TABLE 2 PRIMER SEQUENCES

Gene Protein Sense Anti-sense Tanneal Prod.

SLC5A1 SGLT1 5'-ttccacatcttccgagatcc-3' 5'-ggacgacacaggcaattttt-3' 60 256 SLC5A2 SGLT2 5'-gtggtgttcatcgtggtagt-3' 5'-cacaatggcgaagtagaggt-3' 57 309 SLC2A1 GLUT1 5'-acggccttcactgtcgtgtc-3' 5'-gaagcctgcaacggcaatgg-3' 60 276 SLC15A1 PEPT1 5'-ccttcagcagcctctgttat-3' 5'-cctgcattgatggacaggta-3' 57 319 SLC15A2 PEPT2 5'-agagctgatctcctccacct-3' 5'-aaaattagggccatcagtcc-3' 57 267 SLC22A1 OCT1 5'-gggaacctctacctggattt-3' 5'-attcaccaggcagatcattt-3' 57 243 SLC22A6 OAT1 5'-tactggtctctgcgcctttt-3' 5'-ggagaggcagaggaagaggt-3' 57 275 SLC22A8 OAT3 5'-gggcgtaagtaacctgtgga-3' 5'-tgcctggctaggatcagtct-3' 57 344 SLC4A4 NBC1 5'-cagtctccagtgcaagtagg-3' 5'-ctctgccaatctcgtggtag-3' 57 339 ATP1B1 Na+_/K+ _{ATPase 5'-ccgccaggattaacacagat-3' 5'-gaagcctagaactcggttga-3' 57 339}

ATP6 H+ _{ATPase 5'-ggcagtcagtcggaactacc-3' 5'-ggccagtacaacaggacctc-3' 60 343}

SLC9A3 Na+_/H+ _{ATPase 5'-gaggtccatgtcaacgaggt-3' 5'-gatgatacgcacatgcttgg-3' 60 252}

SLC34A1 NaPi IIa 5'-acctccacatccatcatcgt-3' 5'-ccagcactgacagccagtta-3' 57 205 AQP1 Aquaporin 1 5'-attaaccctgctcggtcctt-3' 5'-ctccaccctggagttgatgt-3' 60 225 COL1A1 Collagen I 5'-ctcccagaacatcacctacc-3' 5'-gagggagtttacaggaagca-3' 57 318 COL3A1 Collagen III 5'-accgatgagattatgacttcact-3' 5'-ctgcacatcaaggacatcttcag-3' 57 369 COL4A1 Collagen IV 5'-tgctgttgaaaggtgaaaga-3' 5'-agcttgtcctggtactcctg-3' 57 233 LAMA1 Laminin 5'-gtacagcgtggccttctatt-3' 5'-tcgctgaggacagacataaa-3' 57 234 Gp330 Megalin 5'-gatgggtctaaccgcactgt-3' 5'-agtgctgcgttcaatcctct-3' 60 252 CYP27B1 DH-vitD3 hydroxyl. 5'-atgctgctggctaagcattt-3' 5'-aaaccaggctagggcagatt-3' 60 292 TJP1 Zona occludens 1 5'-ggagaggtgttccgtgttgt-3' 5'-gagcggacaaatcctctctg-3' 60 253 TGFB1 TGF 5'-ctcgccagagtggttatctt-3' 5'-ggagctgaagcaatagttgg-3' 57 292 HNF1A HNF1 5'-ggcctcttcctcccagtaac-3' 5'-gctttgctcctagctctcca-3' 60 253 CDH1 E-cadherin 5'-cctcctgaaaagagagtgga-3' 5'-gtgtccggattaatctccag-3' 57 155 SM22 SM22 5'-aacagcctgtaccctgagg-3' 5'-atgacatgctttccctcctg-3' 57 390 SMA -SMA 5'-tcatcctcccttgagaagag-3' 5'-atgccagggtacatagtggt-3' 57 230 VIM Vimentin 5'-gcgtgaaatggaagagaact-3' 5'-ggtatcaaccagagggagtg-3' 57 277 GAPDH GAPDH 5'-ctgccgtctagaaaaacctg-3' 5'-gtccaggggtcttactcctt-3' 57 282 The annealing temperature Tanneal is shown in ºC and the product (Prod.) in bp.

