Abstract: Provided herein is the first viable galactosyltransferase (Gal) knock-out sheep having a deletion or mutation of alpha-1,3-galactosyltransferase (GGTA1) gene and methods of making the same. Also provided are methods of screening a biological implant for stimulation of an antibody-mediated inflammatory response to a Gal antigen by implanting the biological implant into a recipient Gal knock-out animal and detecting signs of antibody-mediated inflammatory response in the recipient Gal knock-out animal. Further provided is a method of implanting a biological implant into a human subject by screening a first biological implant for signs of antibody-mediated inflammatory response in a recipient Gal knock-out animal and, upon detecting minimal or no signs of antibody mediated inflammatory response in the recipient Gal knock-out animal, implanting a second biological implant into the human subject, wherein the second biological implant is comparable to the first biological implant.

Abstract: Bioprosthetic heart valves and methods for fabricating bioprosthetic heart valves are provided. Biological tissue is attached to biocompatible material. The biocompatible material is folded to form a tubular structure with the attached biological tissue located on the inner surface of the tubular structure, the biological tissue forming leaflets of the heart valve. A stent is secured around the outer surface of the tubular structure. A region of the biocompatible material is cut. The biocompatible material is folded at the cut region away from the tissue and around the downstream edge of the stent and is secured to the stent's outer surface. The biocompatible material is folded at the upstream end of the tubular structure around the upstream edge of the stent and attached to the stent's outer surface so that the stent's inner and outer surfaces are covered with no more than a single layer of the biocompatible material.

Abstract: Bioprosthetic heart valves and methods for fabricating bioprosthetic heart valves are provided. Biological tissue is attached to biocompatible material. The biocompatible material is folded to form a tubular structure with the attached biological tissue located on the inner surface of the tubular structure, the biological tissue forming leaflets of the heart valve. A stent is secured around the outer surface of the tubular structure. A region of the biocompatible material is cut. The biocompatible material is folded at the cut region away from the tissue and around the downstream edge of the stent and is secured to the stent's outer surface. The biocompatible material is folded at the upstream end of the tubular structure around the upstream edge of the stent and attached to the stent's outer surface so that the stent's inner and outer surfaces are covered with no more than a single layer of the biocompatible material.

Abstract: The present invention relates to a tetracycline repressor-mediated binary regulation system for the control of gene expression in transgenic mice. It is based, at least in part, on the discovery that, in a transgenic mouse that carries a first transgene under the control of a modified promoter comprising a tetR operator sequence and a second transgene encoding the tetR protein, expression of the first transgene may be efficiently induced by administering tetracycline to the mouse.