The study of pathogens relies on adequate model systems to mimic the in vivo infection. For some infective agents, adequate model systems are lacking while some of the used systems are far from optimal. One example is the gastric bacterium Helicobacter pylori (H. pylori), which is causally related to development of gastric cancer. Yet in absence of a more suitable cell culture system, many studies that aim to analyze the molecular mechanisms underlying cancer development use cancer cell lines, which represent the endpoint of the cancerous cascade. Primary, non-transformed cells would be a better model for these studies. However, primary cells are only available from a small number of donors and cannot be cultured over longer periods of time. In recent years, stem cell research has made significant progress to provide new sources for primary cell cultures for the study of infection biology.
Cultures from three stem cell sources have been used: Embryonic stem cells (ESC), induced pluripotent stem cells (iPSC) or adult stem cells. They have been used to model infections with viruses, such as Cytomegalovirus1,2 or Hepatitis C Virus3–7, parasites, such as Plasmodium falciparum8 or Toxoplasma gondii9, and bacteria, such as Bacterioides thetaiotaomicron10 or Salmonella enterica11. Most recently, several approaches have been published to model infection with H. pylori with organoids derived from ESC or iPS cells12, mouse adult stem cells21,22 or human adult stem cells13–15.
The development of organoid cultures from adult stem cells originated from a study, in which single stem cells isolated from murine intestinal epithelium were seeded into a 3-dimensional matrix and embedded in medium that mimicked the environment of the intestinal stem cells containing EGF as mitogen, R-spondin to enhance Wnt signalling and Noggin to inhibit bone morphogenic protein (BMP) signalling16. Notably these cultures do not require co-culture with mesenchymal cells. In these conditions, the stem cells proliferate and form small structures with domains harboring cells of the intestinal crypts, and domains that contain the cells of the intestinal villus. The organoids thus self-organize to mimic the in vivo situation. Today, adult stem cells from many murine and humane tissues can be grown in vitro and self-organize into organoids that resemble their in vivo counterpart, such as small intestine and colon17, stomach13,18, liver19,20, pancreas21 and prostate22.
Here we provide a video protocol to culture mouse or human gastric organoids from adult stem cells and microinject them with H. pylori. This protocol is based on previous reports13,18. This method can be adapted for culturing and infecting other organoid cultures such as intestinal organoids.