“…In recent years, the design and implementation of biopolymer-based microcarriers have contributed to the development of advanced tissue models used for pharmacological and pathological research purposes such as drug screening and tissue engineering . By mimicking a structure-specific extracellular matrix (ECM), biopolymer-based microcarriers could provide unique microenvironments that are distinct from the typical two-dimensional (2D) cell culture condition, resulting in increased cellular activity even to the levels observed in vivo. , Among the numerous biopolymer-based microcarriers, porous microspheres (PMs) have attracted extensive interest in cell-based therapy and drug delivery because of the reported high efficiency in cell/drug loading, cell retention following implantation, and open surgery-free clinical safety. − Tunable porosity, tailored mechanical strength, and comparatively easy fabrication methods also made using PMs a popular choice for bottom-up tissue engineering approaches, such as in the design and implementation of microparticle-reinforced composite scaffolds. − Notably, previous studies have suggested the potential of PMs in stem cell or tissue-specific cell packing during cell therapies, reporting better outcomes over nonporous microspheres and unassisted cell implantation. , Indeed, excellent cell loading ability has been observed of the PMs either as injectable modularized units or PM-constituted scaffold-supported microtissues. , However, construction efficiency remains limited regarding organoids, especially vascularized organoids, that require the input of multiple cell types. Various approaches have been proposed and demonstrated, for example, separate seeding of human bone marrow stromal cells (hBMSCs) and human umbilical vein endothelial cells (HUVECs) into cryogel microspheres to construct PM-composed macroscaffolds for bone regeneration .…”