A team of researchers led by Dr. Douglas Melton of the Harvard Stem Cell Institute, in collaboration with researchers at the Howard Hughes Medical Institute, have successfully transformed mature cells in mice into a different type of cell.

The research, which was published today in the online journal Nature, involves the reprogramming of a cellular “identity switch”, which is a type of master control for determining which genes in the cell are activated and which remain inactive. The findings are the first of their kind to be conducted in vivo, with the transformation of ordinary pancreatic cells into the more specialized beta islet cells, which are the cells that produce insulin.

Such research represents a further step in the ongoing effort by many scientists to avoid embryonic stem cells and their ethical dilemmas, by working with pluripotent stem cells from non-embryonic sources. Earlier studies with iPS (induced pluripotent stem) cells, for example, used ordinary skin cells from adults that were reprogrammed into a more primitive state, from which they could then be directed to develop into various types of tissue, at least theoretically. One of the problems encountered with the iPS cells, however, is the difficulty of controlling their differentiation into the desired, specialized tissue. This latest discovery, however, changes a mature cell into another mature cell without having to revert back to a primitive cell as an intermediate stage.

Using mice in which the beta islet cells had been destroyed, Dr. Melton’s team injected the pancreas of the mice with a viral “vector” that delivered 3 genes into the ordinary pancreatic cells, which 3 days later were found to have been converted into the insulin-producing beta islet cells. After a week, over 20% of the cells had begun producing insulin. The newly formed cells were identified as beta islet cells both morphologically (in structure) as well as functionally. According to Dr. Richard Insel, executive vice president of research at the Juvenile Diabetes Research Foundation, this research represents “an amazingly efficient effect”, much more so than that seen from iPS cells thus far.

Dr. Melton has a personal interest in diabetes, and has been a leading researcher in the field since 1993, when his infant son was diagnosed with Type 1 diabetes. However, scientists are quick to observe that these findings have a wide range of implications which extend far beyond diabetes. Researchers at Stanford, for example, are currently studying applications of the same procedure with liver cells. Indeed, the findings mark an important achievement in understanding the molecular signals that are involved in the reprogramming of cells, which is relevant to the treatment of virtually every type of disease.

Following experiments with mice, Stanford University scientists have announced that stem cell therapies which use human embryonic stem cells (hESCs) have a high probability of failing because of immune rejection. In these studies, mice that were injected with hESCs exhibited an immune response which is at least as severe as that triggered by organ transplantation. Consequently, all the transplanted stem cells were killed by the immune system within a week. The Stanford researchers used molecular imaging technology to monitor the hESCs after injection, which revealed that the hESCs began dying within a week of injection and were completely dead by 10 days. When more hESCs were subsequently injected, they were found to die much more quickly, within 2 to 4 days, due to the already fully activated level of the immune system defense response. Even when the animals were given tacrolimus and sirolimus, two mediations that are commonly used to suppress an immune response, the hESCs lasted 28 days before dying but were still rejected and killed by the immune system. Additionally, in all cases, the overall health of the animals continued to deteriorate, and the researchers were not able to determine any benefit from an increase in time before all the hESCs were eventually destroyed.

The U.S. FDA (Food and Drug Administration) has not approved the use of hESCs as a medical therapy, primarily because of the danger of teratomas, which are a well established risk of hESCs. A teratoma is a specific type of tumor which contains cells from all 3 germ layers of the body, which have often differentiated into specialized tissue such as teeth, hair and organs, and which therefore make these tumors particularly hideous and dangerous. The ability of embryonic stem cells to form teratomas is, in fact, the defining trait of embryonic stem cells, and the ability of a cell to form a teratoma remains the universal laboratory test by which embryonic stem cells are identified: namely, if an unknown cell is found to form a teratoma in the laboratory, then it’s an embryonic stem cell, whereas if it doesn’t form a teratoma, then it’s not an embryonic stem cell. Teratoma formation, however, is certainly not the only risk posed by embryonic stem cells, and once again we are now reminded of the dangers of immune rejection that are inherent in embryonic stem cells. Adult stem cells, by sharp contrast, do not pose any risk of teratoma formation, and some types of adult stem cells, such as mesenchymal stem cells (MSCs), are known to be “immune privileged”, meaning that they do not trigger an immune response.

