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Both systemic and local application of granulocyte-colony stimulating factor (G-CSF) is neuroprotective after retinal ganglion cell axotomy.

Frank T, Schlachetzki JC, Göricke B, Meuer K, Rohde G, Dietz GP, Bähr M, Schneider A, Weishaupt JH - BMC Neurosci (2009)

Bottom Line: We thus evaluated G-CSF as a neuroprotectant for RGCs and found a dose-dependent neuroprotective effect of G-CSF on axotomized RGCs when given subcutaneously.As stem stell mobilization had previously been discussed as a possible contributor to the neuroprotective effects of G-CSF, we compared the local treatment of RGCs by injection of G-CSF into the vitreous body with systemic delivery by subcutaneous application.We thus show that G-CSF neuroprotection is at least partially independent of potential systemic effects and provide further evidence that the clinically applicable G-CSF could become a treatment option for both neurodegenerative diseases and glaucoma.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Neurology, University Medical Center Göttingen, Göttingen, Germany. tobias.frank@med.uni-goettingen.de

ABSTRACT

Background: The hematopoietic Granulocyte-Colony Stimulating Factor (G-CSF) plays a crucial role in controlling the number of neutrophil progenitor cells. Its function is mediated via the G-CSF receptor, which was recently found to be expressed also in the central nervous system. In addition, G-CSF provided neuroprotection in models of neuronal cell death. Here we used the retinal ganglion cell (RGC) axotomy model to compare effects of local and systemic application of neuroprotective molecules.

Results: We found that the G-CSF receptor is robustly expressed by RGCs in vivo and in vitro. We thus evaluated G-CSF as a neuroprotectant for RGCs and found a dose-dependent neuroprotective effect of G-CSF on axotomized RGCs when given subcutaneously. As stem stell mobilization had previously been discussed as a possible contributor to the neuroprotective effects of G-CSF, we compared the local treatment of RGCs by injection of G-CSF into the vitreous body with systemic delivery by subcutaneous application. Both routes of application reduced retinal ganglion cell death to a comparable extent. Moreover, G-CSF enhanced the survival of immunopurified RGCs in vitro.

Conclusion: We thus show that G-CSF neuroprotection is at least partially independent of potential systemic effects and provide further evidence that the clinically applicable G-CSF could become a treatment option for both neurodegenerative diseases and glaucoma.

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Topical application by intravitreal injection is sufficient for G-CSF neuroprotection on retinal ganglion cells. G-CSF was given either systemically by daily subcutaneous injection (20 or 40 μg/kg bodyweight per injection), or by direct application to RGCs via intravitreal injection (500 ng in 2 μl per injection on day 0, 4, 7 and 10 after axotomy; first injection 2 h after axotomy). Leukocyte counts were determined one day before drug administration and after 14 days of treatment (n = 8 per group). Subcutaneous application resulted in the expected leukocytosis, while we could confirm that the intraocular G-CSF injection did not influence leukocyte counts (A). RGC survival was then determined accordingly after subcutaneous or intraocular G-CSF application (B). Both protocols lead to a comparable protective effect on axotomized RGCs in vivo. * p < 0.05 when compared to respective vehicle control; n.s. = not significant; i.o.: intraocular (intravitreal) injection.
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Figure 4: Topical application by intravitreal injection is sufficient for G-CSF neuroprotection on retinal ganglion cells. G-CSF was given either systemically by daily subcutaneous injection (20 or 40 μg/kg bodyweight per injection), or by direct application to RGCs via intravitreal injection (500 ng in 2 μl per injection on day 0, 4, 7 and 10 after axotomy; first injection 2 h after axotomy). Leukocyte counts were determined one day before drug administration and after 14 days of treatment (n = 8 per group). Subcutaneous application resulted in the expected leukocytosis, while we could confirm that the intraocular G-CSF injection did not influence leukocyte counts (A). RGC survival was then determined accordingly after subcutaneous or intraocular G-CSF application (B). Both protocols lead to a comparable protective effect on axotomized RGCs in vivo. * p < 0.05 when compared to respective vehicle control; n.s. = not significant; i.o.: intraocular (intravitreal) injection.

Mentions: Our in vivo optic nerve transection paradigm offers the advantage that protective compounds can be applied locally to the neuronal population of interest by direct intravitreal injection. We thus performed intravitreal injections of vehicle or G-CSF at days 0, 4, 7 and 10 after axotomy (500 ng G-CSF per injection in a volume of 2 μl, first injection approximately 2 h after the axotomy) in order to test whether systemic effects are required for G-CSF neuroprotection in vivo. We confirmed that, in contrast to the expected higher leukocyte counts after subcutaneous G-CSF application, the intraocular injection protocol did not increase blood leukocyte numbers (Fig. 4A). In agreement with the observed protective effect of G-CSF on purified RGCs in culture, we found that direct intraocular application of G-CSF was sufficient for neuroprotective effects (681.8 ± 35.8 surviving RGCs/mm2; p < 0.05 compared to vehicle control), and did not significantly differ from the effect of 40 μg/kg BW G-CSF given subcutaneously (Fig. 4B; table 1).


