Pulsed electromagnetic fields affect phenotype and connexin 43 protein expression in MLO-Y4 osteocyte-like cells and ROS 17/2.8 osteoblast-like cells

C. H. Lohmann, Z. Schwartz, Y. Liu, Z. Li, B. J. Simon, V. L. Sylvia, D. D. Dean, Lynda Bonewald, H. J. Donahue, B. D. Boyan

Research output: Contribution to journalArticle

99 Citations (Scopus)

Abstract

Osteocytes, the predominant cells in bone, are postulated to be responsible for sensing mechanical and electrical stimuli, transducing signals via gap junctions. Osteocytes respond to induced shear by increasing connexin 43 (Cx43) levels, suggesting that they might be sensitive to physical stimuli like low-frequency electromagnetic fields (EMF). Immature osteoblasts exhibit decreased intercellular communication in response to EMF but no change in Cx43. Here, we examined long term effects of pulsed EMF (PEMF) on MLO-Y4 osteocyte-like cells and ROS 17/2.8 osteoblast-like cells. In MLO-Y4 cell cultures, PEMF for 8 h/day for one, two or four days increased alkaline phosphatase activity but had no effect on cell number or osteocalcin. Transforming growth factor beta-1 (TGF-β1) and prostaglandin E2 were increased, and NO2- was altered. PEMFs effect on TGF-β1 was via a prostaglandin-dependent mechanism involving Cox-1 but not Cox-2. In ROS 17/2.8 cells, PEMF for 24, 48 or 72 h did not affect cell number, osteocalcin mRNA or osteocalcin protein. PEMF reduced Cx43 protein in both cells. Longer exposures decreased Cx43 mRNA. This indicates that cells in the osteoblast lineage, including well-differentiated osteoblast-like ROS 17/2.8 cells and terminally differentiated osteocyte-like MLO-Y4 cells, respond to PEMF with changes in local factor production and reduced Cx43, suggesting decreased gap junctional signaling.

Original languageEnglish (US)
Pages (from-to)326-334
Number of pages9
JournalJournal of Orthopaedic Research
Volume21
Issue number2
DOIs
StatePublished - 2003
Externally publishedYes

Fingerprint

Osteocytes
Connexin 43
Electromagnetic Fields
Osteoblasts
Phenotype
Osteocalcin
Proteins
Transforming Growth Factor beta
Cell Count
Messenger RNA
Gap Junctions
Dinoprostone
Prostaglandins
Alkaline Phosphatase
Cell Culture Techniques
Bone and Bones

Keywords

  • Connexin 43
  • Cox-2
  • Gap junctions
  • Osteoblasts
  • Osteocytes
  • Prostaglandin E
  • Pulsed electromagnetic fields
  • Transforming growth factor-β1

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine

Cite this

Pulsed electromagnetic fields affect phenotype and connexin 43 protein expression in MLO-Y4 osteocyte-like cells and ROS 17/2.8 osteoblast-like cells. / Lohmann, C. H.; Schwartz, Z.; Liu, Y.; Li, Z.; Simon, B. J.; Sylvia, V. L.; Dean, D. D.; Bonewald, Lynda; Donahue, H. J.; Boyan, B. D.

In: Journal of Orthopaedic Research, Vol. 21, No. 2, 2003, p. 326-334.

Research output: Contribution to journalArticle

Lohmann, C. H. ; Schwartz, Z. ; Liu, Y. ; Li, Z. ; Simon, B. J. ; Sylvia, V. L. ; Dean, D. D. ; Bonewald, Lynda ; Donahue, H. J. ; Boyan, B. D. / Pulsed electromagnetic fields affect phenotype and connexin 43 protein expression in MLO-Y4 osteocyte-like cells and ROS 17/2.8 osteoblast-like cells. In: Journal of Orthopaedic Research. 2003 ; Vol. 21, No. 2. pp. 326-334.
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abstract = "Osteocytes, the predominant cells in bone, are postulated to be responsible for sensing mechanical and electrical stimuli, transducing signals via gap junctions. Osteocytes respond to induced shear by increasing connexin 43 (Cx43) levels, suggesting that they might be sensitive to physical stimuli like low-frequency electromagnetic fields (EMF). Immature osteoblasts exhibit decreased intercellular communication in response to EMF but no change in Cx43. Here, we examined long term effects of pulsed EMF (PEMF) on MLO-Y4 osteocyte-like cells and ROS 17/2.8 osteoblast-like cells. In MLO-Y4 cell cultures, PEMF for 8 h/day for one, two or four days increased alkaline phosphatase activity but had no effect on cell number or osteocalcin. Transforming growth factor beta-1 (TGF-β1) and prostaglandin E2 were increased, and NO2- was altered. PEMFs effect on TGF-β1 was via a prostaglandin-dependent mechanism involving Cox-1 but not Cox-2. In ROS 17/2.8 cells, PEMF for 24, 48 or 72 h did not affect cell number, osteocalcin mRNA or osteocalcin protein. PEMF reduced Cx43 protein in both cells. Longer exposures decreased Cx43 mRNA. This indicates that cells in the osteoblast lineage, including well-differentiated osteoblast-like ROS 17/2.8 cells and terminally differentiated osteocyte-like MLO-Y4 cells, respond to PEMF with changes in local factor production and reduced Cx43, suggesting decreased gap junctional signaling.",
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AU - Lohmann, C. H.

AU - Schwartz, Z.

AU - Liu, Y.

AU - Li, Z.

AU - Simon, B. J.

AU - Sylvia, V. L.

AU - Dean, D. D.

AU - Bonewald, Lynda

AU - Donahue, H. J.

AU - Boyan, B. D.

PY - 2003

Y1 - 2003

N2 - Osteocytes, the predominant cells in bone, are postulated to be responsible for sensing mechanical and electrical stimuli, transducing signals via gap junctions. Osteocytes respond to induced shear by increasing connexin 43 (Cx43) levels, suggesting that they might be sensitive to physical stimuli like low-frequency electromagnetic fields (EMF). Immature osteoblasts exhibit decreased intercellular communication in response to EMF but no change in Cx43. Here, we examined long term effects of pulsed EMF (PEMF) on MLO-Y4 osteocyte-like cells and ROS 17/2.8 osteoblast-like cells. In MLO-Y4 cell cultures, PEMF for 8 h/day for one, two or four days increased alkaline phosphatase activity but had no effect on cell number or osteocalcin. Transforming growth factor beta-1 (TGF-β1) and prostaglandin E2 were increased, and NO2- was altered. PEMFs effect on TGF-β1 was via a prostaglandin-dependent mechanism involving Cox-1 but not Cox-2. In ROS 17/2.8 cells, PEMF for 24, 48 or 72 h did not affect cell number, osteocalcin mRNA or osteocalcin protein. PEMF reduced Cx43 protein in both cells. Longer exposures decreased Cx43 mRNA. This indicates that cells in the osteoblast lineage, including well-differentiated osteoblast-like ROS 17/2.8 cells and terminally differentiated osteocyte-like MLO-Y4 cells, respond to PEMF with changes in local factor production and reduced Cx43, suggesting decreased gap junctional signaling.

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KW - Osteocytes

KW - Prostaglandin E

KW - Pulsed electromagnetic fields

KW - Transforming growth factor-β1

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