Cellular uptake of magnetic fluid particles and their effects on human adenocarcinoma cells exposed to AC magnetic fields in vitro.

International journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group · 1996 · Mixed · Low evidence

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MixedLow evidencePaper 4267

Study snapshot

PublicationInternational journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group · 1996

Study typein_vitro

Reported directionMixed

Evidence ratingLow

Abstract

Suspensions of coated superparamagnetic particles (magnetic fluids, MF) in AC magnetic fields have a pronounced specific absorption rate (SAR) per mass compared to multidomain particles. The aim of the present study was to investigate cellular uptake and the biological effects of AC magnetic field excited bio-compatible magnetic fluids on human carcinoma cells in vitro. One of the fluids tested was a dextran magnetite, which has a very low cyto-toxicity with survival fractions (SF) between 0.8 and 0.9 at concentrations of up to 5 mg ferrite per ml. Human carcinoma cells intracellularly accumulate up to 1 pg ferrite/cell which has been demonstrated by electron microscopy (TEM), X-ray spectroscopy and measurements of intracellular iron. It has been shown that the ferrite core is not altered intracellularly, but many of the dextran shells are degraded which yields particle chains and other aggregates observed in TEM. Semi-solid pellets of the tumour cells were treated with AC magnetic fields (520 kHz, 4-12.5 kA/m) or waterbath hyperthermia at 43 and 45 degrees C, in presence of extracellular and/or intracellular magnetic fluid particles. Although MF heating is produced from individual particles, the survival fractions of MF heated and water bath heated cells are equal. In fact, the extracellular MF particle distribution is homogeneous enough to obtain similar inactivation. In contrast to earlier reports intracellular dextran magnetite particles in AC magnetic fields did not induce cell inactivation. Since the amount of intracellular ferrite should be indeed large enough for cell inactivation, the loss of dextran shells is most probably the main cause of limited effectiveness of the intracellular magnetite particles. The present work has demonstrated that: (1) MFH is able to inactivate tumour cells in vitro to at least the same extent as water bath hyperthermia; and (2) that there is a sensitizer effect of ferrofluids at 43 degrees C probably caused by free ferric ions which induce oxidative stress; and (3) that there is no cytotoxic effect of intracellular dextran magnetite particles 30-180 min excited with AC magnetic fields used in this study. For the new method the term 'magnetic fluid hyperthermia (MFH)' is proposed.

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AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typein_vitro

Effect directionmixed

PopulationHuman adenocarcinoma/carcinoma cells in vitro (tumour cell pellets)

Sample sizeNot supplied

Exposure0.52 MHz · 30–180 min (intracellular particles excited with AC magnetic fields)

Evidence strengthLowConfidence: 74% · Peer reviewed: yes

Main findings

Human carcinoma cells accumulated up to ~1 pg ferrite/cell; ferrite cores were not altered intracellularly but dextran shells were degraded, yielding aggregates. Magnetic fluid hyperthermia (520 kHz, 4–12.5 kA/m) inactivated tumour cells in vitro to a similar extent as waterbath hyperthermia (43–45°C) when extracellular particle distribution was homogeneous. Intracellular dextran magnetite particles excited for 30–180 min in the AC magnetic fields used did not induce cell inactivation; a sensitizer effect of ferrofluids at 43°C was reported.

Outcomes measured

Cellular uptake of magnetic fluid particles (intracellular ferrite accumulation)
Cell survival fraction / cell inactivation after AC magnetic field treatment vs waterbath hyperthermia
Cytotoxicity of dextran magnetite at various concentrations
Evidence of particle shell degradation/aggregation (TEM, X-ray spectroscopy, intracellular iron measurements)
Sensitizer effect at 43°C (suggested oxidative stress from free ferric ions)

Limitations

Sample size not reported in abstract
In vitro study on tumour cell pellets; generalizability to in vivo/clinical settings not addressed
Exposure metrics such as SAR in W/kg for the biological experiments not reported (only noted qualitatively as pronounced)
Mechanistic explanation (oxidative stress from free ferric ions; shell loss) is proposed but not directly demonstrated in the abstract

View raw extracted JSON

{
  "study_type": "in_vitro",
  "exposure": {
    "band": null,
    "source": "AC magnetic fields (magnetic fluid hyperthermia setup)",
    "frequency_mhz": 0.52,
    "sar_wkg": null,
    "duration": "30–180 min (intracellular particles excited with AC magnetic fields)"
  },
  "population": "Human adenocarcinoma/carcinoma cells in vitro (tumour cell pellets)",
  "sample_size": null,
  "outcomes": [
    "Cellular uptake of magnetic fluid particles (intracellular ferrite accumulation)",
    "Cell survival fraction / cell inactivation after AC magnetic field treatment vs waterbath hyperthermia",
    "Cytotoxicity of dextran magnetite at various concentrations",
    "Evidence of particle shell degradation/aggregation (TEM, X-ray spectroscopy, intracellular iron measurements)",
    "Sensitizer effect at 43°C (suggested oxidative stress from free ferric ions)"
  ],
  "main_findings": "Human carcinoma cells accumulated up to ~1 pg ferrite/cell; ferrite cores were not altered intracellularly but dextran shells were degraded, yielding aggregates. Magnetic fluid hyperthermia (520 kHz, 4–12.5 kA/m) inactivated tumour cells in vitro to a similar extent as waterbath hyperthermia (43–45°C) when extracellular particle distribution was homogeneous. Intracellular dextran magnetite particles excited for 30–180 min in the AC magnetic fields used did not induce cell inactivation; a sensitizer effect of ferrofluids at 43°C was reported.",
  "effect_direction": "mixed",
  "limitations": [
    "Sample size not reported in abstract",
    "In vitro study on tumour cell pellets; generalizability to in vivo/clinical settings not addressed",
    "Exposure metrics such as SAR in W/kg for the biological experiments not reported (only noted qualitatively as pronounced)",
    "Mechanistic explanation (oxidative stress from free ferric ions; shell loss) is proposed but not directly demonstrated in the abstract"
  ],
  "evidence_strength": "low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "magnetic fluid hyperthermia",
    "AC magnetic field",
    "520 kHz",
    "dextran magnetite",
    "superparamagnetic particles",
    "cell survival fraction",
    "tumour cells",
    "intracellular uptake",
    "oxidative stress"
  ],
  "suggested_hubs": [
    {
      "slug": "other",
      "weight": 0.2,
      "reason": "In vitro magnetic-field-assisted hyperthermia using magnetic fluids; not clearly aligned with common RF/ELF public-exposure hubs."
    }
  ]
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.3109/02656739609027678
PubMed: 8950152

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