Abstract

The intracellular effects of focused near-infrared femtosecond laser irradiation are shown to cause contraction in cultured neonatal rat cardiomyocytes. By periodic exposure to femtosecond laser pulse-trains, periodic contraction cycles in cardiomyocytes could be triggered, depleted, and synchronized with the laser periodicity. This was observed in isolated cells, and in small groups of cardiomyocytes with the laser acting as pacemaker for the entire group. A window for this effect was found to occur between 15 and 30 mW average power for an 80 fs, 82 MHz pulse train of 780 nm, using 8 ms exposures applied periodically at 1 to 2 Hz. At power levels below this power window, laser-induced cardiomyocyte contraction was not observed, while above this power window, cells typically responded by a high calcium elevation and contracted without subsequent relaxation. This laser-cell interaction allows the laser irradiation to act as a pacemaker, and can be used to trigger contraction in dormant cells as well as synchronize or destabilize contraction in spontaneously contracting cardiomyocytes. By increasing laser power above the window available for laser-cell synchronization, we also demonstrate the use of cardiomyocytes as optically-triggered actuators. To our knowledge, this is the first demonstration of remote optical control of cardiomyocytes without requiring exogenous photosensitive compounds.

© 2008 Optical Society of America

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  1. D. M. Bers, "Cardiac excitation-contraction coupling," Nature 415, 198-205 (2002).
    [CrossRef] [PubMed]
  2. J. W. Bassani, R. A. Bassani, and D. M. Bers, "Relaxation in rabbit and rat cardiac cells: species-dependent differences in cellular mechanisms," J Physiol. 476, 279-293 (1994).
    [PubMed]
  3. Y. Tanaka, K. Sato, T. Shimizu, M. Yamato, T. Okano, and T. Kitamori, "A micro-spherical heart pump powered by cultured cardiomyocytes," Lab Chip 7, 207-12 (2007).
    [CrossRef] [PubMed]
  4. T. Shimizu, M. Yamato, Y. Isoi, T. Akutsu, T. Setomaru, K. Abe, A. Kikuchi, M. Umezu, and T. Okano, "Fabrication of pulsatile cardiac tissue grafts using a novel 3-dimensional cell sheet manipulation technique and temperature-responsive cell culture surfaces," Circ. Res. 90, e40 (2002).
    [CrossRef] [PubMed]
  5. A. W. Feinberg, A. Feigel, S. S. Shevkoplyas, S. Sheehy, G. M. Whitesides, and K. K. Parker, "Muscular thin films for building actuators and powering devices," Science 317, 1366-70 (2007).
    [CrossRef] [PubMed]
  6. K. Morishima, Y. Tanaka, M. Ebara, T. Shimizu, A. Kikuchi, M. Yamato, T. Okano, and T. Kitamori, "Demonstration of a bio-microactuator powered by cultured cardiomyocytes coupled to hydrogel micropillars," Sens. Actuators B 119, 345-350 (2006).
    [CrossRef]
  7. S. Iwanaga, N. I. Smith, K. Fujita, and S. Kawata, "Slow Ca2+ wave stimulation using low repetition rate femtosecond pulsed irradiation," Opt. Express 14, 717-725 (2006).
    [CrossRef] [PubMed]
  8. N. I. Smith, S. Iwanaga, T. Beppu, K. Fujita, O. Nakamura, and S. Kawata, "Photostimulation of two types of Ca2+ waves in rat pheochromocytoma PC12 cells by ultrashort pulsed near-infrared laser irradiation," Las. Phys. Lett. 3, 154-161 (2006).
    [CrossRef]
  9. S. Iwanaga, T. Kaneko, K. Fujita, N. I. Smith, O. Nakamura, T. Takamatsu, and S. Kawata, "Location-dependent photogeneration of calcium waves in HeLa cells," Cell Biochem. Biophys. 45, 167-76 (2006).
    [CrossRef] [PubMed]
  10. M. Cannell, H. Cheng, and W. Lederer, "The control of calcium release in heart muscle," Science 268, 1045-1049 (1995).
    [CrossRef] [PubMed]
  11. A. M. Gurney, P. Charnet, J. M. Pye, and J. Nargeot, "Augmentation of cardiac calcium current by flash photolysis of intracellular caged-Ca2+ molecules," Nature 341, 65-68 (1989).
    [CrossRef] [PubMed]
  12. J. R. Patel, K. S. McDonald, M. R. Wolff, and R. L. Moss, "Ca2+ binding to troponin C in skinned skeletal muscle fibers assessed with caged Ca2+ and a Ca2+ fluorophore," J. Biol. Chem. 272, 6018-6027 (1997).
    [CrossRef] [PubMed]
  13. E. B Brown, J. B. Shear, S. R. Adams, R. Y. Tsien, and W. W. Webb, "Photolysis of caged calcium in femtoliter volumes using two-photon excitation," Biophys. J. 76, 489-499 (1999).
    [CrossRef] [PubMed]
  14. R. Lubart, H. Friedmann, M. Sinyakov, N. Cohen, and H. Breitbart, "Changes in calcium transport in mammalian sperm mitochondria and plasma membranes caused by 780 nm irradiation," Laser Surg. Med. 21, 493-499 (1997).
    [CrossRef]
  15. A. B. Uzdensky and V. V. Savransky, "Single neuron response to pulse-periodic laser microirradiation. Action spectra and two-photon effect," J. Photochem. Photobiol. B 39, 224-228 (1997).
    [CrossRef]
  16. H. Hirase, V. Nikolenko, J. H. Goldbery, and R. Yuste, "Multiphoton stimulation of neurons," J. Neurobiology 51, 3, 237-247, (2002).
    [CrossRef]
  17. H. J. Koester, D. Baur, R. Uhl, and S. W. Hell, "Ca2+ fluorescence imaging with pico- and femtosecond two-photon excitation: signal and photodamage," Biophys. J. 77, 2226-2236 (1999).
    [CrossRef] [PubMed]
  18. K. Shapira-Schweitzer and D. Seliktar, "Matrix stiffness affects spontaneous contraction of cardiomyocytes cultured within a PEGylated fibrinogen biomaterial," Acta Biomater. 3, 33-41 (2007).
    [CrossRef]
  19. T. Kaneko, K. Kojima, and K. Yasuda, "Dependence of the community effect of cultured cardiomyocytes on the cell network pattern," Biochem. Biophys. Res. Commun. 356, 494-498 (2007).
    [CrossRef] [PubMed]
  20. R. Vetter, K. Monika, S. Wolfgang, and H. Rupp, "Influence of different culture conditions on sarcoplasmic reticular calcium transport in isolated neonatal rat cardiomyocytes," Mol. Cell. Biochem. 188, 177-185 (1998).
    [CrossRef] [PubMed]
  21. A. Vogel, and V. Venugopalan, "Mechanisms of Pulsed Laser Ablation of Biological Tissues," Chem. Rev. 103, 577-644 (2003).
    [CrossRef] [PubMed]
  22. U. K. Tirlapur, K. Konig, C. Peuckert, R. Krieg, and K. Halbhuber, "Femtosecond near-infrared laser pulses elicit generation of reactive oxygen species in mammalian cells leading to apoptosis-like death," Exp. Cell Res. 263, 88-97 (2001).
    [CrossRef]
  23. W. T. Clusin, "Mechanisms of calcium transient and action potential alternans in cardiac cells and tissues," Am. J. Physiol. Heart Circ. Physiol. 294, H1-H10 (2008).
    [CrossRef]

