Division of Medical Physics, Department of Radiation Oncology, School of Medicine, Stanford University, Stanford, CA, 94305, USA.
Molecular Imaging Program at Stanford (MIPS), Stanford University, Stanford, CA, 94305, USA.
Sci Rep. 2022 Feb 22;12(1):2955. doi: 10.1038/s41598-022-06938-6.
Regenerative medicine uses the patient own stem cells to regenerate damaged tissues. Molecular imaging techniques are commonly used to image the transplanted cells, either right after surgery or at a later time. However, few techniques are fast or straightforward enough to label cells intraoperatively. Adipose tissue-derived stem cells (ADSCs) were harvested from knee joints of minipigs. The cells were labeled with PET contrast agent by flowing mechanoporation using a microfluidic device. While flowing through a series of microchannels, cells are compressed repeatedly by micro-ridges, which open transient pores in their membranes and induce convective transport, intended to facilitate the transport of Ga-labeled and lipid-coated mesoporous nanoparticles (MSNs) into the cells. This process enables cells to be labeled in a matter of seconds. Cells labeled with this approach were then implanted into cartilage defects, and the implant was imaged using positron emission tomography (PET) post-surgery. The microfluidic device can efficiently label millions of cells with Ga-labeled MSNs in as little as 15 min. The method achieved labeling efficiency greater than 5 Bq/cell on average, comparable to 30 min-long passive co-incubation with Ga-MSNs, but with improved biocompatibility due to the reduced exposure to ionizing radiation. Labeling time could also be accelerated by increasing throughput through more parallel channels. Finally, as a proof of concept, ADSCs were labeled with Ga-MSNs and quantitatively assessed using clinical PET/MR in a mock transplant operation in pig knee joints. MSN-assisted mechanoporation is a rapid, effective and straightforward approach to label cells with Ga. Given its high efficiency, this labeling method can be used to track small cells populations without significant effects on viability. The system is applicable to a variety of cell tracking studies for cancer therapy, regenerative therapy, and immunotherapy.
再生医学利用患者自身的干细胞来再生受损组织。分子成像技术常用于对移植细胞进行成像，无论是在手术后还是在稍后的时间。然而，很少有技术足够快速或直接，可以在手术过程中对细胞进行标记。从小型猪的膝关节中提取脂肪组织源性干细胞（ADSCs）。使用微流控设备通过流动机械穿孔使 PET 造影剂标记细胞。当细胞流经一系列微通道时，细胞会被微脊反复压缩，这会在其细胞膜上打开瞬时孔，并诱导对流运输，旨在促进 Ga 标记的和脂质包被的介孔纳米粒子（MSNs）进入细胞。这个过程可以在几秒钟内对细胞进行标记。用这种方法标记的细胞然后被植入软骨缺陷中，并在手术后使用正电子发射断层扫描（PET）进行成像。微流控设备可以在短短 15 分钟内有效地用 Ga 标记的 MSNs 标记数百万个细胞。该方法的平均标记效率大于 5 Bq/细胞，与 30 分钟的 Ga-MSN 被动共孵育相当，但由于电离辐射暴露减少，生物相容性得到改善。通过增加更多平行通道的通量，可以加速标记时间。最后，作为概念验证，用 Ga-MSNs 标记 ADSCs，并在猪膝关节的模拟移植手术中使用临床 PET/MR 进行定量评估。MSN 辅助的机械穿孔是一种快速、有效和直接的方法，可以用 Ga 标记细胞。鉴于其高效率，这种标记方法可用于跟踪小细胞群，而对其活力影响不大。该系统适用于癌症治疗、再生治疗和免疫治疗等多种细胞跟踪研究。
