"The general aim of REJOIND is to provide proof-of-principle for the in vitro manufacturing of a growing bone, with a bioartificial growth plate as a “driving engine” at its core. To achieve this, we propose a developmental engineering approach, based on the modular design of in vitro processes consisting of sequential units corresponding to in vivo developmental stages. These processes follow a gradual and coordinated progression of tissue growth and cell differentiation that leads to organization of cells into intermediate tissue forms. At every step of the developmental engineering process, computational models will be applied, in order to form a quantitative foundation for every process and to optimize these. After establishment of a manufacturing process of a growth plate, REJOIND will combine this tissue with osteoblasts or articular chondrocytes to build osteochondral tissues or bioartificial joints. Ultimately, REJOIND aims to achieve an autonomous process of in vitro tissue growth allowing guided size expansion. A close interaction between biologists and engineers will make this possible. Pre-clinical applications that will be explored in animal models range from the repair of deep osteochondral defects in a joint surface, to a total joint replacement for small arthritic joints. We expect that a number of these implants will provide a cartilaginous template for bone formation, therefore some will be tested in vivo in appropriate models for healing of long bone defects. In conclusion, REJOIND aims to provide evidence that through the use of developmental engineering, we can build a tissue in vitro, moving the boundary from manufacturing and control at the cellular level to tissue organization and function. This methodology will result in a more reliable in vivo outcome of tissue engineered products, and thus a more predictable and sustainable clinical outcome in the patient."