Navigation Links
Photodynamic therapy against cancer
Date:2/9/2011

Tumor cells have several routes that enable them to move from the primary tumor to distant tissues, a process called metastasis. It is metastasis of the primary tumor that kills most cancer patients. One of the least studied routes of metastasis is the lymphatic system. Many tumors produce factors that promote the formation of new lymphatic vessels (lymphangiogenesis). The newly formed lymphatic vessels enable tumor cells to travel from the primary tumor to the regional lymph nodes from whence they can spread throughout the body.

Current treatment practice is to surgically remove the primary tumor as well as the metastatic lymph nodes, but tumor cells in metastatic transit inside the lymphatic vessels had not been given much attention.

In a new study, Dr Tuomas Tammela and colleagues at the University of Helsinki, Finland, investigated whether eradicating tumor-associated lymphatic vessels and the tumor cells they contain using photodynamic therapy (PDT) with a light-activated cytotoxic drug could reduce or eliminate tumor metastasis. They selected the mouse ear as their model system because it is easy to image both the lymphatic vessels and the in-transit tumor cells.

The researchers implanted mouse melanoma cells or human lung tumor cells into the mouse ear tip and waited two weeks for the primary tumors to become established and to induce lymphangiogenesis. Using deep-tissue microscopy, they observed that the newly formed lymphatic vessels contained in-transit tumor cells as well as small tumor nodules. Using pathology sections taken from a patient with recurrent melanoma, they confirmed that the tumor-associated lymphatic vessels of cancer patients contain in-transit tumor cells and tumor nodules.

However, could PDT eliminate both tumor-associated lymphatic vessels and the tumor cells inside them? The researchers injected verteporfin in a liposomal preparation intradermally into the mouse ear and showed that this cytotoxic dye accumulated specifically in the lymphatic vessels. When they illuminated the mouse ear with infrared laser light, the lymphatic vessels started to shrink and fragment, and became leaky. Also, the researchers found that the mice receiving PDT and surgery had a much lower relapse rate than those that underwent surgery alone.

Using a pig model, the researchers also showed that PDT can target lymphatic vessels deep within the body and, thus, PDT could be useful eradicating tumor-associated lymphatic vessels deep within the tissues of human cancer patients.

"These findings are new and exciting, because the cells in metastatic transit in tumor-draining lymphatic vessels have not been given much attention previously", Dr. Tammela says.

"We do not expect PDT to replace current surgical techniques, which comprise removal of the primary tumor and metastatic lymph nodes. However, PDT could easily be combined with existing surgical techniques to destroy the lymphatic vessels draining from the tumor, as well as the tumor cell aggregates residing within them."

PDT using verteporfin is currently used clinically to destroy overgrown blood vessels in the retina of patients with macular degeneration. As both the drug and the PDT concept are already in use in patients, they are more likely to receive regulatory approval for targeting tumor-associated lymphatic vessels in cancer patients undergoing surgery than drugs still in earlier phases of development, Tammela states.


'/>"/>

Contact: Dr. Tuomas Tammela
tuomas.tammela@helsinki.fi
358-445-385-272
University of Helsinki
Source:Eurekalert  

Related biology news :

1. Fluorescence monitoring and effect of photodynamic therapy for port wine stains
2. A loose grip provides better chemotherapy
3. Early tests find nanoshell therapy effective against brain cancer
4. New anti-HIV gene therapy makes T-cells resistant to HIV infection
5. Caffeine energizes cells, boosting virus production for gene therapy applications
6. Nanodisk gene therapy
7. Invention could improve cancer drug delivery, lessen harmful effects of chemotherapy
8. New breathing therapy reduces panic and anxiety by reversing hyperventilation
9. Missing molecules hold promise of therapy for pancreatic cancer
10. Cell of origin for brain tumors may predict response to therapy
11. Killing drug-resistant melanoma requires combination therapy
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Photodynamic therapy against cancer
(Date:2/21/2017)... -- Der weltweite Biobanking-Sektor wird bis zum ... mit mehr als 50 Vertretern aus verschiedenen Branchen wurde aber ... diese Prognose zu realisieren. ... Zu den Schwierigkeiten für ... für die Biobank, die Implementierung Zeit sparender Technologien, ein ...
(Date:2/14/2017)... -- Wake Forest Baptist Medical Center today announced Julie Ann Freischlag, ... (CEO). Freischlag joins the medical center on May 1 ... who last year announced that he would transition to ... it since 2008.   As CEO, Freischlag ... academic health system, which includes Wake Forest School of ...
(Date:2/13/2017)... -- Former 9/11 Commission border counsel and Special Counsel ... of Identity Strategy Partners, LLP, today releases the ... Order: Protecting the Nation From Foreign Terrorist Entry Into ... President Trump,s ,Travel Ban, Executive Order gains more notoriety ... travel ban, it is important that our national discourse ...
Breaking Biology News(10 mins):
(Date:3/27/2017)... ... March 27, 2017 , ... Biopsies from non-small cell lung ... limited tumor content in a large background of normal or wild type cells. ... for reliable detection of low abundance somatic mutations, particularly in small specimens with ...
(Date:3/27/2017)... NC (PRWEB) , ... March 27, 2017 , ... ... Clinical Trial Collaborations (CTC) conference presented by The Conference Forum in Boston on ... way they collaborate to drive improved clinical trial outcomes and bring them closer to ...
(Date:3/24/2017)... , March 24, 2017 MiMedx Group, ... company utilizing human placental tissue allografts and patent-protected processes ... multiple sectors of healthcare, announced today  that it will ... New York , NY.  Parker H. "Pete" Petit, ... Financial Officer, Christopher M. Cashman , EVP and ...
(Date:3/24/2017)... , March 24, 2017   Sienna Biopharmaceuticals, Inc. ... company, today announced that Richard Peterson will ... 24.   Peterson, who brings more than two ... Smither , who is retiring at the end of ... advisory capacity. Peterson joins Sienna from Novan, Inc., where ...
Breaking Biology Technology: