Despite the promise of engineered tissue implants for the treatment of end stage organ dysfunction, the limitations of scaling these cell therapies to sizes of therapeutic relevance has hindered their translation to the clinic. Here, we propose an innovative solution to this circumvent this challenge: to instead implant a small-scale construct and then induce it to grow in situ after its engraftment into the host. Using engineered liver tissue as a proof of concept application, in this study we leveraged synthetic biology and tissue engineering approaches to build liver tissues that can be triggered to grow on demand after implantation into a host. To accomplish this goal, we used a suite of 2D and 3D human liver culture models to first define the combination of YAP and growth factor signaling as sufficient for the proliferation of human hepatocytes. We then installed control over these signaling axes through synthetic biology and used this toolkit to drive human liver tissue expansion both in a dish and in an animal host. This work serves as a demonstration of synthetic control over proliferation of engineered 3D liver tissue, and lays the foundation for a genetic approach to generating large organ tissue implants: bioengineered on-demand outgrowth via synthetic biology triggering (BOOST).

Data set attached is of single nucleus RNA sequencing (snRNA-seq) on engineered 3D liver tissues containing WT or growth factor-expressing fibroblasts and WT or YAP5SA-expressing hepatocytes after 1 week of doxycycline induction. Five replicates were assayed per condition, yielding a total data set after doublet removal and QC of 18,991 nuclei, of which 4615 (24%), 6962 (37%), and 7414 (39%) were of hepatocyte, endothelial cell, and fibroblast lineages, respectively. 

condition key:
biosample id/ donor id:
A1 = WT fibroblast/WT hepatocyte; B2 = GF fibroblast/WT hepatocyte; A1 = WT fibroblast/YAP5SA hepatocyte; A1 = GF fibroblast/YAP5SA hepatocyte
eng_tissue_cell_type: 
(fibroblast- neonatal human dermal fibroblast, endothelial cell- human umbilical vein endothelial cell, or hepatocyte- primary human hepatocyte)

Published in Synthetic Control of Implanted Engineered Liver Tissue Growth by Amy Stoddard et al.