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International Journal of Bioprinting Tunable GelMA-based bioinks for keloid modeling

1. Introduction activity, matrix production, and upregulation of fibrosis-
related genes, including the members of MMP, LOX, and
Three-dimensional (3D) bioprinting has emerged as a LOXL gene families. The development of reliable in vitro
18
transformative technology in tissue engineering and models that recapitulate the keloid microenvironment
regenerative medicine, enabling the fabrication of is essential for understanding disease mechanisms and
artificial tissues and organ-like constructs that replicate screening antifibrotic therapies. While several natural
1,2
native biological structure and function. Among the polymers such as collagen, gelatin, alginate, chitosan,
various techniques, extrusion-based bioprinting allows and fibrin have been used to construct skin models, the
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for the precise deposition of cell-laden hydrogels within need remains for bioinks that are both biocompatible and
predesigned architectures to generate biomimetic mechanically tunable—particularly for modeling stiffness-
platforms for tissue-specific applications. Central to the sensitive fibrotic phenotypes.
3
success of this approach is the development of suitable
bioinks—composite materials that integrate living cells Recent advances in 3D bioprinting have enabled the
with tunable biomaterials—to ensure high print fidelity, fabrication of stiffness-tunable artificial keloid constructs
mechanical stability, and cytocompatibility throughout the capable of supporting cell viability, mimicking keloid-like
printing and maturation processes. ECM architecture, and recapitulating relevant signaling
pathways. Building upon these advances, we developed
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A range of natural polymers and nanomaterials have
been explored as bioink constituents, including gelatin a composite bioink system comprising GelMA, sodium
alginate, MC, and laponite-RDS, designed to replicate
methacrylate (GelMA), alginate, methylcellulose (MC), the fibrotic microenvironment of keloid tissue through
and laponite-RDS. GelMA, a photo-crosslinkable gelatin mechanical tuning and cell-instructive matrix design.
4,5
derivative, is widely used for its cytocompatibility, cell-
adhesive motifs, and tunable mechanical properties, In this study, we systematically evaluated the
which can be modulated by its concentration and the contributions of each bioink component to matrix stiffness,
degree of methacrylation. Alginate, a non-toxic viscosity, viscoelasticity, degradation behavior, and cell
6–8
polysaccharide, offers excellent printability through ion- compatibility. Using patient-derived keloid fibroblasts
induced gelation with divalent cations such as Ca² . encapsulated in these hydrogels, we established a
+ 9
When blended with GelMA, it has been shown to enhance 3D-bioprinted keloid model that supports cell viability and
mechanical properties and improve matrix support for cell fibrosis-associated gene expression. This platform offers
attachment. However, excessive crosslinking or increased a robust and modular approach for engineering disease-
10
polymer density can hinder extrusion, prompting the need specific skin models and lays the groundwork for future
for rheological modulators. applications in personalized medicine and antifibrotic
drug screening.
MC serves as one such modifier. As a thermoresponsive
polymer, MC enhances viscoelasticity and contributes to 2. Materials and methods
bioink cohesion by undergoing a sol–gel transition via
hydrophobic interactions and reduced hydrogen bonding 2.1. Bioink preparation
21
upon heating. 11–13 Its incorporation enables improved GelMA was synthesized as previously reported. Briefly,
extrusion performance and structural fidelity at ambient 10% (w/v) gelatin (cat# G1890, Sigma-Aldrich, St. Louis,
temperatures. Laponite-RDS, a synthetic nanoclay, forms USA) was dissolved in deionized water under continuous
electrostatic interactions with charged polymers, thereby stirring at 60°C. Next, 8 mL of methacrylic anhydride
increasing viscosity, enhancing shear-thinning behavior, (# 276685, Sigma-Aldrich, USA) was added dropwise
and modulating pore structure within the hydrogel while stirring. After 2 h of reaction, deionized water
matrix. Beyond its physical reinforcement, laponite- was added, which was maintained for another 30 min.
14
RDS has demonstrated the ability to support a range of Subsequently, the solution was dialyzed using a dialysis
biological functions, including stem cell differentiation, membrane (MWCO; approximately 12–14 kDa; Spectrum
migration, and neural regeneration, making it a promising Laboratories, USA) at 55°C for 7 days. Following dialysis,
additive in bioactive bioinks. 15–17 the solution was filtered and lyophilized.
Keloids are pathological fibrotic scars characterized To prepare a bioink blend, lyophilized GelMA was
by excessive collagen deposition, tissue stiffening, and dissolved in phosphate-buffered saline (PBS) and incubated
abnormal extracellular matrix (ECM) remodeling. These at 60°C for 1 h to ensure proper GelMA dilution. Next,
lesions extend beyond the original wound site and are MC powder (cat# M7027-250G, Sigma-Aldrich, USA),
driven by aberrant fibroblast activation—primarily through alginate (cat# J61887-30, Alfa Aesar, USA), and laponite-
TGF-β1 signaling—which leads to increased migratory RDS (cat# LAPONITE-RDS, BYK, Germany) were added

Volume 11 Issue 4 (2025) 447 doi: 10.36922/IJB025160154