In the post-genomic era, the biotechnology industry is at least partly redrawing the contours of its growth pattern from the traditional development and production of recombinant proteins in microbial, animal and plant vectors, to newer areas of therapeutic modalities, including gene therapy and customised product development, based on pharmacogenomics and proteomics. For example, pharmacogenomics has the potential to target specific genes for drugs, thus assisting the development of tailor-made therapies.
The recent developments in the field of Single Nucleotide Polymorphisms (SNPs) and DNA chip technology have made it possible to detect errors in gene expression and genetic disorders in individuals, groups of individuals or families. A whole new field of regenerative medicine is opening up as a result of newer advances in areas such as stem cell research. While all these possibilities show a tremendous amount of promise in the coming years, several ambiguities and uncertainties still remain and it will be several years before they are removed and the true potential of these new areas is realised. For example, even today, we do not know the number of genes in the human genome, let alone their functions.
Just at the time of the publication of the first draft of the human genome, it was surmised that there are around 1,00,000 genes involved in the genome. Subsequently both the Human Genome Consortium and Celera Genomics, the major players in the Human Genome Project, brought these numbers down to 30,000. Very recently, in an annotation and overview of the human genome, published in Genome Biology, it has been suggested that humans possess between 65,000 to 70,000 genes, clearly pointing out that we are yet to understand the genome, notwithstanding its mapping.
History Of Stem Cell Transplants & Therapy
Considering that the first bone marrow transplant in animals exposed to lethal radiation doses, was carried out in the early fifties, progress in this area has been relatively slow. The first transplant of cells collected from peripheral blood by apheresis was performed only in the eighties, while the first transplant of umbilical cord blood was done in France on a 5-year-old boy with Fanconi''s anaemia in 1988. Since that time, the National Marrow Donor Programme (NMDP) in the US has enabled over 10,000 stem cell therapies on patients, of which a vast majority was bone marrow, with only 335 being peripheral blood stem cells and only 9, cord blood transplants.
The technique of ''expanding'' the stem cells with a device called Replicell ( Aastrom Biosciences) was reported in an adult who received a cord blood transplant in October 2000. Recent reports in the Press have elicited considerable interest in medical and lay circles of the potential of bone marrow stem cells to generate brain neurons and liver cells. A sensational story published in NY Times in January, 2001, reported the struggles of two families (parents of Molly & Henry), who set out to create a designer baby, which could be a donor to a Fanconi anaemia- affected sibling.
There are, however serious concerns on some of these developments, since it was reported that a number of tissue banks in the U.S., many of them not approved by the U.S. FDA, did half a billion dollar business in tissues, in 2000.
Stem Cell Research
Embryonic Stem Cells are the parent cells of all tissues of the human body. The first successful report on the collection and culturing of the human embryonic stem cells was reported by scientists at the University of Wisconsin, Madison on November 6, 1998, under a project sponsored by the California-based Biotech Company, Geron Corporation. While to-day stem cells and their potential applications are taken for granted, it is important to realise that Thomson''s discoveries were the culmination of a 17 year international race to capture and cultivate the first human embryonic stem cells.
The initial experiments showed that the stem cell colonies included a core of undifferentiated cells (surrounded by a margin of differentiated cells), which had the capability to differentiate into three types of cells, the endotherm, ectotherm and mesoderm, which in turn, can produce special cell types for the gut, bone marrow, cartilege, muscle. kidney, liver etc. The challenge is to direct such differentiation from a random process to one that is pre-planned to produce specific cell types.
While the most talked about and potentially the most rewarding application for embryonic stem cells may be for treating a wide range of human diseases, such as cancer, diabetes, heart diseases, Parkinson disease etc, which are generally caused by death, degeneration or dysfunction of the concerned tissues, such treatments are unlikely to be realised for several years for a variety of reasons. However, of more imminent application is their use for understanding the developmental biology of the embryo, which may have implications in birth defects, infertility etc. In addition, these cell lines have the potential for developing screening models for new drug discovery, for which the animal models available are not truly representative or relevant.
Issues On Stem Cell Research
There are several important issues which impinge on the future of stem cell research, which are not only of a scientific or technical nature, but are related to ethical and moral issues on the use of human embryonic or adult cells, intellectual property rights and the sharing of the accompanying reward systems between the inventors and the donors and financial supports and funding. National and International Guidelines and Policies for stem cell research, are all in early days of drafting and implementation. In addition, it has been recently shown that the belief that adult cells are incapable of differentiation and hence are not useful is indeed a myth. In studies in mice, adult cells from certain parts of the body could transform themselves to other cell types. The significance of these observations is that this technique of using adult cells could be more useful for repairing of tissues damaged by injury or disease.