STATISTICAL ANALYSIS

Differences between two groups were analyzed with a two-tailed Mann-Whitney test with a 95% confidence interval. Data is expressed as mean ± standard error of mean. Probabilities of P < 0.05 were considered to be statistically significant; P < 0.05 is depicted as *, P < 0.01 is shown as **, P < 0.001 is indicated as ***.

ACKNOWLEDGEMENTS

We thank Jolanda Spiering for synthesizing the UPy-modified oligocaprolactone, Jan Kolijn for electro-spinning the membranes, Jan van der Wijk for supplying the tissues, Jasper Koerts, Marja Brinker, Jelleke Dokter, Björne Mollet, and Saskia de Rond for technical assistance, and Guido Krenning, Diana Ploeger and Eliane Popa for useful discussions. This work is supported by SupraPolix, the Council for Chemical Sciences of the Netherlands Organization for Scientific Research (CW-NWO), and the Dutch Kidney Foundation.

REFERENCES

1. LeBleu, V.S., MacDonald, B., Kalluri, R. Structure and function of basement membranes. Exp. Biol. Med. 232, 1121-1127 (2007).

2. Yurchenco, P.D., Schittny, J.C. Molecular architecture of basement-membranes. FASEB J. 4, 1577-1590 (1990). 3. Kalluri, R. Basement membranes: Structure, assembly and role in tumour angiogenesis. Nat. Rev. Cancer 3,

422-433 (2003).

4. Alberts, B. Molecular Biology of the Cell (2007).

5. Rosso, F., Giordano, A., Barbarisi, M., Barbarisi, A. From cell-ECM interactions to tissue engineering. J. Cell.

Physiol. 199, 174-180 (2004).

6. Place, E.S., Evans, N.D., Stevens, M.M. Complexity in biomaterials for tissue engineering. Nature Mater. 8, 457-470 (2009).

7. Nur-E-Kamal, A., Ahmed, I., Kamal, J., Schindler, M., Meiners, S. Three-dimensional nanofibrillar surfaces promote self-renewal in mouse embryonic stem cells. Stem Cells 24, 426-433 (2006).

8. Schindler, M., et al. A synthetic nanofibrillar matrix promotes in vivo-like organization and morphogenesis

for cells in culture. Biomaterials 26, 5624-5631 (2005).

9. Mochizuki, M., et al. Integrin-dependent cell behavior on ECM peptide-conjugated chitosan membranes. Pept. Sci. 88, 122-130 (2007).

10. Silva, G.A., et al. Selective differentiation of neural progenitor cells by high-epitope density nanofibers. Science 303, 1352-1355 (2004).

11. Collier, J.H. Modular self-assembling biomaterials for directing cellular responses. Soft Matter 4, 2310-2315 (2008).

12. Dankers, P.Y.W., Meijer, E.W. Supramolecular biomaterials. A modular approach towards tissue engineering. Bull. Chem. Soc. Jpn. 80, 2047-2073 (2007).

13. Dankers, P.Y.W., et al. Oligo(trimethylene carbonate)-based supramolecular biomaterials. Macromolecules 39,

8763-8771 (2006).

14. Dankers, P.Y.W., et al. Chemical and biological properties of supramolecular polymer systems based on

oligocaprolactones. Biomaterials 27, 5490-5501 (2006).

15. Dankers, P.Y.W., Adams, P., Löwik, D., van Hest, J.C.M., Meijer, E.W. Convenient solid-phase synthesis of ureido-pyrimidinone modified peptides. Eur. J. Org. Chem. 22, 3622-3632 (2007).

16. Sijbesma, R.P., et al. Reversible polymers formed from self-complementary monomers using quadruple

hydrogen bonding. Science 278, 1601-1604 (1997).

