The present invention provides a synthetic or naturally occurring implant, such as a vascular graft, for implantation into a human patient. Uncultured, microvascular endothelial cells, isolated from microvascular endothelial cell rich tissue are disposed on at least one surface of the implant to provide at least about 50% confluence of the cells on the surface of the implant prior to implantation. In a preferred embodiment, the microvascular endothelial cells are obtained from fat tissue. Because of the large number of fresh microvascular endothelial cells that may be obtained from such tissue, sufficient cells may be placed on the implant so that they attach to provide at least 50% confluent coverage of the implant surface prior to the time of implantation.