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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

Response to optical stimulation in light-sensitive cardiac syncytia.(a,b) Activation maps resulting from optical stimulation (1 Hz) of in vitro light-sensitive cell monolayers in the island configuration. Optical stimulus strength was at most 0.07 mW/mm2 greater than the threshold irradiance required to elicit a propagating response (Ee,thr). Time zero corresponds to the beginning of a 20 ms-long pulse of blue light (wavelength λ = 470 nm) applied to the 1 cm-diameter region indicated by the dashed black line in (a); spacing between isochrones is 10 ms. (c,d) Same as (a,b) but for in silico cell monolayers. Simulated optical stimuli were at most 0.0005 mW/mm2 greater than Ee,thr. Here time zero corresponds to the end of each 20 ms-long illumination pulse instead of the beginning; spacing between isochrones is 10 ms. Black-coloured locations did not activate. (e,f) Select in vitro calcium transients from the pixel locations 1–4 indicated in (a,b) on opposite sides of the island of ChR2-expressing donor cells (CM in GD and HEK in CD) showing the wavefront activation sequence. (g,h) Select in silico voltage traces (analogous to those in (e,f)) from locations 1–4.
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f5: Response to optical stimulation in light-sensitive cardiac syncytia.(a,b) Activation maps resulting from optical stimulation (1 Hz) of in vitro light-sensitive cell monolayers in the island configuration. Optical stimulus strength was at most 0.07 mW/mm2 greater than the threshold irradiance required to elicit a propagating response (Ee,thr). Time zero corresponds to the beginning of a 20 ms-long pulse of blue light (wavelength λ = 470 nm) applied to the 1 cm-diameter region indicated by the dashed black line in (a); spacing between isochrones is 10 ms. (c,d) Same as (a,b) but for in silico cell monolayers. Simulated optical stimuli were at most 0.0005 mW/mm2 greater than Ee,thr. Here time zero corresponds to the end of each 20 ms-long illumination pulse instead of the beginning; spacing between isochrones is 10 ms. Black-coloured locations did not activate. (e,f) Select in vitro calcium transients from the pixel locations 1–4 indicated in (a,b) on opposite sides of the island of ChR2-expressing donor cells (CM in GD and HEK in CD) showing the wavefront activation sequence. (g,h) Select in silico voltage traces (analogous to those in (e,f)) from locations 1–4.

Mentions: Optical excitation (1 Hz, 20 ms pulses) of light-sensitive cardiac monolayers resulted in similar patterns of homogenous global conduction with earliest activations occurring near the centre of the 1 cm diameter illuminated area (dotted black line in Fig. 5a,c). As with electrical activation (Fig. 4a,d), the CD-I configuration resulted in heterogeneous conduction patterns with the earliest excitation occurring consistently at the interface between ChR2-expressing, non-excitable donor cells and surrounding cardiomyocytes (Fig. 5b). This conduction pattern was corroborated in silico, where the coupling of ChR2-expressing donor cells and cardiomyocytes was an important determinant of optical excitability (Fig. 5d). The homogeneity of light-induced activation patterns for GD compared to CD cases was equally evident in propagation sequences of in vitro calcium transients (Fig. 5e,f) and in silico voltage traces (Fig. 5g,h). As observed previously, the electrotonic effect from non-excitable donor cells was clearly discernible in CD cases, especially in voltage signals from regions near the border of the central island of ChR2-expressing cells (i.e., traces 1 and 2 in Fig. 5h). Activation patterns and propagation sequences for the island configuration (Fig. 5) were conceptually consistent with UL and UH distributions for GD and CD, in that excitations originated from the centres of regions with densely-expressed ChR2 for GD and from the edges of ChR2-rich donor cell clusters for CD.


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)

Response to optical stimulation in light-sensitive cardiac syncytia.(a,b) Activation maps resulting from optical stimulation (1 Hz) of in vitro light-sensitive cell monolayers in the island configuration. Optical stimulus strength was at most 0.07 mW/mm2 greater than the threshold irradiance required to elicit a propagating response (Ee,thr). Time zero corresponds to the beginning of a 20 ms-long pulse of blue light (wavelength λ = 470 nm) applied to the 1 cm-diameter region indicated by the dashed black line in (a); spacing between isochrones is 10 ms. (c,d) Same as (a,b) but for in silico cell monolayers. Simulated optical stimuli were at most 0.0005 mW/mm2 greater than Ee,thr. Here time zero corresponds to the end of each 20 ms-long illumination pulse instead of the beginning; spacing between isochrones is 10 ms. Black-coloured locations did not activate. (e,f) Select in vitro calcium transients from the pixel locations 1–4 indicated in (a,b) on opposite sides of the island of ChR2-expressing donor cells (CM in GD and HEK in CD) showing the wavefront activation sequence. (g,h) Select in silico voltage traces (analogous to those in (e,f)) from locations 1–4.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f5: Response to optical stimulation in light-sensitive cardiac syncytia.(a,b) Activation maps resulting from optical stimulation (1 Hz) of in vitro light-sensitive cell monolayers in the island configuration. Optical stimulus strength was at most 0.07 mW/mm2 greater than the threshold irradiance required to elicit a propagating response (Ee,thr). Time zero corresponds to the beginning of a 20 ms-long pulse of blue light (wavelength λ = 470 nm) applied to the 1 cm-diameter region indicated by the dashed black line in (a); spacing between isochrones is 10 ms. (c,d) Same as (a,b) but for in silico cell monolayers. Simulated optical stimuli were at most 0.0005 mW/mm2 greater than Ee,thr. Here time zero corresponds to the end of each 20 ms-long illumination pulse instead of the beginning; spacing between isochrones is 10 ms. Black-coloured locations did not activate. (e,f) Select in vitro calcium transients from the pixel locations 1–4 indicated in (a,b) on opposite sides of the island of ChR2-expressing donor cells (CM in GD and HEK in CD) showing the wavefront activation sequence. (g,h) Select in silico voltage traces (analogous to those in (e,f)) from locations 1–4.
Mentions: Optical excitation (1 Hz, 20 ms pulses) of light-sensitive cardiac monolayers resulted in similar patterns of homogenous global conduction with earliest activations occurring near the centre of the 1 cm diameter illuminated area (dotted black line in Fig. 5a,c). As with electrical activation (Fig. 4a,d), the CD-I configuration resulted in heterogeneous conduction patterns with the earliest excitation occurring consistently at the interface between ChR2-expressing, non-excitable donor cells and surrounding cardiomyocytes (Fig. 5b). This conduction pattern was corroborated in silico, where the coupling of ChR2-expressing donor cells and cardiomyocytes was an important determinant of optical excitability (Fig. 5d). The homogeneity of light-induced activation patterns for GD compared to CD cases was equally evident in propagation sequences of in vitro calcium transients (Fig. 5e,f) and in silico voltage traces (Fig. 5g,h). As observed previously, the electrotonic effect from non-excitable donor cells was clearly discernible in CD cases, especially in voltage signals from regions near the border of the central island of ChR2-expressing cells (i.e., traces 1 and 2 in Fig. 5h). Activation patterns and propagation sequences for the island configuration (Fig. 5) were conceptually consistent with UL and UH distributions for GD and CD, in that excitations originated from the centres of regions with densely-expressed ChR2 for GD and from the edges of ChR2-rich donor cell clusters for CD.

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