17. Dankers, P.Y.W., Harmsen, M.C., Brouwer, L.A., Van Luyn, M.J.A., Meijer, E.W. A modular and supramolecular approach to bioactive scaffolds for tissue engineering. Nature Mater. 4, 568-574 (2005). 18. Botterhuis, N.E., van Beek, D.J.M., van Gemert, G.M.L., Bosman, A.W., Sijbesma, R.P. Self-assembly and

morphology of polydimethylsiloxane supramolecular thermoplastic elastomers. J. Polym. Sci. Part A, Polym.

Chem. 46, 3877-3885 (2008).

19. Kautz, H., van Beek, D.J.M., Sijbesma, R.P., Meijer, E.W. Cooperative end-to-end and lateral hydrogen- bonding motifs in supramolecular thermoplastic elastomers. Macromolecules 39, 4265-4267 (2006).

20. Wisse, E., Spiering, A.J.H., Dankers, P.Y.W., Mezari, B., Magusin, P.C.M.M., Meijer, E.W. Multicomponent supramolecular thermoplastic elastomer with peptide-modified nanofibers. J. Pol. Sci. Part A 49, 1764-1771 (2011).

21. Zhang, H., Tasmin, F., Ying, J.Y., Zink, D. The impact of extracellular matrix coatings on the performance of human renal renal cells applied in bioartificial kidneys. Biomaterials 30, 2899-2911 (2009).

22. Hersel, U., Dahmen, C., Kessler, H. RGD modified polymers: biomaterials for stimulated cell adhesion and beyond. Biomaterials 24, 4385-4415 (2003).

23. Pierschbacher, M.D., Ruoslahti, E. Cell attachment activity of fibronectin can be duplicated by small synthetic fragments of the molecule. Nature 309, 30-33 (1984).

24. Aota, S., Nomizu, M., Yamada, K.M. The short amino acid sequence Pro-His-Ser-Arg-Asn in human fibronectin enhances cell-adhesive function. J. Biol. Chem. 269, 24756-24761 (1994).

25. Leahy, D.J., Aukhil, I., Erickson, H.P. 2.0 Ang crystal structure of a four-domain segment of human fibronectin encompassing the RGD loop and synergy region. Cell 84, 155-164 (1996).

26. Graf, J., et al. A pentapeptide from the laminin-B1 chain mediates cell-adhesion and binds the 67000-laminin

receptor. Biochemistry 26, 6896-6900 (1987).

27. Massia, S.P., Rao, S.S., Hubbell, J.A. Covalently immobilized laminin peptide Tyr-Ile-Gly-Ser-Arg (YIGSR) supports cell spreading and colocalization of the 67-kilodalton laminin receptor with alpha-actinin and vinculin. J. Biol. Chem. 268, 8053-8059 (1993).

28. Staatz, W.D., et al. Identification of a tetrapeptide recognition sequence for the alpha-2-beta-1-integrin in

31. Simon, E.E., McDonald, J.A. Extracellular-matrix receptors in the kidney cortex. Am. J. Physiol. 259, F783- F792 (1990).

32. Simon, E.E., et al. Characterization of integrins in cultured human renal cortical tubule epithelial-cells. Am. J. Physiol. Renal Physiol. 267, F612-F623 (1994).

33. Nelson, J., et al. The 67 kDa laminin receptor: structure, function and role in disease. Biosci. Reports 28, 33-48

(2008).

34. Cui, W.G., Zhou, Y., Chang, J. Electrospun nanofibrous materials for tissue engineering and drug delivery.

Sci. Technol. Adv. Mater. 11, 014108.1-11 (2010).

35. Yang, J.Y., et al. A mini review: electrospun hierarchical nanofibers. J. Disp. Sci. Technol. 31, 760-769 (2010).

36. Dankers, P.Y.W., Boomker, J.M., Huizinga-van der Vlag, A., Smedts, F.M.M., Harmsen, M.C., van Luyn, M.J.A. The use of fibrous, supramolecular membranes and human tubular cells for renal epithelial tissue engineering: towards a suitable membrane for a bioartificial kidney. Macromolec. Biosci. 10, 1345-1354 (2010). 37. Liu, Y. Epithelial to mesenchymal transition in renal fibrogenesis: pathologic significance, molecular

mechanism, and therapeutic intervention. J. Am. Soc. Nephrol. 15, 1-12 (2004). 38. Neilson, E.G. Setting a trap for tissue fibrosis. Nature Med. 11, 373-374 (2005).

