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A Nanoparticle-based Sensor Platform for Cell Tracking and Status/Function Assessment.

Yeo D, Wiraja C, Chuah YJ, Gao Y, Xu C - Sci Rep (2015)

Bottom Line: Upon intracellular entry, nanosensors reside within the cell cytoplasm, serving as a depot to continuously release sensor molecules for up to 30 days.When the biomarker(s) is expressed, a detectable signal is generated (On).As a proof-of-concept, three nanosensor formulations were synthesized to monitor cell viability, secretion of nitric oxide, and β-actin mRNA expression.

View Article: PubMed Central - PubMed

Affiliation: School of Chemical &Biomedical Engineering, Nanyang Technological University, Singapore.

ABSTRACT
Nanoparticles are increasingly popular choices for labeling and tracking cells in biomedical applications such as cell therapy. However, all current types of nanoparticles fail to provide real-time, noninvasive monitoring of cell status and functions while often generating false positive signals. Herein, a nanosensor platform to track the real-time expression of specific biomarkers that correlate with cell status and functions is reported. Nanosensors are synthesized by encapsulating various sensor molecules within biodegradable polymeric nanoparticles. Upon intracellular entry, nanosensors reside within the cell cytoplasm, serving as a depot to continuously release sensor molecules for up to 30 days. In the absence of the target biomarkers, the released sensor molecules remain 'Off'. When the biomarker(s) is expressed, a detectable signal is generated (On). As a proof-of-concept, three nanosensor formulations were synthesized to monitor cell viability, secretion of nitric oxide, and β-actin mRNA expression.

No MeSH data available.


Related in: MedlinePlus

Longitudinal tracking of nanosensor labeled mesenchymal stem cells (MSCs).(A) Representative fluorescence and phase contrast images of nanosensor and DiO labeled MSCs during a culture period of 35 days post labeling. (B) Normalized fluorescence intensity from nanosensor and DiO labeled MSCs in A. Scale bars represent 100 μm. (N = 6, >200 cells analyzed).
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f4: Longitudinal tracking of nanosensor labeled mesenchymal stem cells (MSCs).(A) Representative fluorescence and phase contrast images of nanosensor and DiO labeled MSCs during a culture period of 35 days post labeling. (B) Normalized fluorescence intensity from nanosensor and DiO labeled MSCs in A. Scale bars represent 100 μm. (N = 6, >200 cells analyzed).

Mentions: Longitudinal studies are typically required to monitor and understand the behavior of transplanted cells, since certain events such as cell differentiation occur over a period ranging from weeks to even months15. To explore the potential of viability nanosensors for longitudinal cell tracking, nanosensor-labeled MSCs were monitored for a 2 month period, while being compared with cells labeled with DiOC18(3) (DiO), a commercial contrast agent for cellular imaging (Fig. 4)16. Unlike nanosensors, DiO is a lipophilic carbocyanine dye that labels the cell plasma membrane. At day 1, there were similar percentage of fluorescent cells in the nanosensors and DiO labeled groups (~92%) (Supplementary S4a,b). Both DiO and nanosensor labeled cells expressed similar fluorescence intensity per cell at this stage (Fig. 4a,b). After 14 days, there was only 70% DiO-labeled cells with detectable fluorescence signal while 85% nanosensor-labeled cells were fluorescent (Supplementary Fig. S4b). More impressively, the average signal of the fluorescent cells decreased approximately 50% for DiO-labeled cells during the 14 day period, yet the signal from nanosensor-labeled cells negligibly decreased (Fig. 4b). Subsequently, average fluorescence intensity from DiO labeled cells continued to decrease weekly (Fig. 4b). In contrast, nanosensor labeled MSCs maintained signal levels at a stable level without significant intensity decrease. Nanosensor labeled MSCs continued to be imaged for a total of 8 weeks (56 days), with nanosensor labeled cells expressing a stable signal throughout (Supplementary Fig. S4c). This dramatic difference between nanosensor and DiO labeled cells demonstrates the advantages of its sustained release mechanism, enabling prolonged cellular retention of imaging contrast.


