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Research Foundation

Method for Deriving Genuine Rat Embryonic Stem Cells

Reference Number: 11-33

Inventors: Mark Weiss and James Hong


Researchers at Kansas State University have developed a new method for deriving embryonic stem cells (ESCs) from the rat blastocyst inner cell mass from rats that could be used to produce new rat models for biomedical research. Several of lines are germline-competent. Additionally, they have produced gene indicator cell lines that fluoresce as a result of specific gene activity. This new method and research tools can be used to greatly decrease the time necessary to produce genetically engineered rats, and they also have potential uses in drug development, disease modeling, transplantation biology and regenerative medicine.

In many areas of research, such as studies related to the cardiovascular and nervous system, rats have been valuable; however, this is not the case for functional genomics. Rat ESC lines are not widely available, and a few rat ESC lines are available for distribution through the National Rat Resource Center. In the past, Dark Agouti (DA) ESCs have shown germline competence, while the popular Fischer 344 (F344) ESCs have not. F344 rats have shown utility in research such as toxicological testing and aging studies; furthermore, they are a relatively efficient strain in terms of litter size compared to other inbred strains.

The inventors’ method allows the F344 strain to produce germline-competent ESCs, and it also increases the efficiency of rat ESCs from many strains to contribute to the germline. Furthermore, this method makes gene-indicator, F344-derivative cell lines possible; these lines can have applications in biotechnology and transplantation studies.


  • Enhances the efficiency of rat ESCs for contribution to the germline
  • Allows the F344 strain to produce germline-competent ESCs
  • Improves the speed to produce new gene-targeted rat strains
  • Allows the creation of ESCs with markers useful for biotechnology and transplantation studies


  • Construction of reporter cell lines from rat ESCs for use in toxicology testing
  • Use of F344 ESCs as research tools to produce animal models of human diseases
  • Testing and development of future methods of stem cells and regenerative medicine
  • Tissue engineering and transplantation studies using F344 rat ESCs

Patent Status:

  • Provisional patent application filed in February 2012.

Technology Development:

ESC lines expressing marker transgenes were derived from F344 and DA rats. Pluripotency was demonstrated in vitro by differentiation to embryoid bodies and in vivo by production of teratoma after an injection into F344 nontransgenic rats and by an injection of male DA ESCs into F344 or Sprague-Dawley blastoclysts. ESCs from both F344 and DA contributed to chimeric rats, both of which produced germline transfer to offspring; F344 ESCs transmitted to the germline at higher efficiency.

Kansas State University Research Foundation seeks to have discussions with companies that are interested in licensing and/or research collaborations.

Interested parties should contact:

Kansas State University Institute for Commercialization (KSU-IC)
2005 Research Park Circle Manhattan, KS 66502
Tel: 785-532-3900 Fax: 785-532-3909
E-Mail: ic@k-state.edu