39. Rastaldi, M.P. Epithelial-mesenchymal transition and its implications for the development of renal tubulointerstitial fibrosis. J. Nephrol. 19, 407-412 (2006).

40. Griffith, L.G., Naughton, Tissue engineering - current challenges and expanding opportunities. Science 295, 1009-1014 (2002).

41. Hench, L.L., Polak, J.M. Third-generation biomedical materials. Science 295, 1014-1017 (2002). 42. Miner, J.H. Renal basement membrane components. Kidney Int. 56, 2016-2024 (1999).

43. Ip, T.K., Galletti, P.M., Aebischer, P. Effects of attachment substrates on the growth and differentiation of LLC-PK1 cells. In Vitro Cell. Develop. Biol. 26, 162-168 (1990).

44. Kanai, N., Fujita, Y., Kakuta, T., Saito, A. The effects of various extracellular matrices on renal cell attachment to polymer surfaces during the development of bioartificial renal tubules. Artif. Organs 23, 114- 118 (1999).

45. Gstraunthaler, G., Seppi, T., Pfaller, W. Impact of culture conditions, culture media volumes, and glucose content on metabolic properties of renal epithelial cell cultures - Are renal cells in tissue culture hypoxic?

Cell. Physiol. Biochem. 9, 150-172 (1999).

46. Minuth, W.W., Steiner, P., Strehl, R., Kloth, S., Tauc, M. Electrolyte environment modulates differentiation in embryonic renal collecting duct epithelia. Exp. Nephrol. 5, 414-422 (1997).

47. Minuth, W.W., Schumacher, K., Strehl, R. Renal epithelia in long term gradient culture for biomaterial testing and tissue engineering. Bio-Med. Mater. Engin. 15, 51-63 (2005).

48. Pfaller, W., Gstraunthaler, G. Nephrotoxicity testing in vitro - What we know and what we need to know.

Environ. Health Persp. 106, 559-569 (1998).

49. Ip, T.K., Aebischer, P. Renal epithelial-cell-controlled solute transport across permeable membranes as the foundation for a bioartificial kidney. Artif. Organs 13, 58-65 (1989).

50. Humes, H.D., Buffington, D.A., MacKay, S.M., Funke, A.J., Weitzel, W.F. Replacement of renal function in uremic animals with a tissue-engineered kidney. Nature Biotechn. 17, 451-455 (1999).

51. Humes, H.D., MacKay, S.M., Funke, A.J., Buffington, D.A. Tissue engineering of a bioartificial renal tubule assist device: In vitro transport and metabolic characteristics. Kidney Int. 55, 2502-2514 (1999).

52. Tumlin, J., et al. Efficacy and safety of renal tubule cell therapy for acute renal failure. J. Am. Soc. Nephrol. 19,

1034-1040 (2008).

53. Tiranathanagul, K., Brodie, J., Humes, H.D. Bioartificial kidney in the treatment of acute renal failure associated with sepsis. Nephrology 11, 285-291 (2006).

54. Fissell, W.H., et al. Differentiated growth of human renal tubule cells on thin-film and nanostructured materials. ASAIO J. 52, 221-227 (2006).

55. Dankers, P.Y.W. Supramolecular biomaterials - Introducing a modular approach. Dissertation (2006). 56. Minuth, W.W., Sittinger, M., Kloth, S. Tissue engineering: generation of differentiated artificial tissues for

biomedical applications. Cell Tissue Res. 291, 1-11 (1998).

57. Schumacher, K., Strehl, R., de Vries, U., Minuth, W.W. Advanced technique for long term culture of epithelia in a continuous luminal-basal medium gradient. Biomaterials 23, 805-815 (2002).

58. Minuth, W.W., Denk, L., Glashauser, A. A modular culture system for the generation of multiple specialized tissues. Biomaterials 31, 2945-2954 (2010).

59. Bradford, M.M. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal. Biochem. 72, 248-254 (1976).

5