According to Dr. Joseph Wu, a Stanford radiologist who led the recent research, these findings, which reveal such a strong immune rejection of embryonic stem cells, constitute “a reality check”.

The biotech company Advanced Cell Technology, Inc., which develops a variety of stem cell therapies, has entered into another licensing agreement with BioTime Inc., which is also a major player in the stem cell field. Although the agreement was struck on August 15th, the companies made the announcement today. This agreement is not the first of its type between the two organizations, which have worked together before in patent licensing agreements. As before, this agreement involves a susidiary of BioTime Inc., known as Embryome Sciences.

BioTime is headed by CEO Michael West, who was formerly with Advanced Cell Technology. Under the terms of the new agreement, Embryome Sciences will receive worldwide rights to the patent that is owned by Advanced Cell Technology, in exchange for a $200,000 licensing fee which Embryome Sciences must pay, as well as a 5% royalty on sales and 20% of fees for sublicensing to a third party, with a royalty cap of $600,000. In a previous, recent licensing agreement that was announced on August 11th, Embryome Sciences licensed the technology for producing embryonic progenitor cells from Advanced Cell Technology, for which Embryome Sciences paid a $250,000 licensing fee plus an 8% royalty on sales, with a royalty cap of $1 million.

Unlike the previous licensing agreement, however, the current agreement involves patented technology for the transformation of skin and other adult human cells into pluripotent cells which are able, through the manipulation of cellular controls, to differentiate into various types of tissue that are found throughout the human body.

As an advanced form of peripheral artery disease, critical limb ischemia (CLI) results in approximately 100,000 amputations every year in the United States alone. It is often seen in diabetics and is a major cause both of morbidity and of mortality, with approximately 20 to 45% of all patients requiring amputation, after which death within the first year is estimated to be as high as 45%. The quality of life in such patients is extremely low, compared by some doctors to that of terminal cancer patients.

In the past, treatment options for patients with CLI have been extremely limited, and without notable success. Now, however, the company Medistem, Inc., has developed a treatment for CLI which uses the powerful endometrial regenerative cells (ERCs) which Medistem brought to international attention last year.

Previous, independent clinical trials have shown some improvement in CLI patients who received autologous (in which the donor and recipient are the same person) stem cells that were either derived from the patient’s own bone marrow or mobilized from peripheral blood. Similarly, ERCs, which are adult stem cells that are derived from menstrual blood and which resemble mesenchymal stem cells (MSCs), are believed to be associated with endometrial angiogenesis and have been shown to have powerful angiogenic properties. Additionally, ERCs contain an exceptionally high level of growth factors and are notable for a wide variety of other impressive properties which include their ability to inhibit the inflammatory response, their ease of expandability in large quantities without incurring a loss of differentiability nor any karyotypic abnormalities, and the fact that ERCs are highly immune privileged and therefore do not trigger immune rejection.

In the recently published study, which was led by the vascular surgeon Dr. Michael Murphy, a group of mice was divided into 8 who were treated for CLI with ERCs, and 8 mice who served as the “controls” and whose CLI was untreated. Following ligation of the femoral artery and its branches in each of the mice, which thereby induced CLI, the 8 mice who were chosen to be treated were each administered approximately 1 million ERCs intramuscularly. By day 14, necrosis was observed in the legs of the 8 “control” mice, who did not receive the ERCs, while the 8 mice who were treated with the ERCs still had intact limbs. Especially striking was the absence of any immune rejection of the ERCs, despite the fact that these were human stem cells, which were administered to mice which had fully competent immune systems.

It has already been known for some time that MSCs exhibit immune modulatory properties, both in vitro and in vivo. For example, the company Osiris Therapeutics is currently involved in Phase III clinical trials with allogeneic MSCs that are derived from bone marrow and which are currently being tested as treatment for two diseases, namely, graft-versus-host disease, and Crohn’s disease. Now, in the study conducted by Dr. Murphy, Medistem has demonstrated the ability of ERCs to prevent limb loss in an animal model of critical limb ischemia, even with animals that were fully immune competent. ERCs are therefore believed to offer what is known as cytokine mediated angiogenesis, which thus far has been especially effective as a therapy for CLI in this particular animal model.

