Monday, June 27, 2011
In vivo cell trafficking just took a leap forward
Today Celsense, Inc. and the University of Pittsburgh Cancer Center announced that the FDA has authorized the use of the Cell Sense imaging reagent for use in a phase I clinical trial of a dendritic cell caccine to treat colorectal cancer patients.
This is the first FDA authorization of the use of Cell Sense in patients. Cell Sense is a novel perfluorocarbon tracer agent used to safely and efficiently label cells ex vivo without the use of transfection agents. Labeled cells are then transplanted into the patient enabling researchers and clinicians to non-invasively track the administration and migration of therapeutic cells using MRI. Applications include tracking cells in immunotherapy or regenerative medicine as well as the diagnosis of inflammatory sites by tracking selected populations of immune cells.
Cell Sense has been studied extensively in preclinical testing with many different human cell types including human cells in animals. For instance, in 2009 a paper was published in Informa's Cytotherapy, in which Celsense’s novel perfluorocarbon tracer agent (product “Cell Sense”) was used to label human DCs ex vivo for the purpose of tracking the cells in vivo post-transplant by 19F MRI. The paper provided an assessment of the technology and demonstrated that human DCs were effectively labeled without significant impact on cell viability, phenotype or function. Furthermore, the labeled dendritic cells were clearly detected in vivo by 19F MRI in a model system, with the labeled cells being shown to migrate selectively towards draining lymph node regions within 18 hours after transplant.
Many investigators looking at various ways to label cells to enable in vivo imaging have expressed concern that the FDA would delay the regulatory progress of their therapeutic candidates if an imaging modality was introduced.
This concern is based on numerous reports of MRI contrast reagents, such as the commonly investigated USPIO (ultrasmall superparamagnet iron oxide), deleteriously affecting the cells (see recent paper in Cell Transplantation).
"We believe that the authorization of this IND will alleviate such concerns and lower the barriers for adoption. The agency’s tangible support for bringing new technologies to bear in the translation of cell-based therapeutics is very encouraging,” s Charlie O'Hanlon, President and CEO of Celsense.
While there have been approved uses of imaging reagents (e.g., Feridex, etc) with cell therapies in other countries (e.g. Isreal), I believe this may be the first FDA-sanctioned use of a particle-based imaging label with a cell-based therapy. Other approaches to cellular imaging include nuclear imaging reagents and genetically modifying cells with reporter genes such as those provided by CellSight Technologies.
Imaging labels are capable of providing investigators with data demonstrating where the cells go, at what volumes, and for how long they stay at the target location.
The industry has been keen to see these kinds of technologies clinically employed but different cell-based labels have created their own technical, clinical, and/or regulatory hurdles. I'm hopeful that Celsense and others like them are now ushering us into a new era where we will eventually be able to use various technologies to monitor and collect valuable data concerning cells after they have been administered as a therapy to a patients.
Additional resources on the topic of imaging for cell therapies:
CIRM recently hosted a webinar - "CIRM/RMC Webinar: Imaging Technology for Cellular Therapies. One of the speakers, Dr. Shahriar Yaghoubi from CellSight Technologies, provides an overview of cell therapy imaging with emphasis on PET. Click hear for the archived playback.
A very interesting article posted today on Harvard's StemBook website. "In-vivo Stem Cell Imaging - Regulatory Challenges and Advances". Nice overview intel from J. Bulte and a snapshot into E. Wirth's (of Geron) perspective re: stem cell imaging.
A new book from CRC Press edited by Dara Kraitchman and Joe Wu will be out soon. It gathers together different methods for comparison. The issue will remain the sensitivity of the methods to track few cells. "Stem Cell Labeling for Delivery and Tracking Using Non-Invasive Imaging".
MRI contrast agents can change stem cell proliferation
There s also a very informative discussion thread on the topic in the Cell Therapy Industry group on LinkedIn.