Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA.
Acta Biomater. 2012 May;8(5):1778-91. doi: 10.1016/j.actbio.2011.12.008. Epub 2011 Dec 13.
Current therapeutic angiogenesis strategies are focused on the development of biologically responsive scaffolds that can deliver multiple angiogenic cytokines and/or cells in ischemic regions. Herein, we report on a novel electrospinning approach to fabricate cytokine-containing nanofibrous scaffolds with tunable architecture to promote angiogenesis. Fiber diameter and uniformity were controlled by varying the concentration of the polymeric (i.e. gelatin) solution, the feed rate, needle to collector distance, and electric field potential between the collector plate and injection needle. Scaffold fiber orientation (random vs. aligned) was achieved by alternating the polarity of two parallel electrodes placed on the collector plate thus dictating fiber deposition patterns. Basic fibroblast growth factor (bFGF) was physically immobilized within the gelatin scaffolds at variable concentrations and human umbilical vein endothelial cells (HUVEC) were seeded on the top of the scaffolds. Cell proliferation and migration was assessed as a function of growth factor loading and scaffold architecture. HUVECs successfully adhered onto gelatin B scaffolds and cell proliferation was directly proportional to the loading concentrations of the growth factor (0-100 bFGF ng/mL). Fiber orientation had a pronounced effect on cell morphology and orientation. Cells were spread along the fibers of the electrospun scaffolds with the aligned orientation and developed a spindle-like morphology parallel to the scaffold's fibers. In contrast, cells seeded onto the scaffolds with random fiber orientation, did not demonstrate any directionality and appeared to have a rounder shape. Capillary formation (i.e. sprouts length and number of sprouts per bead), assessed in a 3-D in vitro angiogenesis assay, was a function of bFGF loading concentration (0 ng, 50 ng and 100 ng per scaffold) for both types of electrospun scaffolds (i.e. with aligned or random fiber orientation).
目前的治疗性血管生成策略集中于开发能够在缺血区域中递呈多种血管生成细胞因子和/或细胞的生物响应性支架。在此，我们报告了一种新的静电纺丝方法，用于制造具有可调节结构的含细胞因子的纳米纤维支架，以促进血管生成。通过改变聚合物（例如明胶）溶液的浓度、进料速率、针到收集器的距离以及收集器板和注射针之间的电场电势来控制纤维直径和均匀性。通过在收集器板上交替放置两个平行电极来实现支架纤维的取向（随机与定向），从而决定纤维沉积模式。将碱性成纤维细胞生长因子（bFGF）物理固定在明胶支架中，浓度可变，将人脐静脉内皮细胞（HUVEC）接种在支架的顶部。作为生长因子负载和支架结构的函数，评估了细胞增殖和迁移。HUVEC 成功地黏附在明胶 B 支架上，细胞增殖与生长因子的负载浓度直接相关（0-100 bFGF ng/mL）。纤维取向对细胞形态和取向有明显的影响。细胞沿着静电纺丝支架的纤维展开，具有定向取向，并与支架的纤维平行形成梭形形态。相比之下，接种在具有随机纤维取向的支架上的细胞没有表现出任何方向性，并且似乎具有更圆的形状。在体外血管生成测定中，评估了毛细血管形成（即芽的长度和每个珠的芽数），其是两种类型的静电纺丝支架（即具有定向或随机纤维取向）的 bFGF 负载浓度（0 ng、50 ng 和 100 ng/支架）的函数。