2008 (1)

W. T. Clusin, "Mechanisms of calcium transient and action potential alternans in cardiac cells and tissues," Am. J. Physiol. Heart Circ. Physiol. 294, H1-H10 (2008).
[CrossRef]

2007 (4)

Y. Tanaka, K. Sato, T. Shimizu, M. Yamato, T. Okano, and T. Kitamori, "A micro-spherical heart pump powered by cultured cardiomyocytes," Lab Chip 7, 207-12 (2007).
[CrossRef] [PubMed]

K. Shapira-Schweitzer and D. Seliktar, "Matrix stiffness affects spontaneous contraction of cardiomyocytes cultured within a PEGylated fibrinogen biomaterial," Acta Biomater. 3, 33-41 (2007).
[CrossRef]

T. Kaneko, K. Kojima, and K. Yasuda, "Dependence of the community effect of cultured cardiomyocytes on the cell network pattern," Biochem. Biophys. Res. Commun. 356, 494-498 (2007).
[CrossRef] [PubMed]

A. W. Feinberg, A. Feigel, S. S. Shevkoplyas, S. Sheehy, G. M. Whitesides, and K. K. Parker, "Muscular thin films for building actuators and powering devices," Science 317, 1366-70 (2007).
[CrossRef] [PubMed]

2006 (4)

K. Morishima, Y. Tanaka, M. Ebara, T. Shimizu, A. Kikuchi, M. Yamato, T. Okano, and T. Kitamori, "Demonstration of a bio-microactuator powered by cultured cardiomyocytes coupled to hydrogel micropillars," Sens. Actuators B 119, 345-350 (2006).
[CrossRef]

S. Iwanaga, N. I. Smith, K. Fujita, and S. Kawata, "Slow Ca2+ wave stimulation using low repetition rate femtosecond pulsed irradiation," Opt. Express 14, 717-725 (2006).
[CrossRef] [PubMed]

N. I. Smith, S. Iwanaga, T. Beppu, K. Fujita, O. Nakamura, and S. Kawata, "Photostimulation of two types of Ca2+ waves in rat pheochromocytoma PC12 cells by ultrashort pulsed near-infrared laser irradiation," Las. Phys. Lett. 3, 154-161 (2006).
[CrossRef]

S. Iwanaga, T. Kaneko, K. Fujita, N. I. Smith, O. Nakamura, T. Takamatsu, and S. Kawata, "Location-dependent photogeneration of calcium waves in HeLa cells," Cell Biochem. Biophys. 45, 167-76 (2006).
[CrossRef] [PubMed]

2003 (1)

A. Vogel, and V. Venugopalan, "Mechanisms of Pulsed Laser Ablation of Biological Tissues," Chem. Rev. 103, 577-644 (2003).
[CrossRef] [PubMed]

2002 (3)

T. Shimizu, M. Yamato, Y. Isoi, T. Akutsu, T. Setomaru, K. Abe, A. Kikuchi, M. Umezu, and T. Okano, "Fabrication of pulsatile cardiac tissue grafts using a novel 3-dimensional cell sheet manipulation technique and temperature-responsive cell culture surfaces," Circ. Res. 90, e40 (2002).
[CrossRef] [PubMed]

D. M. Bers, "Cardiac excitation-contraction coupling," Nature 415, 198-205 (2002).
[CrossRef] [PubMed]

H. Hirase, V. Nikolenko, J. H. Goldbery, and R. Yuste, "Multiphoton stimulation of neurons," J. Neurobiology 51, 3, 237-247, (2002).
[CrossRef]

2001 (1)

U. K. Tirlapur, K. Konig, C. Peuckert, R. Krieg, and K. Halbhuber, "Femtosecond near-infrared laser pulses elicit generation of reactive oxygen species in mammalian cells leading to apoptosis-like death," Exp. Cell Res. 263, 88-97 (2001).
[CrossRef]

1999 (2)

H. J. Koester, D. Baur, R. Uhl, and S. W. Hell, "Ca2+ fluorescence imaging with pico- and femtosecond two-photon excitation: signal and photodamage," Biophys. J. 77, 2226-2236 (1999).
[CrossRef] [PubMed]

E. B Brown, J. B. Shear, S. R. Adams, R. Y. Tsien, and W. W. Webb, "Photolysis of caged calcium in femtoliter volumes using two-photon excitation," Biophys. J. 76, 489-499 (1999).
[CrossRef] [PubMed]

1998 (1)

R. Vetter, K. Monika, S. Wolfgang, and H. Rupp, "Influence of different culture conditions on sarcoplasmic reticular calcium transport in isolated neonatal rat cardiomyocytes," Mol. Cell. Biochem. 188, 177-185 (1998).
[CrossRef] [PubMed]

1997 (3)

R. Lubart, H. Friedmann, M. Sinyakov, N. Cohen, and H. Breitbart, "Changes in calcium transport in mammalian sperm mitochondria and plasma membranes caused by 780 nm irradiation," Laser Surg. Med. 21, 493-499 (1997).
[CrossRef]

A. B. Uzdensky and V. V. Savransky, "Single neuron response to pulse-periodic laser microirradiation. Action spectra and two-photon effect," J. Photochem. Photobiol. B 39, 224-228 (1997).
[CrossRef]

J. R. Patel, K. S. McDonald, M. R. Wolff, and R. L. Moss, "Ca2+ binding to troponin C in skinned skeletal muscle fibers assessed with caged Ca2+ and a Ca2+ fluorophore," J. Biol. Chem. 272, 6018-6027 (1997).
[CrossRef] [PubMed]

1995 (1)

M. Cannell, H. Cheng, and W. Lederer, "The control of calcium release in heart muscle," Science 268, 1045-1049 (1995).
[CrossRef] [PubMed]

1994 (1)

J. W. Bassani, R. A. Bassani, and D. M. Bers, "Relaxation in rabbit and rat cardiac cells: species-dependent differences in cellular mechanisms," J Physiol. 476, 279-293 (1994).
[PubMed]

1989 (1)

A. M. Gurney, P. Charnet, J. M. Pye, and J. Nargeot, "Augmentation of cardiac calcium current by flash photolysis of intracellular caged-Ca2+ molecules," Nature 341, 65-68 (1989).
[CrossRef] [PubMed]

Abe, K.

