Page 10 - IJB-9-3

International Journal of Bioprinting Bioprinting of PDAC microtissues for drug screening

5-year survival rate of <8% . PDAC, which has a complex stable cell growth environment, thereby causing nutrition
[3]
surrounding anatomical structure, is hidden in the human inadequacy and a lack of gas and waste exchange. On the
body. Most of the patients reach middle and late stage by other hand, the position of hydrogel beads prepared by
the time of diagnosis, and the tumor can only be surgically superhydrophobic array was not fixed, which might cause
resected in <20% of the patients [4,5] . Drug therapy thus sample loss and other problems in the subsequent liquid
plays a major role in the treatment of PDAC. However, exchange process.
the development outcome of drug therapy for pancreatic 3D bioprinting has great advantages in building complex
cancer is still far from ideal although a gradual increase of tissue models using accurately controlled assembly of
research funding’s were allocated annually to develop drugs cells, hydrogels and active molecules to form specific
for treating pancreatic cancer. Furthermore, the ineffective structures [22-24] . Herein, we established stroma-tunable
drug prediction ability of preclinical PDAC model impedes PDAC models by printing cell-laden gelatin methacryloyl
the development of novel drug treatment .
[6]
(GelMA) hydrogel beads through the dot extrusion
The pancreatic cancer microenvironment is composed printing (DEP). As shown in Figure 1, GelMA hydrogel
of parenchymal cancer cells, diversiform stromal cells, beads were facile printed and supported pancreatic cancer
and non-cellular components, such as extracellular matrix cells (BxPC-3) and stromal cells to form a dense tumor-
(ECM) and cell secreted factors [7-9] . A line of clinical stroma microtissue, which reproduced the characteristics
evidence has shown that it is difficult to treat PDAC because of stromal microenvironment and ECM component
of low cure rate and poor prognosis, which are closely in vivo. The printed GelMA beads were biocompatible and
related to the unique bioarchitecture of the cancer [10,11] . In in reduced volume, which are conducive to nutrient uptake
the PDAC development process, pancreatic cancer cells by encapsulated cells and waste excretion. In the co-culture
promoted a large number of cancer-associated fibroblasts session, we observed that tumor spheroids acquired
(CAFs) formed by activating the matrix components, enhanced proliferation and the normal fibroblasts were
mainly pancreatic stellate cells (PSCs), scattered around the activated and transformed to CAF phenotype. Further,
acinar follicle. The activated stromal components further in the chemotherapeutic drug (gemcitabine) treatment,
contribute to excessive ECM deposition, and eventually tumor-stroma PDAC models had a stronger drug resistance
lead to pancreatic cancer cells being embedded in a dense when compared with the mono-cultured tumor. The
fibrous barrier [12-14] . This unique tumor-stroma niche engineered PDAC microtissue with stromal cellular barrier
regulates complex crosstalk between pancreatic cancer formed in 3D GelMA beads is useful for studying cancer
cells and CAFs, and further promotes the progression and drug resistance and the underlying molecular mechanisms,
drug resistance of pancreatic cancer cells [15,16] . Therefore, and it is an effective in vitro drug screening platform for
building in vitro biomimetic PDAC models to outline pancreatic cancer drug therapy research.
key tumor-stroma features will facilitate the cancer drug
development. 2. Materials and methods
Three-dimensional (3D) cultured tumor spheroids 2.1. Cell culture
provide key structural features of biomimetic in vivo
solid tumors, including tight cell-cell, cell-ECM physical Human pancreatic cancer cell line (BxPC-3) and normal
contactions, similar pH/nutrient/oxygen gradients, and human dermal fibroblast cells (NHDFs) in this work were
abundant cell communication, as well as exhibit different kindly provided by Hangzhou Regenovo Biotechnology Co.,
responses to drugs better than 2D cultured cells, and have Ltd. For cells cultivation, BxPC-3 and NHDFs were cultured
been widely used in the screening of anti-tumor drugs in RPMI-1640 and Dulbecco’s modified Eagle’s medium
in recent years [17-19] . For example, João F. Mano’s research (DMEM; Gibco, USA), respectively. About 10% (v/v)
group engineered heterogeneous PDAC spheroids to fetal bovine serum (FBS; Excell Bio, China) and 1% (v/v)
mimic PDAC-stroma features by co-culturing tumor penicillin/streptomycin (Thermo, USA) were supplemented
and stromal cells using ultra-low adhesion plate . into the above-mentioned basic medium. Cells were cultured
[20]
Recently, they further reported a novel “cancer-on-a-bead” at 37°C under 5% CO , and passaged at 3-day intervals.
2
platform which produced hydrogel beads encapsulating 2.2. Material preparation
tumor and stroma cells by superhydrophobic surfaces .
[21]
The generated cancer models processing tumor-stroma GelMA was provided by Hangzhou Regenovo
bioarchitectures and ECM microenvironments had an Biotechnology Co., Ltd. The selected concentration of
increased drug resistance performance. However, there GelMA was 8% (w/v) and the concentration of lithium
were some shortcomings: the limited growth space of phenyl-2, 4, 6-trimethylbenzoylphosphinate (LAP; Sigma
ultra-low adhesion plate could not provide a long-term and Aldrich, USA) was 0.5% (w/v). GelMA and photoinitiator

Volume 9 Issue 3 (2023) 2 https://doi.org/10.18063/ijb.v9i3.676