To overcome the diminishing return of passaging stem cells, our team developed an expandable 3D modular substrate that enables adult stem cells to grow continuously in the X, Y, and Z axial directions without the need for passaging. These substrates are called “Tissue Blocks” (T-Blocks). As adult stem cells require more substrate, additional T-Blocks are added on in the X, Y, or Z axial directions. This technology leverages a proprietary combination of different biomaterials and microgeometries to enable adult stem cells to proliferate, migrate, and secrete matrix in 3D to create a growth environment reminiscent of the original tissue. T-Blocks permit adult stem cells to grow outside of their original microenvironment without sacrificing differentiation potential, proliferation capabilities, or migration patterns, which provides a novel method to mass produce adult stem cells from a single donor. In addition, T-Blocks can be used to generate target tissues by manipulating how T-Blocks are combined and by incorporating growth factors that stimulate target tissue formation. This technology produces 30X the yield of primary stem cells as compared against conventional cell culture technologies while only using 0.1% of the space required for cell expansion and at 1% of the cost.