Mouse Vascularized Adipose Spheroids: An Organotypic Model for Thermogenic Adipocytes
Adipose tissues, particularly beige and brown adipose tissue, play crucial roles in energy metabolism. Brown adipose tissues' thermogenic capacity and the appearance of beige cells within white adipose tissue have spurred interest in their metabolic impact and therapeutic potential. Brown and beige fat cells, activated by factors like cold exposure, share mechanisms that drive non-shivering thermogenesis. Understanding their behavior requires sophisticated, yet universal in vitro models that replicate the complex microenvironment and vasculature of adipose tissues. Here we present mouse vascularized adipose spheroids of the stromal vascular microenvironment from inguinal white adipose tissue. We show that scaffold embedding improves vascular sprouting, enhances spheroid growth, and upregulates adipogenic markers. Transcriptional profiling via RNA sequencing revealed distinct metabolic pathways upregulated in our vascularized adipose spheroids, with increased expression of genes involved in glucose metabolism, lipid metabolism, and thermogenesis. Functional assessment demonstrated increased oxygen consumption in vascularized adipose spheroids compared to 2D cultures, which was further enhanced by ß-adrenergic receptor stimulation via isoproterenol correlating with elevated ß-adrenergic receptor expression. Moreover, stimulation with the naturally occurring adipokine, FGF21, induced Ucp1 mRNA expression in the vascularized adipose spheroids. In conclusion, our vascularized inguinal white adipose tissue spheroids provide a physiologically relevant platform to study how the stromal vascular microenvironment shapes adipocyte responses and influence activated thermogenesis in beige adipocytes. Overall design: We investigated whether the stromal vascular fraction from mouse inguinal white adipose tissue cultured in 3D as spheroids were providing a more favorable adipogenic microenvironment than 2D cultures. We utilized RNA sequencing to compare transcriptional profiles between 3D cultures and conventional in vitro differentiated adipocytes in 2D cultures. Furthermore, we stimulated 2D and 3D cultures with Isoproteronol, a pan beta-adrenergic agonist to induce thermogenesis and compared transcriptional profiles using RNA sequencing.