Both systemic and local application of granulocyte-colony stimulating factor (G-CSF) is neuroprotective after retinal ganglion cell axotomy.

Frank T, Schlachetzki JC, Göricke B, Meuer K, Rohde G, Dietz GP, Bähr M, Schneider A, Weishaupt JH - BMC Neurosci (2009)

Topical application by intravitreal injection is sufficient for G-CSF neuroprotection on retinal ganglion cells. G-CSF was given either systemically by daily subcutaneous injection (20 or 40 μg/kg bodyweight per injection), or by direct application to RGCs via intravitreal injection (500 ng in 2 μl per injection on day 0, 4, 7 and 10 after axotomy; first injection 2 h after axotomy). Leukocyte counts were determined one day before drug administration and after 14 days of treatment (n = 8 per group). Subcutaneous application resulted in the expected leukocytosis, while we could confirm that the intraocular G-CSF injection did not influence leukocyte counts (A). RGC survival was then determined accordingly after subcutaneous or intraocular G-CSF application (B). Both protocols lead to a comparable protective effect on axotomized RGCs in vivo. * p < 0.05 when compared to respective vehicle control; n.s. = not significant; i.o.: intraocular (intravitreal) injection.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2691410&req=5

Figure 4: Topical application by intravitreal injection is sufficient for G-CSF neuroprotection on retinal ganglion cells. G-CSF was given either systemically by daily subcutaneous injection (20 or 40 μg/kg bodyweight per injection), or by direct application to RGCs via intravitreal injection (500 ng in 2 μl per injection on day 0, 4, 7 and 10 after axotomy; first injection 2 h after axotomy). Leukocyte counts were determined one day before drug administration and after 14 days of treatment (n = 8 per group). Subcutaneous application resulted in the expected leukocytosis, while we could confirm that the intraocular G-CSF injection did not influence leukocyte counts (A). RGC survival was then determined accordingly after subcutaneous or intraocular G-CSF application (B). Both protocols lead to a comparable protective effect on axotomized RGCs in vivo. * p < 0.05 when compared to respective vehicle control; n.s. = not significant; i.o.: intraocular (intravitreal) injection.
Mentions: Our in vivo optic nerve transection paradigm offers the advantage that protective compounds can be applied locally to the neuronal population of interest by direct intravitreal injection. We thus performed intravitreal injections of vehicle or G-CSF at days 0, 4, 7 and 10 after axotomy (500 ng G-CSF per injection in a volume of 2 μl, first injection approximately 2 h after the axotomy) in order to test whether systemic effects are required for G-CSF neuroprotection in vivo. We confirmed that, in contrast to the expected higher leukocyte counts after subcutaneous G-CSF application, the intraocular injection protocol did not increase blood leukocyte numbers (Fig. 4A). In agreement with the observed protective effect of G-CSF on purified RGCs in culture, we found that direct intraocular application of G-CSF was sufficient for neuroprotective effects (681.8 ± 35.8 surviving RGCs/mm2; p < 0.05 compared to vehicle control), and did not significantly differ from the effect of 40 μg/kg BW G-CSF given subcutaneously (Fig. 4B; table 1).

Bottom Line: We thus evaluated G-CSF as a neuroprotectant for RGCs and found a dose-dependent neuroprotective effect of G-CSF on axotomized RGCs when given subcutaneously.As stem stell mobilization had previously been discussed as a possible contributor to the neuroprotective effects of G-CSF, we compared the local treatment of RGCs by injection of G-CSF into the vitreous body with systemic delivery by subcutaneous application.We thus show that G-CSF neuroprotection is at least partially independent of potential systemic effects and provide further evidence that the clinically applicable G-CSF could become a treatment option for both neurodegenerative diseases and glaucoma.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Neurology, University Medical Center Göttingen, Göttingen, Germany. tobias.frank@med.uni-goettingen.de

ABSTRACT

Background: The hematopoietic Granulocyte-Colony Stimulating Factor (G-CSF) plays a crucial role in controlling the number of neutrophil progenitor cells. Its function is mediated via the G-CSF receptor, which was recently found to be expressed also in the central nervous system. In addition, G-CSF provided neuroprotection in models of neuronal cell death. Here we used the retinal ganglion cell (RGC) axotomy model to compare effects of local and systemic application of neuroprotective molecules.

Results: We found that the G-CSF receptor is robustly expressed by RGCs in vivo and in vitro. We thus evaluated G-CSF as a neuroprotectant for RGCs and found a dose-dependent neuroprotective effect of G-CSF on axotomized RGCs when given subcutaneously. As stem stell mobilization had previously been discussed as a possible contributor to the neuroprotective effects of G-CSF, we compared the local treatment of RGCs by injection of G-CSF into the vitreous body with systemic delivery by subcutaneous application. Both routes of application reduced retinal ganglion cell death to a comparable extent. Moreover, G-CSF enhanced the survival of immunopurified RGCs in vitro.

Conclusion: We thus show that G-CSF neuroprotection is at least partially independent of potential systemic effects and provide further evidence that the clinically applicable G-CSF could become a treatment option for both neurodegenerative diseases and glaucoma.

Show MeSH
Related in: MedlinePlus