BORIS, leukaemia and John Rasko

To say that Professor John Rasko wears a few different hats is to commit a crime against millinery. He has a personal chair in the Faculty of Medicine at the University of Sydney, directs Cell and Molecular Therapies at the Royal Prince Alfred Hospital, heads a team of two dozen research scientists in the Gene and Stem Cell Therapy program at the Centenary Institute, sits on a number of scientific advisory boards and still finds time to see patients in his role as a working haematologist.

He also has an infectious enthusiasm for all that he does, no matter how exhausting it may be. (Taking time out of a long interview with a coughing and wheezing journalist to suggest she see her GP about her bronchial problems while diplomatically avoiding a lecture on the evils of smoking is just part of his charm.)

Rasko and his team are perhaps best known for their work in using recombinant adeno-associated virus (AAV) gene therapy to treat haemophilia B. While not a cell therapy - their ongoing clinical trial involves directly injecting the virus containing the gene for Factor IX into the patient's hepatic artery - a lot of the team's work is focused on improving gene therapy and gene transfer. An interesting area that this focus has led Rasko's team into is gene-directed enzyme pro-drug therapy, or GDEPT, using mesenchymal stem cells.

It is early days for this research, but Rasko's team is exploring the concept of collecting autologous mesenchymal stem cells, expanding them in the lab and genetically modifying them so they are able to convert an otherwise non-toxic drug into a chemotherapeutic drug. One of the team's senior scientists, Dr Rosetta Martiniello-Wilks, is exploring how to use these modified MSCs in the context of treating prostate cancer.

For haematologists, who are obviously more interested in the blood-forming cells, mesenchymal stem cells never been high on the agenda, Rasko says. "They've always been the cells that the haematologists ignore when they're putting bone marrow into a culture dish," he says.

"They are those irritating adherent cells that people have tended to ignore. [Haematologists} are focused on the blood producing cells. But these mesenchymal so-called support cells seem to have quite extraordinary features. They seem to be able to suppress the immune system, or at least be somewhat ignored by the immune system."

A lot of work is now being done internationally using mesenchymal stem cells to treat graft-versus-host disease after bone marrow transplant, worked spearheaded by Katarina Le Blanc in Sweden (see box out).

And while he doesn't want to give too much away as the research is at a very early stage, Rasko's team is using its non-human primate model to show that mesenchymal stem cell numbers can be increased in the body. This observation arose during Dr Stephen Larsen's now-completed PhD on mobilising haemopoietic progenitors and stem cells into the peripheral blood.

"[MSCs] are not difficult to find when you do a bone marrow biopsy, but the really attractive thing that distinguishes them from haemopoietic stem cells is that the haemopoietic stem cells, even if you grow them for a few days outside the body, lose their ability to be stem cells," he says. "Mesenchymal stem cells may lose some features - and that's an area of active research - but in essence they appear to be readily grown outside the body without major changes in their applicability."

Clinical and translational research

Rasko's team's work in cell therapeutics should be boosted by another project he has long championed - the establishment of GMP cell therapy facilities at major teaching hospitals in Australia. This project is at an exciting stage, with the RPA Hospital the first in NSW to receive a licence from the Therapeutic Goods Administration to deliver cell therapeutics, including stem cells, to treat leukaemias.

One of the inspirations for this new capacity at the RPA - which should be completed later this year - has been the Centre for Blood Cell Therapies (CBCT) at the Peter MacCallum Cancer Centre in Melbourne, which was pioneered by Professor Miles Prince and Dr Dominic Wall, who are close collaborators with Rasko's team.

Rasko describes the cell therapy facility being built as akin to a spaceship, with four separate laboratories, fitted with high performance filters, which will allow scientists to perform sterile procedures as well as to genetically modify cells.

Rasko chaired the committee that made a successful bid through the National Collaborative Research Infrastructure Strategy (NCRIS) for $7.6 million - with matching state funds - to establish similar facilities in all states in Australia.

This is what Rasko calls "cell therapeutics at the clinical interface". He is also involved in translational research, particularly for the treatment of blood disorders such as chronic myeloid leukaemia and myeloid dysplasia.

He recently penned an editorial for the journal Pathology to celebrate the amazing success scientists and doctors around the world have had in treating CML, particularly through tyrosine kinase inhibitors like Glivec. Rasko says Australia should be enormously proud of its reputation in this area, particularly the work of Professor Tim Hughes and his team at the Institute for Medical and Veterinary Science at the Royal Adelaide Hospital.

