Page 416 - IJB-9-2

International Journal of Bioprinting Design and 3D printing of TPMS breast scaffolds

possible while removing the tumor. Nonetheless, cavities and gelatin methacrylate (GelMA) are two common
will form in breast tissue after the surgery, resulting in hydrogels in biomedicine due to their good formability
morphological and functional deficits of the breast and and biocompatibility, respectively. For example, Wang
further leading to post-operative anxiety and psychosocial et al. developed a GelMA-PEGDA-nano-hydroxyapatite
[30]
dysfunction in patients . Clinically, breast repair and composite hydrogel scaffold for bone tissue engineering,
[2]
reconstruction are achieved mainly through fat autograft and the results showed that the scaffold had good cell
and allograft. The former causes secondary trauma, while viability and biocompatibility. Yuan et al. fabricated a
[31]
the latter faces the disadvantages of donor deficiency, GelMA/PEGDA microneedles patch loaded with human
immunological rejection, and high cost [3,4] . Although umbilical vein endothelial cells for wound healing, and this
prosthesis, such as silicone and saline fillings, exhibit hydrogel patch exhibited distinctive biological features.
flexibility and tissue-like elasticity for breast reconstruction, Numerous studies [32-35] have proven that only when
they will cause an inflammatory reaction and the risks of the elastic modulus of breast tissue scaffold matches that
rapture and leakage, leading to various complications [5-7] . of native breast tissue (0.002 – 1 MPa) can the scaffold
Three-dimensional (3D) printing technology has emerged effectively stimulate cell growth and differentiation into
as an effective way to address the issues due to its ability to breast tissue. The mechanical properties of breast scaffolds
fabricate biodegradable breast scaffolds economically [8-10] .
are affected not only by materials, but also by scaffold
Fused deposition modeling (FDM), the most structures. The type of structure unit cell determines
common 3D printing technology, can rapidly build the mechanical properties of the breast tissue scaffold,
complex 3D structures through layer-by-layer deposition including elastic modulus, stress distribution, and stability.
of thermoplastic materials [11-14] . Due to its rapidity, Many unit cells were harnessed to construct breast tissue
personalized customization, flexibility, and low cost, scaffolds, such as grid , crystal lattice , coil, and
[36]
[37]
[38]
it is widely adopted in breast tissue engineering for sinusoidal unit cells for different purposes. However,
[32]
fabricating geometrically complex scaffolds to better current breast tissue scaffolds consisted of the unit cells
mimic the intrinsic complexities of native tissue [2,15,16] . mentioned above exhibit much higher elastic modulus
Of many commonly used FDM-printable biomaterials, than that of native breast tissue. Thus, many studies have
polylactic acid (PLA) and polycaprolactone (PCL) are made effort to optimize the elastic modulus of scaffold.
broadly employed in biomedical fields due to their Rba et al. modulated the elastic modulus of PLA lattice
[39]
biodegradability, printability, and adjustable mechanical scaffolds by optimizing parameters, such as printing
properties [17,18] . However, the degradation process of temperature, speed, and layer thickness, but the elastic
PLA scaffolds is accompanied by the production of lactic modulus of the scaffold is still 942 MPa, much higher
acid, leading to enhanced acidity of its surrounding than that of native tissue. Chhaya et al. utilized PCL to
[38]
environment, subsequently, causing tissue inflammation print coil scaffold, and its elastic modulus was reduced to
and necrosis at the implantation position [19,20] . PCL, a softer 21.5 MPa, which is also not appropriate for breast tissue.
biomaterial compared to PLA, is more appropriate for soft- Although some researchers [32,36] reduced the elastic modulus
tissue engineering. For instance, Chhaya et al. designed of PCL scaffolds to several MPa through structural design
[21]
and fabricated a patient-specific PCL breast scaffold which and parameter optimization, the fidelity of the fabricated
was implanted into a minipig and then injected with 4 cm scaffolds is poor, and the structural instability (fracture or
3
of lipoaspirate. After 24 weeks, the area of adipose tissue tilt) occurred when compressed, which could not provide a
in this scaffold was similar to that of native breast tissue, long-term effective environment for breast reconstruction.
proving the ability of PCL scaffold for breast regeneration. Recently, the highly-porous PCL breast scaffolds with
In addition, PCL scaffolds were also widely used in helical architectures designed by Meng et al. performed
[40]
trachea , bile duct , meniscus, and auricle repair stability with uniform deformation pattern and low elastic
[24]
[25]
[23]
[22]
and reconstruction. modulus (below 1 MPa). Nevertheless, the small specific
Nevertheless, although PCL scaffolds are biocompatible, surface area of these helical architectures is unfavorable
cell adhesion ability is poor on these materials because of the for the cell adhesion, further leading to the difficulty of
low hydrophilicity , which influences the subsequent cell tissue formation. A fundamental issue for breast scaffold
[26]
proliferation, differentiation, and new tissue in-growth . design is how to simultaneously modulate the elastic
[27]
A more cell-friendly material is needed to be incorporated modulus for better stimulating cell differentiation and
into these scaffolds to improve the cell environment. maintain structural stability for protecting cells and tissue,
Hydrogel is a widely used biomaterial that is similar to and provide large specific surface area for allowing cell
extracellular matrix and has been widely used in biomedical adhesion and tissue formation, a significant challenge in
applications [28,29] . Poly (ethylene glycol) diacrylate (PEGDA) breast reconstruction.

Volume 9 Issue 2 (2023) 408 https://doi.org/10.18063/ijb.685