A microfluidic platform integrating functional vascularized organoids-on-chip.

The development of vascular networks in microfluidic chips is crucial for the long-term culture of three-dimensional cell aggregates such as spheroids, organoids, tumoroids, or tissue explants. Despite rapid advancement in microvascular network systems and organoid technologies, vascularizing organoids-on-chips remains a challenge in tissue engineering. Most existing microfluidic devices poorly reflect the complexity of in vivo flows and require complex technical set-ups. Considering these constraints, we develop a platform to establish and monitor the formation of endothelial networks around mesenchymal and pancreatic islet spheroids, as well as blood vessel organoids generated from pluripotent stem cells, cultured for up to 30 days on-chip. We show that these networks establish functional connections with the endothelium-rich spheroids and vascular organoids, as they successfully provide intravascular perfusion to these structures. We find that organoid growth, maturation, and function are enhanced when cultured on-chip using our vascularization method. This microphysiological system represents a viable organ-on-chip model to vascularize diverse biological 3D tissues and sets the stage to establish organoid perfusions using advanced microfluidics.

A critical relationship between bone and fat: the role of bone marrow adipose-derived RANKL in bone metabolism.

Recent studies have unveiled unique functions of the bone marrow adipose tissue (BMAT), which represent over 10% of the total adipose tissue mass in healthy adults. Increasing evidence is emerging as to how BMAT deposition and osteoporosis are linked under normal and pathophysiological conditions, which is opening up novel treatment avenues. However, the means by which bone marrow adipocytes (BMAs) regulate bone remodeling and their involvement in osteoporosis remained unknown. A study in this issue of EMBO Reports (Hu et al, 2021) and a study in Journal of Clinical Investigation (Yu et al, 2021) reports independently that BMA-derived RANKL regulates osteoclastogenesis and bone remodeling, indicating that excessive RANKL generated by BMAs is an underlying cause for osteoporosis.