A Nanoparticle-based Sensor Platform for Cell Tracking and Status/Function Assessment.

Yeo D, Wiraja C, Chuah YJ, Gao Y, Xu C - Sci Rep (2015)

Longitudinal tracking of nanosensor labeled mesenchymal stem cells (MSCs).(A) Representative fluorescence and phase contrast images of nanosensor and DiO labeled MSCs during a culture period of 35 days post labeling. (B) Normalized fluorescence intensity from nanosensor and DiO labeled MSCs in A. Scale bars represent 100 μm. (N = 6, >200 cells analyzed).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4593999&req=5

f4: Longitudinal tracking of nanosensor labeled mesenchymal stem cells (MSCs).(A) Representative fluorescence and phase contrast images of nanosensor and DiO labeled MSCs during a culture period of 35 days post labeling. (B) Normalized fluorescence intensity from nanosensor and DiO labeled MSCs in A. Scale bars represent 100 μm. (N = 6, >200 cells analyzed).
Mentions: Longitudinal studies are typically required to monitor and understand the behavior of transplanted cells, since certain events such as cell differentiation occur over a period ranging from weeks to even months15. To explore the potential of viability nanosensors for longitudinal cell tracking, nanosensor-labeled MSCs were monitored for a 2 month period, while being compared with cells labeled with DiOC18(3) (DiO), a commercial contrast agent for cellular imaging (Fig. 4)16. Unlike nanosensors, DiO is a lipophilic carbocyanine dye that labels the cell plasma membrane. At day 1, there were similar percentage of fluorescent cells in the nanosensors and DiO labeled groups (~92%) (Supplementary S4a,b). Both DiO and nanosensor labeled cells expressed similar fluorescence intensity per cell at this stage (Fig. 4a,b). After 14 days, there was only 70% DiO-labeled cells with detectable fluorescence signal while 85% nanosensor-labeled cells were fluorescent (Supplementary Fig. S4b). More impressively, the average signal of the fluorescent cells decreased approximately 50% for DiO-labeled cells during the 14 day period, yet the signal from nanosensor-labeled cells negligibly decreased (Fig. 4b). Subsequently, average fluorescence intensity from DiO labeled cells continued to decrease weekly (Fig. 4b). In contrast, nanosensor labeled MSCs maintained signal levels at a stable level without significant intensity decrease. Nanosensor labeled MSCs continued to be imaged for a total of 8 weeks (56 days), with nanosensor labeled cells expressing a stable signal throughout (Supplementary Fig. S4c). This dramatic difference between nanosensor and DiO labeled cells demonstrates the advantages of its sustained release mechanism, enabling prolonged cellular retention of imaging contrast.

Bottom Line: Upon intracellular entry, nanosensors reside within the cell cytoplasm, serving as a depot to continuously release sensor molecules for up to 30 days.When the biomarker(s) is expressed, a detectable signal is generated (On).As a proof-of-concept, three nanosensor formulations were synthesized to monitor cell viability, secretion of nitric oxide, and β-actin mRNA expression.

View Article: PubMed Central - PubMed

Affiliation: School of Chemical &Biomedical Engineering, Nanyang Technological University, Singapore.

ABSTRACT
Nanoparticles are increasingly popular choices for labeling and tracking cells in biomedical applications such as cell therapy. However, all current types of nanoparticles fail to provide real-time, noninvasive monitoring of cell status and functions while often generating false positive signals. Herein, a nanosensor platform to track the real-time expression of specific biomarkers that correlate with cell status and functions is reported. Nanosensors are synthesized by encapsulating various sensor molecules within biodegradable polymeric nanoparticles. Upon intracellular entry, nanosensors reside within the cell cytoplasm, serving as a depot to continuously release sensor molecules for up to 30 days. In the absence of the target biomarkers, the released sensor molecules remain 'Off'. When the biomarker(s) is expressed, a detectable signal is generated (On). As a proof-of-concept, three nanosensor formulations were synthesized to monitor cell viability, secretion of nitric oxide, and β-actin mRNA expression.

No MeSH data available.


Related in: MedlinePlus