Effects of N-methyl pyrrolidone on the uptake of hypericin in human bladder carcinoma and co-staining with DAPI investigated by confocal microscopy.
Photodynamic diagnosis (PDD) using hypericin (HY), a natural photosensitizer, detects bladder cancer significantly better than white light endoscopy. However, the lipophilicity of HY complicates its administration for clinical applications. Currently, pharmaceutical preparations for HY without plasma protein are being developed. Formulations containing a biocompatible solvent, N-methyl pyrrolidone (NMP) have been shown to enhance the photodynamic therapeutic effects of HY. It was recently reported that, NMP formulations of HY were able to produce significantly higher contrast for fluorescence detection of tumors than albumin-containing HY formulations. This present work hypothesizes that NMP acts both as a solvent and penetration enhancer to improve the delivery of HY into cells by increasing the permeability of cell membranes. This paper reports the use of 3-D confocal microscopy to monitor real-time uptake of HY in human carcinoma. 3-D confocal microscopy was used to investigate the possibility of nuclear localization of HY in MGH cells. The fluorescence of HY was confirmed to be emitted from HY containing cells using spectrometry. The localization of a DNA fluorescent probe 4', 6-diamidino-2-phenylindole dihydrochloride (DAPI) was used to confirm the possibility of colocalization of DAPI and HY. The colocalization analysis in the present study suggests that it was very unlikely that HY colocalized in the nucleus that was stained by DAPI. Fluorescein leakage tests showed that 1% NMP changes the permeability of cell membranes, and enhanced the delivery of HY into cells resulting in lower cell survival ratios. Thus, NMP was able to enhance the photodynamic therapeutic effects of HY on cancer cells.
Saw
Constance Lay Lay
CL
Department of Pharmacy, National University of Singapore, 18 Science Drive 4, Singapore, Singapore 117543.
Olivo
Malini
M
Wohland
Thorsten
T
Fu
Chit Yaw
CY
Kho
Kiang Wei
KW
Soo
Khee Chee
KC
Sia Heng
Paul Wan
PW
D000873:Anthracenes; D000970:Antineoplastic Agents / Q000493:pharmacokinetics; D001682:Biological Availability; D002277:Carcinoma / Q000175:diagnosis* / Q000188:drug therapy* / Q000378:metabolism*; D003952:Diagnostic Imaging / Q000379:methods; D004305:Dose-Response Relationship, Drug; D005456:Fluorescent Dyes; D006801:Humans; D021621:Imaging, Three-Dimensional; D007211:Indoles; D018613:Microscopy, Confocal; D010569:Perylene / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D010778:Photochemotherapy; D011760:Pyrrolidinones / Q000494:pharmacology*; D013723:Teratogens / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D001749:Urinary Bladder Neoplasms / Q000175:diagnosis* / Q000188:drug therapy* / Q000378:metabolism*
D000873:Anthracenes; D000970:Antineoplastic Agents; D005456:Fluorescent Dyes; D007211:Indoles; D011760:Pyrrolidinones; D013723:Teratogens; C007293:DAPI; D010569:Perylene; C004965:hypericin; C038678:N-methylpyrrolidone