Credit: Michael Czerwinski

Credit: Michael Czerwinski

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Q: What is an organoid? 

A:  The long answer: (adapted from Hill et al., CMGH, 2016) Organoid means "organ-like", and represents a tissue grown in culture that retains some aspects of the complex structure, physiology and/or cellular diversity of the native organ system. Organoids are grown in a 3-dimensional (3D) culture environment. The rapid growth in diverse 3D  tissue culture systems  has outpaced the adoption of standardized nomenclature. Cultured human tissues that retain some amount of complex in vivo function and cellular diversity are considered “organotypic,” a term encompassing both cultured whole-tissue explants and organoids. However, given the plethora of models now available as research tools, it is important to keep in mind that not all organoids are directly comparable. For example, organoids derived from patient samples can be grown with or without mesenchyme, or can be derived from healthy or diseased adult tissue. 


Q: What is an enteroid, or other 'oid'? 

A: A specialized organoid, derived from the epithelial portion of the enteric system. More specifically, 'enteroid' has come to be synonymous with epithelium-only orgnaoids derived from the small intestine. Terms have arisen for different tissues, for example 'colonoid' for colonic epithelium, 'hepatoid' for hepatic (liver) cells, 'pancreatoid' for pancreas. Similar terms with '-sphere' affixed have become prevalent: 'enterosphere' for small intestinal epithelium, bronchosphere for bronchiolar epithelium, 'alveolosphere' for alveoli.

Confused? So are we. We prefer to avoid this jargon, and try to use more descriptive language to define a system we are referring to. This often becomes cumbersome, but, we'd rather it be cumbersome than confusing. 

Q: Do all human tissue models need to be grown as 3D organoids? 

A: No, growth of primary human tissues does not necessarily require a 3D environment; however, early studies used the basement membrane Matrigel to support epithelial growth of primary tissues. Emerging studies are now beginning to shed light on the physical and chemical properties of the extracellular environment that are critical for supporting tissue growth, and these studies are leading to the ability to grow primary tissue in 2D.   Moreover, the use of specialized feeder cell lines can also allow one to grow primary human tissue in 2D cultures. 

Q: Does the TTML use 3D and 2D systems? 

A. Mostly 3D, but we are working on transitioning 3D --> 2D, and we are working on establishing conditional reprogramming conditions. 


Q: Are 3D systems better than 2D systems? 

A: We view 2D and 3D systems, traditional transformed cell lines and primary human tissue culture systems as research tools. Our bias is that one picks the right tool for the job.  


Q: Will TTML prepare and facilitate implantation of enteroids/organoids as xenografts, both subcutaneously or orthotopically?

A: We will gladly help enable these studies by working with you to establish new organoid cultures as needed for your xenograft transplants, but the xenografts and required IACUC permissions will be the responsibility to the individual investigator.  While you're thinking about xenografts, did you see this? 


Q: Will a TTML user be required to obtain IRB approval to use TTML-established patient-derived cultures?

A: No. All of the current human tissue lines available at the TTML are absent of identifiable information (i.e. they have been de-identified), which means that according to NIH regulations, this is not considered to be human subjects research (click here for more info). Since these cells are not considered 'human subjects research', work concucted with these cells/tissues also falls outside of the IRB umbrella. We do not have plans moving forward to link patient information to patient-derived tissue cultures. 

Q. Will the TTML be able to help us get access to new patient tissue? 

A. No and Yes. Click here for details