Photodynamic therapy of a mouse glioma: intracranial tumours are resistant while subcutaneous tumours are sensitive
1991

Photodynamic Therapy for Mouse Glioma

Sample size: 47 publication Evidence: moderate

Author Information

Author(s): E.A. Lindsay, M.C. Berenbaum, R. Bonnett, D.G.T. Thomas

Primary Institution: St Mary's Hospital Medical School

Hypothesis

Why are intracranial implants of the VMDk glioma much more resistant to PDT than subcutaneous implants?

Conclusion

Subcutaneous tumours are highly sensitive to photodynamic therapy, while intracranial tumours are resistant, requiring significantly higher doses of sensitiser for similar effects.

Supporting Evidence

  • Subcutaneous VMDk tumours showed complete necrosis with low doses of sensitiser and light.
  • Intracranial tumours required a 30-fold increase in sensitiser dose to achieve similar necrosis levels.
  • Breathing 100% oxygen increased necrosis in intracranial tumours significantly.

Takeaway

This study found that treating skin tumors with light and a special drug works really well, but brain tumors are much harder to treat the same way.

Methodology

Mice with subcutaneous and intracranial VMDk tumours were treated with photodynamic therapy using the sensitiser m-THPP, and the effects on tumour necrosis were measured.

Limitations

The study does not provide a convincing explanation for the marked difference in photosensitivity between subcutaneous and intracranial tumours.

Participant Demographics

Male and female VM strain mice weighing 20-25 g were used.

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