Regenetech, a US company founded on discoveries originally made by the National Aeronautics and Space Administration (NASA), is close to announcing its first major licence for technology that could overcome barriers to producing viable quantities of therapeutic adult stem cells for clinical trials and the treatment of conditions such as diabetes and heart disease.

The company, which says it has a “queue” of potential licensees interested in taking its proprietary Intrifuge cellXpansion technology into the clinical arena, recently announced a significant advance in its cell multiplication capabilities for CD34+38- peripheral blood progenitor cells, an early form of adult stem cell.

Normally the proportion of adult stem cells in the human bloodstream is as low as 0.001% prior to mobilisation with granulocyte colony stimulating factor (a procedure that induces the release of stem cells from bone marrow), points out David Bonner, chief executive officer of Regenetech. This is a significant limiting factor in expanding the use of autologous adult stem cell therapy, whereby cells from the patient’s own body are reimplanted into damaged tissue.

Post-mobilisation with G-CSF, around two million adult stem cells can be obtained from one pint of blood. With the Intrifuge cellXpansion technology, however, this volume can be boosted to 60-70 million cells in just a couple of weeks, Bonner says. The method is also far cheaper and less invasive than the traditional procedure of harvesting adult stem cells from the patient’s bone marrow (aspiration), he adds.

The Intrifuge approach can produce sufficient quantities of stem cells for several therapeutic doses – often involving a straightforward injection into the bloodstream – at a cost of around US$10,000, Bonner told PharmaTimes. The current cost of bone marrow aspiration in the US ranges from US$25,000 to US$150,000; coupled with the risk of serious surgical trauma, this usually makes it a treatment of last resort.

At the moment, around 150,000 bone marrow treatments are performed in the US each year. With a low-cost, readily scalable source of stem cells from peripheral or umbilical cord blood, though, the number of procedures could “skyrocket”, Bonner believes.

Space experiments

The origins of the Intrifuge technology go back to space experiments performed by NASA scientists, who found that human cells could be grown rapidly in a simulated weightless environment created by a time-varying electromagnetic field. Regenetech has conducted preclinical trials using this system as a Class III orthopaedic medical device for rapid healing of damaged tissue or bone, and expects to be on the veterinary market with this application within the next year. A launch in the human orthopaedics market could follow two-two and a half years later, Bonner predicts.

This should provide an early revenue stream along with expected income from the supply of adult stem cells, multiplied through the Intrifuge cellXpansion technology, to support clinical trials and, eventually, therapeutic use in applications ranging from heart disease to type 1 diabetes and repairing damage to the liver or pancreas. Founded in April 2002 Regenetech has raised around US$7 million in funding to date and expects to be “truly cash flow-positive” in 2009.

In some cases, full therapeutic treatments using the Intrifuge system could be as little as two years away, Bonner believes. The regulatory system for adult stem-cell therapies in the US, administered by the Food and Drug Administration’s Center for Biologics Evaluation and Research, is both highly innovative in and considerably less burdensome that the approval pathway for drugs, he notes.

While clinical trials for adult stem cell therapies must show evidence of safety and efficacy, they do not share the uncertainties and huge statistical populations characteristic of drug development, Bonner explains. Some stem-cell trials in myocardial infarction and other cardiovascular indications have been completed in less than 18 months, with approval following shortly afterwards.

$10 billion plus market

The potential market for adult stem cell therapies could be “well in excess” of $10 billion, he predicts. While Bonner acknowledges the much-cited advantages of using embryonic over adult stem cells (pluripotency, more rapid tissue generation, etc), he also believes it could be a number of years before embryonic stem-cell therapies are commercially available, notwithstanding the current political and ethical resistance to their use in the US.

From a scientific perspective, the main problem with embryonic stem cells is their inherent carcinogenicity, Bonner says – in other words, growing a large number of cells very rapidly and in a less controlled environment than the foetus brings the risk of unregulated growth and tumour formation. By contrast, adult stem cells have already shown effectiveness as therapies, “and for us that’s the bottom line”, Bonner comments.