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Simultaneous MR imaging for tissue engineering in a rat model of stroke.

Nicholls FJ, Ling W, Ferrauto G, Aime S, Modo M - Sci Rep (2015)

Bottom Line: Considering the varied lesion topology within each subject, the placement and distribution of cells within the lesion cavity is challenging.The use of multiple cell types to reconstruct damaged tissue illustrates the complexity of the process, but also highlights the challenges to provide a non-invasive assessment.The distribution of implanted cells within the lesion cavity and crucially the contribution of neural stem cells and endothelial cells to morphogenesis could be visualized simultaneously using two paramagnetic chemical exchange saturation transfer (paraCEST) agents.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Pittsburgh, PA.

ABSTRACT
In situ tissue engineering within a stroke cavity is gradually emerging as a novel therapeutic paradigm. Considering the varied lesion topology within each subject, the placement and distribution of cells within the lesion cavity is challenging. The use of multiple cell types to reconstruct damaged tissue illustrates the complexity of the process, but also highlights the challenges to provide a non-invasive assessment. The distribution of implanted cells within the lesion cavity and crucially the contribution of neural stem cells and endothelial cells to morphogenesis could be visualized simultaneously using two paramagnetic chemical exchange saturation transfer (paraCEST) agents. The development of sophisticated imaging methods is essential to guide delivery of the building blocks for in situ tissue engineering, but will also be essential to understand the dynamics of cellular interactions leading to the formation of de novo tissue.

No MeSH data available.


Related in: MedlinePlus

Cell labeling.(A) With pinocytosis, uptake was increased in both cell types by increasing concentration (F = 132, p < 0.0001 for NSCs and F = 101, p < 0.0001 for ECs) and incubation time (F = 72, p < 0.0001 for NSCs and F = 12, p < 0.001 for ECs), with a significant interaction between time and concentration (F = 20, p < 0.0001 for NSCs and F = 13, p < 0.05 for ECs). (B) Survival was decreased in both cell types by increasing concentration (F = 29, p < 0.0001 for NSCs and F = 64, p < 0.0001 for ECs) and incubation time (F = 6, p < 0.01 for NSCs and F = 22, p < 0.0001 for ECs), with a significant interaction between time and concentration (F = 4, p < 0.01 for NSCs and F = 8, p < 0.001 for ECs). (C) For electroporation in NSCs, uptake was increased by increasing voltage (F = 12, p < 0.001) and decreased by increasing cell density (F = 24, p < 0.0001). For ECs, uptake by electroporation was increased by increasing pulse length (F = 13, p < 0.0001), but was not affected by cell density (F = 0.1, p = 0.90). (D) In NSCs, survival after electroporation was decreased by increasing voltage (F = 259, p < 0.0001) but increased by increasing cell density (F = 55, p < 0.0001). For ECs, survival after electroporation was decreased by increasing pulse length (F = 197, p < 0.0001), but was not affected by cell density (F = 0.02, p = 0.98).
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f2: Cell labeling.(A) With pinocytosis, uptake was increased in both cell types by increasing concentration (F = 132, p < 0.0001 for NSCs and F = 101, p < 0.0001 for ECs) and incubation time (F = 72, p < 0.0001 for NSCs and F = 12, p < 0.001 for ECs), with a significant interaction between time and concentration (F = 20, p < 0.0001 for NSCs and F = 13, p < 0.05 for ECs). (B) Survival was decreased in both cell types by increasing concentration (F = 29, p < 0.0001 for NSCs and F = 64, p < 0.0001 for ECs) and incubation time (F = 6, p < 0.01 for NSCs and F = 22, p < 0.0001 for ECs), with a significant interaction between time and concentration (F = 4, p < 0.01 for NSCs and F = 8, p < 0.001 for ECs). (C) For electroporation in NSCs, uptake was increased by increasing voltage (F = 12, p < 0.001) and decreased by increasing cell density (F = 24, p < 0.0001). For ECs, uptake by electroporation was increased by increasing pulse length (F = 13, p < 0.0001), but was not affected by cell density (F = 0.1, p = 0.90). (D) In NSCs, survival after electroporation was decreased by increasing voltage (F = 259, p < 0.0001) but increased by increasing cell density (F = 55, p < 0.0001). For ECs, survival after electroporation was decreased by increasing pulse length (F = 197, p < 0.0001), but was not affected by cell density (F = 0.02, p = 0.98).

Mentions: To achieve an intracellular agent concentration that affords detection, a significant uptake of agent is required for each cell type. However, as Eu-HPDO3A is a more efficient imaging agent, a lower intracellular concentration or fewer cells are required to warrant detection. Since NSCs are generally more susceptible to toxicity and less efficient in cellular uptake than ECs, NSCs were labeled with Eu-HPDO3A and ECs with Yb-HPDO3A. For pinocytosis, both NSCs and ECs showed increasing intracellular concentration of paraCEST agents with increasing incubation time and concentration (Fig. 2A), whereas cell yield (i.e. those cells that attached and survived for 24hrs) showed the opposite response, decreasing with increasing incubation time and concentration (Fig. 2B). Incubation times of at least 24 hours at 100 mM paraCEST agent concentration yielded cell uptake that was sufficient for imaging experiments, as measured by ICP-MS. Cell uptake of Eu was verifiable based on the fluorescent properties of this molecule (Supplementary Fig. 1A). However, a concern of pinocytosis is that agents are sequestered in endosomes that can affect its effect on water and hence affect chemical exchange leading to a quenching of the detectable signal.


