Opposite effects of low intensity light of different wavelengths on the planarian regeneration rate

J Photochem Photobiol B · 2020 · Mixed · Low evidence

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MixedLow evidencePaper 6827

Study snapshot

PublicationJ Photochem Photobiol B · 2020

Study typeanimal

Reported directionMixed

Evidence ratingLow

Abstract

Planarian freshwater flatworms have the unique ability to regenerate due to stem cell activity. The process of regeneration is extremely sensitive to various factors, including light radiation. Here, the effect of low-intensity LED light of different wavelengths on regeneration, stem cell proliferation and gene expression associated with these processes was studied. LED matrices with different wavelengths (red (λmax = 635 nm), green (λmax = 520 nm) and blue (λmax = 463 nm), as well as LED laser diodes (red (λmax = 638.5 nm), green (λmax = 533 nm) and blue (λmax = 420 nm), were used in the experiments. Computer-assisted morphometry, whole-mount immunocytochemical study and RT-PCR were used to analyze the biological effects of LED light exposure on the planarian regeneration in vivo. It was found that a one-time exposure of regenerating planarians with low-intensity red light diodes stimulated head blastema growth in a dose-dependent manner (up to 40%). The green light exposure of planarians resulted in the opposite effect, showing a reduced head blastema growth rate by up to 21%. The blue light exposure did not lead to any changes in the rate of head blastema growth. The maximum effects of light exposure were observed at a dose of 175.2 mJ/cm2. No significant differences were revealed in the dynamics of neoblasts' (planarian stem cells) proliferation under red and green light exposure. However, the RT-PCR gene expression analysis of 46 wound-induced genes revealed their up-regulation upon red LED light exposure, and down-regulation upon green light exposure. Thus, we have demonstrated that the planarian regeneration process is rather sensitive to the effects of low-intensity light radiation of certain wavelengths, the biological activity of red and green light being dictated by the different expression of the genes regulating transcriptional activity.

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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 typeanimal

Effect directionmixed

PopulationRegenerating planarian freshwater flatworms

Sample sizeNot supplied

Exposureother · one-time exposure; maximum effects at 175.2 mJ/cm2

Evidence strengthLowConfidence: 95% · Peer reviewed: yes

Main findings

In regenerating planarians, one-time low-intensity red light exposure stimulated head blastema growth in a dose-dependent manner by up to 40%, while green light reduced growth by up to 21%; blue light showed no change. No significant differences were found in neoblast proliferation under red and green light, but red light up-regulated and green light down-regulated wound-induced gene expression.

Outcomes measured

Head blastema growth rate
Neoblast (stem cell) proliferation
Expression of 46 wound-induced genes

Limitations

Animal study
Sample size not stated in the abstract
Findings are limited to low-intensity visible light exposures of specific wavelengths and doses

View raw extracted JSON

{
  "study_type": "animal",
  "exposure": {
    "band": "other",
    "source": "other",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": "one-time exposure; maximum effects at 175.2 mJ/cm2"
  },
  "population": "Regenerating planarian freshwater flatworms",
  "sample_size": null,
  "outcomes": [
    "Head blastema growth rate",
    "Neoblast (stem cell) proliferation",
    "Expression of 46 wound-induced genes"
  ],
  "main_findings": "In regenerating planarians, one-time low-intensity red light exposure stimulated head blastema growth in a dose-dependent manner by up to 40%, while green light reduced growth by up to 21%; blue light showed no change. No significant differences were found in neoblast proliferation under red and green light, but red light up-regulated and green light down-regulated wound-induced gene expression.",
  "effect_direction": "mixed",
  "limitations": [
    "Animal study",
    "Sample size not stated in the abstract",
    "Findings are limited to low-intensity visible light exposures of specific wavelengths and doses"
  ],
  "evidence_strength": "low",
  "confidence": 0.95,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "planarian",
    "regeneration",
    "LED light",
    "red light",
    "green light",
    "blue light",
    "blastema growth",
    "gene expression",
    "neoblast proliferation",
    "photobiomodulation"
  ],
  "suggested_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: 10.1016/j.jphotobiol.2019.111714
PubMed: 31830733

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