Funding Of Stem Cell Research
The August 9 announcement of US president Bush that US Federal funding for stem cell research will be restricted to the 64 cell lines known around the World at that time and no more, has raised a number of issues as well as major concerns. Presumably, all these 64 ''approved'' cell lines were harvested from fertility clinics around the World. It is not certain as to how many of them are viable and functionally useful, since much work needs to be done before this question is answered.
In addition only 16 of the cell lines known at that point in time were derived by U.S. institutions, five of them from the original work at the University of Wisconsin. Two laboratories in India, the Reliance Life Sciences Laboratory in Mumbai and the National Centre for Biological Sciences at Bangalore, have seven and three stem cell lines, respectively, Bresa Gen, an Australian Company has five, Goteburg University in Sweden nineteen, the Karolinska Institute, five and Technion Institute in Haifa, Israel, four. All in all, institutes in five countries in the World control the 64 stem cell lines included in the NIH list.
Many experts feel that considering the very long gestation period required to convert research results into meaningful and profitable products, private funding may not be adequate or forthcoming to keep the momentum in stem cell research going and Government funding would be required. Very few large pharmaceutical companies are into stem cell research in a big way; they, however, are waiting on the wings to capitalise on the research results of small companies, largely set up with Venture Capital funding, through the licencing route.
The U.S. decree on stem cell research motivated by the concerns expressed by the anti-abortion lobby has two main implications. The first is that U.S. is likely to fund research in stem cells in all Centres which have access to them around the World, and second, new efforts at creating, culturing and characterising new cell lines will take place outside the United States.
Many questions regarding access to the available cell lines are yet to be answered. The stem cell Registry being created by the NIH, plans to have a Database of the cell lines, their owners, the sources, informed consent documents etc. The distribution of the cell lines for research or for commercialisation purposes will be solely at the discretion of the individual laboratories which created them.
Technical Problems
One of the major issues impinging on the future of stem cell research is related to the quality of the available cell lines or even of those, which are yet to be harvested. They may be subject to mutations, which may decrease their viability for extended manipulation or replication. According to Don Cramer of the University of Southern California Keck School of Medicine, "all cell lines have a limited life span, even cell lines which are considered to be able to proliferate indefinitely die out".
There are also concerns regarding the contamination of the cell lines and their effects on the hosts at the time of implantation. This is primarily because most of the cell lines have been cultured with animal cells or serum, which could be carriers of infective organisms including bacteria and viruses.
Yet another major technical hurdle is the propensity of the human body to reject transplanted stem cells. Fundamentally new methods to prevent such rejection need to be developed if stem cells are to be useful as therapies.
A Case In Point - Diabetes
The creation de novo of healthy beta cells in the place of the islet cells from pancreas for transplantation has been an area of priority for the treatment of chronic diabetes. It is obvious that one of the strategies would be to isolate the right stem cell and make them differentiate into the desired beta cells. For this purpose, both embryonic undifferentiated cells or partially differentiated adult cells can be used. Work on murine embryonic stem cells have established the feasibility of this approach, even though the levels of insulin produced were far too low, to be of practical use. Further, researchers at the Harvard Medical School & Joslin Diabetes Centre have shown that human ductal cells discarded during the preparation of islet cultures for transplantation were potential sources of pancreatic stem cells. Such adult cells could be used along with a transcription factor responsible for endocrine cell development to develop what is called Cultivated Human Islet Buds (CHIBS). In fact, the experiments showed that once the CHIBS were formed, the cells produced insulin in response to glucose - an indication that functional beta cells have been created. Whether the cells used are truly pancreatic stem cells (none have been isolated so far) or are ductile epithelial cells which have been re-programmed to produce beta cells is yet to be confirmed.
In short, these very promising results indicate that with appropriate transcription factors, beta cells responsible for glucose - responsive insulin production can be produced from pancreatic stem cells (?) or from ductile epithelial cells. The challenge is to produce adequate number of transplantable beta cells to reach meaningful production of Insulin.
Problems of Tissue Engineering
Since the ultimate use of Stem Cell Technology involves tissue engineering, biological and biotechnological research alone will not lead to useful products and therapies. Based on current knowledge, it is conceivable that advances in stem cell research can lead to several products, such as tissue-engineered heart valves, skin, blood vessels, liver, pancreas, cartilege, cornea and nerve and muscle tissues.
