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The A9 dopamine neuron component in grafts of ventral mesencephalon is an important determinant for recovery of motor function in a rat model of Parkinson's disease.

Grealish S, Jönsson ME, Li M, Kirik D, Björklund A, Thompson LH - Brain (2010)

Bottom Line: Here, we report results from a series of grafting experiments where the anatomical and functional properties of grafts either selectively lacking in A9 neurons, or with a typical A9/A10 composition were compared.The findings highlight dopamine neuronal subtype composition as a potentially important parameter to monitor in order to understand the variable nature of functional outcome better in transplantation studies.Furthermore, the results have interesting implications for current efforts in this field to generate well-characterized and standardized preparations of transplantable dopamine neuronal progenitors from stem cells.

View Article: PubMed Central - PubMed

Affiliation: Wallenberg Neuroscience Centre, Lund University, Lund, Sweden.

ABSTRACT
Grafts of foetal ventral mesencephalon, used in cell replacement therapy for Parkinson's disease, are known to contain a mix of dopamine neuronal subtypes including the A9 neurons of the substantia nigra and the A10 neurons of the ventral tegmental area. However, the relative importance of these subtypes for functional repair of the brain affected by Parkinson's disease has not been studied thoroughly. Here, we report results from a series of grafting experiments where the anatomical and functional properties of grafts either selectively lacking in A9 neurons, or with a typical A9/A10 composition were compared. The results show that the A9 component of intrastriatal grafts is of critical importance for recovery in tests on motor performance, in a rodent model of Parkinson's disease. Analysis at the histological level indicates that this is likely to be due to the unique ability of A9 neurons to innervate and functionally activate their target structure, the dorsolateral region of the host striatum. The findings highlight dopamine neuronal subtype composition as a potentially important parameter to monitor in order to understand the variable nature of functional outcome better in transplantation studies. Furthermore, the results have interesting implications for current efforts in this field to generate well-characterized and standardized preparations of transplantable dopamine neuronal progenitors from stem cells.

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Subtype analysis of dopamine neurons in Pitx3WT/GFP and Pitx3GFP/GFP grafts. Immunohistochemistry for GFP (green), GIRK2 (red) and Calbindin (blue) in coronal sections through the striatum of representative animals from the Pitx3WT/GFP (A) and Pitx3GFP/GFP (B) groups, 12 weeks after transplantation. The boxed areas in the main panels are shown in greater detail as individual colour channels on the left. The Pitx3WT/GFP grafts contained a mix of GFP+ midbrain dopamine subtypes including GIRK2+/Calbindin− (arrows), GIRK2−/Calbindin+ (filled arrowheads) and GIRK2+/Calbindin+ (empty arrowheads) neurons. The Pitx3GFP/GFP grafts were dominated by the GIRK2−/Calbindin+ cell type (filled arrowheads) and contained few GIRK2+ cells (not shown). Quantification of GIRK2+ and Calbindin+ GFP expressing neurons in all grafted animals confirmed that there was a substantial difference in the midbrain dopamine subtype composition between the two graft types, with Pitx3WT/GFP grafts (n = 8; open bars) containing predominately the GIRK2+/Calbindin− subtype and Pitx3GFP/GFP (n = 7; filled bars) grafts containing mainly GIRK2−/Calbindin+ cells. Scale: 200 µm.
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Figure 8: Subtype analysis of dopamine neurons in Pitx3WT/GFP and Pitx3GFP/GFP grafts. Immunohistochemistry for GFP (green), GIRK2 (red) and Calbindin (blue) in coronal sections through the striatum of representative animals from the Pitx3WT/GFP (A) and Pitx3GFP/GFP (B) groups, 12 weeks after transplantation. The boxed areas in the main panels are shown in greater detail as individual colour channels on the left. The Pitx3WT/GFP grafts contained a mix of GFP+ midbrain dopamine subtypes including GIRK2+/Calbindin− (arrows), GIRK2−/Calbindin+ (filled arrowheads) and GIRK2+/Calbindin+ (empty arrowheads) neurons. The Pitx3GFP/GFP grafts were dominated by the GIRK2−/Calbindin+ cell type (filled arrowheads) and contained few GIRK2+ cells (not shown). Quantification of GIRK2+ and Calbindin+ GFP expressing neurons in all grafted animals confirmed that there was a substantial difference in the midbrain dopamine subtype composition between the two graft types, with Pitx3WT/GFP grafts (n = 8; open bars) containing predominately the GIRK2+/Calbindin− subtype and Pitx3GFP/GFP (n = 7; filled bars) grafts containing mainly GIRK2−/Calbindin+ cells. Scale: 200 µm.

Mentions: Although the two groups of grafted animals contained similar total numbers of GFP+ midbrain dopamine neurons, immunohistochemistry for GIRK2 and Calbindin revealed substantial differences in midbrain dopamine subtype composition between the two graft types. The Pitx3WT/GFP grafts contained a mix of GIRK2 and Calbindin-expressing GFP+ cells such that the largest population, 65 ± 2%, was GIRK2+, while 26 ± 2% were Calbindin+ and 9 ± 0.3% expressed both proteins (Fig. 8A and C). The Pitx3GFP/GFP grafts, by contrast, were dominated by the calbindin+ cell type (68 ± 3%), with only 15 ± 2% GIRK2+, and a remaining 17 ± 2% expressing both markers (Fig. 8B and C). Both graft types also contained a small population of GFP+ cells that expressed neither GIRK2 nor Calbindin and, based on size and location, most of these appeared to correspond to the small, midline population of GFP+/TH− cells (data not shown).Figure 8


The A9 dopamine neuron component in grafts of ventral mesencephalon is an important determinant for recovery of motor function in a rat model of Parkinson's disease.

