The invention relates generally to genetically modified non-human animals expressing human polypeptides and their methods of use.

Genetically modified pigs having at least one cancer and/or at least one co-morbid condition are provided. Also provided are methods of using the pig and derived tumor cells to screen for therapeutic compounds, medical devices or procedures, and/or combinations thereof. Further provided are methods of producing personalized cancer models, including obtaining a tumor sample from a subject, identifying mutations in the tumor sample, and producing a genetically modified tumor or tumor cell line having the same mutations.

Genetically modified non-human animals expressing human EPO from the animal genome are provided. Also provided are methods for making non-human animals expressing human EPO from the non-human animal genome, and methods for using non-human animals expressing human EPO from the non-human animal genome. These animals and methods find many uses in the art, including, for example, in modeling human erythropoiesis and erythrocyte function; in modeling human pathogen infection of erythrocytes; in in vivo screens for agents that modulate erythropoiesis and/or erythrocyte function, e.g. in a healthy or a diseased state; in in vivo screens for agents that are toxic to erythrocytes or erythrocyte progenitors; in in vivo screens for agents that prevent against, mitigate, or reverse the toxic effects of toxic agents on erythrocytes or erythrocyte progenitors; in in vivo screens of erythrocytes or erythrocyte progenitors from an individual to predict the responsiveness of an individual to a disease therapy.

A mouse with a humanization of the mIL-3 gene and the mGM-CSF gene, a knockout of a mRAG gene, and a knockout of a mIl2rg subunit gene; and optionally a humanization of the TPO gene is described. A RAG/Il2rg KO/hTPO knock-in mouse is described. A mouse engrafted with human hematopoietic stem cells (HSCs) that maintains a human immune cell (HIC) population derived from the HSCs and that is infectable by a human pathogen, e.g., S. typhi or M. tuberculosis is described. A mouse that models a human pathogen infection that is poorly modeled in mice is described, e.g., a mouse that models a human mycobacterial infection, wherein the mouse develops one or more granulomas comprising human immune cells. A mouse that comprises a human hematopoietic malignancy that originates from an early human hematopoietic cells is described, e.g., a myeloid leukemia or a myeloproliferative neoplasia.

Provided are compositions and methods of using engineered myogenic cells for delivery of an agent to an individual. Also provided are methods of producing reprogrammed myogenic cells from adult myogenic cells, and use of the reprogrammed myogenic cells for therapy and agent delivery.

The invention features a method of identifying therapeutically relevant compositions which include a therapeutic agent and 2,2-dimethylaminomethyl-[1-3]-dioxolane by screening for an effect of the agent on the liver of a model subject.

Non-human animals, cells, methods and compositions for making and using the same are provided, wherein the non-human animals and cells comprise a humanized B-cell activating factor gene. Non-human animals and cells that express a human or humanized B-cell activating factor protein from an endogenous B-cell activating factor locus are described.

The present invention relates to a human artificial chromosome which is genetically transmissible to the next generation with high efficiency and the method for using the same. More specifically, the present invention relates to: a human artificial chromosome in which an about 3.5 Mb to about 1 Mb region containing an antibody λ light chain gene derived from human chromosome 22 is bound to a chromosome fragment which is transmissible to a progeny through a germ line of a non-human animal, said chromosome fragment is derived from another human chromosome; a non-human animal carrying the human artificial chromosome and an offspring thereof; a method for producing the non-human animal; a method for producing a human antibody using the nonhuman animal or an offspring thereof; and a human antibody-producing mouse carrying the human artificial chromosome.

Compositions and methods are provided for modifying a rat genomic locus of interest using a large targeting vector (LTVEC) comprising various endogenous or exogenous nucleic acid sequences as described herein. Compositions and methods for generating a genetically modified rat comprising one or more targeted genetic modifications in their germline are also provided. Compositions and methods are provided which comprise a genetically modified rat or rat cell comprising a targeted genetic modification in the rat interleukin-2 receptor gamma locus, the rat ApoE locus, the rat Rag2 locus, the rat Rag1 locus and/or the rat Rag2/Rag1 locus. The various methods and compositions provided herein allows for these modified loci to be transmitted through the germline.

The invention provides compositions and methods useful for the treatment and prevention of conditions associated with short telomere length.