School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom.
Biomacromolecules. 2012 Dec 10;13(12):4032-8. doi: 10.1021/bm301321d. Epub 2012 Nov 2.
Hydrogels have been widely investigated as 3D culture substrates because of their reported structural similarity to the extracellular matrix (ECM). Limited ECM deposition, however, occurs within these materials, so the resulting "tissues" bear little resemblance to those found in the body. Here matrix deposition by fibroblasts encapsulated within a calcium alginate (Ca-alg) hydrogel was investigated. Although the cells transcribed mRNA for coll Iα over a period of 3 weeks, very little collagen protein deposition was observed within the gel by histology or immunohistochemistry (IHC). Although molecular diffusion demonstrated charge dependency, this did not prevent the flux of both positively and negative charged amino acids through the gel, suggesting that the absence of ECM could not be attributed to substrate limitation. The flux of protein, however, was charge-dependent as proteins with a net negative charge passed quickly through the Ca-alg into the medium. The minimal collagen deposition within the Ca-alg was attributed to a combination of rapid movement of negatively charged procollagen through the gel and steric hindrance of fibril formation.
水凝胶因其结构与细胞外基质（ECM）相似而被广泛研究作为 3D 培养基质。然而，这些材料中 ECM 的沉积有限，因此产生的“组织”与体内的组织相差甚远。本研究中，通过将成纤维细胞包埋在钙藻酸盐（Ca-alg）水凝胶中来实现基质沉积。尽管细胞在 3 周的时间内转录了 coll Iα 的 mRNA，但组织学或免疫组织化学（IHC）观察到凝胶内几乎没有胶原蛋白沉积。尽管分子扩散表现出电荷依赖性，但这并没有阻止正电荷和负电荷氨基酸通过凝胶的通量，这表明缺乏 ECM 不能归因于基质限制。然而，蛋白质的通量是电荷依赖性的，因为带有净负电荷的蛋白质可以快速通过 Ca-alg 进入培养基。Ca-alg 内最小的胶原蛋白沉积归因于带负电荷的前胶原蛋白通过凝胶的快速移动和纤维形成的空间位阻的共同作用。
