Purpose of review: To summarize our current understanding of small intestinal stem cell biology and the current tools available for studying intestinal stem cells (ISCs).
Recent findings: Recent reviews and original reports point toward the presence of two distinct populations of stem cells (ISCs) within the intestinal crypts. Until recently, the study of these two populations has been hindered by the lack of biomarkers available for isolation and characterization of ISCs and the absence of suitable culture conditions for expansion of ISCs in vitro. With the accumulation of various surface markers and transgenic mouse models, we have been able to gain a better understanding of the genetic signature of ISCs. In addition, these tools have provided opportunities to begin to study how ISCs are influenced by the various components of the ISC niche, including fibroblasts, bacteria, lymphoid cells, and Paneth cells. Advances in culture conditions now allow for the establishment of in-vitro studies of ISC function and dynamics.
Summary: This brief review provides a general historical perspective of our understanding of the delineation of the two ISC populations. Furthermore, it discusses the known ISC markers and how these markers have been used to isolate and characterize ISC populations.