An engineered valve (300, 400) comprising: a tubular wall (310, 410) comprising micron, submicron or nanometer dimension polymer fibers defining a shape of the tubular wall (310, 410), the tubular wall (310, 410) having an inner surface, a first portion, and a second portion; one or more leaflets (320a, 320b) extending from, and integral with, the inner surface of the tubular wall (310, 410), the one or more leaflets (320a, 320b) each comprising micron, submicron or nanometer dimension polymer fibers defining the shape of the corresponding leaflet (320a, 320b); wherein the one or more leaflets (320a, 320b) are configured for one-way fluid flow through the first portion of the tubular wall (310, 410), past the one or more leaflets (320a, 320b), and into the second portion of the tubular wall (310, 410), and wherein the second portion of the tubular wall includes all of the tubular wall (310, 410) downstream of the one or more leaflets (320a, 320b); wherein, for each of the one or more leaflets (320a, 320b), at least some of the micron, submicron or nanometer dimension polymer fibers forming a part of the leaflet (320a, 320b) interpenetrate with at least some of the micron, submicron or nanometer dimension polymer fibers forming a part of the first portion of the tubular wall (310, 410); and wherein the micron, submicron or nanometer dimension polymer fibers of the tubular wall (310, 410) and the micron, submicron or nanometer dimension polymer fibers of the one or more leaflets (320a, 320b) are configured to form a polymeric fiber scaffold for cellular ingrowth into the tubular wall (310, 410) and the one or more leaflets (320a, 320b). a tubular wall (310, 410) comprising micron, submicron or nanometer dimension polymer fibers defining a shape of the tubular wall (310, 410), the tubular wall (310, 410) having an inner surface, a first portion, and a second portion; one or more leaflets (320a, 320b) extending from, and integral with, the inner surface of the tubular wall (310, 410), the one or more leaflets (320a, 320b) each comprising micron, submicron or nanometer dimension polymer fibers defining the shape of the corresponding leaflet (320a, 320b); wherein the one or more leaflets (320a, 320b) are configured for one-way fluid flow through the first portion of the tubular wall (310, 410), past the one or more leaflets (320a, 320b), and into the second portion of the tubular wall (310, 410), and wherein the second portion of the tubular wall includes all of the tubular wall (310, 410) downstream of the one or more leaflets (320a, 320b); wherein, for each of the one or more leaflets (320a, 320b), at least some of the micron, submicron or nanometer dimension polymer fibers forming a part of the leaflet (320a, 320b) interpenetrate with at least some of the micron, submicron or nanometer dimension polymer fibers forming a part of the first portion of the tubular wall (310, 410); and wherein the micron, submicron or nanometer dimension polymer fibers of the tubular wall (310, 410) and the micron, submicron or nanometer dimension polymer fibers of the one or more leaflets (320a, 320b) are configured to form a polymeric fiber scaffold for cellular ingrowth into the tubular wall (310, 410) and the one or more leaflets (320a, 320b).