Brunel Lucia G, Long Chris M, Christakopoulos Fotis, Cai Betty, Johansson Patrik K, Singhal Diya, Enejder Annika, Myung David, Heilshorn Sarah C
Department of Chemical Engineering, Stanford University, Stanford, CA, USA.
Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA.
Acta Biomater. 2025 Jan 24;193:128-142. doi: 10.1016/j.actbio.2025.01.009. Epub 2025 Jan 9.
Hydrogels composed of collagen, the most abundant protein in the human body, are widely used as scaffolds for tissue engineering due to their ability to support cellular activity. However, collagen hydrogels with encapsulated cells often experience bulk contraction due to cell-generated forces, and conventional strategies to mitigate this undesired deformation often compromise either the fibrillar microstructure or cytocompatibility of the collagen. To support the spreading of encapsulated cells while preserving the structural integrity of the gels, we present an interpenetrating network (IPN) of two distinct collagen networks with different crosslinking mechanisms and microstructures. First, a physically self-assembled collagen network preserves the fibrillar microstructure and enables the spreading of encapsulated human corneal mesenchymal stromal cells. Second, an amorphous collagen network covalently crosslinked with bioorthogonal chemistry fills the voids between fibrils and stabilizes the gel against cell-induced contraction. This collagen IPN balances the biofunctionality of natural collagen with the stability of covalently crosslinked, engineered polymers. Taken together, these data represent a new avenue for maintaining both the fiber-induced spreading of cells and the structural integrity of collagen hydrogels by leveraging an IPN of fibrillar and amorphous collagen networks. STATEMENT OF SIGNIFICANCE: Collagen hydrogels are widely used as scaffolds for tissue engineering due to their support of cellular activity. However, collagen hydrogels often undergo undesired changes in size and shape due to cell-generated forces, and conventional strategies to mitigate this deformation typically compromise either the fibrillar microstructure or cytocompatibility of the collagen. In this study, we introduce an innovative interpenetrating network (IPN) that combines physically self-assembled, fibrillar collagen-ideal for promoting cell adhesion and spreading-with covalently crosslinked, amorphous collagen-ideal for enhancing bulk hydrogel stability. Our IPN design maintains the native fibrillar structure of collagen while significantly improving resistance against cell-induced contraction, providing a promising solution to enhance the performance and reliability of collagen hydrogels for tissue engineering applications.
水凝胶由人体中最丰富的蛋白质胶原蛋白组成，由于其能够支持细胞活性，因此被广泛用作组织工程的支架。然而，含有封装细胞的胶原蛋白水凝胶常常会因细胞产生的力而发生整体收缩，而减轻这种不良变形的传统策略往往会损害胶原蛋白的纤维微观结构或细胞相容性。为了在保持水凝胶结构完整性的同时支持封装细胞的铺展，我们提出了一种由两种具有不同交联机制和微观结构的独特胶原蛋白网络组成的互穿网络（IPN）。首先，物理自组装的胶原蛋白网络保留了纤维微观结构，并使封装的人角膜间充质基质细胞能够铺展。其次，通过生物正交化学共价交联的无定形胶原蛋白网络填充了纤维之间的空隙，并稳定水凝胶以抵抗细胞诱导的收缩。这种胶原蛋白IPN平衡了天然胶原蛋白的生物功能与共价交联工程聚合物的稳定性。综上所述，这些数据代表了一条新途径，即通过利用纤维状和无定形胶原蛋白网络的IPN来维持细胞的纤维诱导铺展和胶原蛋白水凝胶的结构完整性。重要性声明：胶原蛋白水凝胶由于其对细胞活性的支持而被广泛用作组织工程的支架。然而，胶原蛋白水凝胶常常会因细胞产生的力而发生不期望的尺寸和形状变化，而减轻这种变形的传统策略通常会损害胶原蛋白的纤维微观结构或细胞相容性。在本研究中，我们引入了一种创新的互穿网络（IPN），它将物理自组装的纤维状胶原蛋白（有利于促进细胞粘附和铺展）与共价交联的无定形胶原蛋白（有利于增强整体水凝胶稳定性）结合在一起。我们的IPN设计保持了胶原蛋白的天然纤维结构，同时显著提高了对细胞诱导收缩的抵抗力，为提高胶原蛋白水凝胶在组织工程应用中的性能和可靠性提供了一个有前景的解决方案。
