Department of Chemical & Biological Engineering, University of Idaho, Moscow, ID 83844-1021, USA.
Biosensors (Basel). 2021 Feb 16;11(2):50. doi: 10.3390/bios11020050.
Tendons are collagenous musculoskeletal tissues that connect muscles to bones and transfer the forces necessary for movement. Tendons are susceptible to injury and heal poorly, with long-term loss of function. Mesenchymal stem cell (MSC)-based therapies are a promising approach for treating tendon injuries but are challenged by the difficulties of controlling stem cell fate and of generating homogenous populations of stem cells optimized for tenogenesis (differentiation toward tendon). To address this issue, we aim to explore methods that can be used to identify and ultimately separate tenogenically differentiated MSCs from non-tenogenically differentiated MSCs. In this study, baseline and tenogenically differentiating murine MSCs were characterized for dielectric properties (conductivity and permittivity) of their outer membrane and cytoplasm using a dielectrophoretic (DEP) crossover technique. Experimental results showed that unique dielectric properties distinguished tenogenically differentiating MSCs from controls after three days of tenogenic induction. A single shell model was used to quantify the dielectric properties and determine membrane and cytoplasm conductivity and permittivity. Together, cell responses at the crossover frequency, cell morphology, and shell models showed that changes potentially indicative of early tenogenesis could be detected in the dielectric properties of MSCs as early as three days into differentiation. Differences in dielectric properties with tenogenesis indicate that the DEP-based label-free separation of tenogenically differentiating cells is possible and avoids the complications of current label-dependent flow cytometry-based separation techniques. Overall, this work illustrates the potential of DEP to generate homogeneous populations of differentiated stem cells for applications in tissue engineering and regenerative medicine.
肌腱是连接肌肉和骨骼并传递运动所需力量的胶原性肌肉骨骼组织。肌腱容易受伤，愈合不良，长期丧失功能。基于间充质干细胞（MSC）的治疗方法是治疗肌腱损伤的一种很有前途的方法，但面临着控制干细胞命运和产生优化用于肌腱发生（向肌腱分化）的同质干细胞群体的困难。为了解决这个问题，我们旨在探索可以用于鉴定和最终分离肌腱发生的 MSC 与非肌腱发生的 MSC 的方法。在这项研究中，使用介电泳（DEP）交叉技术，对基线和肌腱诱导的鼠 MSC 的细胞膜和细胞质的介电特性（电导率和介电常数）进行了特征描述。实验结果表明，在经过三天的肌腱诱导后，独特的介电特性将肌腱诱导的 MSC 与对照区分开来。使用单壳模型来量化介电特性，并确定膜和细胞质的电导率和介电常数。细胞在交叉频率的响应、细胞形态和壳模型一起表明，在分化的第三天，MSC 的介电特性中可能就可以检测到早期肌腱发生的潜在变化。随着肌腱发生的介电特性的差异表明，基于 DEP 的无标记分离肌腱发生细胞是可能的，并且避免了当前基于标记的流式细胞术分离技术的复杂性。总的来说，这项工作说明了 DEP 在产生同质的分化干细胞群体用于组织工程和再生医学应用方面的潜力。
