br Both alginate and PDA were
Both alginate and PDA were biocompatible; hence, no apparent toxicity and other severe side effects occurred on all mice implanted with Alg-PDA scaffolds. In addition, the mice treated with the Alg-PDA scaffold plus NIR laser irradiation were alive for 40 days without any death or tumor recurrence (Fig. 5c). Fur-thermore, the scaffold maintained the regular structure after implantation in mice over 1 month, which indicates that the degra-dation rate of the scaffold was acceptable for the following tissue repair.
3.5. Proliferation of MCF-10A human breast epithelial AMG 925 on the fabricated scaffolds
As the filler for breast cavity after surgical treatment, the scaf-fold possessed the function of killing the residual and recurrent cancer cells. In addition, the porous scaffold should have the capa-bility to support the attachment and proliferation of normal breast cells for the following adipose tissue engineering . Therefore,
Fig. 5. Relative tumor volume (a), relative body weight changes (b), and survival curves (c) of mice bearing 4T1 tumor after various treatments. Photographs of mice in five groups at day 0 (before) and day 15; red circles indicate the tumor in mice (d). H&E-stained images of the heart, liver, spleen, lung, and kidney of healthy mice and tumor-bearing mice treated with the Alg-PDA scaffold plus 0.5 W cm 2 808 nm laser (e). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
hemolysis of red blood cells and proliferation of human breast cells on the scaffolds were further investigated. The hemolysis of the Alg-PDA scaffold was evaluated by incubation with red blood cells, and the data showed that no significant hemolytic phenomenon occurred in the printed Alg-PDA scaffold (Fig. 6a). After the fabri-cated alginate and Alg-PDA scaffolds were treated with an 808 nm laser for 5 min, human breast epithelial cells (MCF-10A) were seeded on both types of the scaffolds and cultured for 7 days. The proliferation of the cells on the scaffolds was evaluated by the CCK-8 assay. According to the results (Fig. 6b), both the alginate and the Alg-PDA scaffold were able to support MCF-10A cell prolif-eration. Particularly, cells on the Alg-PDA scaffold showed signifi-cantly higher proliferation rate than those on alginate scaffolds. PDA has been widely used for the surface coating of tissue-engineered scaffolds, showing significant improvement in cell adhesion and proliferation [52,53]. In this study, although PDA was not directly used for surface coating, the surface of the scaffold was changed (Fig. S4). This might be the main reason for the signif-icantly increased proliferation of cells on the Alg-PDA scaffold, and
it suggested that the fabricated Alg-PDA scaffold might be a poten-tial candidate for adipose tissue engineering.
Breast tissue filler for adipose tissue engineering has gained increasing attention, and some interesting results have recently been obtained both in vitro and in vivo using gelatin, alginate, and polycaprolactone (PCL)-based porous 3D scaffolds . However, most of these studies were generally performed for small-volume breast reconstruction using small animal models (such as mice) [55,56]. It is very important to extrapolate these interesting results to large-volume breast tissue engineering in human scales for clin-ical trials and applications. It has to be pointed out that this study is still a preliminary work, as well as many limitations and further inquiries that need to be addressed before processing clinical study. For example, in the next steps, larger animal models (such as pig) should be created to further clarify the PTT and tissue repair of the fabricated scaffolds in detail. In addition, longer time of implan-tation in vivo (such as more than 12 months) is also required to fur-ther evaluate the biocompatibility, biodegradation, and prevention of local recurrence of breast cancer, as well as breast reconstruction.