fetal cartilage can provide structural replacement for at least up to 10 weeks after autologous, postnatal implantation in the chest wall. Fetal tissue engineering may prove useful for the treatment of severe congenital chest wall defects at birth.