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Directed Fusion of Mesenchymal Stem Cells with Cardiomyocytes via VSV-G Facilitates Stem Cell Programming.

Kouris NA, Schaefer JA, Hatta M, Freeman BT, Kamp TJ, Kawaoka Y, Ogle BM - Stem Cells Int (2012)

Bottom Line: That stem cells can be programmed, or somatic cells reprogrammed, in this fashion suggests that stem cell fusion holds promise as a therapeutic approach for the repair of damaged tissues, especially tissues not readily capable of functional regeneration, such as the myocardium.In an attempt to increase the frequency of stem cell fusion and, in so doing, increase the potential for cardiac tissue repair, we expressed the fusogen of the vesicular stomatitis virus (VSV-G) in human MSCs.In vivo, vMSCs delivered to damaged mouse myocardium via a collagen patch were able to home to the myocardium and fuse to cells within the infarct and peri-infarct region of the myocardium.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, University of Wisconsin at Madison, Madison, WI 53706, USA.

ABSTRACT
Mesenchymal stem cells (MSCs) spontaneously fuse with somatic cells in vivo, albeit rarely, and the fusion products are capable of tissue-specific function (mature trait) or proliferation (immature trait), depending on the microenvironment. That stem cells can be programmed, or somatic cells reprogrammed, in this fashion suggests that stem cell fusion holds promise as a therapeutic approach for the repair of damaged tissues, especially tissues not readily capable of functional regeneration, such as the myocardium. In an attempt to increase the frequency of stem cell fusion and, in so doing, increase the potential for cardiac tissue repair, we expressed the fusogen of the vesicular stomatitis virus (VSV-G) in human MSCs. We found VSV-G expressing MSCs (vMSCs) fused with cardiomyocytes (CMs) and these fusion products adopted a CM-like phenotype and morphology in vitro. In vivo, vMSCs delivered to damaged mouse myocardium via a collagen patch were able to home to the myocardium and fuse to cells within the infarct and peri-infarct region of the myocardium. This study provides a basis for the investigation of the biological impact of fusion of stem cells with CMs in vivo and illustrates how viral fusion proteins might better enable such studies.

No MeSH data available.


Related in: MedlinePlus

Fusion of VSV-G-expressing human mesenchymal stem cells (donor) with cardiomyocytes (host) in vivo. (a) Fluorescence in situ hybridization with species-specific centromeric probes to detect fusion products in the murine myocardium. Human MSCs (red), mouse cells (green), all nuclei (blue), and fusion products (FP; red and green signal in the same nucleus) are found within the border and TM regions, while typically only mouse cells are found in the myocardium, “myo.” Insets display (b) human (arrow) and mouse (arrowhead) cells, (c) representative fusion product, and (d) fusion product undergoing anaphase, indicative of proliferation.
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fig4: Fusion of VSV-G-expressing human mesenchymal stem cells (donor) with cardiomyocytes (host) in vivo. (a) Fluorescence in situ hybridization with species-specific centromeric probes to detect fusion products in the murine myocardium. Human MSCs (red), mouse cells (green), all nuclei (blue), and fusion products (FP; red and green signal in the same nucleus) are found within the border and TM regions, while typically only mouse cells are found in the myocardium, “myo.” Insets display (b) human (arrow) and mouse (arrowhead) cells, (c) representative fusion product, and (d) fusion product undergoing anaphase, indicative of proliferation.

Mentions: To determine whether MSCs expressing VSV-G could fuse with cardiac cell types in vivo, vMSCs were delivered to the damaged myocardium via a TissueMend patch. We have previously demonstrated that MSCs delivered in this way are maintained in the patch and in the tissue between the patch and the myocardium up to 3 weeks after delivery at higher percentages than with conventional delivery modalities [48]. Furthermore, Laflamme et al. have found one of the major factors for cell loss during transplantation is anoikis [59], and thus providing anchorage support to transplanted cells increases viability and retention. In this study, we sought to determine whether VSV-G expressing MSCs (donor) would be able to migrate to the damaged myocardium and fuse with recipient cardiac cell types. Thus, one day following induction of infarction via ligation of the left anterior descending artery, a patch containing vMSCs was applied to the heart in contact with healthy and damaged tissue. Three weeks after cell transplantation, heart excision, and histology were performed on left ventricular tissue as previously reported [48]. Histological sections were probed using FISH for human-specific and mouse-specific centromeres and all nuclei containing both probes were considered fusion products. Human cells were found in the TissueMend patch and in the “border region” (the area between the patch and the myocardium). Donor-host cell fusion was evident in the TissueMend patch, the border zone, and in the infarcted myocardium of hearts receiving TissueMend with vMSCs. No human cells or fusion products were found in the healthy cardiac tissue of hearts receiving TissueMend with vMSCs. In addition, no human cells or fusion products were found in the TissueMend patch, border zone or infarcted myocardium of hearts receiving TissueMend only. In regions of hearts receiving TissueMend with vMSCs and selected for high density of fusion events, the frequency of cell fusion relative to the total number of nuclei in a given region was 22% ± 16%, TissueMend patch (n = 3 hearts, 12 fields); 14% ± 10%, border zone (n = 3 hearts, 5 fields); 19% ± 10%, infarcted myocardium (n = 3 hearts, 8 fields). Though these levels represent the maximum amount of fusion per region, they are substantially higher than those previously reported for spontaneous fusion following MSC transplantation, wherein one fusion event per field or image containing hundreds of nuclei was rare [13, 60, 61] (Figure 4). These results demonstrate that expression of viral fusogen VSV-G can be used to induce fusion of MSCs, and potentially other clinically relevant cell types, to enable study of the biologic and therapeutic impact of cell fusion in the heart.


