Induced pluripotent stem cells (iPSCs) are developmentally equivalent to embryonic stem cells (ESCs) in many aspects of their regenerative properties and proliferation. iPSCs hold advantages over ESCs partly because they lack the same ethical constraints posed by the scientifi c community. Exogenous factor-based reprogramming of somatic cells into a pluripotent embryonic stem cell-like state was described in Dr. Shinya Yamanaka’s seminal work in 2006(1). Yamanaka’s discovery enables current iPSC technology; furthermore, iPSC technology enables ethical derivation of instrumental tools vital to research spanning fundamental biology, regenerative medicine, drug discovery and, more recently, food sciences.

The culture, handling, and sorting of induced pluripotent stem cells require special care for reliable results. Culturing iPSCs is a time consuming and laborious process with challenges that require a substantial commitment of energy and resources. iPSC technology has increased the availability of cells to study many applications that are otherwise difficult or impossible, such as neuroscience and predictive disease modeling(2). Maintaining the naïve state and pluripotency (ability to differentiate into three primary germ layers) is reliant on regulating variables such as nutrient composition, temperature, and other developmental cues. Differentiating cultures are heterogeneous, and although maintaining a homogeneous stem cell culture is possible, researchers often need other tools to succeed. The WOLF cell sorter is advantageous to the success of gently sorting homogeneous stem cells and eliminating unwanted cells. In addition to the WOLF cell sorter, the WOLF G2 can also facilitate these gentle sorts by increasing the color capabilities with the addition of a second laser. The 488 nm and 637 nm lasers were leveraged to obtain approximately 93% percent purity and > 99% viability using the methods as outlined below. In addition, NanoCellect’s microfl uidic sorting technology together with defi ned and animal-free growth medium that enhances retention of naivety and pluripotency, enables researchers to generate consistent high-quality results(3,4).

Fluorochrome-conjugated antibodies directed to surface antigens can verify whether stem cells have maintained or lost indicators of pluripotency. Here we demonstrate that the cell surface markers SSEA-4 (Stage-specifi c Embryonic Antigen-4) and TRA-1-60-R (Tumor-related Antigen-1-60 [R]), expressed by naïve ESCs and iPSCs, are robust surface markers for gentle microfl uidic enrichment of hiPSCs on the WOLF G2. Expression of both SSEA-4 and TRA-1-60-R is downregulated following cell differentiation(5).