Zavazava Lab  
 

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The University of Iowa

UI Healthcare

UI Stem Cell Group

UI Department of Internal Medicine

 

  Transplantation tolerance  

 

 

 

The major obstacle to successful organ transplantation is rejection. Despite use of advanced immunosuppressive agents, more than 50 % of transplanted organs are lost within 10 years due to chronic rejection. Yet achieving transplantation tolerance could eliminate the need for medication and overcome the causes of chronic rejection. Our laboratory is interested in utilizing embryonic stem cells (ESC) to reach that goal. We recently reported that ESC show low MHC expression of class I antigens and have no class II expression. However, ESC cannot be directly injected into patients as they cause teratoma formation. The strategy that appears to be essential for the successful use of ESC in the treatment of disease, is their pre-differentiation into the desired cell type followed by a purification procedurewith subsequent transplantation. For example, we now have established a protocol that efficiently allows ESC to be differentiated into hematopoietic precursor cells (HPCs). These cells poorly express class I and have no class II antigens, allowing their engraftment in allogenic recipients without further conditioning. Purification of the CD45+ cells allows their safe use in achieving stable mixed chimerism.

After differentiation into HPCs, the cells express CD45+, a pan leukocyte marker indicating that they have adopted a hematopoietic lineage. These cells can be purified by immunomagnetic beads to >99 % purity. These HPCs can safely be used for the induction of transplantation tolerance that is donor-specific.

SSEA
SSEA counterstained with...

 

 
  GFP Flow  

 

ESC-derived HPCs express CD45. GFP-transduced ESC can be differentiated into HPCs by a special medium that directs their differentiation into hematopoietic cells.  
 

 

Derivation of insulin-producing cells from ESC

 
   
Qdots
Insulin producing cells can be labeled with qdots for non-invasive imaging in vivo.

Diabetes is a devastating disease for patients. About 4-5 % of the population suffers from type I diabetes, which can be treated by insulin. However, transplantation of a new pancreas or that of pancreatic islets is effective in curing this disease. The major caveat is there is a chronic shortage of organs. Thus, the pluripotency of ESC can be exploited to generate new insulin-producing cells that can be used for the treatment of diabetes.

The differentiation of ESC into insulin-producing cells is a lot more complex than that of hematopoietic cells. This is due to the number of transcription factors required for the expression of the various hormones. Our preliminary data indicate that we can differentiate ESC into insulin-producing cells that, however, less efficiently produce insulin than pancreatic islets isolated directly from mice. Our goal is to improve existing protocols in order to get more efficient insulin producing cells that can be used to treat diabetes.

 
   
Islets

Mouse pancreatic islets express insulin, C-peptide, neurogenin-3, glucagon and Pdx-1.

 
    Derivation of beating cardiomyocytes from ESC
One of the many advantages of ESC is their ability to be directed in a particular lineage for their use in the treatment of disease. In particular, ESC readily form embryoid bodies from which differentiated tissues emerge such as beating cardiomyocytes. Our current experiments show that ESC-derived cardiomyocytes efficiently repair damaged cardiac tissue and are integrated in the damaged tissue, restoring normal cardiac function.
 
   

Recent Publications

1. Barnea, E., Beer, I., Patoka, R., Ziv, T., Tzehoval, E., Eisenbach, L., Zavazava, N. and Admon, A.: Analysis of Endogenous Peptides Bound by Soluble MHC Class I Molecules: A Novel Approach for Identifying Tumor Specific Antigens. Eur. J. Immunol. 32:213-222, 2002.

2. Fändrich, F., Lin, X., Chai, G.X., Schulze, M., Ganten, D., Bader, M., Holle, J., Huang, D-S., Parwaresch, T., Zavazava, N., and Binas, B.: Preimplantation-Stage Stem Cells Induce Long-Term Allogeneic Graft Acceptance without Supplementary Host Conditioning.  Nature Med. 8:171-178, 2002.

3.Freese, A. and Zavazava, N. HLA-B7 b-pleated Sheet-Derived Synthetic Peptides are Immunodominant T-cell Epitopes Regulating Alloresponses.  Blood 99:3286-3292, 2002.

4. Welke J, Zavazava N: P59fyn is Upregulated in Anergic CD8+ T-Cells.  Human Immun 63:834-843, 2002.

5. Dresske, B., Zavazava, N., Jenisch, S, Exner, B., Lenz, P., El Mokhtari, N.E., Kremer, B., and   Faendrich, F.:  Wolfie Synergizes with Calcineurin-Inhibitor Treatment and Early Steroid Withdrawal in Kidney Transplantation.  Transplantation 75:1286-1291, 2003.

6. Zavazava, N.: Embryonic Stem Cells and Potency to Induce Transplantation Tolerance.  Expert Opin. Biol.  Ther. 3:5-13, 2003.

7. Zou, M and Zavazava, N.:  Potential Applications of Embryonic Stem Cells in Organ Transplantation.  Transplant Proc 35:2827-2829, 2003.

8 . Berg, M, Barnea, E, Admon, A and Zavazava N. A Novel DNA Methy Transferase I-Derived Peptide Eluted from Soluble HLA-A*0201 Induces Peptide-Specific Tumor Directed Cytotoxic T Cells. Int J Cancer 112:426-432, 2004.

9. Fabricius, D., Bonde, S. and Zavazava, N. Induction of Stable Mixed Chimerism by Embryonic Stem Cells Requires Functional Fas/Fasl Engagement. Transplantation 79:1040-44, 2005.

10. Fried, A., Berg, M., Sharma, B., Bonde, S., and Zavazava, N.:  Recombinant Dimeric MHC Antigens Protect Cardiac Allografts from Rejection and Visualize Alloreactive T Cells.  J Leukoc Biol 78(3):595-604, 2005.

11. Rickert, U., Welke, J., Behrens, D., and Zavazava, N.:  A divalent HLA-B7 Fusion-Protein upregulates CD25 and CD69 in Alloreactive CD8+ T-Cells Bypassing CD28 Co-Stimulation.  Transplantation. 81(9):1337-44, 2006.

12. Dresske, B., Haendschke, F., Lenz, P., Ungefroren, H., Jenisch, S., Exner, B., El Mokhtari, N.D., Lu, T., Zavazava, N. and Fred Faendrich.  WOFIE stimulates regulatory T cells: A 2-year follow-up in renal transplant recipients.  Transplantation 81(11):1549-57, 2006.

13. Lindaman, A., Dowden, A. and Zavazava N..  Soluble HLA-G Molecules (sHLA-G) Induce Apoptosis in Natural Killer Cells (NK-Cells).  Am. J Reprod. Immunol. 56(1):68-76., 2006.

14. Raikwar, S., P., Mueller, T., and Zavazava, N.:  Strategies for Developing Therapeutic Application of Human Embryonic Stem Cells.  Physiology,  21:19-28, 2006.

15. Bonde, S. and N. Zavazava.  Immunogenecity and Engraftment of Mouse Embryonic Stem Cells in Allogenic Recipients.  Stem Cells 24 (10), 2192-2201, 2006.
 
       
 
 
 
 
 
 
 
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