Simultaneous MR imaging for tissue engineering in a rat model of stroke.

Nicholls FJ, Ling W, Ferrauto G, Aime S, Modo M - Sci Rep (2015)

Cell labeling.(A) With pinocytosis, uptake was increased in both cell types by increasing concentration (F = 132, p < 0.0001 for NSCs and F = 101, p < 0.0001 for ECs) and incubation time (F = 72, p < 0.0001 for NSCs and F = 12, p < 0.001 for ECs), with a significant interaction between time and concentration (F = 20, p < 0.0001 for NSCs and F = 13, p < 0.05 for ECs). (B) Survival was decreased in both cell types by increasing concentration (F = 29, p < 0.0001 for NSCs and F = 64, p < 0.0001 for ECs) and incubation time (F = 6, p < 0.01 for NSCs and F = 22, p < 0.0001 for ECs), with a significant interaction between time and concentration (F = 4, p < 0.01 for NSCs and F = 8, p < 0.001 for ECs). (C) For electroporation in NSCs, uptake was increased by increasing voltage (F = 12, p < 0.001) and decreased by increasing cell density (F = 24, p < 0.0001). For ECs, uptake by electroporation was increased by increasing pulse length (F = 13, p < 0.0001), but was not affected by cell density (F = 0.1, p = 0.90). (D) In NSCs, survival after electroporation was decreased by increasing voltage (F = 259, p < 0.0001) but increased by increasing cell density (F = 55, p < 0.0001). For ECs, survival after electroporation was decreased by increasing pulse length (F = 197, p < 0.0001), but was not affected by cell density (F = 0.02, p = 0.98).
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
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f2: Cell labeling.(A) With pinocytosis, uptake was increased in both cell types by increasing concentration (F = 132, p < 0.0001 for NSCs and F = 101, p < 0.0001 for ECs) and incubation time (F = 72, p < 0.0001 for NSCs and F = 12, p < 0.001 for ECs), with a significant interaction between time and concentration (F = 20, p < 0.0001 for NSCs and F = 13, p < 0.05 for ECs). (B) Survival was decreased in both cell types by increasing concentration (F = 29, p < 0.0001 for NSCs and F = 64, p < 0.0001 for ECs) and incubation time (F = 6, p < 0.01 for NSCs and F = 22, p < 0.0001 for ECs), with a significant interaction between time and concentration (F = 4, p < 0.01 for NSCs and F = 8, p < 0.001 for ECs). (C) For electroporation in NSCs, uptake was increased by increasing voltage (F = 12, p < 0.001) and decreased by increasing cell density (F = 24, p < 0.0001). For ECs, uptake by electroporation was increased by increasing pulse length (F = 13, p < 0.0001), but was not affected by cell density (F = 0.1, p = 0.90). (D) In NSCs, survival after electroporation was decreased by increasing voltage (F = 259, p < 0.0001) but increased by increasing cell density (F = 55, p < 0.0001). For ECs, survival after electroporation was decreased by increasing pulse length (F = 197, p < 0.0001), but was not affected by cell density (F = 0.02, p = 0.98).
Mentions: To achieve an intracellular agent concentration that affords detection, a significant uptake of agent is required for each cell type. However, as Eu-HPDO3A is a more efficient imaging agent, a lower intracellular concentration or fewer cells are required to warrant detection. Since NSCs are generally more susceptible to toxicity and less efficient in cellular uptake than ECs, NSCs were labeled with Eu-HPDO3A and ECs with Yb-HPDO3A. For pinocytosis, both NSCs and ECs showed increasing intracellular concentration of paraCEST agents with increasing incubation time and concentration (Fig. 2A), whereas cell yield (i.e. those cells that attached and survived for 24hrs) showed the opposite response, decreasing with increasing incubation time and concentration (Fig. 2B). Incubation times of at least 24 hours at 100 mM paraCEST agent concentration yielded cell uptake that was sufficient for imaging experiments, as measured by ICP-MS. Cell uptake of Eu was verifiable based on the fluorescent properties of this molecule (Supplementary Fig. 1A). However, a concern of pinocytosis is that agents are sequestered in endosomes that can affect its effect on water and hence affect chemical exchange leading to a quenching of the detectable signal.

Bottom Line: Considering the varied lesion topology within each subject, the placement and distribution of cells within the lesion cavity is challenging.The use of multiple cell types to reconstruct damaged tissue illustrates the complexity of the process, but also highlights the challenges to provide a non-invasive assessment.The distribution of implanted cells within the lesion cavity and crucially the contribution of neural stem cells and endothelial cells to morphogenesis could be visualized simultaneously using two paramagnetic chemical exchange saturation transfer (paraCEST) agents.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Pittsburgh, PA.

ABSTRACT
In situ tissue engineering within a stroke cavity is gradually emerging as a novel therapeutic paradigm. Considering the varied lesion topology within each subject, the placement and distribution of cells within the lesion cavity is challenging. The use of multiple cell types to reconstruct damaged tissue illustrates the complexity of the process, but also highlights the challenges to provide a non-invasive assessment. The distribution of implanted cells within the lesion cavity and crucially the contribution of neural stem cells and endothelial cells to morphogenesis could be visualized simultaneously using two paramagnetic chemical exchange saturation transfer (paraCEST) agents. The development of sophisticated imaging methods is essential to guide delivery of the building blocks for in situ tissue engineering, but will also be essential to understand the dynamics of cellular interactions leading to the formation of de novo tissue.

No MeSH data available.


Related in: MedlinePlus