Our People

Meet the people who make Transposagen a leader in genetically modified animal models, cell engineering services, and gene editing tools.

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Dr. Tseten Yeshi

Head of Molecular Biology 

Dr. Yeshi is a molecular biologist and an expert in genome editing, with full range experience in performing complex gene editing in a broad array of cell types including rodent embryonic stem cells and spermatogonial stem cells. He has worked extensively in development of proprietary modifications in the architecture of piggyBac, TALENs and CRISPR/Cas genome modification tools and combining these technologies for efficient Footprint Free Gene editing: making precise mutations without leaving any undesired changes or “footprint” behind in the genome. Dr. Yeshi has well-developed scientific program management skills and experience, has been a Principle Investigator on multiple NIH SBIR grants and a co-inventor of several patents.


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Dr. Valeriya Steffey

Director, Cell Line Engineering 

Dr. Valeriya Steffey has worked for Transposagen Biopharmaceuticals Inc. for seven years, where she has distinguished herself as an innovative leader in both technology and business development.  Dr. Steffey is the Director of Cell Line Engineering at Transposagen.  Under her management, her team has a proven track record of successful completion of cell line engineering, engineered animal models and R&D projects. As Director, she creates relationships and liaises with customers in academia and industry to initiate and manage projects. As a leader at Transposagen, she oversees new product development.

In addition to her experience in the biotechnology industry, Dr. Steffey practiced medicine for over ten years and performed academic research, with an emphasis in anatomy and neurobiology, providing her with a broad and varied background.  She is a published author and co-author of many scientific articles.