Establishment of in vitro experimental method for biological evaluation of biodegradable magnesium

可生物降解镁生物学评价体外实验方法的建立

• 批准号: 22K12903
• 负责人: 張 麓ルウ
• 金额: $ 2.66万
• 依托单位: National Institute of Advanced Industrial Science and Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2022
• 资助国家: 日本
• 起止时间: 2022-04-01 至 2025-03-31
• 项目状态: 未结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-22K12903/
• 关键词: 生分解性マグネシウム; 初期分解挙動; In vitro; In vivo; 表面分析

本研究の目的は，医療応用が期待されている生分解性Mg材料を対象に， In vitro（浸漬）試験とIn vivo（家兎埋植）試験における材料の生分解挙動とその関連性を解明し，生体内のMg分解挙動を適切に再現できるIn vitro試験法を確立することである．令和4年度では、分解初期の挙動を明らかにするために，純Mgを細胞培養液（DMEM+10%FBS）に1日の浸漬，また家兎の大腿骨端部と背部皮下に1日の埋植を実施し，走査電子顕微鏡（SEM）及びX線光電子分光法（XPS）を用いて表面分解生成物の観察と組成分析を行った．浸漬試験及び家兎埋植試験のいずれのMg表面においてMg(OH)2，Ca-phosphateとMgCO3等の分解生成物の存在が確認され，浸漬試験試料表面の分解生成物には亀裂が，埋植試料表面の分析生成物には亀裂に加え局部的な剥離も観察された．また，浸漬試験結果から，Ca-phosphate層は緻密であり保護層としてMg表面の腐食挙動に大きく影響し，その生成は緩衝系の重炭素イオン濃度に依存することが分かった．具体的には，重炭素イオン濃度が低い場合には，Ca-phosphate層が生成しやすく腐食が抑制され，表面が相対的平坦であった；一方，重炭素イオン濃度が高い場合には，Ca-phosphate層が生成し難く腐食が進行し亀裂が生じる．以上，浸漬と埋植の両試験の結果より，重炭素イオン濃度がMgの分解挙動に影響する重要な因子であると結論付けた．これまで長期試験での通説として埋植試験におけるMg腐食率は浸漬試験より低いとされてきたが，本研究成果である初期埋植試験におけるMg腐食率は浸漬試験より高いことが分かった．これは局所的な重炭素イオン濃度の違い，また家兎の活動に伴う大腿骨内の骨髄が流れる動的環境に影響された結果と考えられる．

The purpose of this study is to clarify the relationship between the biological decomposition behavior of Mg In vivo and the biological decomposition behavior of Mg in vivo, and to establish an appropriate method for reproducing the decomposition behavior of Mg in vivo. In the fourth year of the experiment, the cell culture solution (DMEM+10%FBS) was immersed in pure Mg for 1 day, and the femoral bone tip and back were implanted subcutaneously for 1 day. The surface decomposition products were observed and analyzed by electron microscopy (SEM) and X ray photoelectron spectroscopy (XPS). The existence of decomposition products such as Mg(OH)2, Ca-phosphate and MgCO3 on the surface of Mg in immersion test and implantation test was confirmed. The decomposition products on the surface of immersion test sample were cracked, and the analytical products on the surface of implantation test sample were cracked and partially peeled off. As a result of the immersion test, the Ca-phosphate layer is dense, the protective layer is highly affected by the corrosion of Mg surface, and the formation of buffer system is dependent on the concentration of heavy carbon. Specifically, when the concentration of heavy carbon is low, Ca-phosphate layer is formed, corrosion is inhibited, and the surface is relatively flat; on the other hand, when the concentration of heavy carbon is high, Ca-phosphate layer is formed, corrosion is inhibited, and cracking occurs. The results of immersion and implantation tests show that the concentration of heavy carbon is an important factor affecting the decomposition of Mg. The results of this study show that the Mg scavenging rate in the initial stage of implantation is higher than that in the immersion stage. The concentration of heavy carbon in the body is not in accordance with the law, and the activity of the family is accompanied by the flow of bone in the thigh bone.