T. Shimizu, M. Yamato, Y. Isoi, T. Akutsu, T. Setomaru, K. Abe, A. Kikuchi, M. Umezu, and T. Okano, "Fabrication of pulsatile cardiac tissue grafts using a novel 3-dimensional cell sheet manipulation technique and temperature-responsive cell culture surfaces," Circ. Res. 90, e40 (2002).
[CrossRef] [PubMed]

Adams, S. R.

E. B Brown, J. B. Shear, S. R. Adams, R. Y. Tsien, and W. W. Webb, "Photolysis of caged calcium in femtoliter volumes using two-photon excitation," Biophys. J. 76, 489-499 (1999).
[CrossRef] [PubMed]

Akutsu, T.

T. Shimizu, M. Yamato, Y. Isoi, T. Akutsu, T. Setomaru, K. Abe, A. Kikuchi, M. Umezu, and T. Okano, "Fabrication of pulsatile cardiac tissue grafts using a novel 3-dimensional cell sheet manipulation technique and temperature-responsive cell culture surfaces," Circ. Res. 90, e40 (2002).
[CrossRef] [PubMed]

Bassani, J. W.

J. W. Bassani, R. A. Bassani, and D. M. Bers, "Relaxation in rabbit and rat cardiac cells: species-dependent differences in cellular mechanisms," J Physiol. 476, 279-293 (1994).
[PubMed]

Bassani, R. A.

J. W. Bassani, R. A. Bassani, and D. M. Bers, "Relaxation in rabbit and rat cardiac cells: species-dependent differences in cellular mechanisms," J Physiol. 476, 279-293 (1994).
[PubMed]

Baur, D.

H. J. Koester, D. Baur, R. Uhl, and S. W. Hell, "Ca2+ fluorescence imaging with pico- and femtosecond two-photon excitation: signal and photodamage," Biophys. J. 77, 2226-2236 (1999).
[CrossRef] [PubMed]

Beppu, T.

N. I. Smith, S. Iwanaga, T. Beppu, K. Fujita, O. Nakamura, and S. Kawata, "Photostimulation of two types of Ca2+ waves in rat pheochromocytoma PC12 cells by ultrashort pulsed near-infrared laser irradiation," Las. Phys. Lett. 3, 154-161 (2006).
[CrossRef]

Bers, D. M.

D. M. Bers, "Cardiac excitation-contraction coupling," Nature 415, 198-205 (2002).
[CrossRef] [PubMed]

J. W. Bassani, R. A. Bassani, and D. M. Bers, "Relaxation in rabbit and rat cardiac cells: species-dependent differences in cellular mechanisms," J Physiol. 476, 279-293 (1994).
[PubMed]

Breitbart, H.

R. Lubart, H. Friedmann, M. Sinyakov, N. Cohen, and H. Breitbart, "Changes in calcium transport in mammalian sperm mitochondria and plasma membranes caused by 780 nm irradiation," Laser Surg. Med. 21, 493-499 (1997).
[CrossRef]

Brown, E. B

E. B Brown, J. B. Shear, S. R. Adams, R. Y. Tsien, and W. W. Webb, "Photolysis of caged calcium in femtoliter volumes using two-photon excitation," Biophys. J. 76, 489-499 (1999).
[CrossRef] [PubMed]

Cannell, M.

M. Cannell, H. Cheng, and W. Lederer, "The control of calcium release in heart muscle," Science 268, 1045-1049 (1995).
[CrossRef] [PubMed]

Charnet, P.

A. M. Gurney, P. Charnet, J. M. Pye, and J. Nargeot, "Augmentation of cardiac calcium current by flash photolysis of intracellular caged-Ca2+ molecules," Nature 341, 65-68 (1989).
[CrossRef] [PubMed]

Cheng, H.

M. Cannell, H. Cheng, and W. Lederer, "The control of calcium release in heart muscle," Science 268, 1045-1049 (1995).
[CrossRef] [PubMed]

Clusin, W. T.

W. T. Clusin, "Mechanisms of calcium transient and action potential alternans in cardiac cells and tissues," Am. J. Physiol. Heart Circ. Physiol. 294, H1-H10 (2008).
[CrossRef]

Cohen, N.

R. Lubart, H. Friedmann, M. Sinyakov, N. Cohen, and H. Breitbart, "Changes in calcium transport in mammalian sperm mitochondria and plasma membranes caused by 780 nm irradiation," Laser Surg. Med. 21, 493-499 (1997).
[CrossRef]

Ebara, M.

K. Morishima, Y. Tanaka, M. Ebara, T. Shimizu, A. Kikuchi, M. Yamato, T. Okano, and T. Kitamori, "Demonstration of a bio-microactuator powered by cultured cardiomyocytes coupled to hydrogel micropillars," Sens. Actuators B 119, 345-350 (2006).
[CrossRef]

Feigel, A.

A. W. Feinberg, A. Feigel, S. S. Shevkoplyas, S. Sheehy, G. M. Whitesides, and K. K. Parker, "Muscular thin films for building actuators and powering devices," Science 317, 1366-70 (2007).
[CrossRef] [PubMed]

Feinberg, A. W.

A. W. Feinberg, A. Feigel, S. S. Shevkoplyas, S. Sheehy, G. M. Whitesides, and K. K. Parker, "Muscular thin films for building actuators and powering devices," Science 317, 1366-70 (2007).
[CrossRef] [PubMed]

Friedmann, H.

R. Lubart, H. Friedmann, M. Sinyakov, N. Cohen, and H. Breitbart, "Changes in calcium transport in mammalian sperm mitochondria and plasma membranes caused by 780 nm irradiation," Laser Surg. Med. 21, 493-499 (1997).
[CrossRef]

Fujita, K.

S. Iwanaga, N. I. Smith, K. Fujita, and S. Kawata, "Slow Ca2+ wave stimulation using low repetition rate femtosecond pulsed irradiation," Opt. Express 14, 717-725 (2006).
[CrossRef] [PubMed]

S. Iwanaga, T. Kaneko, K. Fujita, N. I. Smith, O. Nakamura, T. Takamatsu, and S. Kawata, "Location-dependent photogeneration of calcium waves in HeLa cells," Cell Biochem. Biophys. 45, 167-76 (2006).
[CrossRef] [PubMed]

N. I. Smith, S. Iwanaga, T. Beppu, K. Fujita, O. Nakamura, and S. Kawata, "Photostimulation of two types of Ca2+ waves in rat pheochromocytoma PC12 cells by ultrashort pulsed near-infrared laser irradiation," Las. Phys. Lett. 3, 154-161 (2006).
[CrossRef]

Goldbery, J. H.

