Craniofacial Development and Tissue Biology, Tohoku University Graduate School of Dentistry.
Department of Optical Imaging, Institute for Medical Photonics Research, Preeminent Medical Photonics Education & Research Center, Hamamatsu University School of Medicine.
Biomed Res. 2023;44(4):173-179. doi: 10.2220/biomedres.44.173.
Matrix-assisted laser desorption/ionization imaging mass spectrometry (IMS) is used to comprehensively visualize the spatial distribution of numerous biomolecules. The present study was designed to investigate the distribution of phospholipids in developing rat teeth by IMS to identify the characteristic phospholipid molecules for tooth development, and to evaluate the suitability of tissue preparation methods. Rats at postnatal day 3 were euthanized, and the resected head specimens were either fixed or not fixed with 4% paraformaldehyde (PFA), and decalcified or not decalcified in 10% ethylenediaminetetraacetic acid (EDTA) before being frozen. Subsequently, sections were prepared and mounted on glass slides coated with indium tin oxide, and analyzed by IMS. The mass spectra showed the highest peaks around m/z 706, 732, and 734 in the region of interest. Characteristic localization of signals in the tooth buds was seen around m/z 706 and 732, and a database search indicated that the corresponding molecules were phosphatidylcholines. The signals were localized to the dental papillae and enamel epithelia in the tooth buds. The PFA-fixed specimens with or without EDTA decalcification showed preserved IMS signals, while the non-fixed specimens showed fewer signals. Thus, PFA fixation with EDTA decalcification appears to be suitable for IMS analysis of calcified tissues.
基质辅助激光解吸/电离成像质谱（IMS）用于全面可视化众多生物分子的空间分布。本研究旨在通过 IMS 研究磷脂在发育中的大鼠牙齿中的分布，以鉴定牙齿发育的特征磷脂分子，并评估组织准备方法的适用性。在出生后第 3 天处死大鼠，切除的头部标本用 4%多聚甲醛（PFA）固定或不固定，然后用 10%乙二胺四乙酸（EDTA）脱钙或不脱钙，然后冷冻。随后，制备切片并安装在涂有铟锡氧化物的载玻片上，通过 IMS 进行分析。质谱显示在感兴趣区域中 m/z 706、732 和 734 附近出现最高峰值。在牙蕾区域观察到 m/z 706 和 732 处的信号特征定位，数据库搜索表明相应的分子是磷脂酰胆碱。信号定位在牙蕾的牙髓和釉质上皮中。用或不用 EDTA 脱钙的 PFA 固定标本显示保存的 IMS 信号，而未固定的标本显示信号较少。因此，用 EDTA 脱钙的 PFA 固定似乎适合于钙化组织的 IMS 分析。
