Drexel University, School of Biomedical Engineering, Science and Health System, Philadelphia, PA, USA.
Biomaterials. 2012 Dec;33(36):9167-78. doi: 10.1016/j.biomaterials.2012.09.009. Epub 2012 Sep 27.
Reconstruction of large bone defects remains problematic in orthopedic and craniofacial clinical practice. Autografts are limited in supply and are associated with donor site morbidity while other materials show poor integration with the host's own bone. This lack of integration is often due to the absence of periosteum, the outer layer of bone that contains osteoprogenitor cells and is critical for the growth and remodeling of bone tissue. In this study we developed a one-step platform to electrospin nanofibrous scaffolds from chitosan, which also contain hydroxyapatite nanoparticles and are crosslinked with genipin. We hypothesized that the resulting composite scaffolds represent a microenvironment that emulates the physical, mineralized structure and mechanical properties of non-weight bearing bone extracellular matrix while promoting osteoblast differentiation and maturation similar to the periosteum. The ultrastructure and physicochemical properties of the scaffolds were studied using scanning electron microscopy and spectroscopic techniques. The average fiber diameters of the electrospun scaffolds were 227 ± 154 nm as spun, and increased to 335 ± 119 nm after crosslinking with genipin. Analysis by X-ray diffraction, Fourier transformed infrared spectroscopy and energy dispersive spectroscopy confirmed the presence of characteristic features of hydroxyapatite in the composite chitosan fibers. The Young's modulus of the composite fibrous scaffolds was 142 ± 13 MPa, which is similar to that of the natural periosteum. Both pure chitosan scaffolds and composite hydroxyapatite-containing chitosan scaffolds supported adhesion, proliferation and osteogenic differentiation of mouse 7F2 osteoblast-like cells. Expression and enzymatic activity of alkaline phosphatase, an early osteogenic marker, were higher in cells cultured on the composite scaffolds as compared to pure chitosan scaffolds, reaching a significant, 2.4 fold, difference by day 14 (p < 0.05). Similarly, cells cultured on hydroxyapatite-containing scaffolds had the highest rate of osteonectin mRNA expression over 2 weeks, indicating enhanced osteoinductivity of the composite scaffolds. Our results suggest that crosslinking electrospun hydroxyapatite-containing chitosan with genipin yields bio-composite scaffolds, which combine non-weight-bearing bone mechanical properties with a periosteum-like environment. Such scaffolds will facilitate the proliferation, differentiation and maturation of osteoblast-like cells. We propose that these scaffolds might be useful for the repair and regeneration of maxillofacial defects and injuries.
在骨科和颅面临床实践中，重建大骨缺损仍然是一个问题。自体移植物的供应有限，并且与供体部位的发病率有关，而其他材料与宿主自身的骨骼结合不良。这种结合不良通常是由于缺乏骨膜所致，骨膜是骨骼的外层，包含成骨前体细胞，对于骨骼组织的生长和重塑至关重要。在这项研究中，我们开发了一种从壳聚糖一步电纺纳米纤维支架的平台，该支架还含有羟基磷灰石纳米颗粒，并与京尼平交联。我们假设，所得的复合支架代表了一个微环境，该微环境模拟了非承重骨细胞外基质的物理、矿化结构和机械性能，同时促进成骨细胞的分化和成熟，类似于骨膜。使用扫描电子显微镜和光谱技术研究了支架的超微结构和理化性质。电纺支架的平均纤维直径为 227±154nm，交联后增加到 335±119nm。X 射线衍射、傅里叶变换红外光谱和能量色散光谱分析证实了复合壳聚糖纤维中存在羟基磷灰石的特征。复合纤维支架的杨氏模量为 142±13MPa，与天然骨膜相似。纯壳聚糖支架和复合含羟基磷灰石壳聚糖支架均支持小鼠 7F2 成骨样细胞的黏附、增殖和成骨分化。与纯壳聚糖支架相比，在复合支架上培养的细胞中碱性磷酸酶（一种早期成骨标志物）的表达和酶活性更高，第 14 天达到显著的 2.4 倍差异（p<0.05）。同样，在含羟基磷灰石支架上培养的细胞在 2 周内具有最高的骨桥蛋白 mRNA 表达率，表明复合支架具有增强的成骨诱导性。我们的结果表明，用京尼平交联含羟基磷灰石的电纺壳聚糖可得到具有非承重骨机械性能和骨膜样环境的生物复合材料支架。这种支架将促进成骨样细胞的增殖、分化和成熟。我们提出，这些支架可能对修复和再生颌面缺陷和损伤有用。
