Disclosed herein are methods for harvesting adipose tissue so as to preserve an increased population of viable microvascular endothelial cells. Adipose tissue containing microvascular endothelial cells is harvested using a collection apparatus incorporating an elongate cannula having apertures with tissue cutting edges. A sub-ambient pressure is applied to a lumen in the cannula to draw the adipose tissue through the aperture where it is then severed using the cutting edge to disrupt the connective adipose matrix. This harvesting provides a cleaner, more homogeneous sample of adipose tissue, thereby increasing the population of viable microvascular endothelial cells obtained through further processing. Rapid and easy methods for the further homogenization of the harvested adipose tissue are also disclosed.