Various scaffolds have been developed that ABT737 gradually release growth factors (GFs) to orchestrate angiogenesis and osteogenesis ,  and . Different kinetic delivery patterns were obtained by incorporating different GFs in either the inner or outer spatial structure of scaffolds, or by altering the degradability of blended biomaterial components loaded with distinct GFs . Several types of encapsulating techniques have been developed including supercritical CO2 mixing , hydrogel fiber entrapment , and microsphere encapsulation , , ,  and , to achieve temporal release of different GFs. These methods can also provide a protective shell to avoid possible reciprocal interactions between different GFs in direct contact. Considering their versatile administration methods, and the ease with which nephridium can be incorporated within numerous scaffold matrices, core–shell spheres are among the most attractive options for sequentially delivering GFs.