研究のタイプ: 医学/生物学の研究 (experimental study)

[電磁界は細胞の多能性状態への効率的な再プログラミングを仲介する] med./bio.

Electromagnetic fields mediate efficient cell reprogramming into a pluripotent state.

掲載誌: ACS Nano 2014; 8 (10): 10125-10138

この研究は、多能性への直接的エピジェネティックな再プログラミング中の細胞の運命決定の変化の調節において電磁界は不可欠であるという著者の仮説を検証したと報告している。

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研究目的(著者による)

The effects of exposure to a extremely low frequency magnetic field and of magnetic field deprivation on the cell reprogramming into a pluripotent state of mouse fibroblasts and the underlying mechanisms of action should be investigated. It was hypothesized that exposure to the magnetic field could influence reprogramming via epigenetic mechanisms. The study was conducted in view of a possible therapeutic use of magnetic fields in cell reprogramming.

詳細情報

Somatic cells can be reprogrammed into induced pluripotent stem cells by an overexpression of the transcription factors Oct4, Sox2, Klf4 and c-Myc (OSKM). In a first step, the influence of the magnetic field on this type of reprogramming was examined and mouse fibroblasts were divided into the following groups:
Transfection with OSKM and exposure to 1) 10 Hz, 2) 50 Hz, 3) 100 Hz, 4) OSKM transfection and no exposure (control group), 5) OSKM transfection and magnetic withdrawal and 6) fibroblasts without transfection. The effect of the magnetic field on the reprogramming success was compared with the addition of valproic acid and vitamin C, which are well-known stimulants of cell reprogramming.
To investigate the mechanisms of action, inhibitors like e.g. of the histone lysine methyltransferase Mll2 and an experimentally-induced overexpression of Mll2 were examined.
In a further step, it was examined whether the magnetic field exposure can replace individual transcription factors: 7) transfection with Oct4 only and 50 Hz exposure, 8) transfection with Oct4 and Sox2 and 50 Hz exposure. A control group was carried out without exposure for both groups, respectively.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 10 Hz
ばく露時間: continuous for 15 days
ばく露2: 50 Hz
ばく露時間: continuous for up to 45 days
ばく露3: 100 Hz
ばく露時間: continuous for 15 days
ばく露4:
ばく露時間: continuous for up to 10 days
magnetic field deprivation
  • zero-field environment

ばく露1

主たる特性
周波数 10 Hz
タイプ
  • magnetic field
ばく露時間 continuous for 15 days
ばく露装置
ばく露の発生源/構造
チャンバの詳細 6-well culture dishes in CO2 incubator
ばく露装置の詳細 the solenoid parameters were: axial symmetry, radius (R = 7.5 cm), current (I = 200 mA), and number of loops (N = 1000); the geometry of the system assured field uniformity for the exposed cultures; the surfaces of the culture plates were parallel to the force lines of the alternating magnetic field; temperature in the cultures was maintained at 37 ± 0.1°C
パラメータ
測定量 種別 Method Mass 備考
磁束密度 1 mT - 測定値 - -

ばく露2

主たる特性
周波数 50 Hz
タイプ
  • magnetic field
ばく露時間 continuous for up to 45 days
ばく露装置
ばく露の発生源/構造
  • E1と同じ装置
パラメータ
測定量 種別 Method Mass 備考
磁束密度 1 mT - 測定値 - -

ばく露3

主たる特性
周波数 100 Hz
タイプ
  • magnetic field
ばく露時間 continuous for 15 days
ばく露装置
ばく露の発生源/構造
  • E1と同じ装置
パラメータ
測定量 種別 Method Mass 備考
磁束密度 1 mT - 測定値 - -

ばく露4

主たる特性
ばく露時間 continuous for up to 10 days
Additional information magnetic field deprivation
ばく露装置
ばく露の発生源/構造
チャンバの詳細 see E1
ばく露装置の詳細 three-axis Helmholtz coils and the three-axis magnetic sensor, which measured the geomagnetic field accurately and made the system capable of canceling the earth's field inside the coil; cell cultures were located in the center of the three-axis Helmholtz coil in the incubator
パラメータ
測定量 種別 Method Mass 備考
参照 - - - - zero-field environment

Reference articles

  • Cho H et al. (2012): [超低周波電磁界によるヒト骨髄間葉系幹細胞の神経刺激]
  • Loginov VA (1992): [パルス電磁界にばく露した拘束ラットの心筋筋小胞体内でのカルシウムイオン蓄積[ロシア語]]

ばく露を受けた生物:

方法 影響評価項目/測定パラメータ/方法

研究対象とした生物試料:
調査の時期:
  • ばく露中
  • ばく露後

研究の主なアウトカム(著者による)

Exposure to a magnetic field (groups 1, 2, 3) significantly improved reprogramming efficiency compared to the control group (group 4), with the most enhanced effect found in group 2 (50 Hz).
It was found that exposure to a 50 Hz magnetic field (group 2) during reprogramming induced epigenetic changes via the increased expression of Mll2, a histone lysine methyltransferase, which is known to contribute to the methylation of histone 3 lysine 4 (H3K4me3). H3K4me3 was accumulated in the cells at the same time.
Magnetic field deprivation (group 5) impaired reprogramming into a pluripotent state, indicating the necessity of a magnetic field in the generation of induced pluripotent stem cells. However, it was demonstrated that reprogramming could be induced in this group via experimental overexpression of Mll2.
A transfection with Oct4 alone and exposure to the magnetic field (group 7) could create pluripotent cells, indicating that the magnetic field could replace the transcription factors Sox2, Klf4 and c-Myc and thus facilitate reprogramming.
The authors conclude that exposure of mouse fibroblasts to a 50 Hz magnetic field could promote cell reprogramming into a pluripotent state by increasing the Mll2 expression. Mll2 seems to mediate the magnetic field induced reprogramming via epigenetical histone methylation. Magnetic field exposure might be an efficient tool for the acquisition of pluripotent cells.

研究の種別:

研究助成

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