The invention provides double knockout transgenic pigs (GT/CMAH-KO pigs) lacking expression of any functional ?GAL and CMAH. Double knockout GT/CMAH-KO transgenic organs, tissues and cells are also provided. Methods of making and using the GT/CMAH-KO pigs and tissue are also provided.

Transgenic swine that express human coagulation factors, e.g., human coagulation factor VII, and/or one or more of human coagulation factors II, X and XII, and do not express the corresponding porcine coagulation factor or factors, as well as cells, tissues and organs derived therefrom, and their use in transplantation procedures.

A method of modulating some or all copies of a gene in a cell is provided including introducing into a cell one or more ribonucleic acid (RNA) sequences that comprise a portion that is complementary to all or a portion of each of the one or more target nucleic acid sequences, and a nucleic acid sequence that encodes a Cas protein and maintaining the cells under conditions in which the Cas protein is expressed and the Cas protein binds and modulates the one or more target nucleic acid sequences in the cell.

Genetically modified cells, tissues, and organs for treating or preventing diseases are disclosed. Also disclosed are methods of making the genetically modified cells and non-human animals.

The invention provides for transgenic donor animals (e.g., pigs) whose cells, tissues and organs have a better long-term survival when transplanted into a human patient. The transgenic donor animal carries one or more human transgenes which is expressed only when the endogenous gene of the donor animal is knocked out shortly before a graft is harvested for transplantation. This genetic switch allows the donor animal to remain healthy during the majority of its lifetime, while still allowing expression of the human transgene for optimal transplant tolerance in a human recipient. The transgene may encode a cytokine receptor, an adhesion molecule, or a complement regulatory protein.

Genetically modified cells, tissues, and organs for treating or preventing diseases are disclosed. Also disclosed are methods of making the genetically modified cells and non-human animals.

The invention provides double knockout transgenic pigs (GT/CMAH-KO pigs) lacking expression of any functional aGAL and CMAH. Double knockout GT/CMAH-KO transgenic organs, tissues and cells are also provided. Methods of making and using the GT/CMAH-KO pigs and tissue are also provided.

Described herein is a method for producing a chimeric non-human animal expressing a human ETV2 gene comprising: a) generating an ETV2 null non-human animal cell, wherein both copies of the non-human ETV2 gene carry a mutation that prevents production of functional ETV2 protein in said non-human animal; b) creating an ETV2 null non-human blastocyst by somatic cell nuclear transfer comprising fusing a nucleus from said ETV2 null non-human animal cell of a) into an enucleated non-human oocyte and activating said oocyte to divide so as to form an ETV2 null non-human blastocyst; c) introducing human stem cells into the ETV2 null non-human blastocyst of b); and d) implanting said blastocyst from c) into a pseudopregnant surrogate non-human animal to generate a chimeric non-human animal expressing human ETV2.

A method of modulating some or all copies of a gene in a cell is provided including introducing into a cell one or more ribonucleic acid (RNA) sequences that comprise a portion that is complementary to all or a portion of each of the one or more target nucleic acid sequences, and a nucleic acid sequence that encodes a Cas protein and maintaining the cells under conditions in which the Cas protein is expressed and the Cas protein binds and modulates the one or more target nucleic acid sequences in the cell.

Provided herein are genetically modified pigs, porcine organs, tissue, and cells having a reduced propensity to cause a rejection response in a human subject following xenotransplantation. In particular, provided herein are genetically modified pigs lacking nonGal xenoantigens, and porcine cells, tissues, and organs obtained from such genetically modified pigs that are suitable for transplantation into a human. Also provided herein are methods of improving a rejection related symptom in a human subject.