在美国康涅狄格大学生物医学工程师Thanh Nguyen的带领下，该研究团队开发出了一种可生物降解且可提供电刺激的支架材料。它是由一种无毒的压电聚合物PLLA的纳米纤维制成的。压电材料在施加机械应力后会产生电荷。其想法是，在骨折部位植入该材料后，医生或患者会定期使用外部手持设备向其发送超声波脉冲。这些脉冲会使脚手架产生振动，这些振动产生的应力又会使它产生一个微弱但有治疗作用的电场。当人体受刺激的骨细胞在支架内继续繁殖时，它将逐渐无害地溶解。最终，该材料将完全被自然骨所取代。在目前进行的测试中，这种材料已经被用来促进小鼠头骨骨折的愈合。科学家们现在正致力于让这种支架更有利于骨骼生长，并更好地了解电场究竟是如何刺激骨细胞繁殖的。最终，人们希望这项技术还能帮助其他类型的组织，如肌肉、神经或软骨的再生长。

Electrical stimulation (ES) has been shown to induce and enhance bone regeneration. By combining this treatment with tissue-engineering approaches (which rely on biomaterial scaffolds to construct artificial tissues), a replacement bone-graft with strong regenerative properties can be achieved while avoiding the use of potentially toxic levels of growth factors. Unfortunately, there is currently a lack of safe and effective methods to induce electrical cues directly on cells/tissues grown on the biomaterial scaffolds. Here, we present a novel bone regeneration method which hybridizes ES and tissue-engineering approaches by employing a biodegradable piezoelectric PLLA (Poly(L-lactic acid)) nanofiber scaffold which, together with externally-controlled ultrasound (US), can generate surface-charges to drive bone regeneration. We demonstrate that the approach of using the piezoelectric scaffold and US can enhance osteogenic differentiation of different stem cells in vitro, and induce bone growth in a critical-sized calvarial defect in vivo. The biodegradable piezoelectric scaffold with applied US could significantly impact the field of tissue engineering by offering a novel biodegradable, battery-free and remotely-controlled electrical stimulator.

doi.org/10.1016/j.nanoen.2020.105028

王鹏