H. Hirase, V. Nikolenko, J. H. Goldbery, and R. Yuste, "Multiphoton stimulation of neurons," J. Neurobiology 51, 3, 237-247, (2002).
[CrossRef]

Gurney, A. M.

A. M. Gurney, P. Charnet, J. M. Pye, and J. Nargeot, "Augmentation of cardiac calcium current by flash photolysis of intracellular caged-Ca2+ molecules," Nature 341, 65-68 (1989).
[CrossRef] [PubMed]

Halbhuber, K.

U. K. Tirlapur, K. Konig, C. Peuckert, R. Krieg, and K. Halbhuber, "Femtosecond near-infrared laser pulses elicit generation of reactive oxygen species in mammalian cells leading to apoptosis-like death," Exp. Cell Res. 263, 88-97 (2001).
[CrossRef]

Hell, S. W.

H. J. Koester, D. Baur, R. Uhl, and S. W. Hell, "Ca2+ fluorescence imaging with pico- and femtosecond two-photon excitation: signal and photodamage," Biophys. J. 77, 2226-2236 (1999).
[CrossRef] [PubMed]

Hirase, H.

H. Hirase, V. Nikolenko, J. H. Goldbery, and R. Yuste, "Multiphoton stimulation of neurons," J. Neurobiology 51, 3, 237-247, (2002).
[CrossRef]

Isoi, Y.

T. Shimizu, M. Yamato, Y. Isoi, T. Akutsu, T. Setomaru, K. Abe, A. Kikuchi, M. Umezu, and T. Okano, "Fabrication of pulsatile cardiac tissue grafts using a novel 3-dimensional cell sheet manipulation technique and temperature-responsive cell culture surfaces," Circ. Res. 90, e40 (2002).
[CrossRef] [PubMed]

Iwanaga, S.

S. Iwanaga, N. I. Smith, K. Fujita, and S. Kawata, "Slow Ca2+ wave stimulation using low repetition rate femtosecond pulsed irradiation," Opt. Express 14, 717-725 (2006).
[CrossRef] [PubMed]

S. Iwanaga, T. Kaneko, K. Fujita, N. I. Smith, O. Nakamura, T. Takamatsu, and S. Kawata, "Location-dependent photogeneration of calcium waves in HeLa cells," Cell Biochem. Biophys. 45, 167-76 (2006).
[CrossRef] [PubMed]

N. I. Smith, S. Iwanaga, T. Beppu, K. Fujita, O. Nakamura, and S. Kawata, "Photostimulation of two types of Ca2+ waves in rat pheochromocytoma PC12 cells by ultrashort pulsed near-infrared laser irradiation," Las. Phys. Lett. 3, 154-161 (2006).
[CrossRef]

Kaneko, T.

T. Kaneko, K. Kojima, and K. Yasuda, "Dependence of the community effect of cultured cardiomyocytes on the cell network pattern," Biochem. Biophys. Res. Commun. 356, 494-498 (2007).
[CrossRef] [PubMed]

S. Iwanaga, T. Kaneko, K. Fujita, N. I. Smith, O. Nakamura, T. Takamatsu, and S. Kawata, "Location-dependent photogeneration of calcium waves in HeLa cells," Cell Biochem. Biophys. 45, 167-76 (2006).
[CrossRef] [PubMed]

Kawata, S.

S. Iwanaga, T. Kaneko, K. Fujita, N. I. Smith, O. Nakamura, T. Takamatsu, and S. Kawata, "Location-dependent photogeneration of calcium waves in HeLa cells," Cell Biochem. Biophys. 45, 167-76 (2006).
[CrossRef] [PubMed]

N. I. Smith, S. Iwanaga, T. Beppu, K. Fujita, O. Nakamura, and S. Kawata, "Photostimulation of two types of Ca2+ waves in rat pheochromocytoma PC12 cells by ultrashort pulsed near-infrared laser irradiation," Las. Phys. Lett. 3, 154-161 (2006).
[CrossRef]

S. Iwanaga, N. I. Smith, K. Fujita, and S. Kawata, "Slow Ca2+ wave stimulation using low repetition rate femtosecond pulsed irradiation," Opt. Express 14, 717-725 (2006).
[CrossRef] [PubMed]

Kikuchi, A.

K. Morishima, Y. Tanaka, M. Ebara, T. Shimizu, A. Kikuchi, M. Yamato, T. Okano, and T. Kitamori, "Demonstration of a bio-microactuator powered by cultured cardiomyocytes coupled to hydrogel micropillars," Sens. Actuators B 119, 345-350 (2006).
[CrossRef]

T. Shimizu, M. Yamato, Y. Isoi, T. Akutsu, T. Setomaru, K. Abe, A. Kikuchi, M. Umezu, and T. Okano, "Fabrication of pulsatile cardiac tissue grafts using a novel 3-dimensional cell sheet manipulation technique and temperature-responsive cell culture surfaces," Circ. Res. 90, e40 (2002).
[CrossRef] [PubMed]

Kitamori, T.

Y. Tanaka, K. Sato, T. Shimizu, M. Yamato, T. Okano, and T. Kitamori, "A micro-spherical heart pump powered by cultured cardiomyocytes," Lab Chip 7, 207-12 (2007).
[CrossRef] [PubMed]

K. Morishima, Y. Tanaka, M. Ebara, T. Shimizu, A. Kikuchi, M. Yamato, T. Okano, and T. Kitamori, "Demonstration of a bio-microactuator powered by cultured cardiomyocytes coupled to hydrogel micropillars," Sens. Actuators B 119, 345-350 (2006).
[CrossRef]

Koester, H. J.

H. J. Koester, D. Baur, R. Uhl, and S. W. Hell, "Ca2+ fluorescence imaging with pico- and femtosecond two-photon excitation: signal and photodamage," Biophys. J. 77, 2226-2236 (1999).
[CrossRef] [PubMed]

Kojima, K.

T. Kaneko, K. Kojima, and K. Yasuda, "Dependence of the community effect of cultured cardiomyocytes on the cell network pattern," Biochem. Biophys. Res. Commun. 356, 494-498 (2007).
[CrossRef] [PubMed]

Konig, K.

U. K. Tirlapur, K. Konig, C. Peuckert, R. Krieg, and K. Halbhuber, "Femtosecond near-infrared laser pulses elicit generation of reactive oxygen species in mammalian cells leading to apoptosis-like death," Exp. Cell Res. 263, 88-97 (2001).
[CrossRef]

Krieg, R.

U. K. Tirlapur, K. Konig, C. Peuckert, R. Krieg, and K. Halbhuber, "Femtosecond near-infrared laser pulses elicit generation of reactive oxygen species in mammalian cells leading to apoptosis-like death," Exp. Cell Res. 263, 88-97 (2001).
[CrossRef]

Lederer, W.

