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Controlled Delivery of Human Cells by Temperature Responsive Microcapsules.

Mak WC, Olesen K, Sivlér P, Lee CJ, Moreno-Jimenez I, Edin J, Courtman D, Skog M, Griffith M - J Funct Biomater (2015)

Bottom Line: However, its full potential is limited by the rapid loss of introduced therapeutic cells before their full effects can be exploited, due in part to anoikis, and in part to the adverse environments often found within the pathologic tissues that the cells have been grafted into.Cell encapsulation and controlled release was demonstrated using human fibroblasts as model cells, as well as a therapeutically relevant cell line-human umbilical vein endothelial cells (HUVECs).While such temperature responsive cell microcapsules promise effective, controlled release of potential therapeutic cells at physiological temperatures, further work will be needed to augment the composition of the microcapsules and optimize the numbers of cells per capsule prior to clinical evaluation.

View Article: PubMed Central - PubMed

Affiliation: Integrative Regenerative Medicine Centre, Department of Clinical and Experimental Medicine, Linköping University, SE58185, Linköping, Sweden. mamak@ifm.liu.se.

ABSTRACT
Cell therapy is one of the most promising areas within regenerative medicine. However, its full potential is limited by the rapid loss of introduced therapeutic cells before their full effects can be exploited, due in part to anoikis, and in part to the adverse environments often found within the pathologic tissues that the cells have been grafted into. Encapsulation of individual cells has been proposed as a means of increasing cell viability. In this study, we developed a facile, high throughput method for creating temperature responsive microcapsules comprising agarose, gelatin and fibrinogen for delivery and subsequent controlled release of cells. We verified the hypothesis that composite capsules combining agarose and gelatin, which possess different phase transition temperatures from solid to liquid, facilitated the destabilization of the capsules for cell release. Cell encapsulation and controlled release was demonstrated using human fibroblasts as model cells, as well as a therapeutically relevant cell line-human umbilical vein endothelial cells (HUVECs). While such temperature responsive cell microcapsules promise effective, controlled release of potential therapeutic cells at physiological temperatures, further work will be needed to augment the composition of the microcapsules and optimize the numbers of cells per capsule prior to clinical evaluation.

No MeSH data available.


Related in: MedlinePlus

Decomposition kinetics of hydrogel microcapsules measured by release of gelatin (A) at 37 °C and (B) control at 4 °C as a function of time. (C,D) Optical images showing the decomposition and release of fluorescent-labeled gelatin into the suspended PBS solution, causing an increase of background fluorescence intensity at 37 °C, but not at 4 °C.
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jfb-06-00439-f004: Decomposition kinetics of hydrogel microcapsules measured by release of gelatin (A) at 37 °C and (B) control at 4 °C as a function of time. (C,D) Optical images showing the decomposition and release of fluorescent-labeled gelatin into the suspended PBS solution, causing an increase of background fluorescence intensity at 37 °C, but not at 4 °C.

Mentions: As previously mentioned, the temperature responsive microcapsules were designed based on our hypothesis that doping of agarose hydrogels that are solid from 30 to 60 °C with gelatin that melts <35 °C) can facilitate the decomposition of the microcapsules at a physiological temperature of 37 °C, due to the gelatin melting and diffusing out of the microcapsules. A decomposition study of agarose only, agarose–gelatin and agarose–gelatin–fibrinogen microcapsules was performed to verify the hypothesis by quantifying the release of gelatin over time, for a total of 72 h when the microcapsules in PBS were incubated at 37 °C. The released gelatin was quantified by performing a total protein assay. The decomposition kinetics as a function of gelatin release is shown in Figure 4A,B. Agarose only microcapsules were used as controls. The results obtained showed that at 37 °C, the decomposition and release of melted gelatin from the microcapsules was completed within the first 8 h, followed by a constant steady state observed from 8 to 72 h where no further release of gelatin occurred. In contrast, microcapsules incubated at 4 °C showed insignificant release of gelatin over the entire 72 h, confirming that the decomposition mechanism was triggered by the elevated, physiological temperature. Both the agarose–gelatin and agarose–gelatin–fibrinogen microcapsules showed a similar release profile, although the agarose–gelatin–fibrinogen microcapsules had a larger signal amplitude. This can be explained by the relatively stable encapsulation of fibrinogen within hydrogel microcapsules similar to previously reported [4], whereby the releasing only small amount of fibrinogen contributed to the total protein content. The decomposition of agarose–gelatin–fibrinogen microcapsules was further confirmed by observation of fluorescent-labeled gelatin released when incubated at 37 °C, while release of fluorescent-labeled gelatin was not observed when incubated at 4 °C. The released fluorescent-labeled gelatin into the buffer resulted in an overall increase of background fluorescence intensity of the PBS solution (Figure 4C,D).


