- Library Home /
- Search Collections /
- Open Collections /
- Browse Collections /
- UBC Theses and Dissertations /
- Lipoprotein delivery of benzoporphyrin derivative :...
Open Collections
UBC Theses and Dissertations
UBC Theses and Dissertations
Lipoprotein delivery of benzoporphyrin derivative : a photosensitizer for photodynamic therapy Allison, Beth Anne
Abstract
Photodynamic Therapy (PDT) involves the systemic administration of a light activated drug combined with the precise delivery of light to produce a selective cytotoxic reaction. Benzoporphyrin derivative (BPD) has been shown to be a potent photosensitizer both in vitro and in vivo and is therefore a good candidate for PDT. Since BPD is administered systemically, it is important to know the factors which affect its biodistribution. In this thesis, the in vitro and in vivo distribution of BPD in plasma was examined and the majority of BPD was recovered with the plasma lipoproteins. Association of other photosensitizers with plasma lipoproteins has been show to increase accumulation in tumours and enhance tumour cell damage upon light activation. Based on this information, we hypothesized that association of BPD with lipoproteins, before administration, would increase the accumulation of the photosensitizer in neoplastic tissue and therefore enhance the efficacy of PDT. The effect of precomplexing BPD with purified lipoproteins on the biodistribution of the drug in vivo was studied in tumour bearing mice. Low density lipoprotein (LDL) or high density lipoprotein (HDL) associated BPD accumulated in tumour tissue in greater amounts than aqueous BPD. The association of BPD with either LDL or HDL increased tumour cell killing in vitro and the efficacy of in vivo photosensitization. In particular, LDL-BPD mixtures led to enhanced tumour eradication compared to BPD administered in aqueous solution or unfractionated plasma. These results suggest that the association of BPD with lipoproteins can have a profound effect on the eradication of tumours in vivo. In an attempt to define the mechanism by which LDL enhanced the delivery of BPD to tumours, we performed in vitro accumulation experiments using ¹⁴C-labelled BPD LDL mixtures on human fibroblast cell lines. LDL receptor-mediated internalization of LDL-BPD complexes, as well as LDL receptor facilitated diffusion mechanisms, were involved in cellular accumulation of the drug and, therefore, may be partially responsible for the enhanced efficacy of PDT in the presence of LDL. The results of these studies suggest that lipid based formulations should be designed to deliver photosensitzers preferentially to the LDL fraction of plasma.
Item Metadata
Title |
Lipoprotein delivery of benzoporphyrin derivative : a photosensitizer for photodynamic therapy
|
Creator | |
Publisher |
University of British Columbia
|
Date Issued |
1992
|
Description |
Photodynamic Therapy (PDT) involves the systemic administration of a light
activated drug combined with the precise delivery of light to produce a selective cytotoxic
reaction. Benzoporphyrin derivative (BPD) has been shown to be a potent photosensitizer
both in vitro and in vivo and is therefore a good candidate for PDT. Since BPD is
administered systemically, it is important to know the factors which affect its biodistribution.
In this thesis, the in vitro and in vivo distribution of BPD in plasma was examined and the
majority of BPD was recovered with the plasma lipoproteins. Association of other
photosensitizers with plasma lipoproteins has been show to increase accumulation in tumours
and enhance tumour cell damage upon light activation. Based on this information, we
hypothesized that association of BPD with lipoproteins, before administration, would increase
the accumulation of the photosensitizer in neoplastic tissue and therefore enhance the efficacy
of PDT.
The effect of precomplexing BPD with purified lipoproteins on the
biodistribution of the drug in vivo was studied in tumour bearing mice. Low density
lipoprotein (LDL) or high density lipoprotein (HDL) associated BPD accumulated in tumour
tissue in greater amounts than aqueous BPD. The association of BPD with either LDL or
HDL increased tumour cell killing in vitro and the efficacy of in vivo photosensitization. In
particular, LDL-BPD mixtures led to enhanced tumour eradication compared to BPD
administered in aqueous solution or unfractionated plasma. These results suggest that the
association of BPD with lipoproteins can have a profound effect on the eradication of
tumours in vivo.
In an attempt to define the mechanism by which LDL enhanced the delivery
of BPD to tumours, we performed in vitro accumulation experiments using ¹⁴C-labelled BPD
LDL mixtures on human fibroblast cell lines. LDL receptor-mediated internalization of
LDL-BPD complexes, as well as LDL receptor facilitated diffusion mechanisms, were
involved in cellular accumulation of the drug and, therefore, may be partially responsible for
the enhanced efficacy of PDT in the presence of LDL. The results of these studies suggest
that lipid based formulations should be designed to deliver photosensitzers preferentially to
the LDL fraction of plasma.
|
Extent |
5276931 bytes
|
Genre | |
Type | |
File Format |
application/pdf
|
Language |
eng
|
Date Available |
2008-12-12
|
Provider |
Vancouver : University of British Columbia Library
|
Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
|
DOI |
10.14288/1.0086509
|
URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
|
Graduation Date |
1992-11
|
Campus | |
Scholarly Level |
Graduate
|
Aggregated Source Repository |
DSpace
|
Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.