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Optogenetics-enabled assessment of viral gene and cell therapy for restoration of cardiac excitability.

Ambrosi CM, Boyle PM, Chen K, Trayanova NA, Entcheva E - Sci Rep (2015)

Bottom Line: Multiple cardiac pathologies are accompanied by loss of tissue excitability, which leads to a range of heart rhythm disorders (arrhythmias).Taken directly, these results can help guide optogenetic interventions for light-based control of cardiac excitation.More generally, our findings can help optimize gene therapy for restoration of cardiac excitability.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY.

ABSTRACT
Multiple cardiac pathologies are accompanied by loss of tissue excitability, which leads to a range of heart rhythm disorders (arrhythmias). In addition to electronic device therapy (i.e. implantable pacemakers and cardioverter/defibrillators), biological approaches have recently been explored to restore pacemaking ability and to correct conduction slowing in the heart by delivering excitatory ion channels or ion channel agonists. Using optogenetics as a tool to selectively interrogate only cells transduced to produce an exogenous excitatory ion current, we experimentally and computationally quantify the efficiency of such biological approaches in rescuing cardiac excitability as a function of the mode of application (viral gene delivery or cell delivery) and the geometry of the transduced region (focal or spatially-distributed). We demonstrate that for each configuration (delivery mode and spatial pattern), the optical energy needed to excite can be used to predict therapeutic efficiency of excitability restoration. Taken directly, these results can help guide optogenetic interventions for light-based control of cardiac excitation. More generally, our findings can help optimize gene therapy for restoration of cardiac excitability.

No MeSH data available.


Related in: MedlinePlus

Conduction properties of light-sensitive cardiac syncytia.(a,b) Activation maps during electrical stimulation (1 Hz) of in vitro (a) and in silico (b) light-sensitive cell monolayers with distribution types (I, UL, UH) and delivery mode (GD, CD) corresponding to the same lettered panels in Figs 2 and 3. In all cases, time zero corresponds to the start of the electrical stimulus; black coloured locations did not activate. For in vitro cases, the asterisk (*) marks the location of the bipolar pacing electrode and the spacing between isochrones lines is 10 ms. For in silico cases, the dashed rectangle indicates the area where transmembrane current stimulus was applied. (c) In vitro calcium transients at 1 Hz electrical pacing, plotted overlaid as group mean ± SEM, for control CMs, ChR2-expressing CMs (GD-UH), and co-cultures of CMs and ChR2-expressing HEK cells (CD-UL) (n = 5 per group); no significant differences. (d) Select calcium transients from the pixel locations 1–3 indicated in ((a), GD-UL and CD-UL) showing in vitro wavefront propagation across the monolayer. (e) Select voltage traces (analogous to those in (c)) from the pixel locations 1–6 indicated in (b, GD-UL and CD-UL) showing in silico wavefront propagation and upstroke morphology.
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f4: Conduction properties of light-sensitive cardiac syncytia.(a,b) Activation maps during electrical stimulation (1 Hz) of in vitro (a) and in silico (b) light-sensitive cell monolayers with distribution types (I, UL, UH) and delivery mode (GD, CD) corresponding to the same lettered panels in Figs 2 and 3. In all cases, time zero corresponds to the start of the electrical stimulus; black coloured locations did not activate. For in vitro cases, the asterisk (*) marks the location of the bipolar pacing electrode and the spacing between isochrones lines is 10 ms. For in silico cases, the dashed rectangle indicates the area where transmembrane current stimulus was applied. (c) In vitro calcium transients at 1 Hz electrical pacing, plotted overlaid as group mean ± SEM, for control CMs, ChR2-expressing CMs (GD-UH), and co-cultures of CMs and ChR2-expressing HEK cells (CD-UL) (n = 5 per group); no significant differences. (d) Select calcium transients from the pixel locations 1–3 indicated in ((a), GD-UL and CD-UL) showing in vitro wavefront propagation across the monolayer. (e) Select voltage traces (analogous to those in (c)) from the pixel locations 1–6 indicated in (b, GD-UL and CD-UL) showing in silico wavefront propagation and upstroke morphology.

Mentions: Using optical mapping, combined with electrical or optical stimulation, we first experimentally tracked the functional bioelectric responses of the cardiac monolayers: 1) to confirm that the optogenetic transduction did not interfere with function beyond light-induced excitation, and thus ascertain that the experimental system is suitable for assessing the effects of a transgene’s spatial distribution; and 2) to validate the functional predictions of the corresponding in silico models (with matching D and C parameters). Upon electrical stimulation (1 Hz, 5 ms pulses), for each of the six transgene spatial distributions, activation patterns for the in vitro and in silico cases showed similarities at both the macroscopic and microscopic scales (Fig. 4). For GD, the presence of ChR2 within excitable cardiomyocytes did not disrupt conduction (Fig. 4a,b, top row); in contrast, as expected, the presence of ChR2-expressing, non-excitable somatic cells for CD resulted in heterogeneous conduction patterns (Fig. 4a,b, bottom row), particularly in the case of clustered donor cells in CD-I (Fig. 4a,b, bottom left). Overall, there were no statistically significant differences between the in vitro and in silico macroscopic conduction velocities (CVs at 30 ± 0.5 °C, 18.4 ± 0.7 cm/sec vs 22.7 ± 0.3 cm/sec, respectively) for different delivery modes and/or transgene patterns (Fig. S2).


