You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Intestinal Organoids as Tissue Surrogates for Toxicological and Pharmacological Studies. Recently developed cell culture protocols have allowed for the derivation of multi-cellular structures dubbed intestinal "organoids" from embryonic stem cells (ESCs), induced pluripotent stem cells (IPSCs), and adult intestinal stem cells (ISCs). These structures resemble in vivo intestinal crypts, both in structure and developmental processes, and can be grown quickly and in relatively large quantities. Although much research has focused on developing intestinal organoids for tissue repair, more immediate applications include high-throughput screening for agents that target intestinal epithelium. Here we describe current methods for deriving mouse and human intestinal organoids and discuss some applications aimed at developing novel therapies or preventive agents for diseases of the lower GI tract such as inflammatory bowel diseases and colorectal cancer.
{"Chemical": []}