Summary

This document identifies quality standards and outlines basic core principles for the laboratory use of both tissue and pluripotent human stem cells and the in vitro model systems that rely on them. Building upon previous recommendations for the characterization of cell lines (Crook et al., 2010; Crook and Stacey, 2014; Stacey et al., 2013; The International Stem Cell Banking Initiative, 2009; The International Stem Cell Initiative, 2007; The Steering Committee of the International Stem Cell Initiative, 2005), these standards are best practice recommendations designed to improve the reproducibility of stem cell research within and between laboratories, and from cell line to cell line. While some of the principles articulated also apply to other species, this document focuses on human stem cells exclusively, and does not seek to provide recommendations regarding non-human species. It addresses standard research practices shared by human pluripotent and adult stem cells but does not include specific protocols or address individual differences in methodologies used to culture or characterize stem cells, which are extremely diverse. Overall, the emphasis of this document is creating a set of recommendations that, when taken together, establish the minimum characterization and reporting criteria for scientists, students, and technicians in basic research laboratories working with human stem cells.

This document focuses on:
1) basic characterization to describe cell identity, ensure culture integrity, and promote material safety;
2) the assessment of the undifferentiated state and pluripotency to appropriately evaluate cells and their developmental potential;
3) genomic characterization to assess genetic integrity and monitor the emergence of cellular changes that could interfere with the interpretation of results or manifest as potentially malignant traits; and
4) stem cell-based model systems to improve fidelity and utility of stem cell-derived model systems (organoids, microphysiological systems, engineered cells, etc.) in basic and preclinical research. The guidelines provided are intended to be both technically and financially feasible for the average research laboratory and, if undertaken, will promote rigor and reproducibility not only within the laboratory but broadly throughout the field.

Introduction

One of the primary goals of stem cell research is to identify and harness the mechanisms that control stem cell behavior, enabling the generation of cell types or tissues for basic and preclinical research. For the results and outputs from this research to be accurate and durable, high standards that ensure reproducibility and reliability should be applied to all stages of the research pipeline. For experiments involving in vitro stem cell cultures this is underpinned by the application of standardized characterization principles, that, when carefully and consistently implemented, increase confidence in experimental outputs and facilitate reproducibility across research laboratories.

All cultured cells are dynamic, living model systems that seek to capture a cellular state and serve as a surrogate that facilitates experimental interrogation of a biological system. In the case of stem cells, these cultures provide accessible experimental models for studying early development and disease and allow for the generation of functional cells and tissues with therapeutic potential. Characterization is an essential practice for ensuring culture integrity, establishing baseline phenotypic profiles, and providing insight into the fidelity with which the cells will accurately model the target biological system. For this reason, appropriate, systematic characterization has a direct and significant impact on the ability to obtain reproducible data, and the accuracy of the interpretation of that data.

Reproducibility issues in both basic and translational research can hinder progress and erode trust (Baker, 2016; Drucker, 2016). When systematically implemented, the deployment of appropriate characterization strategies, combined with good documentation practices, drive rigor and harmonization, which in turn facilitates the reproducibility and accuracy of experimental outputs. The benefits of adopting systematic characterization are substantial: Long- term efficiencies are realized, as waste and time lost to irreproducible experiments are reduced. Further, publications based on suitably characterized cell lines provide more accurate data that enables and accelerates research progress.

The need to implement standards and improve reproducibility of published scientific data has been a topic of high-level discussion in recent years and has been highlighted by major scientific journals (“Nature Editorial,” 2013; Baker, 2016). The advancement of culture methods to include tissue and pluripotent stem cells, and, specifically, the technical demands of generating consistent cell cultures and reproducible data outputs with these cells, is an area requiring considerable diligence and expertise. Thus, universally accepted quality standards are needed to improve the rigor and reproducibility of all research utilizing stem cells. Standards set researchers up for success, ensure rigor in preclinical research, ultimately strengthening the pipeline of therapies for patients.