Optogenetics-enabled assessment of viral gene and cell therapy for restoration of cardiac excitability.

Ambrosi CM, Boyle PM, Chen K, Trayanova NA, Entcheva E - Sci Rep (2015)

Conduction properties of light-sensitive cardiac syncytia.(a,b) Activation maps during electrical stimulation (1 Hz) of in vitro (a) and in silico (b) light-sensitive cell monolayers with distribution types (I, UL, UH) and delivery mode (GD, CD) corresponding to the same lettered panels in Figs 2 and 3. In all cases, time zero corresponds to the start of the electrical stimulus; black coloured locations did not activate. For in vitro cases, the asterisk (*) marks the location of the bipolar pacing electrode and the spacing between isochrones lines is 10 ms. For in silico cases, the dashed rectangle indicates the area where transmembrane current stimulus was applied. (c) In vitro calcium transients at 1 Hz electrical pacing, plotted overlaid as group mean ± SEM, for control CMs, ChR2-expressing CMs (GD-UH), and co-cultures of CMs and ChR2-expressing HEK cells (CD-UL) (n = 5 per group); no significant differences. (d) Select calcium transients from the pixel locations 1–3 indicated in ((a), GD-UL and CD-UL) showing in vitro wavefront propagation across the monolayer. (e) Select voltage traces (analogous to those in (c)) from the pixel locations 1–6 indicated in (b, GD-UL and CD-UL) showing in silico wavefront propagation and upstroke morphology.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4664892&req=5

f4: Conduction properties of light-sensitive cardiac syncytia.(a,b) Activation maps during electrical stimulation (1 Hz) of in vitro (a) and in silico (b) light-sensitive cell monolayers with distribution types (I, UL, UH) and delivery mode (GD, CD) corresponding to the same lettered panels in Figs 2 and 3. In all cases, time zero corresponds to the start of the electrical stimulus; black coloured locations did not activate. For in vitro cases, the asterisk (*) marks the location of the bipolar pacing electrode and the spacing between isochrones lines is 10 ms. For in silico cases, the dashed rectangle indicates the area where transmembrane current stimulus was applied. (c) In vitro calcium transients at 1 Hz electrical pacing, plotted overlaid as group mean ± SEM, for control CMs, ChR2-expressing CMs (GD-UH), and co-cultures of CMs and ChR2-expressing HEK cells (CD-UL) (n = 5 per group); no significant differences. (d) Select calcium transients from the pixel locations 1–3 indicated in ((a), GD-UL and CD-UL) showing in vitro wavefront propagation across the monolayer. (e) Select voltage traces (analogous to those in (c)) from the pixel locations 1–6 indicated in (b, GD-UL and CD-UL) showing in silico wavefront propagation and upstroke morphology.
Mentions: Using optical mapping, combined with electrical or optical stimulation, we first experimentally tracked the functional bioelectric responses of the cardiac monolayers: 1) to confirm that the optogenetic transduction did not interfere with function beyond light-induced excitation, and thus ascertain that the experimental system is suitable for assessing the effects of a transgene’s spatial distribution; and 2) to validate the functional predictions of the corresponding in silico models (with matching D and C parameters). Upon electrical stimulation (1 Hz, 5 ms pulses), for each of the six transgene spatial distributions, activation patterns for the in vitro and in silico cases showed similarities at both the macroscopic and microscopic scales (Fig. 4). For GD, the presence of ChR2 within excitable cardiomyocytes did not disrupt conduction (Fig. 4a,b, top row); in contrast, as expected, the presence of ChR2-expressing, non-excitable somatic cells for CD resulted in heterogeneous conduction patterns (Fig. 4a,b, bottom row), particularly in the case of clustered donor cells in CD-I (Fig. 4a,b, bottom left). Overall, there were no statistically significant differences between the in vitro and in silico macroscopic conduction velocities (CVs at 30 ± 0.5 °C, 18.4 ± 0.7 cm/sec vs 22.7 ± 0.3 cm/sec, respectively) for different delivery modes and/or transgene patterns (Fig. S2).

Bottom Line: Multiple cardiac pathologies are accompanied by loss of tissue excitability, which leads to a range of heart rhythm disorders (arrhythmias).Taken directly, these results can help guide optogenetic interventions for light-based control of cardiac excitation.More generally, our findings can help optimize gene therapy for restoration of cardiac excitability.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY.

ABSTRACT
Multiple cardiac pathologies are accompanied by loss of tissue excitability, which leads to a range of heart rhythm disorders (arrhythmias). In addition to electronic device therapy (i.e. implantable pacemakers and cardioverter/defibrillators), biological approaches have recently been explored to restore pacemaking ability and to correct conduction slowing in the heart by delivering excitatory ion channels or ion channel agonists. Using optogenetics as a tool to selectively interrogate only cells transduced to produce an exogenous excitatory ion current, we experimentally and computationally quantify the efficiency of such biological approaches in rescuing cardiac excitability as a function of the mode of application (viral gene delivery or cell delivery) and the geometry of the transduced region (focal or spatially-distributed). We demonstrate that for each configuration (delivery mode and spatial pattern), the optical energy needed to excite can be used to predict therapeutic efficiency of excitability restoration. Taken directly, these results can help guide optogenetic interventions for light-based control of cardiac excitation. More generally, our findings can help optimize gene therapy for restoration of cardiac excitability.

No MeSH data available.


Related in: MedlinePlus