Neural Regeneration Research ›› 2026, Vol. 21 ›› Issue (5): 2031-2039.doi: 10.4103/NRR.NRR-D-24-00431

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Magnetic resonance imaging tracing of superparamagnetic iron oxide nanoparticle–labeled mesenchymal stromal cells for repairing spinal cord injury

Xiaoli Mai1, #, Yuanyuan Xie2, #, Zhichong Wu3, #, Junting Zou1 , Jiacheng Du4 , Yunpeng Shen5 , Hao Liu6 , Bo Chen7 , Mengxia Zhu1 , Jiong Shi8 , Yang Chen5 , Bing Zhang1, *, Zezhang Zhu3, *, Bin Wang2, *, Ning Gu9   

  1. 1 Department of Radiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, Jiangsu Province, China;  2 Clinical Stem Cell Center, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, Jiangsu Province, China;  3 Department of Spinal Surgery, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, Jiangsu Province, China;  4 State Key Laboratory of Bioelectronics and Jiangsu Key Laboratory of Biomaterials and Devices, School of Biological Sciences and Medical Engineering, Southeast University, Nanjing, Jiangsu Province, China;  5 Laboratory of Image Science and Technology, Southeast University, Nanjing, Jiangsu Province, China;  6 Department of Neurosurgery, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, Jiangsu Province, China;  7 Institute of Materials Science and Devices, School of Materials Science and Engineering, Suzhou University of Science and Technology, Suzhou, Jiangsu Province, China;  8 Department of Pathology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, Jiangsu Province, China;  9 Nanjing Key Laboratory for Cardiovascular Information and Health Engineering Medicine, Institute of Clinical Medicine, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, Jiangsu Province, China
  • Online:2026-05-15 Published:2025-08-23
  • Contact: Bin Wang, MD, PhD, wanbin022800@126.com; Bing Zhang, MD, PhD, zhangbing_nj@vip.163.com; Zezhang Zhu, MD, PhD, zhuzezhang@126.com.
  • Supported by:
    This study was supported by the National Key R&D Program of China, Nos. 2017YFA0104302 (to NG and XM) and 2017YFA0104304 (to BW and ZZ).

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Abstract: Mesenchymal stromal cell transplantation is an effective and promising approach for treating various systemic and diffuse diseases. However, the biological characteristics of transplanted mesenchymal stromal cells in humans remain unclear, including cell viability, distribution, migration, and fate. Conventional cell tracing methods cannot be used in the clinic. The use of superparamagnetic iron oxide nanoparticles as contrast agents allows for the observation of transplanted cells using magnetic resonance imaging. In 2016, the National Medical Products Administration of China approved a new superparamagnetic iron oxide nanoparticle, Ruicun, for use as a contrast agent in clinical trials. In the present study, an acute hemi-transection spinal cord injury model was established in beagle dogs. The injury was then treated by transplantation of Ruicun-labeled mesenchymal stromal cells. The results indicated that Ruicunlabeled mesenchymal stromal cells repaired damaged spinal cord fibers and partially restored neurological function in animals with acute spinal cord injury. T2*-weighted imaging revealed low signal areas on both sides of the injured spinal cord. The results of quantitative susceptibility mapping with ultrashort echo time sequences indicated that Ruicun-labeled mesenchymal stromal cells persisted stably within the injured spinal cord for over 4 weeks. These findings suggest that magnetic resonance imaging has the potential to effectively track the migration of Ruicun-labeled mesenchymal stromal cells and assess their ability to repair spinal cord injury.

Key words: acute spinal cord injury, diffusion tensor imaging, dynamic migration, mesenchymal stromal cells, neural function, neuronal regeneration, quantitative susceptibility mapping, repairability, ruicun, superparamagnetic iron oxide nanoparticle