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Thrombopoietic-mesenchymal interaction that may facilitate both endochondral ossification and platelet maturation via CCN2.

Sumiyoshi K, Kubota S, Furuta RA, Yasui K, Aoyama E, Kawaki H, Kawata K, Ohgawara T, Yamashiro T, Takigawa M - J Cell Commun Signal (2009)

Bottom Line: In this study, we initially pursued the possible origin of the CCN2 in platelets.As suspected, CCN2 production by HCS-2/8 was significantly enhanced by the conditioned medium.We further confirmed that human platelets were able to absorb/uptake exogenous CCN2 in vitro.

View Article: PubMed Central - PubMed

ABSTRACT
CCN2 plays a central role in the development and growth of mesenchymal tissue and promotes the regeneration of bone and cartilage in vivo. Of note, abundant CCN2 is contained in platelets, which is thought to play an important role in the tissue regeneration process. In this study, we initially pursued the possible origin of the CCN2 in platelets. First, we examined if the CCN2 in platelets was produced by megakaryocyte progenitors during differentiation. Unexpectedly, neither megakaryocytic CMK cells nor megakaryocytes that had differentiated from human haemopoietic stem cells in culture showed any detectable CCN2 gene expression or protein production. Together with the fact that no appreciable CCN2 was detected in megakaryocytes in vivo, these results suggest that megakaryocytes themselves do not produce CCN2. Next, we suspected that mesenchymal cells situated around megakaryocytes in the bone marrow were stimulated by the latter to produce CCN2, which was then taken up by platelets. To evaluate this hypothesis, we cultured human chondrocytic HCS-2/8 cells with medium conditioned by differentiating megakaryocyte cultures, and then monitored the production of CCN2 by the cells. As suspected, CCN2 production by HCS-2/8 was significantly enhanced by the conditioned medium. We further confirmed that human platelets were able to absorb/uptake exogenous CCN2 in vitro. These findings indicate that megakaryocytes secrete some unknown soluble factor(s) during differentiation, which factor stimulates the mesenchymal cells to produce CCN2 for uptake by the platelets. We also consider that, during bone growth, such thrombopoietic-mesenchymal interaction may contribute to the hypertrophic chondrocyte-specific accumulation of CCN2 that conducts endochondral ossification.

No MeSH data available.


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Evaluation of the intercellular transfer of CCN2 from HCS-2/8 to CMK cells. a Experimental strategy. CMK cells were seeded onto HCS-2/8 cells that had been attached to tissue culture wells and allowed to make cell-to-cell contact. b No transfer of CCN2 into CMK cells. After the indicated intervals, CCN2 in CMK cell lysates and co-culture media was quantified by ELISA
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Fig6: Evaluation of the intercellular transfer of CCN2 from HCS-2/8 to CMK cells. a Experimental strategy. CMK cells were seeded onto HCS-2/8 cells that had been attached to tissue culture wells and allowed to make cell-to-cell contact. b No transfer of CCN2 into CMK cells. After the indicated intervals, CCN2 in CMK cell lysates and co-culture media was quantified by ELISA

Mentions: In addition to the direct uptake by platelets, another possible pathway to package exogenous CCN2 in platelets is the endocytotic incorporation by megakaryocytic progenitors. To evaluate this possibility, we co-cultured CMK cells with HCS-2/8 cells (Fig. 6a), and then quantitatively analyzed CCN2 in CMK cells after conducting a time-course experiment. However, although CCN2 is efficiently produced by HCS-2/8 cells, no incorporation of CCN2 by CMK cells was observed (Fig. 6b). Therefore, transfer of CCN2 from mesenchymal cells to megakaryocytic progenitors cells may not occur, even under the direct cell-to-cell contact between them.Fig. 6


Thrombopoietic-mesenchymal interaction that may facilitate both endochondral ossification and platelet maturation via CCN2.

Sumiyoshi K, Kubota S, Furuta RA, Yasui K, Aoyama E, Kawaki H, Kawata K, Ohgawara T, Yamashiro T, Takigawa M - J Cell Commun Signal (2009)

Evaluation of the intercellular transfer of CCN2 from HCS-2/8 to CMK cells. a Experimental strategy. CMK cells were seeded onto HCS-2/8 cells that had been attached to tissue culture wells and allowed to make cell-to-cell contact. b No transfer of CCN2 into CMK cells. After the indicated intervals, CCN2 in CMK cell lysates and co-culture media was quantified by ELISA
© Copyright Policy
Related In: Results  -  Collection

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Fig6: Evaluation of the intercellular transfer of CCN2 from HCS-2/8 to CMK cells. a Experimental strategy. CMK cells were seeded onto HCS-2/8 cells that had been attached to tissue culture wells and allowed to make cell-to-cell contact. b No transfer of CCN2 into CMK cells. After the indicated intervals, CCN2 in CMK cell lysates and co-culture media was quantified by ELISA
Mentions: In addition to the direct uptake by platelets, another possible pathway to package exogenous CCN2 in platelets is the endocytotic incorporation by megakaryocytic progenitors. To evaluate this possibility, we co-cultured CMK cells with HCS-2/8 cells (Fig. 6a), and then quantitatively analyzed CCN2 in CMK cells after conducting a time-course experiment. However, although CCN2 is efficiently produced by HCS-2/8 cells, no incorporation of CCN2 by CMK cells was observed (Fig. 6b). Therefore, transfer of CCN2 from mesenchymal cells to megakaryocytic progenitors cells may not occur, even under the direct cell-to-cell contact between them.Fig. 6

Bottom Line: In this study, we initially pursued the possible origin of the CCN2 in platelets.As suspected, CCN2 production by HCS-2/8 was significantly enhanced by the conditioned medium.We further confirmed that human platelets were able to absorb/uptake exogenous CCN2 in vitro.

View Article: PubMed Central - PubMed

ABSTRACT
CCN2 plays a central role in the development and growth of mesenchymal tissue and promotes the regeneration of bone and cartilage in vivo. Of note, abundant CCN2 is contained in platelets, which is thought to play an important role in the tissue regeneration process. In this study, we initially pursued the possible origin of the CCN2 in platelets. First, we examined if the CCN2 in platelets was produced by megakaryocyte progenitors during differentiation. Unexpectedly, neither megakaryocytic CMK cells nor megakaryocytes that had differentiated from human haemopoietic stem cells in culture showed any detectable CCN2 gene expression or protein production. Together with the fact that no appreciable CCN2 was detected in megakaryocytes in vivo, these results suggest that megakaryocytes themselves do not produce CCN2. Next, we suspected that mesenchymal cells situated around megakaryocytes in the bone marrow were stimulated by the latter to produce CCN2, which was then taken up by platelets. To evaluate this hypothesis, we cultured human chondrocytic HCS-2/8 cells with medium conditioned by differentiating megakaryocyte cultures, and then monitored the production of CCN2 by the cells. As suspected, CCN2 production by HCS-2/8 was significantly enhanced by the conditioned medium. We further confirmed that human platelets were able to absorb/uptake exogenous CCN2 in vitro. These findings indicate that megakaryocytes secrete some unknown soluble factor(s) during differentiation, which factor stimulates the mesenchymal cells to produce CCN2 for uptake by the platelets. We also consider that, during bone growth, such thrombopoietic-mesenchymal interaction may contribute to the hypertrophic chondrocyte-specific accumulation of CCN2 that conducts endochondral ossification.

No MeSH data available.


Related in: MedlinePlus