M. Cannell, H. Cheng, and W. Lederer, "The control of calcium release in heart muscle," Science 268, 1045-1049 (1995).
[CrossRef] [PubMed]

Lubart, R.

R. Lubart, H. Friedmann, M. Sinyakov, N. Cohen, and H. Breitbart, "Changes in calcium transport in mammalian sperm mitochondria and plasma membranes caused by 780 nm irradiation," Laser Surg. Med. 21, 493-499 (1997).
[CrossRef]

McDonald, K. S.

J. R. Patel, K. S. McDonald, M. R. Wolff, and R. L. Moss, "Ca2+ binding to troponin C in skinned skeletal muscle fibers assessed with caged Ca2+ and a Ca2+ fluorophore," J. Biol. Chem. 272, 6018-6027 (1997).
[CrossRef] [PubMed]

Monika, K.

R. Vetter, K. Monika, S. Wolfgang, and H. Rupp, "Influence of different culture conditions on sarcoplasmic reticular calcium transport in isolated neonatal rat cardiomyocytes," Mol. Cell. Biochem. 188, 177-185 (1998).
[CrossRef] [PubMed]

Morishima, K.

K. Morishima, Y. Tanaka, M. Ebara, T. Shimizu, A. Kikuchi, M. Yamato, T. Okano, and T. Kitamori, "Demonstration of a bio-microactuator powered by cultured cardiomyocytes coupled to hydrogel micropillars," Sens. Actuators B 119, 345-350 (2006).
[CrossRef]

Moss, R. L.

J. R. Patel, K. S. McDonald, M. R. Wolff, and R. L. Moss, "Ca2+ binding to troponin C in skinned skeletal muscle fibers assessed with caged Ca2+ and a Ca2+ fluorophore," J. Biol. Chem. 272, 6018-6027 (1997).
[CrossRef] [PubMed]

Nakamura, O.

N. I. Smith, S. Iwanaga, T. Beppu, K. Fujita, O. Nakamura, and S. Kawata, "Photostimulation of two types of Ca2+ waves in rat pheochromocytoma PC12 cells by ultrashort pulsed near-infrared laser irradiation," Las. Phys. Lett. 3, 154-161 (2006).
[CrossRef]

S. Iwanaga, T. Kaneko, K. Fujita, N. I. Smith, O. Nakamura, T. Takamatsu, and S. Kawata, "Location-dependent photogeneration of calcium waves in HeLa cells," Cell Biochem. Biophys. 45, 167-76 (2006).
[CrossRef] [PubMed]

Nargeot, J.

A. M. Gurney, P. Charnet, J. M. Pye, and J. Nargeot, "Augmentation of cardiac calcium current by flash photolysis of intracellular caged-Ca2+ molecules," Nature 341, 65-68 (1989).
[CrossRef] [PubMed]

Nikolenko, V.

H. Hirase, V. Nikolenko, J. H. Goldbery, and R. Yuste, "Multiphoton stimulation of neurons," J. Neurobiology 51, 3, 237-247, (2002).
[CrossRef]

Okano, T.

Y. Tanaka, K. Sato, T. Shimizu, M. Yamato, T. Okano, and T. Kitamori, "A micro-spherical heart pump powered by cultured cardiomyocytes," Lab Chip 7, 207-12 (2007).
[CrossRef] [PubMed]

K. Morishima, Y. Tanaka, M. Ebara, T. Shimizu, A. Kikuchi, M. Yamato, T. Okano, and T. Kitamori, "Demonstration of a bio-microactuator powered by cultured cardiomyocytes coupled to hydrogel micropillars," Sens. Actuators B 119, 345-350 (2006).
[CrossRef]

T. Shimizu, M. Yamato, Y. Isoi, T. Akutsu, T. Setomaru, K. Abe, A. Kikuchi, M. Umezu, and T. Okano, "Fabrication of pulsatile cardiac tissue grafts using a novel 3-dimensional cell sheet manipulation technique and temperature-responsive cell culture surfaces," Circ. Res. 90, e40 (2002).
[CrossRef] [PubMed]

Parker, K. K.

A. W. Feinberg, A. Feigel, S. S. Shevkoplyas, S. Sheehy, G. M. Whitesides, and K. K. Parker, "Muscular thin films for building actuators and powering devices," Science 317, 1366-70 (2007).
[CrossRef] [PubMed]

Patel, J. R.

J. R. Patel, K. S. McDonald, M. R. Wolff, and R. L. Moss, "Ca2+ binding to troponin C in skinned skeletal muscle fibers assessed with caged Ca2+ and a Ca2+ fluorophore," J. Biol. Chem. 272, 6018-6027 (1997).
[CrossRef] [PubMed]

Peuckert, C.

U. K. Tirlapur, K. Konig, C. Peuckert, R. Krieg, and K. Halbhuber, "Femtosecond near-infrared laser pulses elicit generation of reactive oxygen species in mammalian cells leading to apoptosis-like death," Exp. Cell Res. 263, 88-97 (2001).
[CrossRef]

Pye, J. M.

A. M. Gurney, P. Charnet, J. M. Pye, and J. Nargeot, "Augmentation of cardiac calcium current by flash photolysis of intracellular caged-Ca2+ molecules," Nature 341, 65-68 (1989).
[CrossRef] [PubMed]

Rupp, H.

R. Vetter, K. Monika, S. Wolfgang, and H. Rupp, "Influence of different culture conditions on sarcoplasmic reticular calcium transport in isolated neonatal rat cardiomyocytes," Mol. Cell. Biochem. 188, 177-185 (1998).
[CrossRef] [PubMed]

Sato, K.

Y. Tanaka, K. Sato, T. Shimizu, M. Yamato, T. Okano, and T. Kitamori, "A micro-spherical heart pump powered by cultured cardiomyocytes," Lab Chip 7, 207-12 (2007).
[CrossRef] [PubMed]

Savransky, V. V.

A. B. Uzdensky and V. V. Savransky, "Single neuron response to pulse-periodic laser microirradiation. Action spectra and two-photon effect," J. Photochem. Photobiol. B 39, 224-228 (1997).
[CrossRef]

Seliktar, D.

K. Shapira-Schweitzer and D. Seliktar, "Matrix stiffness affects spontaneous contraction of cardiomyocytes cultured within a PEGylated fibrinogen biomaterial," Acta Biomater. 3, 33-41 (2007).
[CrossRef]

Setomaru, T.

T. Shimizu, M. Yamato, Y. Isoi, T. Akutsu, T. Setomaru, K. Abe, A. Kikuchi, M. Umezu, and T. Okano, "Fabrication of pulsatile cardiac tissue grafts using a novel 3-dimensional cell sheet manipulation technique and temperature-responsive cell culture surfaces," Circ. Res. 90, e40 (2002).
[CrossRef] [PubMed]

Shapira-Schweitzer, K.

