Vascularized and Complex Organ Buds from Diverse Tissues via Mesenchymal Cell-Driven Condensation

Abstract

Transplantation of in-vitro-generated organ buds is a promising approach toward regenerating functional and vascularized organs. Though it has been recently shown in the context of liver models, demonstrating the applicability of this approach to other systems by delineating the molecular mechanisms guiding organ bud formation is critical. Here, we demonstrate a generalized method for organ bud formation from diverse tissues by combining pluripotent stem cell-derived tissue-specific progenitors or relevant tissue samples with endothelial cells and mesenchymal stem cells (MSCs). The MSCs initiated condensation within these heterotypic cell mixtures, which was dependent upon substrate matrix stiffness. Defining optimal mechanical properties promoted formation of 3D, transplantable organ buds from tissues including kidney, pancreas, intestine, heart, lung, and brain. Transplanted pancreatic and renal buds were rapidly vascularized and self-organized into functional, tissue-specific structures. These findings provide a general platform for harnessing mechanical properties to generate vascularized, complex organ buds with broad applications for regenerative medicine.

Human Induced Pluripotent Stem Cell–Derived Podocytes Mature into Vascularized Glomeruli upon Experimental Transplantation

“…We also cotransplanted mixed aggregates of human umbilical vein endothelial cells (HUVECs) and mesenchymal stem cells (MSCs) because these cells are useful for the generation of vascularized organ buds in vitro. 38,39 When these aggregates were transplanted using a conventional method that we used for the transplantation of mouse ES cell-derived nephron progenitors, 13 minimal nephron differentiation was observed at 10 days after transplantation (n=4) ( Figure 6A). Because human iPS cell-derived aggregates were larger (approximately 1000 mm in diameter) than those from mouse ES cells (approximately 600 mm) and were instantly flattened upon transplantation (Supplemental Figure 5A), we hypothesized that mechanical tension of the capsule may have hampered nephron differentiation.…”

Pluripotent stem cell-derived organoids: using principles of developmental biology to grow human tissues in a dish

“…This resulted in the generation of a selforganizing 3D liver bud in vitro (Takebe et al, 2013) that contained clearly defined vascular capillaries capable of blood flow when transplanted into mice. This approach was used to generate and achieve vascularization of other organ bud-like structures when transplanted in vivo, including the pancreas (Takebe et al, 2015).…”

Translational potential of human brain organoids

“…Alternatively, methods to accelerate the appearance and maturation of astroglial cells should be developed. For the inclusion of non‐neural cell types, one way may be to first generate them separately, and later add them to the brain organoids 60, 61, 62…”