Preclinical models for immunotherapy, including transnuclear and CRISPR gene-modified mice
Somatic cell nuclear transfer (SCNT) may be used to clone mice from lymphocytes of defined specificity. By harvesting as few as 200 primary lymphocytes from animals that are at the peak of an immune response, and by transfer of the nucleus from such antigen specific lymphocytes into an enucleated oocyte, embryonic stem cells that harbor the genetic rearrangements encoding the original antigen receptor may be obtained and used for the construction of transnuclear mice.
These animals contain T or B cells of the appropriate specificity, have no genetic alterations other than the physiological TCR/BCR rearrangements, and are the closest approximation of physiological immune responses to date. Importantly, the generation of transnuclear mice is rapid, requiring approximately 6 weeks from T cell harvest to obtaining chimeric animals. Like TCR and BCR transgenics, transnuclear mice are broadly useful for addressing diverse questions. The Dougan lab generates transnuclear mouse models to explore questions of anti-tumor immunity.
Our long term goal is to understand the complex network of cellular interactions that shape the tumor microenvironment. CD8 T cells do not occur in isolation; they operate in oligoclonal fashion amid regulatory T cells, myeloid cells, and other immune infiltrates, not to mention heterogeneous tumor cells, stroma, and vasculature. These interactions cannot be accurately modeled using xenografts, nor are they fully replicated in humanized mice that develop human leukocytes, but still face cross-species barriers with respect to immune-stromal interactions and T cell development.
The Dougan lab clones mice from a variety of tumor-infiltrating lymphocytes in order to study the effects of each lymphocyte type in isolation, and more importantly, when combined with each other and with various immune-based therapies. We also use the technology in reverse to clone mice from tumor-infiltrating Tregs as a means of determining their antigen-specificity.
Currently the lab focuses on three major tumor types: melanoma, sarcoma, and pancreatic cancer. Of these, pancreatic cancer has been the most refractory to immunotherapy. We are using a combination of RNAseq profiling and targeted gene silencing in pancreatic-tumor specific CD8 T cells to design effective immunotherapies for pancreatic cancer.