Control of both tissue architecture and scale is a fundamental translational roadblock in tissue engineering. An experimental framework that enables investigation into how architecture and scaling may be coupled is needed. We fabricated a structurally organized engineered tissue unit that expanded in response to regenerative cues after implantation into mice with liver injury. Specifically, we found that tissues containing patterned human primary hepatocytes, endothelial cells, and stromal cells in a degradable hydrogel expanded more than 50-fold over the course of 11 weeks in mice with injured livers. There was a concomitant increase in graft function as indicated by the production of multiple human liver proteins. Histologically, we observed the emergence of characteristic liver stereotypical microstructures mediated by coordinated growth of hepatocytes in close juxtaposition with a perfused vasculature. We demonstrated the utility of this system for probing the impact of multicellular geometric architecture on tissue expansion in response to liver injury. This approach is a hybrid strategy that harnesses both biology and engineering to more efficiently deploy a limited cell mass after implantation.
Bibliographical noteFunding Information:
We thank A. Sappington for help with bioinformatics analysis, L. Wilson of Yecuris for advice regarding animal care, the Koch Institute BioMicroCenter for help with library sequencing, and the Swanson Biotechnology Center Microscopy Core for help with imaging. Funding: This study was supported by grants from the NIH (R01EB008396, R01DK85713, EB00262, U24DK059635, and P30-CA14051), the Skolkovo Institute of Science and Technology (022423-003), and the National Institute of Environmental Health Sciences (P30-ES002109). M.A.S. was supported by the National Research Service Award (F32AI091207), and K.A.K. was supported by the National Institute of General Medical Sciences Training Grant (T32GM007753). S.N.B. is a Howard Hughes Medical Institute investigator. Author contributions: K.R.S., M.A.S., V.R., C.L.F., R.R.C., K.A.K., J.W.X., C.F., T.M., A.X.C., M.G.M., M.T.Y., Y.P.d.J., and H.E.F. designed and performed all experiments. M.A.S., M.T.Y., Y.P.d.J., R.R.C., J.W.X., C.F., T.M., and C.L.F. designed and performed the transplant experiments. V.R. designed and analyzed the transcriptome experiments. K.A.K. designed and performed the partial hepatectomy experiments. M.G.M. and K.C. designed and performed the lectin analysis experiments. K.R.S., H.E.F., C.S.C., C.M.R., and S.N.B. wrote the paper. K.C., Y.P.d.J., C.S.C., C.M.R., and S.N.B. provided funding, contributed to experiment planning, and provided overall oversight of the study. Competing interests: S.N.B. is a co-founder of Hepregen. C.S.C. is co-founder of Innolign Biomedical. K.R.S., C.S.C., and S.N.B. are co-inventors on a patent entitled "SEEDs (in situ expansion of engineered devices) for templated regeneration" (#PCT/US2016/055972).
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