CML is an area of great interest for a number of reasons, not least of which is that it is one of the best examples to study cancer stem cells. CML of course has a unique molecular signature - the Philadelphia chromosome discovered back in the 1960s by Peter Nowell and David Hungerford, which was the first time that a translocation was linked to a human disease.

Rasko's team is looking at CML in relation to the microRNAs involved in normal and malignant haemopoiesis. "We have a small group within our program who are actively exploring the role of these miRNAs both in relation to leukaemia and particularly CML, as well as normal cell development. That goes hand in hand of course - if you understand how the perturbation of leukaemia alters cell development and differentiation then it also helps you understand the normal development.

"We reported in the inaugural issue of the journal RNAi and Gene Silencing a means of quantifying miRNAs that has subsequently been used by a lot of people and has stood the test of time. Now of course there are commercial tests that you can buy but we've put considerable effort into it and are actively pursuing such technologies. We would have love to have published a lot of our work over the last two or three years but the field is so hot that we've been scooped on a number of occasions and there's no point in publishing the fact that you've been scooped. It's a very competitive field."

---PB--- New directions in leukaemia research

Rasko will address the New Directions in Leukaemia Research Conference, being held on the Sunshine Coast from March 30 to April 2, on another area of leukaemia research that his team is actively pursuing - the role of two zinc finger transcription factors called BORIS and CTCF and their implied role in cancer.

"Our studies have taken us a long way towards seeing how the pathway of these two important genes relates to cell development and control of cell proliferation and differentiation. We have a small group of half a dozen who are exploring the interactome of these zinc finger transcription factors to see what these molecular machines are actually composed of so we can basically understand their mechanism of action."

BORIS and CTCF are part of the basic research aspect of Rasko's work. "I embrace the idea that in order to achieve successful gene therapy you have to identify the genes involved in a given disease, and genes of course can't work outside the context of cells. So in order to understand how to improve gene therapy, you have to not only understand the root cause of any given disease but you also have to understand the target cells and how to alter them genetically in order to achieve that therapy."

A lot of the team's work is focused on improving gene therapy and gene transfer into haemopoietic cells, specifically using adenovirus, adeno-associated virus, retrovirus and lentivirus vectors.

"We've also collaborated in delivering oncogenes and the 'Yamanaka genes' into stem cell types," he says. "Our focus and our role in that has been in improving the gene delivery. Refining the viral vector technology to improve the efficiency of gene delivery rather than exploring those particular genes in of themselves.

"We have collaborations where we are helping modify embryonic stem cells to achieve the kind of results that Yamanaka has achieved and also to deliver the genes involved in CML so we can explore the biology of these diseases."

Embracing the future

So, basic, translational and clinical research are all feathers in John Rasko's cap. He's a working haematologist, however, so is obviously interested in clinical applications and how we can improve treatments for patients. He's particularly concerned at how difficult it is to run clinical trials in Australia, particularly long-term ones, and would like to urge the new Minister for Innovation, Industry, Science and Research to pay some attention to this field.

"I'd like to congratulate the minister on continuing on with the important NCRIS initiative," he says. "That is extraordinarily important for promoting cell therapeutics in Australia. I want to encourage him to continue on that theme, to specifically invest in both the clinical as well as the basic aspects of cell therapeutics. In other words, divert specific funds to those initiatives.

"One of the difficulties in some of these areas is that because they are exclusively clinical in their applicability they oftentimes don't get the immediate attention of the standard grant review process. Having sat on such committees for many years, the basic research tends to succeed and get the grants, whereas the clinical has much more difficulty. The translational is very much third place in line, but if you are trying to establish a rationale and preliminary data to underpin a clinical trial, it is almost impossible to get funds to do that in Australia.

"For example, we started our haemophilia gene therapy trial in 2001. It was put on hold for various reasons by the regulatory authorities, but the current trial that we have now requires us to monitor our subjects for 15 years. There is no means by which that can be funded in Australia. There is no funding body that is prepared to commit to funding to follow a recipient of gene therapy for that long, but that's exactly the kind of time-frame we need. These kinds of things are crucial, the kind of Clever Country innovations, that the minister might be looking towards.

"We have an opportunity in Australia, we have such respect internationally, but we have lost some of our key stem cell researchers, for example, and I won't hesitate to mention who they are - Paul Simmons, Martin Pera and Alan Trounson - and that haemorrhage will continue whenever we hesitate to embrace the future. We've had our Senate meetings, we've gone past the time when these things are the subject of serious controversy. Every opportunity is there for governments to really make a mark in the f