K. Shapira-Schweitzer and D. Seliktar, "Matrix stiffness affects spontaneous contraction of cardiomyocytes cultured within a PEGylated fibrinogen biomaterial," Acta Biomater. 3, 33-41 (2007).
[CrossRef]

Shear, J. B.

E. B Brown, J. B. Shear, S. R. Adams, R. Y. Tsien, and W. W. Webb, "Photolysis of caged calcium in femtoliter volumes using two-photon excitation," Biophys. J. 76, 489-499 (1999).
[CrossRef] [PubMed]

Sheehy, S.

A. W. Feinberg, A. Feigel, S. S. Shevkoplyas, S. Sheehy, G. M. Whitesides, and K. K. Parker, "Muscular thin films for building actuators and powering devices," Science 317, 1366-70 (2007).
[CrossRef] [PubMed]

Shevkoplyas, S. S.

A. W. Feinberg, A. Feigel, S. S. Shevkoplyas, S. Sheehy, G. M. Whitesides, and K. K. Parker, "Muscular thin films for building actuators and powering devices," Science 317, 1366-70 (2007).
[CrossRef] [PubMed]

Shimizu, T.

Y. Tanaka, K. Sato, T. Shimizu, M. Yamato, T. Okano, and T. Kitamori, "A micro-spherical heart pump powered by cultured cardiomyocytes," Lab Chip 7, 207-12 (2007).
[CrossRef] [PubMed]

K. Morishima, Y. Tanaka, M. Ebara, T. Shimizu, A. Kikuchi, M. Yamato, T. Okano, and T. Kitamori, "Demonstration of a bio-microactuator powered by cultured cardiomyocytes coupled to hydrogel micropillars," Sens. Actuators B 119, 345-350 (2006).
[CrossRef]

T. Shimizu, M. Yamato, Y. Isoi, T. Akutsu, T. Setomaru, K. Abe, A. Kikuchi, M. Umezu, and T. Okano, "Fabrication of pulsatile cardiac tissue grafts using a novel 3-dimensional cell sheet manipulation technique and temperature-responsive cell culture surfaces," Circ. Res. 90, e40 (2002).
[CrossRef] [PubMed]

Sinyakov, M.

R. Lubart, H. Friedmann, M. Sinyakov, N. Cohen, and H. Breitbart, "Changes in calcium transport in mammalian sperm mitochondria and plasma membranes caused by 780 nm irradiation," Laser Surg. Med. 21, 493-499 (1997).
[CrossRef]

Smith, N. I.

S. Iwanaga, N. I. Smith, K. Fujita, and S. Kawata, "Slow Ca2+ wave stimulation using low repetition rate femtosecond pulsed irradiation," Opt. Express 14, 717-725 (2006).
[CrossRef] [PubMed]

N. I. Smith, S. Iwanaga, T. Beppu, K. Fujita, O. Nakamura, and S. Kawata, "Photostimulation of two types of Ca2+ waves in rat pheochromocytoma PC12 cells by ultrashort pulsed near-infrared laser irradiation," Las. Phys. Lett. 3, 154-161 (2006).
[CrossRef]

S. Iwanaga, T. Kaneko, K. Fujita, N. I. Smith, O. Nakamura, T. Takamatsu, and S. Kawata, "Location-dependent photogeneration of calcium waves in HeLa cells," Cell Biochem. Biophys. 45, 167-76 (2006).
[CrossRef] [PubMed]

Takamatsu, T.

S. Iwanaga, T. Kaneko, K. Fujita, N. I. Smith, O. Nakamura, T. Takamatsu, and S. Kawata, "Location-dependent photogeneration of calcium waves in HeLa cells," Cell Biochem. Biophys. 45, 167-76 (2006).
[CrossRef] [PubMed]

Tanaka, Y.

Y. Tanaka, K. Sato, T. Shimizu, M. Yamato, T. Okano, and T. Kitamori, "A micro-spherical heart pump powered by cultured cardiomyocytes," Lab Chip 7, 207-12 (2007).
[CrossRef] [PubMed]

K. Morishima, Y. Tanaka, M. Ebara, T. Shimizu, A. Kikuchi, M. Yamato, T. Okano, and T. Kitamori, "Demonstration of a bio-microactuator powered by cultured cardiomyocytes coupled to hydrogel micropillars," Sens. Actuators B 119, 345-350 (2006).
[CrossRef]

Tirlapur, U. K.

U. K. Tirlapur, K. Konig, C. Peuckert, R. Krieg, and K. Halbhuber, "Femtosecond near-infrared laser pulses elicit generation of reactive oxygen species in mammalian cells leading to apoptosis-like death," Exp. Cell Res. 263, 88-97 (2001).
[CrossRef]

Tsien, R. Y.

E. B Brown, J. B. Shear, S. R. Adams, R. Y. Tsien, and W. W. Webb, "Photolysis of caged calcium in femtoliter volumes using two-photon excitation," Biophys. J. 76, 489-499 (1999).
[CrossRef] [PubMed]

Uhl, R.

H. J. Koester, D. Baur, R. Uhl, and S. W. Hell, "Ca2+ fluorescence imaging with pico- and femtosecond two-photon excitation: signal and photodamage," Biophys. J. 77, 2226-2236 (1999).
[CrossRef] [PubMed]

Umezu, M.

T. Shimizu, M. Yamato, Y. Isoi, T. Akutsu, T. Setomaru, K. Abe, A. Kikuchi, M. Umezu, and T. Okano, "Fabrication of pulsatile cardiac tissue grafts using a novel 3-dimensional cell sheet manipulation technique and temperature-responsive cell culture surfaces," Circ. Res. 90, e40 (2002).
[CrossRef] [PubMed]

Uzdensky, A. B.

A. B. Uzdensky and V. V. Savransky, "Single neuron response to pulse-periodic laser microirradiation. Action spectra and two-photon effect," J. Photochem. Photobiol. B 39, 224-228 (1997).
[CrossRef]

Venugopalan, V.

A. Vogel, and V. Venugopalan, "Mechanisms of Pulsed Laser Ablation of Biological Tissues," Chem. Rev. 103, 577-644 (2003).
[CrossRef] [PubMed]

Vetter, R.

R. Vetter, K. Monika, S. Wolfgang, and H. Rupp, "Influence of different culture conditions on sarcoplasmic reticular calcium transport in isolated neonatal rat cardiomyocytes," Mol. Cell. Biochem. 188, 177-185 (1998).
[CrossRef] [PubMed]

Vogel, A.

A. Vogel, and V. Venugopalan, "Mechanisms of Pulsed Laser Ablation of Biological Tissues," Chem. Rev. 103, 577-644 (2003).
[CrossRef] [PubMed]

Webb, W. W.