Controlled Delivery of Human Cells by Temperature Responsive Microcapsules.

Mak WC, Olesen K, Sivlér P, Lee CJ, Moreno-Jimenez I, Edin J, Courtman D, Skog M, Griffith M - J Funct Biomater (2015)

Decomposition kinetics of hydrogel microcapsules measured by release of gelatin (A) at 37 °C and (B) control at 4 °C as a function of time. (C,D) Optical images showing the decomposition and release of fluorescent-labeled gelatin into the suspended PBS solution, causing an increase of background fluorescence intensity at 37 °C, but not at 4 °C.
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Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4493523&req=5

jfb-06-00439-f004: Decomposition kinetics of hydrogel microcapsules measured by release of gelatin (A) at 37 °C and (B) control at 4 °C as a function of time. (C,D) Optical images showing the decomposition and release of fluorescent-labeled gelatin into the suspended PBS solution, causing an increase of background fluorescence intensity at 37 °C, but not at 4 °C.
Mentions: As previously mentioned, the temperature responsive microcapsules were designed based on our hypothesis that doping of agarose hydrogels that are solid from 30 to 60 °C with gelatin that melts <35 °C) can facilitate the decomposition of the microcapsules at a physiological temperature of 37 °C, due to the gelatin melting and diffusing out of the microcapsules. A decomposition study of agarose only, agarose–gelatin and agarose–gelatin–fibrinogen microcapsules was performed to verify the hypothesis by quantifying the release of gelatin over time, for a total of 72 h when the microcapsules in PBS were incubated at 37 °C. The released gelatin was quantified by performing a total protein assay. The decomposition kinetics as a function of gelatin release is shown in Figure 4A,B. Agarose only microcapsules were used as controls. The results obtained showed that at 37 °C, the decomposition and release of melted gelatin from the microcapsules was completed within the first 8 h, followed by a constant steady state observed from 8 to 72 h where no further release of gelatin occurred. In contrast, microcapsules incubated at 4 °C showed insignificant release of gelatin over the entire 72 h, confirming that the decomposition mechanism was triggered by the elevated, physiological temperature. Both the agarose–gelatin and agarose–gelatin–fibrinogen microcapsules showed a similar release profile, although the agarose–gelatin–fibrinogen microcapsules had a larger signal amplitude. This can be explained by the relatively stable encapsulation of fibrinogen within hydrogel microcapsules similar to previously reported [4], whereby the releasing only small amount of fibrinogen contributed to the total protein content. The decomposition of agarose–gelatin–fibrinogen microcapsules was further confirmed by observation of fluorescent-labeled gelatin released when incubated at 37 °C, while release of fluorescent-labeled gelatin was not observed when incubated at 4 °C. The released fluorescent-labeled gelatin into the buffer resulted in an overall increase of background fluorescence intensity of the PBS solution (Figure 4C,D).

Bottom Line: However, its full potential is limited by the rapid loss of introduced therapeutic cells before their full effects can be exploited, due in part to anoikis, and in part to the adverse environments often found within the pathologic tissues that the cells have been grafted into.Cell encapsulation and controlled release was demonstrated using human fibroblasts as model cells, as well as a therapeutically relevant cell line-human umbilical vein endothelial cells (HUVECs).While such temperature responsive cell microcapsules promise effective, controlled release of potential therapeutic cells at physiological temperatures, further work will be needed to augment the composition of the microcapsules and optimize the numbers of cells per capsule prior to clinical evaluation.

View Article: PubMed Central - PubMed

Affiliation: Integrative Regenerative Medicine Centre, Department of Clinical and Experimental Medicine, Linköping University, SE58185, Linköping, Sweden. mamak@ifm.liu.se.

ABSTRACT
Cell therapy is one of the most promising areas within regenerative medicine. However, its full potential is limited by the rapid loss of introduced therapeutic cells before their full effects can be exploited, due in part to anoikis, and in part to the adverse environments often found within the pathologic tissues that the cells have been grafted into. Encapsulation of individual cells has been proposed as a means of increasing cell viability. In this study, we developed a facile, high throughput method for creating temperature responsive microcapsules comprising agarose, gelatin and fibrinogen for delivery and subsequent controlled release of cells. We verified the hypothesis that composite capsules combining agarose and gelatin, which possess different phase transition temperatures from solid to liquid, facilitated the destabilization of the capsules for cell release. Cell encapsulation and controlled release was demonstrated using human fibroblasts as model cells, as well as a therapeutically relevant cell line-human umbilical vein endothelial cells (HUVECs). While such temperature responsive cell microcapsules promise effective, controlled release of potential therapeutic cells at physiological temperatures, further work will be needed to augment the composition of the microcapsules and optimize the numbers of cells per capsule prior to clinical evaluation.

No MeSH data available.


Related in: MedlinePlus