2D Magnetic Microswimmers for Targeted Cell Transport and 3D Cell Culture Structure Construction

Cell
delivery using magnetic microswimmers is a promising tool
for targeted therapy. However, it remains challenging to rapidly and
uniformly manufacture cell-loaded microswimmers that can be assembled
into cell-supporting structures at diseased sites. Here, rapid and
uniform manufacturable 2D magnetic achiral microswimmers with pores
were fabricated to deliver bone marrow mesenchymal stem cells (BMSCs)
to regenerate articular-damaged cartilage. Under actuation with magnetic
fields, the BMSC-loaded microswimmers take advantage of the achiral
structure to exhibit rolling or swimming motions to travel on smooth
and rough surfaces, up inclined planes, or in the bulk fluid. Cell
viability, proliferation, and differentiation tests performed days
after cell seeding verified the microswimmers’ biocompatibility.
Long-distance targeting and in situ assemblies into 3D cell-supporting
structures with BMSC-loaded microswimmers were demonstrated using
a knee model and U-shaped wells. Overall, combining the advantages
of preparing an achiral 2D structured microswimmer with magnetically
driven motility results in a platform for cell transport and constructing
3D cell cultures that can improve cell delivery at lesion sites for
biomedical applications.

基于磁性微型游泳器（magnetic microswimmers）的细胞递送技术，是靶向治疗领域极具应用前景的技术手段。然而，如何快速且均匀地制备可在病变部位组装为细胞支持性结构（cell-supporting structures）的负载细胞微型游泳器，仍是一项颇具挑战的课题。本研究制备了具备孔隙结构的可快速均匀量产的二维非手性磁性微型游泳器（2D magnetic achiral microswimmers），用于递送骨髓间充质干细胞（bone marrow mesenchymal stem cells, BMSCs）以再生关节损伤软骨。在磁场驱动下，负载BMSCs的微型游泳器可借助非手性结构，展现滚动或游动运动模式，能够在光滑与粗糙表面、上行倾斜坡面乃至体相流体中移动。在细胞接种数日后开展的细胞活力、增殖与分化检测，证实了该微型游泳器具备良好的生物相容性。通过膝关节模型与U型孔板实验，本研究证实负载BMSCs的微型游泳器可实现长距离靶向递送，并能在病变部位原位组装为三维细胞支持性结构。综上，本研究将非手性二维结构微型游泳器的制备优势与磁驱动运动能力相结合，构建了一款可用于细胞递送与三维细胞培养（3D cell cultures）的平台，有望提升病变部位的细胞递送效率，助力生物医学应用。