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International Journal of Bioprinting dECM bioink for in vitro disease modeling

regulates bodily functions, including motor, cognitive, and at the core of the model were printed, and endothelial cells
autonomic functions, through signal processing between were printed using BdECM bioink at the outer ring of the
neurons. Damages to the nervous system are accompanied core to recapitulate angiogenesis in the cancer model. The
by ultimate apoptosis of neurons and the inevitable printed GBM with animal-derived BdECM effectively
deterioration of the aforementioned functions. Typically, exhibited the chemoradiotherapy sensitivity seen in the
it is challenging to treat neural diseases, which also induce cancer cells. For example, the GBM printed with BdECM
permanent disorders affecting the patients throughout their had an upregulated expression in angiogenesis markers
lifetime. Therefore, neurological studies are focused on (e.g., serine hydroxymethyltransferase 2 [SHMT2], SRY-
elucidating disease mechanisms and exploring therapeutic box transcription factor 2 [SOX2], vascular endothelial
solutions. To support these studies, models that delicately growth factor A [VEGFA], and nestin [NES]) and exhibited
simulate neural tissues are required. higher radiotherapy resistance compared with the model

The brain is composed of multilayered structures and printed with collagen only. Collectively, experimental
several types of neural cells, such as neurons, astrocytes, evidence confirmed that BdECM-based models possess
and microglia. Ever since Lancaster et al. developed brain the features of a patient-specific cancer therapy model and
organoids with complex layers and cellular compositions, can sufficiently recapitulate cancer–ECM interaction effect.
various studies on brain tissue formation have been Another application of dECMs in nervous system
performed. 85,125,137 Matrigel, one of the most widely used disease research is creating motor neuron models for
materials in organ fabrication, is a non-neuronal matrix neuromuscular disease study. Motor neurons in the CNS
that generally lacks brain-specific proteins essential to connect to skeletal muscle fibers to control muscular motion.
the brain developmental process. In addition, traditional However, aging process drives the degradation of multiple
neural culture platforms (e.g., in vitro 2D cell culture) motor systems, thereby inducing neuromuscular diseases
are not capable of simulating the sophisticated structure such as amyotrophic lateral sclerosis and myasthenia
of the brain—particularly the neural-network model gravis. These neurodegenerative diseases have yet to be
and vascularized units. Moreover, the neural cell fully elucidated, and satisfactory clinical outcomes cannot
behavior depends on the culture environment, including be effectively achieved with drug treatments. 143-145 An in
the mechanical stiffness of the substrate and ECM vitro neuromuscular model suitable for neuromuscular
structures 138,139 ; for example, the neuroinflammatory disease mechanism study and drug testing stands as an
responses from glial cells are more intense on a 2D substrate ideal avenue for circumventing the limitations inherent in
than in the native tissue. Thus, conventional neural cell animal models. A neuromuscular model should contain
culture models differ from the native brain, which can be native-like long nerve bundles as well as muscular bundles,
an obstacle for elucidating the neural physiology. which are capable of recapitulating signal transduction
To offset the limitations in fabrication, brain between neurons and muscles. Kong et al. developed
decellularized extracellular matrix (BdECM) has been 3D-bioprinted neuromuscular junction (NMJ) models with
applied, in combination with 3D bioprinting, to in vitro a porcine spinal cord-derived dECM (CNSdECM) (Figure
brain modeling including brain cancer modeling. The 3B) by building 3D-printed pillar with poly(ethylene-co-
major features of cancer are uncontrolled cell proliferation, vinyl acetate) (PEVA) to induce mechanical stimulation of
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increased angiogenesis, and chemotherapy resistance. muscle cells for forming myotubes. The muscle cells were
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The origin of cancer should be ideally studied using encapsulated in a skeletal muscular dECM (MdECM), and
preclinical models for patient-specific cancer therapy. induced pluripotent stem cell (iPSC)-derived motor neurons
Under the impact of mutations in relevant genes, were encapsulated in the CNSdECM. Then, a cell-laden
tumorigenesis is particularly vulnerable to the effects MdECM was printed in a belt shape for a muscular module
of cell–ECM crosstalk. For example, brain glioblastoma beside the printed pillar to induce mechanical extension of
(GBM) manifests varying levels of chemoresistance to the muscle cells and provide structural stability. In addition,
therapies in different patients, thus requiring patient- the cell-laden CNSdECM was printed after 4 days of
specific anticancer therapy, such as a combination of maturation of the muscular module and was connected to
medication and radiotherapy. The features of GBM are the muscular models as a neural module. Thus, the printed
related to the hypoxic core in necrotizing zones. A hypoxic- muscular module and neural module were connected
core-formed GBM model has been developed using 3D to form an NMJ. The physiological synchronization of
bioprinting (Figure 3A), 141,142 and the hypoxic core has been connected modules was confirmed with the presence
simulated using a computer-aided design (CAD) program, electrophysiological signal transduction. The NMJ model is
with a focus on the oxygen diffusion gradient. Based on favorable for maintaining a long-term culture of the NMJ
the simulation, GBM cells encapsulated in BdECM bioink module, which allows degenerative disease modeling.

Volume 10 Issue 2 (2024) 143 doi: 10.36922/ijb.1970