Hepatocyte transplantation may provide a therapy for a variety of liver diseases. The applicant hypothesizes that the inability of current hepatocyte transplant systems to provide long-term replacement of lost or deficient liver function may be caused by a loss of liver-specific gene expression in the transplanted cells. The applicant proposes to quantitate and experimentally optimize the liver-specific gene expression of transplanted hepatocytes. A large number of previous studies have indicated that the phenotype of cultured hepatocytes is regulated both by the presence of soluble hormones or growth factors and by cell adhesion to specific extracellular matrix (ECM) adhesion ligands. The applicant hypothesizes that the liver-specific phenotype of transplanted hepatocytes can be maintained by presenting them with specific and defined combinations of ECM molecules and growth factors. Controlled drug delivery technology will be utilized to incorporate hepatocyte growth factors and cofactors (epidermal growth factor, insulin and dexamethasone) into polymer microspheres which will release the factors over extended periods of time. The polymer microspheres will be mixed with hepatocyte suspensions and seeded into hollow fibers with a defined ECM gel matrix (laminin, type I collagen, alginate, and no ECM). Hollow fiber devices fabricated with semipermeable membranes will be used to prevent cellular migration into or out of hollow fibers, and thus prevent alteration of the ECM by cells other than the seeded hepatocytes. The ability of specific combinations of growth factors and ECM matrices to promote long-term maintenance of liver-specific gene expression in vitro and in vivo will be tested. The alterations in the ECM surrounding hepatocytes will be analyzed to determine whether cells present in different microenvironments selectively secrete and organize a new matrix over time that supplements the original ECM. These studies may aid in bringing hepatocyte transplantation closer to a clinically relevant therapy. Additionally, the issues addressed in this proposal are common to any attempt to engineer a functional new tissue, and novel systems developed in this proposal may find application in a variety of engineered tissues.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
5R29DK050715-04
Application #
2905814
Study Section
Surgery and Bioengineering Study Section (SB)
Program Officer
Serrano, Jose
Project Start
1996-08-01
Project End
2001-07-31
Budget Start
1999-08-01
Budget End
2000-07-31
Support Year
4
Fiscal Year
1999
Total Cost
Indirect Cost
Name
University of Michigan Ann Arbor
Department
Biology
Type
Schools of Dentistry
DUNS #
791277940
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109
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Sheridan, M H; Shea, L D; Peters, M C et al. (2000) Bioabsorbable polymer scaffolds for tissue engineering capable of sustained growth factor delivery. J Control Release 64:91-102
Rowley, J A; Madlambayan, G; Mooney, D J (1999) Alginate hydrogels as synthetic extracellular matrix materials. Biomaterials 20:45-53
Kim, B S; Mooney, D J (1998) Development of biocompatible synthetic extracellular matrices for tissue engineering. Trends Biotechnol 16:224-30
Peters, M C; Isenberg, B C; Rowley, J A et al. (1998) Release from alginate enhances the biological activity of vascular endothelial growth factor. J Biomater Sci Polym Ed 9:1267-78
Kaufmann, P M; Heimrath, S; Kim, B S et al. (1997) Highly porous polymer matrices as a three-dimensional culture system for hepatocytes. Cell Transplant 6:463-8
Kaufmann, P M; Heimrath, S; Kim, B S et al. (1997) Highly porous polymer matrices as a three-dimensional culture system for hepatocytes: initial results. Transplant Proc 29:2032-4