One recent headline in Forbes
magazine read,
“Stem Cell Therapy To Fix The Heart: A House Of Cards About To Fall?”
Over at the Boston Globe, another story
this month said,
“A provocative new study calls into question the rationale for using stem cells to repair the heart — a much-hyped experimental therapy that grew out of insights from a groundbreaking Boston researcher’s laboratory.”
Eduardo Marban Cedars-Sinai photo |
But it appears that heart stem cell
regeneration is like cheese, you might say. There are many different
varieties. And in the case of a $27 million investment in heart cell regeneration by the California stem cell agency, all the players say
things are just fine with their project.
The state's research effort involves a
publicly traded company called Capricor Therapeutics. The Beverly
Hills firm and one of its founders. Eduardo Marban, director of the
Cedars-Sinai Heart Institute in Los Angeles, received the $27 million
from the state stem cell agency.
In the wake of the news reports
involving heart stem cell regeneration, the California Stem Cell
Report queried both Marban and the stem cell agency. Marban replied
within 37 minutes last week. Here is the text of what he had to say
in his email.
“All of the critiques have been leveled at competing technologies. Indeed, I have been among the more vocal critics (for example see http://www.tctmd.com/show.aspx?id=124193).
“Although some alarmist headlines have inappropriately questioned all cardiac stem cell work, the issues have to do with only one specific subtype of cardiac stem cell, which is marked by the expression of an antigen called c-kit. This is NOT the cell type being developed by Capricor; in fact, my laboratory has found that c-kit-positive cells play no role in Capricor’s cell product. That product, known as CAP-1002, contains a small fraction (less than 5 percent) of c-kit-positive cells which can be completely removed with no loss in potency. CAP-1002 is believed to work by indirect 'paracrine' mechanisms that differ fundamentally from those postulated for the c-kit-positive cells.
“By way of background, the critiques of c-kit-positive heart cells have come in two forms: first, in concerns expressed by the editors of the Lancet regarding data integrity in the SCIPIO trial; this was conducted by Piero Anversa and colleagues using c-kit-positive cells. Second, a recent Nature paper (attached in case you do not have a copy), of which I am an author, questions the claim that c-kit-positive cells are true cardiac progenitors.
“These concerns in no way undermine Capricor’s technology. In fact, CAP-1002 remains the only heart-derived cell product in commercial development. I am proceeding full speed ahead with mechanistic and translational work on CAP-1002, and Capricor continues to feel bullish about the product, which is now in phase 2 trials (the furthest along of any CIRM-funded project).”
Kevin McCormack, a spokesman for the
stem cell agency, also said that Capricor is using a different method
and a different stem cell than the one being called into question.
You can hear the May 15 Capricor
conference call on its first quarter results here. Its stock price
jumped from $6.15 on May 14 to as high as $7.65 during the day May 15. Its 52-week low was $1.15 and its
52-week high $17.15.
(Editor's note: If you would like a copy of the Nature paper that Marban referenced, please send an email to djensen@californiastemcellreport.com.)
What about Capricor's recent news surrounding the identification of exosomes as the carriers of the paracrine growth and trophic factors that are proposed to be the mechanism of action for the CAP-1002 that CIRM invested in? Seems like the cells will be dropping off the map if the exosomes' efforts pan out.
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