Directed Fusion of Mesenchymal Stem Cells with Cardiomyocytes via VSV-G Facilitates Stem Cell Programming.

Kouris NA, Schaefer JA, Hatta M, Freeman BT, Kamp TJ, Kawaoka Y, Ogle BM - Stem Cells Int (2012)

Fusion of VSV-G-expressing human mesenchymal stem cells (donor) with cardiomyocytes (host) in vivo. (a) Fluorescence in situ hybridization with species-specific centromeric probes to detect fusion products in the murine myocardium. Human MSCs (red), mouse cells (green), all nuclei (blue), and fusion products (FP; red and green signal in the same nucleus) are found within the border and TM regions, while typically only mouse cells are found in the myocardium, “myo.” Insets display (b) human (arrow) and mouse (arrowhead) cells, (c) representative fusion product, and (d) fusion product undergoing anaphase, indicative of proliferation.
© Copyright Policy - open-access
Related In: Results  -  Collection

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fig4: Fusion of VSV-G-expressing human mesenchymal stem cells (donor) with cardiomyocytes (host) in vivo. (a) Fluorescence in situ hybridization with species-specific centromeric probes to detect fusion products in the murine myocardium. Human MSCs (red), mouse cells (green), all nuclei (blue), and fusion products (FP; red and green signal in the same nucleus) are found within the border and TM regions, while typically only mouse cells are found in the myocardium, “myo.” Insets display (b) human (arrow) and mouse (arrowhead) cells, (c) representative fusion product, and (d) fusion product undergoing anaphase, indicative of proliferation.
Mentions: To determine whether MSCs expressing VSV-G could fuse with cardiac cell types in vivo, vMSCs were delivered to the damaged myocardium via a TissueMend patch. We have previously demonstrated that MSCs delivered in this way are maintained in the patch and in the tissue between the patch and the myocardium up to 3 weeks after delivery at higher percentages than with conventional delivery modalities [48]. Furthermore, Laflamme et al. have found one of the major factors for cell loss during transplantation is anoikis [59], and thus providing anchorage support to transplanted cells increases viability and retention. In this study, we sought to determine whether VSV-G expressing MSCs (donor) would be able to migrate to the damaged myocardium and fuse with recipient cardiac cell types. Thus, one day following induction of infarction via ligation of the left anterior descending artery, a patch containing vMSCs was applied to the heart in contact with healthy and damaged tissue. Three weeks after cell transplantation, heart excision, and histology were performed on left ventricular tissue as previously reported [48]. Histological sections were probed using FISH for human-specific and mouse-specific centromeres and all nuclei containing both probes were considered fusion products. Human cells were found in the TissueMend patch and in the “border region” (the area between the patch and the myocardium). Donor-host cell fusion was evident in the TissueMend patch, the border zone, and in the infarcted myocardium of hearts receiving TissueMend with vMSCs. No human cells or fusion products were found in the healthy cardiac tissue of hearts receiving TissueMend with vMSCs. In addition, no human cells or fusion products were found in the TissueMend patch, border zone or infarcted myocardium of hearts receiving TissueMend only. In regions of hearts receiving TissueMend with vMSCs and selected for high density of fusion events, the frequency of cell fusion relative to the total number of nuclei in a given region was 22% ± 16%, TissueMend patch (n = 3 hearts, 12 fields); 14% ± 10%, border zone (n = 3 hearts, 5 fields); 19% ± 10%, infarcted myocardium (n = 3 hearts, 8 fields). Though these levels represent the maximum amount of fusion per region, they are substantially higher than those previously reported for spontaneous fusion following MSC transplantation, wherein one fusion event per field or image containing hundreds of nuclei was rare [13, 60, 61] (Figure 4). These results demonstrate that expression of viral fusogen VSV-G can be used to induce fusion of MSCs, and potentially other clinically relevant cell types, to enable study of the biologic and therapeutic impact of cell fusion in the heart.

Bottom Line: That stem cells can be programmed, or somatic cells reprogrammed, in this fashion suggests that stem cell fusion holds promise as a therapeutic approach for the repair of damaged tissues, especially tissues not readily capable of functional regeneration, such as the myocardium.In an attempt to increase the frequency of stem cell fusion and, in so doing, increase the potential for cardiac tissue repair, we expressed the fusogen of the vesicular stomatitis virus (VSV-G) in human MSCs.In vivo, vMSCs delivered to damaged mouse myocardium via a collagen patch were able to home to the myocardium and fuse to cells within the infarct and peri-infarct region of the myocardium.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, University of Wisconsin at Madison, Madison, WI 53706, USA.

ABSTRACT
Mesenchymal stem cells (MSCs) spontaneously fuse with somatic cells in vivo, albeit rarely, and the fusion products are capable of tissue-specific function (mature trait) or proliferation (immature trait), depending on the microenvironment. That stem cells can be programmed, or somatic cells reprogrammed, in this fashion suggests that stem cell fusion holds promise as a therapeutic approach for the repair of damaged tissues, especially tissues not readily capable of functional regeneration, such as the myocardium. In an attempt to increase the frequency of stem cell fusion and, in so doing, increase the potential for cardiac tissue repair, we expressed the fusogen of the vesicular stomatitis virus (VSV-G) in human MSCs. We found VSV-G expressing MSCs (vMSCs) fused with cardiomyocytes (CMs) and these fusion products adopted a CM-like phenotype and morphology in vitro. In vivo, vMSCs delivered to damaged mouse myocardium via a collagen patch were able to home to the myocardium and fuse to cells within the infarct and peri-infarct region of the myocardium. This study provides a basis for the investigation of the biological impact of fusion of stem cells with CMs in vivo and illustrates how viral fusion proteins might better enable such studies.

No MeSH data available.


Related in: MedlinePlus