However, side by side with these developments, it is essential that there is a convergence of various other disciplines and technologies that deal with isolation, characterisation and storage of embryonic and adult cells, biomaterials, use of new biocompatable scaffolds for effective delivery of cell-based therapeutics and the development of new products for dealing with immunological reactions and rejections. Only through an integrated multi-disciplined approach with concurrent developments in all these fields, can success be assured.
Ethical And Moral Issues
Most countries including those in the forefront of stem cell research, are bogged down by serious considerations of an ethical and moral nature, particularly since the use of embryonic stem cells involves the destruction of the human embryo. While disputes and debates continue, the U.S., a potential leader in biological research on stem cells and their translation into viable products, has taken a "principled stand" in response to public pressure on federal support for such research. The other developed countries are yet to pronounce their policies on this issue. In countries such as India, where assisted reproduction techniques are legally permitted, wased embryos available from fertility clinics are allowed to be used by researchers, subject to obtaining informed consent from the donors. The proprietary rights of the donors on the results of R&D and on the products which emanate from them are still not clear.
Patenting Of Cell Lines
Right from the early days of work on embryonic stem cells by James Thomson at Wisconsin, patents for stem cells, as well as for the methods of their production and replication have been applied for and granted by the U.S. Patent Office. The patents issued to Aastrom Biosciences protect several of the fundamental technologies based on stem cells and ex-vivo gene therapy for the repair and replacement of damaged tissues.
These patents also cover replication and genetic modification of human stem cells, as well as processes for growing human hematopoietic stem cells, the source of all blood and immune cell types.
It has been felt by most research scientists as well as by various National Agencies, such as the NIH, that the proprietary position claimed by the Patentees and their assignees such as Geron Corporation or Aastrom Biosciences are likely to stifle and deter further research in this area. As a result of the pressure from federal funding agencies, very recently, the University of Wisconsin, the owner of several Patents in this area, has signed an Agreement with the U.S. Government to allow embryonic cells developed by the former to be used by other research teams. It is hoped that such exceptions would be allowed for using cell lines protected in other patents, including the Aastrom patents.
The Indian Scene
By choice, chance or by coincidence, India too is into stem cell research. The two Institutes, the Reliance Life Sciences Laboratories in Mumbai and the National Centre for Biological Sciences in Bangalore have been listed by the NIH, U.S.A. as Centres which have recognised stem cell lines. The Department of Biotechnology (DBT), has launched three major R&D programmes on stem cell research, aimed at Blindness, CNS disorders as well as genetic diseases such as beta Thalassemia. The Guidelines issued by the Indian Council of Medical Research, stipulate stem cell research to be restricted to discarded embryos and aborted foetuses. At the L.V. Prasad Eye Research Institute in Hyderabad, a project sponsored by DBT will use stem cells harvested from the normal eye tissue to treat blindness in the donor patients other eye.
The National Brain Research Institute in New Delhi plans to work extensively on neural stem cells and their use in several congenital and acquired CNS disorders, including Parkinson''s disease. The National Centre for Cell Sciences in Pune, which is developing a Repository of cell cultures and cell lines is working on cryo-preservation technologies for bone marrow, development of artificial skin for burns and vitiligo cases, bio-compatable liver devices for liver disorders etc. The Reliance Life Sciences group has ambitious plans to fully utilise their stem cells to transform them into viable products, perhaps through net-working R&D collaborations with international research groups.
Indian position on patenting of stem cells or even of products developed from them is not clear, as in the case of patenting of genes, under the new Patent amendments now under consideration for enactment. Although TRIPS stipulates that microorganisms should be patentable, it is to be seen as to how India interprets this during the finalisation of the amended Patent Act. The 1970 Indian Patents Act does not provide for patenting of any form of living matter, and by that token, genes and stem cells and their methods of production and delivery, would not qualify for patents.
In view of the fact that U.S. and many Western Countries allow patenting of stem cells, notwithstanding the Indian position, Laboratories in India have an opportunity to protect their Stem Cells based discoveries in those countries.
While all these efforts are at an early phase even from an R&D perspective, it will be prudent to consider even at this stage the multitude of problems that this emerging technology will face in the coming years, before therapeutically useful products for at least some of the underserved medical problems are developed.
About the author:-- The author is one of India''s top research scientists and is based in Chennai