E. B Brown, J. B. Shear, S. R. Adams, R. Y. Tsien, and W. W. Webb, "Photolysis of caged calcium in femtoliter volumes using two-photon excitation," Biophys. J. 76, 489-499 (1999).
[CrossRef] [PubMed]

Whitesides, G. M.

A. W. Feinberg, A. Feigel, S. S. Shevkoplyas, S. Sheehy, G. M. Whitesides, and K. K. Parker, "Muscular thin films for building actuators and powering devices," Science 317, 1366-70 (2007).
[CrossRef] [PubMed]

Wolff, M. R.

J. R. Patel, K. S. McDonald, M. R. Wolff, and R. L. Moss, "Ca2+ binding to troponin C in skinned skeletal muscle fibers assessed with caged Ca2+ and a Ca2+ fluorophore," J. Biol. Chem. 272, 6018-6027 (1997).
[CrossRef] [PubMed]

Wolfgang, S.

R. Vetter, K. Monika, S. Wolfgang, and H. Rupp, "Influence of different culture conditions on sarcoplasmic reticular calcium transport in isolated neonatal rat cardiomyocytes," Mol. Cell. Biochem. 188, 177-185 (1998).
[CrossRef] [PubMed]

Yamato, M.

Y. Tanaka, K. Sato, T. Shimizu, M. Yamato, T. Okano, and T. Kitamori, "A micro-spherical heart pump powered by cultured cardiomyocytes," Lab Chip 7, 207-12 (2007).
[CrossRef] [PubMed]

K. Morishima, Y. Tanaka, M. Ebara, T. Shimizu, A. Kikuchi, M. Yamato, T. Okano, and T. Kitamori, "Demonstration of a bio-microactuator powered by cultured cardiomyocytes coupled to hydrogel micropillars," Sens. Actuators B 119, 345-350 (2006).
[CrossRef]

T. Shimizu, M. Yamato, Y. Isoi, T. Akutsu, T. Setomaru, K. Abe, A. Kikuchi, M. Umezu, and T. Okano, "Fabrication of pulsatile cardiac tissue grafts using a novel 3-dimensional cell sheet manipulation technique and temperature-responsive cell culture surfaces," Circ. Res. 90, e40 (2002).
[CrossRef] [PubMed]

Yasuda, K.

T. Kaneko, K. Kojima, and K. Yasuda, "Dependence of the community effect of cultured cardiomyocytes on the cell network pattern," Biochem. Biophys. Res. Commun. 356, 494-498 (2007).
[CrossRef] [PubMed]

Yuste, R.

H. Hirase, V. Nikolenko, J. H. Goldbery, and R. Yuste, "Multiphoton stimulation of neurons," J. Neurobiology 51, 3, 237-247, (2002).
[CrossRef]

Acta Biomater. (1)

K. Shapira-Schweitzer and D. Seliktar, "Matrix stiffness affects spontaneous contraction of cardiomyocytes cultured within a PEGylated fibrinogen biomaterial," Acta Biomater. 3, 33-41 (2007).
[CrossRef]

Am. J. Physiol. Heart Circ. Physiol. (1)

W. T. Clusin, "Mechanisms of calcium transient and action potential alternans in cardiac cells and tissues," Am. J. Physiol. Heart Circ. Physiol. 294, H1-H10 (2008).
[CrossRef]

Biochem. Biophys. Res. Commun. (1)

T. Kaneko, K. Kojima, and K. Yasuda, "Dependence of the community effect of cultured cardiomyocytes on the cell network pattern," Biochem. Biophys. Res. Commun. 356, 494-498 (2007).
[CrossRef] [PubMed]

Biophys. J. (2)

H. J. Koester, D. Baur, R. Uhl, and S. W. Hell, "Ca2+ fluorescence imaging with pico- and femtosecond two-photon excitation: signal and photodamage," Biophys. J. 77, 2226-2236 (1999).
[CrossRef] [PubMed]

E. B Brown, J. B. Shear, S. R. Adams, R. Y. Tsien, and W. W. Webb, "Photolysis of caged calcium in femtoliter volumes using two-photon excitation," Biophys. J. 76, 489-499 (1999).
[CrossRef] [PubMed]

Cell Biochem. Biophys. (1)

S. Iwanaga, T. Kaneko, K. Fujita, N. I. Smith, O. Nakamura, T. Takamatsu, and S. Kawata, "Location-dependent photogeneration of calcium waves in HeLa cells," Cell Biochem. Biophys. 45, 167-76 (2006).
[CrossRef] [PubMed]

Chem. Rev. (1)

A. Vogel, and V. Venugopalan, "Mechanisms of Pulsed Laser Ablation of Biological Tissues," Chem. Rev. 103, 577-644 (2003).
[CrossRef] [PubMed]

Circ. Res. (1)

T. Shimizu, M. Yamato, Y. Isoi, T. Akutsu, T. Setomaru, K. Abe, A. Kikuchi, M. Umezu, and T. Okano, "Fabrication of pulsatile cardiac tissue grafts using a novel 3-dimensional cell sheet manipulation technique and temperature-responsive cell culture surfaces," Circ. Res. 90, e40 (2002).
[CrossRef] [PubMed]

Exp. Cell Res. (1)

U. K. Tirlapur, K. Konig, C. Peuckert, R. Krieg, and K. Halbhuber, "Femtosecond near-infrared laser pulses elicit generation of reactive oxygen species in mammalian cells leading to apoptosis-like death," Exp. Cell Res. 263, 88-97 (2001).
[CrossRef]

J Physiol. (1)

J. W. Bassani, R. A. Bassani, and D. M. Bers, "Relaxation in rabbit and rat cardiac cells: species-dependent differences in cellular mechanisms," J Physiol. 476, 279-293 (1994).
[PubMed]

J. Biol. Chem. (1)

J. R. Patel, K. S. McDonald, M. R. Wolff, and R. L. Moss, "Ca2+ binding to troponin C in skinned skeletal muscle fibers assessed with caged Ca2+ and a Ca2+ fluorophore," J. Biol. Chem. 272, 6018-6027 (1997).
[CrossRef] [PubMed]

J. Neurobiology (1)

H. Hirase, V. Nikolenko, J. H. Goldbery, and R. Yuste, "Multiphoton stimulation of neurons," J. Neurobiology 51, 3, 237-247, (2002).
[CrossRef]

J. Photochem. Photobiol. B (1)

A. B. Uzdensky and V. V. Savransky, "Single neuron response to pulse-periodic laser microirradiation. Action spectra and two-photon effect," J. Photochem. Photobiol. B 39, 224-228 (1997).
[CrossRef]

Lab Chip (1)

Y. Tanaka, K. Sato, T. Shimizu, M. Yamato, T. Okano, and T. Kitamori, "A micro-spherical heart pump powered by cultured cardiomyocytes," Lab Chip 7, 207-12 (2007).
[CrossRef] [PubMed]

Las. Phys. Lett. (1)

