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Tissue Engineering

3D Bioprinting and Patterning of Tissues

Optimizing the Design of P4HB 3D-printed Scaffolds for Nipple Reconstruction

Friday, October 13, 2023
8:45 AM – 9:00 AM PDT
Location: 344 (Center, Level 3)
Introduction:: Surgically creating nipples is a crucial step in breast reconstruction but all contemporary techniques suffer from significant loss of projection. We designed and optimized a 3D-printed cylindrical nipple scaffold with an interior lattice structure made from the FDA approved biodegradable polymer Poly-4-Hydroxybutyrate (P4HB), to facilitate permanent tissue formation to better mimic the biomechanical properties of the native nipple while maintaining long-term projection.

Materials and Methods:: Nipple scaffolds were 3D-printed (1.0cm in diameter and height) with different internal 3D conformations of P4HB filaments (infill density (20, 25 and 30%), filament diameter (0.15mm and 0.2mm), external shell present/no shell) and subcutaneously implanted in WT rats using a CV flap technique. Cook Biodesign® Nipple Cylinder, empty P4HB scaffolds (only external shell present) and manually-rolled P4HB Phasix™ mesh scaffolds were implanted for comparison.

Results, Conclusions, and Discussions:: Nipple reconstructions with 3D-printed P4HB interior latticework were well maintained in both diameter and projection over 6 months (>95% and >80% respectively). No significant differences were observed between different design parameters. The Phasix™ mesh and empty P4HB group lost slightly more in both diameter and projection, while the Cook Biodesign® group lost 60% projection (p < 0.05) after 6 months. The starting stiffnesses were different between 3D-printed groups, but all declined over time and approached that of native nipples by 6 months, as the P4HB polymer gradually degraded and was replaced by fibrovascular tissue ingrowth.

With interior structural support from 3D-printed P4HB lattice, the reconstructed nipples demonstrated improved diameter and projection maintenance over 6 months. As P4HB degrades over time and the scaffold loses structural integrity, the fibrovascular tissue formed within provides the structure which allows the engineered nipple to maintain proper shape, volume and biomechanical qualities similar to that of native nipples.


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