Grealish S, Jönsson ME, Li M, Kirik D, Björklund A, Thompson LH - Brain (2010)

Subtype analysis of dopamine neurons in Pitx3WT/GFP and Pitx3GFP/GFP grafts. Immunohistochemistry for GFP (green), GIRK2 (red) and Calbindin (blue) in coronal sections through the striatum of representative animals from the Pitx3WT/GFP (A) and Pitx3GFP/GFP (B) groups, 12 weeks after transplantation. The boxed areas in the main panels are shown in greater detail as individual colour channels on the left. The Pitx3WT/GFP grafts contained a mix of GFP+ midbrain dopamine subtypes including GIRK2+/Calbindin− (arrows), GIRK2−/Calbindin+ (filled arrowheads) and GIRK2+/Calbindin+ (empty arrowheads) neurons. The Pitx3GFP/GFP grafts were dominated by the GIRK2−/Calbindin+ cell type (filled arrowheads) and contained few GIRK2+ cells (not shown). Quantification of GIRK2+ and Calbindin+ GFP expressing neurons in all grafted animals confirmed that there was a substantial difference in the midbrain dopamine subtype composition between the two graft types, with Pitx3WT/GFP grafts (n = 8; open bars) containing predominately the GIRK2+/Calbindin− subtype and Pitx3GFP/GFP (n = 7; filled bars) grafts containing mainly GIRK2−/Calbindin+ cells. Scale: 200 µm.
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Related In: Results  -  Collection

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Figure 8: Subtype analysis of dopamine neurons in Pitx3WT/GFP and Pitx3GFP/GFP grafts. Immunohistochemistry for GFP (green), GIRK2 (red) and Calbindin (blue) in coronal sections through the striatum of representative animals from the Pitx3WT/GFP (A) and Pitx3GFP/GFP (B) groups, 12 weeks after transplantation. The boxed areas in the main panels are shown in greater detail as individual colour channels on the left. The Pitx3WT/GFP grafts contained a mix of GFP+ midbrain dopamine subtypes including GIRK2+/Calbindin− (arrows), GIRK2−/Calbindin+ (filled arrowheads) and GIRK2+/Calbindin+ (empty arrowheads) neurons. The Pitx3GFP/GFP grafts were dominated by the GIRK2−/Calbindin+ cell type (filled arrowheads) and contained few GIRK2+ cells (not shown). Quantification of GIRK2+ and Calbindin+ GFP expressing neurons in all grafted animals confirmed that there was a substantial difference in the midbrain dopamine subtype composition between the two graft types, with Pitx3WT/GFP grafts (n = 8; open bars) containing predominately the GIRK2+/Calbindin− subtype and Pitx3GFP/GFP (n = 7; filled bars) grafts containing mainly GIRK2−/Calbindin+ cells. Scale: 200 µm.
Mentions: Although the two groups of grafted animals contained similar total numbers of GFP+ midbrain dopamine neurons, immunohistochemistry for GIRK2 and Calbindin revealed substantial differences in midbrain dopamine subtype composition between the two graft types. The Pitx3WT/GFP grafts contained a mix of GIRK2 and Calbindin-expressing GFP+ cells such that the largest population, 65 ± 2%, was GIRK2+, while 26 ± 2% were Calbindin+ and 9 ± 0.3% expressed both proteins (Fig. 8A and C). The Pitx3GFP/GFP grafts, by contrast, were dominated by the calbindin+ cell type (68 ± 3%), with only 15 ± 2% GIRK2+, and a remaining 17 ± 2% expressing both markers (Fig. 8B and C). Both graft types also contained a small population of GFP+ cells that expressed neither GIRK2 nor Calbindin and, based on size and location, most of these appeared to correspond to the small, midline population of GFP+/TH− cells (data not shown).Figure 8

Bottom Line: Here, we report results from a series of grafting experiments where the anatomical and functional properties of grafts either selectively lacking in A9 neurons, or with a typical A9/A10 composition were compared.The findings highlight dopamine neuronal subtype composition as a potentially important parameter to monitor in order to understand the variable nature of functional outcome better in transplantation studies.Furthermore, the results have interesting implications for current efforts in this field to generate well-characterized and standardized preparations of transplantable dopamine neuronal progenitors from stem cells.

View Article: PubMed Central - PubMed

Affiliation: Wallenberg Neuroscience Centre, Lund University, Lund, Sweden.

ABSTRACT
Grafts of foetal ventral mesencephalon, used in cell replacement therapy for Parkinson's disease, are known to contain a mix of dopamine neuronal subtypes including the A9 neurons of the substantia nigra and the A10 neurons of the ventral tegmental area. However, the relative importance of these subtypes for functional repair of the brain affected by Parkinson's disease has not been studied thoroughly. Here, we report results from a series of grafting experiments where the anatomical and functional properties of grafts either selectively lacking in A9 neurons, or with a typical A9/A10 composition were compared. The results show that the A9 component of intrastriatal grafts is of critical importance for recovery in tests on motor performance, in a rodent model of Parkinson's disease. Analysis at the histological level indicates that this is likely to be due to the unique ability of A9 neurons to innervate and functionally activate their target structure, the dorsolateral region of the host striatum. The findings highlight dopamine neuronal subtype composition as a potentially important parameter to monitor in order to understand the variable nature of functional outcome better in transplantation studies. Furthermore, the results have interesting implications for current efforts in this field to generate well-characterized and standardized preparations of transplantable dopamine neuronal progenitors from stem cells.

Show MeSH
Related in: MedlinePlus