EXPECT: A thermosensitive embedded bioprinting platform for guided spatial cell organization
Smart Materials in Medicine 2025
Athanasia Pylostomou, Dagnija Loča

Complex tissue engineering requires precise spatial cell organization, but static or isotropic hydrogels hinder long-term pattern maintenance due to random cell migration. We developed EXtrusion Patterned Embedded ConstruCT (EXPECT), a thermosensitive hydrogel embedding medium for 3D bioprinting, integrating Carbopol® 940 and gelatin for rheological properties and print fidelity, with poly (N-isopropylacrylamide)-graft-chondroitin sulfate (pNIPAAm-CS) for biocompatibility and temperature-responsive behavior (~32 ◦C lower critical solution temperature (LCST)). Rheological and small-angle X-ray scattering (SAXS) analyses confirmed EXPECT's selfhealing printability and reversible LCST-driven transitions from hydrophobic (above ~32 ◦C) to hydrophilic (below ~32 ◦C) states. Temperature actuation (15 min at 25 ◦C every ~5 days, otherwise 37 ◦C) in 10 mm toroid channels embedded within EXPECT guided cellular organization of cells seeded in these channels. In chondrogenic medium, actuated single mesenchymal stromal cells (MSCs) showed ~50 % narrower patterns by day 7, sustained to day 36 (p < 0.001 vs. static, which widened to 137 ± 20 %). Actuated MSC spheroids elongated, forming bipedal shapes and fusing into extended patterns (length 480 ± 158 μm, p < 0.0001) over 36 days. In 14-day human umbilical vein endothelial cells (HUVEC)-MSC co-cultures (10:1), actuation reduced pattern width by 27.5 % (p = 0.0236), promoted early protrusions, and decreased cell circularity (vs. 2 % increase in static, p = 0.0173), indicating enhanced elongation and potential vascularization. EXPECT's dynamic, actuationmediated control of anisotropic cell organization overcomes limitations of static hydrogels, offering significant potential for engineering complex, organized tissues in regenerative medicine.


Keywords
Embedded 3D bioprinting Thermosensitive hydrogels Mesenchymal stromal cells Cell alignment Endothelial cells
DOI
10.1016/j.smaim.2025.09.002

Pylostomou, A., Loča, D. EXPECT: A thermosensitive embedded bioprinting platform for guided spatial cell organization. Smart Materials in Medicine, 2025, Vol. 6, pp.347-367. Available from: doi:10.1016/j.smaim.2025.09.002

Publication language
English (en)
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