Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, P. R. China.
Yixing People's Hospital, Yixing, P. R. China.
J Tissue Eng Regen Med. 2018 Apr;12(4):e2085-e2098. doi: 10.1002/term.2641. Epub 2018 Feb 6.
A main challenge for use of scaffolds in bone engineering involves non-invasive monitoring in vivo and enhanced bone regeneration. The tissue repair effect of superparamagnetic iron oxide nanoparticles (SPIONs) was demonstrated previously by our group. However, testing in vivo is needed to confirm in vitro results. Here, SPIONs loaded gelatin sponge (GS) was used as a scaffold (SPIONs-GS) and implanted in the incisor sockets of Sprague-Dawley rats. Incisor sockets filled with nothing and filled with GS served as controls. Rats were sacrificed at 2 and 4 weeks. A significant decrease in the signal intensity of T2-weighted magnetic resonance imaging (MRI) in the SPIONs-GS group was noted. Changes in image intensity of scaffolds (indicating scaffold degradation and interaction with host tissues) could be visually monitored over time. Microcomputed tomography showed that the SPIONs-GS group had more newly formed bone (64.44 ± 10.92 vs. 28.1 ± 4.49, p < .0001) and a better preserved alveolar ridge than blank control group at 4 weeks (0.962 ± 0.01 vs. 0.92 ± 0.01, p < .0001). Histology confirmed imaging results, showing good consistency in new bone formation and scaffold degradation. The number of SPIONs decreased rapidly with time due to quick degradation of GS, whereas the number of endocytic SPIONs in cells increased with time. These residual SPIONs, together with newly formed bone, could be detected by MRI at 4 weeks. Therefore, it was clear that SPIONs induced active osteogenesis. In conclusion, good visibility on MRI and enhanced regeneration of bone can be obtained by implanting SPIONs-GS in vivo without using an external magnetic field.
支架在骨工程中的应用面临的一个主要挑战是体内的非侵入性监测和增强骨再生。我们小组之前已经证明了超顺磁氧化铁纳米粒子（SPIONs）的组织修复效果。然而，需要进行体内测试来确认体外结果。在这里，负载明胶海绵（GS）的 SPIONs 被用作支架（SPIONs-GS）并植入 Sprague-Dawley 大鼠的切牙牙槽中。没有填充任何物质和填充 GS 的切牙牙槽作为对照。大鼠在 2 周和 4 周时被处死。SPIONs-GS 组的 T2 加权磁共振成像（MRI）信号强度显著降低。随着时间的推移，可以直观地监测支架图像强度的变化（表明支架降解和与宿主组织的相互作用）。微计算机断层扫描显示，与空白对照组相比，SPIONs-GS 组在 4 周时具有更多的新骨形成（64.44±10.92 比 28.1±4.49，p<.0001）和更好的牙槽嵴保存（0.962±0.01 比 0.92±0.01，p<.0001）。组织学证实了成像结果，显示了新骨形成和支架降解的良好一致性。由于 GS 的快速降解，SPIONs 的数量随时间迅速减少，而细胞内内吞的 SPIONs 的数量随时间增加。这些残留的 SPIONs 与新形成的骨一起，可在 4 周时通过 MRI 检测到。因此，很明显 SPIONs 诱导了活性成骨。总之，通过在体内植入 SPIONs-GS 而无需使用外部磁场，可以在 MRI 上获得良好的可视性，并增强骨的再生。
