Provided is a gene therapy composition for transferring one of a therapeutical gene, a maker gene, or a mixture thereof to a cell that expresses interleukin-8(IL-8) or GRO-alpha and induces tropism of mesenchymal stem cells isolated from umbilical cord blood and/or the mesenchymal stem cells expanded from said mesenchymal stem cells (UCB-MSCs), wherein the cell-treating composition includes UCB-MSCs. Provided is a composition for treating disease related to a cell expressing IL-8 or GRO-alpha, that is, a brain tumor in gene therapy, by using UCB-MSCs. Provided is a composition or kit for diagnosing brain tumors, preventing brain tumors, treating brain tumors, or monitoring brain tumor treatment progression by using UCB-MSCs.
