To provide micro-organs, extracts derived therefrom, a method for stimulating angiogenesis in host tissues using a pharmaceutical composition containing the extracts, micro-organs transformed with exogenous nucleotide sequences, and a method of utilizing the transformed micro-organs for providing angiogenic factors to host tissues.

A micro-organ explant contains a cell population, in which at least a part of cells contains at least one exogenous nucleotide sequence, keeps a microstructure of an organ which the explant itself is derived from, and simultaneously has a size selected to minimize death caused by cytotoxicity, excrement accumulation in the micro organ explant, and insufficient nutrient by diffusing sufficient nutrients and gas into cells and diffusing cell excrements from the micro-organ explant.