Geron is gone, but the stem cells won't be gone
On November 14, the American Geron Corporation (Menlo Park, California), the largest and oldest of the stem cell companies, announced a change in the priority of activities for the development of antitumor drugs. The most severe blow to the industry was the termination of a clinical trial in which a method of using embryonic stem cells to restore mobility to patients paralyzed as a result of spinal cord injuries was tested.
The company spent several years and hundreds of millions of dollars just to get permission from the U.S. Food and Drug Administration to conduct a clinical trial that began about a year ago. At the time of its termination, 4 out of 11 planned patients were included in the study. In addition to treating spinal cord injuries, Geron has stopped working in at least three other areas dedicated to exploring the possibilities of using stem cells to treat diabetes, heart disease and arthritis.
What will happen to these programs and what does Geron's decision mean for other companies and researchers who continue to work to realize the dream of introducing stem cell-based therapies into clinical practice?
Why did Geron stop working and what will happen to the programs started by the companies?Representatives of the company claim that the decision was made solely on the basis of financial considerations – lack of funds to carry out two main programs of the company: work with stem cells and the development of antitumor drugs.
The company decided that, from a financial point of view, working on antitumor therapy is the best choice. However, in the hope of new sponsors or partners, the company retains its core staff working with stem cells.
Who will help?One of the possible saviors is the California Institute of Regenerative Medicine.
Previously, he has already allocated grants for the promotion of cell therapy towards the introduction into the clinic, the total amount of which exceeds $ 230 million, and in the past sponsored a clinical study conducted by Geron on the treatment of spinal cord injuries.
According to Alan Trounson, president of the Institute, the institute is currently in talks with at least three other potential sponsors who could support this research in the future. But it takes time, and if the process drags on for longer than a couple of months, it will be impossible to gather specialists working in this direction.
Why is Geron's decision to abandon stem cell research an event of exceptional importance?Geron is the first company in the world to start developing therapies based on the use of human embryonic stem cells (CESCS).
The company was an obvious leader in the development of methods for creating cells from cESC that meet the strictest quality standards and production standards applied to conventional pharmaceutical products. However, due to the need to destroy human embryos in order to obtain the initial CESCS, the company's work caused some public outrage. Some people, including representatives of the Catholic and Protestant churches, have always spoken out against working with embryonic cells, citing moral aspects.
Why, then, did Geron devote her activities to working with CHESK?These cells are able to transform into cells of all (approximately 200) types of tissues that make up the human body.
This property potentially gives embryonic cells the ability to repair any part of the body, so the company's specialists considered them to have the most pronounced potential from a clinical point of view.
In this case, is Geron's decision the end of the development of treatment methods based on the use of cESC?No, although in general it significantly narrows the direction of work.
Specialists of the Advanced Cell Technology company (Santa Monica, California) have already injected retinal pigment epithelial cells obtained from cESC to five patients with a rare hereditary disease – Stargardt macular dystrophy. In the UK, a group of researchers from University College London, working under the leadership of Pete Coffey, plans to test a method of using tiny flaps formed from pigment epithelial cells to treat another eye disease – age-related macular degeneration. Another California-based company, ViaCyte from San Diego, hopes to use insulin-producing cells obtained from cESC to treat diabetes. This work is partially funded by the California Institute of Regenerative Medicine.
What other approaches are there based on the use of stem cells, and how close are they on the way to clinical use?In 2006, Japanese researcher Shinya Yamanaka from Kyoto University developed a method for converting ordinary somatic cells into cells, like CESCS, with the ability to differentiate into cells of a wide range of body tissues.
Dubbed induced pluripotent stem cells (iPSCs), these cells have been recognized by opponents of abortion and embryo destruction as an acceptable alternative to CESCS.
Are there any other approaches?Over the past decade, researchers have identified several dozen living tissues and biological fluids from which "adult" stem cells can be isolated.
Just last week, it was announced that the stem cells contained in breast milk have properties similar to those of embryonic cells. This increases the list of already known sources of stem cells, which includes blood, urine, bone marrow, amniotic fluid, placental tissue, adipose tissue and even olfactory neurons.
What are the advantages and disadvantages of these alternatives?The obvious advantage of iPSC is that there is no need for embryo destruction.
However, this method still has a number of significant drawbacks.
One of the problems that arose already at the early stages of work is due to the fact that the transformation of ordinary cells into stem cells requires their infection with viruses, which automatically turns iPSCs into potentially carcinogenic and, accordingly, unsafe for clinical use. Currently, active work is underway to overcome this barrier.
Earlier this year, Yang Xu from the University of California, San Diego demonstrated that the immune system of mice recognizes iPSCs derived from their own cells as foreign and triggers the corresponding immune responses. Therefore, despite the huge potential of iPSCs, today they are unacceptable for clinical use.
At the same time, unlike universal CESCS and iPSCs, adult stem cells can only give rise to a limited range of tissues, that is, they can only be used to treat a limited number of diseases. However, their huge advantage, compared with stem cells from other sources, is the ease of isolation from tissues and body fluids and the low risk of malignancy.
Which approach is closest to clinical application?The leading position is undoubtedly occupied by adult stem cells, the use of which this year has demonstrated a number of very encouraging results.
The Australian company Mesoblast, based in Melbourne, is developing methods for the treatment of myocardial infarction, diabetes, as well as bone and eye diseases, based on the introduction of specialized bone marrow stem cells, called mesenchymal progenitor stem cells.
Other research groups and companies are testing treatments based on the use of adult stem cells on patients with heart disease. The results obtained to date are also very promising.
Last year, ReNeuron, of Guildford, UK, used neural stem cells for the first time to treat a stroke patient. These cells were isolated from fetal brain tissue.
Thus, today the leading position in the clinic belongs to adult stem cells?Uniquely.
For example, there are currently almost 200 clinical trials worldwide testing treatments based on the introduction of mesenchymal bone marrow stem cells. In terms of absolute numbers and commercial potential, these cells have gone far ahead.
However, the success of the clinical application of cESC is also quite real, especially in the case of options for continuing the programs started by Geron. Of all the approaches discussed, the use of iPSCs is the farthest from the clinic, but the development of this direction will accelerate significantly as soon as the problems related to the safety of their use are solved.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of New Scientist:
Is there life for stem cells after Geron?
22.11.2011