Tuning the mechanics of 3D-printed scaffolds by crystal lattice-like structural design for breast tissue engineering

Abstract

Breast tissue engineering is a promising alternative to standard treatments for breast defects. Although there is a consensus that the mechanical property of the scaffold should best match the reconstructed tissue, the simulation of the soft and elastic tactility of native breast tissues using conventional materials and architecture design requires further study. Previous research has shown that the crystal microstructure-like design can drastically alter the mechanical properties of the constructed scaffolds. In this study, we designed and additive manufactured four kinds of breast scaffolds using polyurethane and termed their architectures as N5S4, N9S8, N7S6 and N4S6. The basic unit cell of each scaffold was similar to a lattice structure from the isometric crystal system. The scaffolds possessed identical porosity but different mechanical properties in which the compressive modulus of the softest scaffolds (N5S4) were similar to that of native breast tissue. When applied in the construction of tissue-engineered breast combining with delayed fat injection technique in nude rat models, the soft scaffolds(N5S4) performed better compared to its stiff counterpart (N4S6), as higher adipose survival, vascularization and milder fibrosis could be observed in N5S4 scaffolds . Lastly, using finite element analysis, we further investigated the influence of the unit cell architectures on the mechanical properties of the scaffolds and simulated the deformation as well as stress distribution patterns of the implanted scaffolds in detail. Thus, a crystal lattice-like architecture design was introduced to tune the mechanical properties of the scaffolds and match the requirements for tissue engineering applications.

Design Data and Finite Element Analysis of 3D Printed Poly(ε-Caprolactone)-Based Lattice Scaffolds: Influence of Type of Unit Cell, Porosity, and Nozzle Diameter on the Mechanical Behavior

“…Highly controlled lattice architectures are seeing growing interest in different application fields, ranging from the manufacturing of lightweight orthosis [1][2][3], scaffolds for tissue engineering [4][5][6][7][8][9][10][11], implantable medical devices [12][13][14], stimuli-responsive softrobotics [15][16][17], and topology optimization for architectural structures [18]. Such lattice structures comprise a base form, namely unit cell, which is spatially repeated across the entire structure either in a fixed x, y, z geometry or with varying degrees of asymmetry [19][20][21][22][23].…”

Human umbilical cord mesenchymal stem cell promotes angiogenesis via integrin β1/ERK1/2/HIF-1α/VEGF-A signaling pathway for off-the-shelf breast tissue engineering

“…TPU materials and 3D printing technology were selected to construct diamond-shaped (N5S4) breast scaffolds. Our previous study demonstrated that the scaffolds with N5S4 architecture that mimic the lattice microstructure of diamond are soft and resilient enough for breast reconstruction [ 24 ]. Since the ratio of 0.5 × 10 6 hUCMSCs to 0.5 ml fat achieves the highest volume retention rate of the graft among all three concentrations and the diameter of the breast scaffold is 1 cm depending on the size of the nude mice, we injected 0.2 ml of fat.…”

“…In the hUCMSC groups, mice were implanted subcutaneously using the same method on each side of the back with scaffold filled with 0.2 ml of human fat and 20 µl of sterile saline containing 0.2 × 10 6 hUCMSCs. The material and architecture of scaffold in the present study refer to our previous research [ 24 ]. The scaffold is built with N5S4 architecture which mimic the lattice microstructure of diamond are soft and resilient enough for breast tissue engineering, which has showed considerable advantages in animal study.…”

“…Previously, we explored the actual structure of the 3D printing scaffold applied in breast tissue engineering [ 24 ]. This study explores whether hUCMSCs can serve as seed cells for breast tissue engineering and elucidate the underlying mechanism.…”

Electrospun Porous Biobased Polymer Mats for Biomedical Applications

“…Continued efforts are needed to investigate in vivo biotoxicity, biodegradability, and mechanical performance to open the way for clinical applications (Zhou et al 2019).…”