Department of Biomedical Engineering, UC Davis, Davis, CA 95616, USA.
Tissue Eng Part A. 2011 Dec;17(23-24):2931-42. doi: 10.1089/ten.tea.2011.0030. Epub 2011 Sep 1.
Fibrin is a promising matrix for use in promoting nerve repair given its natural occurrence in peripheral nerve injuries, and the biophysical properties of this matrix can be regulated to modulate tissue regeneration. In this study, we examined the effect of physical and mechanical properties of fibrin gels on dorsal root ganglia (DRG) neurite extension. Increases in fibrinogen concentration increased the number of fibrin strands, resulting in decreased pore size and increased stiffness. Neurite extension was reduced when DRG explants were cultured within fibrin gels of increasing fibrinogen concentrations (from 9.5 to 141 mg/mL). The addition of NaCl also increased the number of fibrin strands, reducing fiber diameter and porosity, while increasing mechanical strength, and reductions in neurite extension correlated with increases in NaCl content. We determined that neurite extension within fibrin gels is dependent on fibrinolysis and is mediated by the secretion of serine proteases and matrix metalloproteinases by entrapped DRGs, as confirmed by culturing cells in the presence of inhibitors against these enzymes and real-time-polymerase chain reaction. Taken together, the results of this study provide new insight into the effect of fibrin gel biophysical properties on neurite extension and suggest new opportunities to improve the efficacy of these materials when used as nerve guidance conduits.
纤维蛋白是一种很有前途的基质，可用于促进神经修复，因为它在周围神经损伤中自然存在，并且可以调节这种基质的物理和机械性能来调节组织再生。在这项研究中，我们研究了纤维蛋白凝胶的物理和机械性能对背根神经节（DRG）轴突延伸的影响。纤维蛋白原浓度的增加会增加纤维蛋白丝的数量，从而导致孔径减小和刚性增加。当 DRG 外植体在纤维蛋白原浓度逐渐增加的纤维蛋白凝胶中培养时（从 9.5 到 141mg/ml），轴突延伸会减少。NaCl 的添加也会增加纤维蛋白丝的数量，从而减小纤维直径和孔隙率，同时增加机械强度，轴突延伸的减少与 NaCl 含量的增加相关。我们确定纤维蛋白凝胶内的轴突延伸依赖于纤维蛋白溶解，并由包埋的 DRG 分泌丝氨酸蛋白酶和基质金属蛋白酶介导，这一点通过在存在这些酶抑制剂的情况下培养细胞和实时聚合酶链反应得到证实。总之，这项研究的结果提供了对纤维蛋白凝胶生物物理特性对轴突延伸影响的新见解，并为改善这些材料作为神经引导导管的疗效提供了新的机会。
