Studies on Bone Formation by Resorbable and Piezoelectric Polylactide

电磁再生器已在临床上用于促进骨痂的形成。此外，金属丝和金属板还被用于骨科手术，用于骨折的固定。这项工作的目的是为聚L-丙交酯(PLLA)的更广泛的临床应用积累科学信息。聚乳酸在机械拉伸时可以发电。PLLA在植入体内的同时也被吸收。1)改变PLLA的合成条件，制备出具有不同力学性能和吸收动力学的PLLA片材、板材和纤维。2)在可吸收载体中掺入细胞生长因子，如碱性成纤维细胞生长因子和转化生长因子-β，可促进异位骨再生和骨组织的骨形成。3)在大鼠股骨内植入磁化的钐钴块可促进骨的形成，与相同大小的未磁化的钐钴块形成明显的对比。4)PLLA纤维与可吸收聚己内酯纤维相结合，可方便地固定骨折，与传统的金属丝固定效果相似。将聚己内酯纤维加热至熔化温度以上，即可用可吸收纤维复合体固定骨折。5)PLLA纤维在扭转后向纤维方向伸展时可以产生电能。这表明，缠绕的PLLA纤维的组装除了在体内具有吸收能力外，还获得了压电性能。

Electromagnetic regenerators have been clinically used for enhancement of callus formation. In addition, metallic wires and plates have been used in orthopaedic surgery for fixation of fractured bones. The objective of this work was to accumulate scientific information for wider clinical applications of poly(L-lactide(PLLA) which can generate electricity upon being mechanically strained. PLLA is at the same time resorbed in the body when implanted.The following findings were obtained by this work. 1) Changes of synthetic conditions of PLLA produced PLLA sheet, plate, and fiber with a variety of mechanical properties and resorption kinetics. 2) Incorporation of cell growth factors such as bFGF and TGF-beta in resorbable carriers and subsequent implantation resulted in ectopic bone regeneration as well as in bone formation in native bone tissues. 3) Implantation of a magnetized metal block made from samarium cobalt in the rat femur promoted bone formation, in marked contrast with a non-magnetized samarium cobalt block of the same size. 4) Combination of PLLA fibers and resorbable poIy(epsilon-capro1actone) fibers could readily fix a fractured bone, similar to the conventional metal wire. The fixation of a fractured bone with the resorbable fiber combination could be carried out by heating the po1y(epsilon-capro1actone) fibers above the melting temperature. 5) PLLA fibers could generate electricity when they were twisted and then extended to the fiber direction. This indicates that the assemble of twisted PLLA fibers acquired a piezoelectric property in addition to resorbability in the body.