Comparing and combining light dose fractionation and iron chelation to enhance experimental photodynamic therapy with aminolevulinic acid.
OBJECTIVE
Enhancement of photodynamic therapy (PDT) with 5-aminolevulinic acid (ALA) has been demonstrated experimentally using light dose fractionation or CP94 iron chelation. This study extends this research.


METHODS
In normal rat colon, CP94 administration and light dose fractionation were independently and concurrently employed to enhance ALA-PDT. In colonic rat tumors, the most successful enhancement regimes were employed separately.


RESULTS
Independent use of light dose fractionation and iron chelation produced similar results in normal colon (2.4- and 2.9-fold more necrosis than controls, respectively). Using both techniques simultaneously produced fivefold enhancement. In the colonic tumors, light dose fractionation and iron chelation (using different parameters) produced two and five times the volume of necrosis, respectively.


CONCLUSIONS
Both techniques significantly enhanced ALA-PDT in the normal and neoplastic tissues investigated and produced similar levels of enhancement when comparable parameters were employed. Concurrent use of light dose fractionation and iron chelation in normal colon produced considerably more enhancement than either technique could achieve independently.
Curnow
Alison
A
Cornwall Dermatology Research, Peninsula Medical School, Truro, Cornwall TR1 3HD, UK. alison.curnow@pms.ac.uk
MacRobert
Alexander J
AJ
Bown
Stephen G
SG
D000622:Aminolevulinic Acid / Q000627:therapeutic use*; D000818:Animals; D003106:Colon / Q000473:pathology / Q000528:radiation effects; D003110:Colonic Neoplasms / Q000473:pathology / Q000628:therapy*; D019583:Dose Fractionation, Radiation; D005260:Female; D005354:Fibrosarcoma / Q000473:pathology / Q000628:therapy*; D007502:Iron Chelating Agents / Q000627:therapeutic use*; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D011728:Pyridones / Q000627:therapeutic use*; D051381:Rats; D017208:Rats, Wistar
D007502:Iron Chelating Agents; D017319:Photosensitizing Agents; D011728:Pyridones; C068543:1,2-diethyl-3-hydroxypyridin-4-one; D000622:Aminolevulinic Acid