N. I. Smith, S. Iwanaga, T. Beppu, K. Fujita, O. Nakamura, and S. Kawata, "Photostimulation of two types of Ca2+ waves in rat pheochromocytoma PC12 cells by ultrashort pulsed near-infrared laser irradiation," Las. Phys. Lett. 3, 154-161 (2006).
[CrossRef]

Laser Surg. Med. (1)

R. Lubart, H. Friedmann, M. Sinyakov, N. Cohen, and H. Breitbart, "Changes in calcium transport in mammalian sperm mitochondria and plasma membranes caused by 780 nm irradiation," Laser Surg. Med. 21, 493-499 (1997).
[CrossRef]

Mol. Cell. Biochem. (1)

R. Vetter, K. Monika, S. Wolfgang, and H. Rupp, "Influence of different culture conditions on sarcoplasmic reticular calcium transport in isolated neonatal rat cardiomyocytes," Mol. Cell. Biochem. 188, 177-185 (1998).
[CrossRef] [PubMed]

Nature (2)

D. M. Bers, "Cardiac excitation-contraction coupling," Nature 415, 198-205 (2002).
[CrossRef] [PubMed]

A. M. Gurney, P. Charnet, J. M. Pye, and J. Nargeot, "Augmentation of cardiac calcium current by flash photolysis of intracellular caged-Ca2+ molecules," Nature 341, 65-68 (1989).
[CrossRef] [PubMed]

Opt. Express (1)

Science (2)

A. W. Feinberg, A. Feigel, S. S. Shevkoplyas, S. Sheehy, G. M. Whitesides, and K. K. Parker, "Muscular thin films for building actuators and powering devices," Science 317, 1366-70 (2007).
[CrossRef] [PubMed]

M. Cannell, H. Cheng, and W. Lederer, "The control of calcium release in heart muscle," Science 268, 1045-1049 (1995).
[CrossRef] [PubMed]

Sens. Actuators B (1)

K. Morishima, Y. Tanaka, M. Ebara, T. Shimizu, A. Kikuchi, M. Yamato, T. Okano, and T. Kitamori, "Demonstration of a bio-microactuator powered by cultured cardiomyocytes coupled to hydrogel micropillars," Sens. Actuators B 119, 345-350 (2006).
[CrossRef]

Supplementary Material (2)

» Media 1: MOV (11527 KB)     
» Media 2: MOV (2270 KB)     

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Figures (7)

Fig. 1.
Fig. 1.

(a). Cardiomyocyte loaded with Fluo-4 calcium indicator. The region ‘i’ shows the laser focal spot allowing visualization of the irradiation timing (8 ms exposures at 1 Hz, 25 mW). Region ‘ii’ encapsulates the surrounding area of the cell. (b) Shows the induced contraction due to the calcium response over time. The laser is visible as a series of spikes in the fluorescence signal in trace ‘i’, while the overall cell response is averaged over time and plotted as trace ‘ii’. The first 3 laser exposures are indicated by vertical arrows.

Fig. 2.
Fig. 2.

Cardiomyocyte synchronized at 120 beats per minute periodicity during laser irradiation of 8 ms exposures at 2 Hz with 25 mW average power, and then spontaneously contracting at 40 beats per minute following irradiation. (a) The region ‘i’ shows the laser focal spot, while region ‘ii’ encapsulates the surrounding area of the cell. (b) Shows the induced contraction due to the calcium response over time. The first 3 laser exposures are indicated by vertical arrows.

Fig. 3.
Fig. 3.

Laser pacemaking in a group of cardiomyocytes. The cardiomyocyte group consists of more than 6 cells, spontaneously contracting in synchronization. The laser power was set to 20 mW with 8 ms exposures at 1 Hz and targeted in the region marked ‘i’ in Fig. 3(a), with surrounding cells labeled by regions ii–v. The laser irradiation timing can be seen most clearly in Fig. 3(b) by the spikes in trace ‘i’. Arrows indicate the onset of laser irradiation. No observable effect in surrounding cells (traces ii–v, Fig. 3(b)) is seen for the first 20 seconds of periodic laser exposures, after which, all cells can be seen to contract at the periodicity of the laser exposures. Of particular interest is that all cells respond identically even though only one cell is targeted by laser irradiation (evident by the negligible differences in traces ii–v). Following irradiation, all cells enter a 5 s duration rest phase during which the intracellular calcium level is lowered before spontaneous contractions restart. (See supplemental video material for the data shown in Fig. 3(a)). [Media 1][Media 2]

Fig. 4.
Fig. 4.

Laser synchronized cardiomyocyte contraction cycles that continue after the irradiation of 25mW at 1 Hz is stopped. (a) shows fluorescent signals from the cell regions, with region ‘i’ corresponding to the laser focal spot, and region ‘ii’ representing the surrounding cell area, as outlined in (b). Panels (c) and (d) show the time-dependent Fourier transforms (TDFT) of the signals in the laser region ‘i’ and surrounding cell region ‘ii’. The color lookup table shows the amplitude of the frequency components in log scale. The cardiomyocyte retains the laser periodicity for approximately 20 contraction cycles after irradiation is stopped. The cell contraction cycles stabilize during irradiation and continue in the absence of irradiation with no significant changes in the time or frequency domain behavior. Final application of periodic laser exposure at a higher rate of 1.5 Hz brings the contractions to a halt.

Fig. 5.
Fig. 5.

The probability of generating a synchronized cell response or a calcium response without synchronization. Both are functions of laser power. The graph in (a) shows all data sets for a laser irradiation periodicity of 1 Hz. In (b), the graph shows the cases where the target cell was an isolated cardiomyocyte, and (c) shows the cases where the target cell was within a group of 2–14 cardiomyocytes. For synchronization to occur in cases shown in (c), all cells in the group were seen to synchronize with the laser periodicity. Conditions necessary to merit the term “synchronization” are described in the main text.

Fig. 6.
Fig. 6.

Time analysis of a phase contrast video showing the effect of 1 Hz, 15 mW periodic irradiation. Frame (a) shows an image from the video where the laser region is outlined and marked ‘i’, while the region for cell movement analysis includes all pixels outlined by the box marked ‘ii’. (b) shows correlation coefficients between the laser signature and the cell movement with the laser on, and for multiple time-shifted locations where the laser was off. (c) shows the time dependent signal representing cell movement plotted under the laser fluorescence signal. See main text for details.

Fig. 7.
Fig. 7.

Laser actuation of a single cultured cardiomyocyte by irradiation, causing it to contract and stay contracted. The image sequence was taken by phase contrast microscopy and the outline of the cell is highlighted. The laser was focused inside the cell using 30 mW of average power, and 8 ms exposures occurred at 1 Hz intervals. The time sequence is (a) 1 sec, (b) 8 sec, (c) 14.7 sec, and (d) 16.7 sec.

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