Electrical signature of heterogeneous human mesenchymal stem cells

Abstract

Human mesenchymal stem cells (hMSCs) have gained traction in transplantation therapy due to their immunomodulatory, paracrine, immune-evasive, and multipotent differentiation potential. Given the heterogeneous nature of hMSCs, therapeutic treatments and robust in vivo and in vitro experiments require additional biomarkers to ensure reproducibility when using these stem cells. In this work, we utilized dielectrophoresis (DEP), a label-free electrokinetic phenomenon, to investigate and quantify the heterogeneity of hMSCs derived from the bone marrow (BM) and adipose tissue (AD). Through computer simulation, we identified that the transient slope of the DEP force spectra can be used as a metric of heterogeneity. The electrical properties of BM-hMSCs were compared to homogeneous mouse fibroblasts (NIH-3T3), human fibroblasts (WS1), and human embryonic kidney cells (HEK-293). BM-hMSCs DEP profile was most different from HEK-293 cells. We compared the DEP profiles of BM-hMSCs and AD-hMSCs and found they have similar membrane capacitances, differing cytoplasm conductivity, and transient slopes. Inducing both populations to differentiate into adipocyte and osteocyte cells revealed they behave differently in response to differentiation-inducing cytokines. Histology and RT-qPCR analyses of the differentiation-related genes revealed differences in heterogeneity between BM-hMSCs and AD-hMSCs. The differentiation profiles correlate well with the DEP profiles developed and indicate that these BM-hMSCs have higher differentiation potential than AD-hMSCs. Our results demonstrate using DEP, membrane capacitance, cytoplasm conductivity, and transient slope can uniquely characterize the inherent heterogeneity of hMSCs to guide robust and reproducible stem cell transplantation therapies.