Testore Daniele, Zoso Alice, Paoletti Camilla, Groppo Sara, Marcello Elena, Chiono Valeria
Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy.
POLITO BiomedLab, Politecnico di Torino, Torino, Italy.
Mater Today Bio. 2025 Jul 22;34:102121. doi: 10.1016/j.mtbio.2025.102121. eCollection 2025 Oct.
Growing evidence has shown that cells respond to the viscoelastic properties of the extracellular matrix (ECM), particularly its stress-relaxation, which influences their spreading, proliferation, and remodeling. Since cardiac tissue viscoelasticity plays a key role in modulating cellular mechanosensing, the development of biomimetic viscoelastic hydrogels is highly needed in cardiac tissue engineering (CTE). This work presents bio-orthogonal double cross-linked alginate-gelatin hydrogels with tunable viscoelasticity, designed to replicate the dynamic mechanical properties of cardiac ECM. Alginate and gelatin were functionalized with azide groups and cross-linked by a 4-arm-dibenzocyclooctyne (DBCO) crosslinker using strain-promoted azide-alkyne cycloaddition (SPAAC) with 0.5:1 (AG_Click(R0.5)) and 1:1 (AG_Click(R1)) DBCO:azide molar ratios. Calcium ions were also introduced to obtain double cross-linked hydrogels (AG_DC(R0.5) and AG_DC(R1)). Rheology showed that hydrogels exhibited tunable stiffness and stress relaxation, closely mimicking the properties of native cardiac tissue. The behavior of human cardiac fibroblasts (HCFs), seeded on hydrogels, was analyzed. When compared to purely elastic polyacrylamide (pAAm) hydrogels with comparable stiffness, soft stress-relaxing hydrogels (AG_Click(R0.5) and AG_DC(R0.5)) were found to promote cell spreading area, while stiffer stress-relaxing hydrogels (AG_Click(R1) and AG_DC(R1)) enhanced asymmetric cell elongation, reflecting substrate-mediated mechanosensing. Additionally, HCFs showed high viability when cultured in 3D hydrogels over 7 days. Overall, rapid gelation, biocompatibility, and tunable viscoelastic properties of bio-orthogonal double cross-linked alginate-gelatin hydrogels support their use as injectable formulations or engineered cardiac tissues for CTE.
越来越多的证据表明，细胞会对细胞外基质（ECM）的粘弹性特性做出反应，尤其是其应力松弛特性，这会影响细胞的铺展、增殖和重塑。由于心脏组织的粘弹性在调节细胞机械传感中起关键作用，因此心脏组织工程（CTE）非常需要开发仿生粘弹性水凝胶。这项工作展示了具有可调粘弹性的生物正交双交联藻酸盐-明胶水凝胶，旨在复制心脏ECM的动态力学性能。藻酸盐和明胶用叠氮基团进行功能化，并使用四臂二苯并环辛炔（DBCO）交联剂通过应变促进的叠氮-炔环加成反应（SPAAC）进行交联，DBCO与叠氮的摩尔比分别为0.5:1（AG_Click(R0.5)）和1:1（AG_Click(R1)）。还引入了钙离子以获得双交联水凝胶（AG_DC(R0.5)和AG_DC(R1)）。流变学表明，水凝胶表现出可调的刚度和应力松弛，紧密模拟天然心脏组织的特性。分析了接种在水凝胶上的人心脏成纤维细胞（HCF）的行为。与具有可比刚度的纯弹性聚丙烯酰胺（pAAm）水凝胶相比，发现柔软的应力松弛水凝胶（AG_Click(R0.5)和AG_DC(R0.5)）可促进细胞铺展面积，而较硬的应力松弛水凝胶（AG_Click(R1)和AG_DC(R1)）则增强了不对称细胞伸长，反映了底物介导的机械传感。此外，HCF在3D水凝胶中培养7天时显示出高活力。总体而言，生物正交双交联藻酸盐-明胶水凝胶的快速凝胶化、生物相容性和可调粘弹性特性支持它们用作CTE的可注射制剂或工程化心脏组织。
