The invention described herein provides a structure for growing isolated differentiable human mesenchymal cells, which includes a three-dimensional matrix of fibers. The matrix serves as an implantable scaffolding for delivery of differentiable human mesenchymal cells in tissue engineering. The invention further provides compositions that contain the three-dimensional matrix of fibers seeded with isolated differentiable human mesenchymal cells, wherein the matrix forms a supporting scaffold for growing the isolated differentiable human mesenchymal cells, and wherein the differentiable human mesenchymal cells differentiate into a mature cell phenotype. The invention further provides methods of preparing the implantable nanofiber matrix scaffolding seeded with differentiable human mesenchymal cells for use in tissue engineering.