Isolation of Human Colon Stem Cells Using Surface Expression of PTK7

• Ex vivo cultured human colon stem cells (hCoSCs) express the surface marker PTK7
• hCoSCs with highest PTK7 surface abundance display highest self-renewal capacity
• Antibodies against PTK7 enable purification of hCoSCs from patient samples
• A fraction of PTK7+ hCoSCs display genetic features of crypt label retaining cells

SummaryInsertion of reporter cassettes into the Lgr5 locus has enabled the characterization of mouse intestinal stem cells (ISCs). However, low cell surface abundance of LGR5 protein and lack of high-affinity anti-LGR5 antibodies represent a roadblock to efficiently isolate human colonic stem cells (hCoSCs). We set out to identify stem cell markers that would allow for purification of hCoSCs. In an unbiased approach, membrane-enriched protein fractions derived from in vitro human colonic organoids were analyzed by quantitative mass spectrometry. Protein tyrosine pseudokinase PTK7 specified a cell population within human colonic organoids characterized by highest self-renewal and re-seeding capacity. Antibodies recognizing the extracellular domain of PTK7 allowed us to isolate and expand hCoSCs directly from patient-derived mucosa samples. Human PTK7+ cells display features of canonical Lgr5+ ISCs and include a fraction of cells that undergo differentiation toward enteroendocrine lineage that resemble crypt label retaining cells (LRCs).