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Schwann Cell Response on Polypyrrole Substrates Upon Electrical Stimulation

Leandro Forciniti , Jose Ybarra III, John Maldonado, Muhammad H. Zaman , Christine E. Schmidt Chemical Engineering Doctoral Candidate, University of Texas, Austin. Schwann Cell Response on Polypyrrole Substrates Upon Electrical Stimulation. Causes of peripheral neuropathy (PN).

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Schwann Cell Response on Polypyrrole Substrates Upon Electrical Stimulation

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  1. Leandro Forciniti, Jose Ybarra III, John Maldonado, Muhammad H. Zaman, Christine E. Schmidt Chemical Engineering Doctoral Candidate, University of Texas, Austin Schwann Cell Response on Polypyrrole Substrates Upon Electrical Stimulation

  2. Causes of peripheral neuropathy (PN)

  3. PN due to injury a growing concern • Easy to injure • Trauma • Incident rate 2.4 % of the U.S. population • Expected to grow to 8.3% of the population due to an aging1 • War • 35% troops extremities wounded in combat2 1Gale Encyclopedia of Neurological Disorders 2Journal of Craniofacial Surgery. 21(4):998-1001, July 2010.

  4. Peripheral nerve anatomy and types of injuries Peripheral Nerve Axon Epineurium Perineurium Endoneurium where Schwann cells are Injuries Requiring Treatment Injuries That Autologously Recover First Degree Second Degree Fourth Degree Third Degree Fifth Degree

  5. Three treatment options for peripheral neuropathy (PN) due to injury

  6. Biomaterials for PN requires proper integration of stimuli Chemical Electrical Contact Huang et al. (2008) Lee et al. (2002) Gomez et al. (2006) For more information on stimuli integration see Forcinitiet al. ABME. (2008).

  7. Polypyrrole (PPy) contains all three types of stimuli - - + + Nerve Growth Factor (NGF)-Stimof PC-122 ElectricalStimulation (Estim)of PC-121 Controllable Topology3 1 Schmidt, C.E. et al. PNAS. 1997; 2 Lee, J.Y. et al. J.R. Soc. Interface 2009; 3Ateh, D.D. et al. J.R. Soc. Interface. 2006.

  8. Electrochemical Synthesis Methods of synthesizing PPy Chemical Synthesis

  9. Polypyrrole a tunable material Forcinitiet al.Biomedical Materials. 2008.

  10. PPy material properties affect cell viability Forcinitiet al.Biomedical Materials. (2008).

  11. Schwann cell (SC) behavior on PPy:PSS upon electrical stimulation Fibronectin (FN), Laminin (LN) or Nerve Growth Factor (NGF) Petri Dish PDMS Glue Petri Dish Cell Culture Media 10,000 SC Film 10,000 SC Copper tape Film e- Film From Working electrode socket (anode) From Counter and Reference Electrode socket (cathode) Cell Culture Media 10 X Magnification Phase Contrast 10 min/frame 10 X Magnification Phase Contrast 10 min/frame

  12. Electrical currents pass through both the PPy:PSS organic polymer and the underlying ITO slide Indium Tin Oxide (ITO) PPy:PSS on ITO 300-600 Å 1,090 Å • 0.1 V + 10% FBS • Electric Field seen in media ~ 80 mV @ 2 mm distance from surface

  13. Current profiles for electrical stimulation of Schwann cells

  14. Laminin (LN) adsorbed to surface PPy:PSS 100 ug/mL LN + Estim PPy:PSS No protein PPy:PSS 100 ug/mL LN

  15. Time lapse movies allow us to monitor SC behavior in the presence of e-fields W.E. PPy:PSS + 100 ng/mL NGF (18 hours) PPy:PSS + 100 ng/mL NGF + Estim (18 hours)

  16. Electrical stimulation orients SC but does not affect migration speed a a b a b a a a b b b c b c c d Number of * denotes statistically similarity (p<0.05)

  17. Electrical stimulation orients SC NGF FN LN Top Anode Cathode Center Bottom

  18. NGF secretion up regulated by protein adsorption and changes in surface topology upon e-stim c c b b a a

  19. NGF secretion up regulated by protein adsorption and changes in surface topology upon e-stim b a,b a a c d

  20. NGF secretion up regulated by protein adsorption and changes in surface topology upon e-stim c b b b a a

  21. E-stim increases surface nanoscale surface roughness in DPBS PPy:PSS Pre-stimulation PPy:PSS Post-stimulation

  22. Conclusions • Electrical stimulation affects only the directionality of the migration rather than cell migration speed. • Adsorption levels of stimulatory proteins affect cell migration speed. • Adsorption level and changes in surface topology may affect secretion levels of NGF by Schwann cells.

  23. Future Directions • We would like to determine ion flux passing by the cell upon electrical stimulation. We propose to monitor the flux of a charged dye upon electrical stimulation. • We would like to determine the effect increase protein adsorption upon electrical stimulation has on surface topology. We propose to get AFM roughness data. • We would like to determine whether electrical stimulation is reversible. We propose to monitor cell migration upon reversible electrical gradients.

  24. Acknowledgements • Dr. Christine E. Schmidt • Dr. Muhammad H. Zaman • Dr. Schmidt’s Lab • Dr. Zaman’s Lab • ZinKhaing • Jae Y. Lee • Funding Resources: • UT Graduate Continuing Fellowship • NIH R21

  25. Questions?

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