PURPOSE: Creating the nipple is the last surgical step of breast reconstruction. However, autologous tissue techniques are limited due to
scar contracture and significant loss of neo-nipple projection. Poly-4-Hydroxybutyrate (P4HB) is a biodegradable polymer with a long track
record of clinical use as a surgical mesh and we have previously shown long-term maintenance of nipple projection using 3D-printed P4HB
nipple scaffolds filled with processed cartilage in nude rats. Here we aim to modify the interior reticular structure of the 3D-printed P4HB
cylindrical scaffold to better mimic the biomechanical properties of the native nipple while maintaining the nipple projection in an
immunocompetent rodent model.
METHODS: Nipple scaffolds were 3D-P4HB printed (diameter: 1.0cm, height: 1.0cm) with different internal 3D latticework of P4HB filaments
(infill density: 20, 25 and 30%; filament diameter: 0.15 and 0.2mm). All the scaffolds were subcutaneously implanted in rats using a CV flap
technique. P4HB scaffolds without the internal latticework and Cook Biodesign® Nipple Cylinder were implanted as controls.
RESULTS: The projection of 3D-P4HB nipples were well maintained over 3 months (>90%, p>0.05) and nipple stiffness slowly declined as
the polymer was gradually replaced by tissue. In contrast, the Cook Biodesign® nipple lost 25% and 50% projection at 1- and 3-month
respectively (p<0.05).
CONCLUSION: We have successfully engineered neo-nipples that maintain projection over time, while simultaneously allowing for tissue
ingrowth that is biomechanically similar to that of native nipples. Long-term observation will be warranted to verify the translatability of this
novel 3D-P4HB nipple scaffold.