Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712, USA.
Biomaterials. 2010 May;31(14):3930-40. doi: 10.1016/j.biomaterials.2010.01.125. Epub 2010 Feb 19.
We report the ability to direct the differentiation pathway of neural progenitor cells (NPCs) within hydrogels having tunable mechanical properties. By modifying the polymeric sugar hyaluronic acid (HA), a major extracellular matrix component in the fetal mammalian brain, with varying numbers of photocrosslinkable methacrylate groups, hydrogels could be prepared with bulk compressive moduli spanning the threefold range measured for neonatal brain and adult spinal cord. Ventral midbrain-derived NPCs were photoencapsulated into HA hydrogels and remained viable after encapsulation. After three weeks, the majority of NPCs cultured in hydrogels with mechanical properties comparable to those of neonatal brain had differentiated into neurons (ss-III tubulin-positive), many of which had extended long, branched processes, indicative of a relatively mature phenotype. In contrast, NPCs within stiffer hydrogels, with mechanical properties comparable to those of adult brain, had differentiated into mostly astrocytes (glial fibrillary acidic protein (GFAP)-positive). Primary spinal astrocytes cultured in the hydrogel variants for two weeks acquired a spread and elongated morphology only in the stiffest hydrogels evaluated, with mechanical properties similar to adult tissue. Results demonstrate that the mechanical properties of these scaffolds can assert a defining influence on the differentiation of ventral midbrain-derived NPCs, which have strong clinical relevance because of their ability to mature into dopaminergic neurons of the substantia nigra, cells that idiopathically degenerate in individuals suffering from Parkinson's disease.
我们报告了在具有可调机械性能的水凝胶中指导神经祖细胞（NPC）分化途径的能力。通过用不同数量的光交联甲基丙烯酰基修饰高分子糖透明质酸（HA），一种在胎鼠大脑中主要的细胞外基质成分，可以制备出具有三倍于新生脑和成年脊髓的压缩模量范围的水凝胶。腹侧中脑神经祖细胞被光包封到 HA 水凝胶中，包封后仍然存活。三周后，在与新生脑机械性能相当的水凝胶中培养的大多数 NPC 分化为神经元（ss-III 微管蛋白阳性），其中许多神经元延伸出长而分支的突起，表明其具有相对成熟的表型。相比之下，在与成年脑机械性能相当的更硬水凝胶中培养的 NPC 大多分化为星形胶质细胞（胶质纤维酸性蛋白（GFAP）阳性）。在水凝胶变体中培养两周的原代脊髓星形胶质细胞仅在评估的最硬水凝胶中获得了扩展和伸长的形态，其机械性能与成年组织相似。结果表明，这些支架的机械性能可以对腹侧中脑神经祖细胞的分化产生决定性影响，因为它们具有成熟为黑质多巴胺能神经元的能力，而黑质多巴胺能神经元在患有帕金森病的个体中会自发性退化，因此具有很强的临床相关性。