Medistem, which has pioneered the development of ERCs as a “universal donor” product, has received global recognition for its work in this field, including the “Publication of the Year” award for 2007, recognizing its discovery of ERCs, which was awarded to Medistem at London’s Royal Society of Medicine in early 2008. Medistem is now seeking to use ERCs as a therapy for patients who are at risk of amputation due to CLI.

Researchers at the Harvard Stem Cell Institute (HSCI) have reported the creation of twenty stable cell lines from patients with genetic diseases that include Type I diabetes, Parkinson’s disease, Hungtinton’s disease, Down Syndrome, and two types of muscular dystrophy. Although the cell lines resemble stem cells in their pluripotency, none of the cell lines were created from stem cells.

Instead of stem cells, the scientists used iPS (induced pluripotent stem) cells, which are mature cells, usually taken from the skin or blood of adults, that have been reprogrammed to revert to a more primitive state that resembles a stem cell. From these iPS cells, new cell lines were specifically created for various genetic disorders. According to Dr. George Daley, a professor in Harvard’s Medical School, senior author of the paper in which the announcement was made, and a member of the executive committee of the HSCI, “This has really been one of the goals of stem cell biology for many years, to be able to produce customized disease-specific lines for different patients.”

Other scientists around the world who are studying these various diseases will soon be able to order shipments from the HSCI of these disease-specific cell lines. Indeed, “patient-specific” iPS cells, which are reprogrammed cells derived from specific patients, allow for an individually tailored study, in the laboratory, of the unique characteristics of a particular person’s disease, thereby opening up the opportunity for therapies that are customized to each individual person. Dr. Konrad Hochedlinger, also a professor at Harvard Medical School, whose lab contributed to the Lesch-Nyhan syndrome cell line in the project, has referred to the “iPS trick” as something that is changing the face of stem cell research, by genetically reprogramming human, non-stem cell, cells to behave as though they were stem cells.

In July of this year, a new iPS Core Facility was created at the Harvard-affiliated Massachusetts General Hospital, where the disease-specific iPS cell lines will be deposited not only for storage but also for production on a larger scale, in order to accommodate distribution to the scientific community. According to Laurence Daheron, manager of the iPS Core Facility, the iPS cell lines will be available free of charge for HSCI members and collaborators, although non-HSCI members and biopharmaceutical companies will be required to pay a fee in order to cover the cost of expansion of the iPS cell lines.

The creation of the iPS cell lines, and the establishment of the Core Facility at Massachusetts General Hospital, has vast implications not only for stem cell therapies involving the particular diseases under consideration, but also for the stem cell field and for cell biology in general.

Restenosis is a pathologically extreme inflammatory condition which results in the narrowing of blood vessels, and as such is commonly associated with endothelial damage. Worldwide, restenosis remains a frequent problem following vascular injury. Now, researchers in Italy have used mesenchymal stem cells (MSCs) that were derived from bone marrow to treat restenosis in rats.

The study was conducted by a team of scientists led by Dr. Amalia Forte in the Department of Experimental Medicine at the Excellence Research Center for Cardiovascular Diseases at the Second University of Naples in Italy. After performing carotid arteriotomies in rats, the researchers intravenously administered approximately 5 million allogeneic MSCs derived from bone marrow to each rat, after which the cells were then found to “home in” on the injured carotids but not on the uninjured carotids, thereby preventing narrowing of the injured arteries during the duration of the treatment, which lasted 30 days. Specifically, the lumen area in the MSC-treated carotids was measured to be a statistically significant 36% greater than in the uninjured, control arteries. Not only did the allogeneic MSCs limit stenosis in the injured carotid arteries, but the MSCs were also found to exhibit local immunomodulatory action which resulted in a decrease of inflammatory cytokines.

Such a combination of desirable properties – namely, a natural homing ability to the injured tissue, prevention of further narrowing in the injured artery, local immunomodulatory action and a lessening of inflammation – makes MSCs a promising therapy for the treatment of such diseases in humans.

Mesenchymal stem cells (MSCs) have already been known to differentiate into neural tissue, but usually the MSCs are extracted from bone marrow, peripheral blood, umbilical cord blood, or even, most recently, menstrual blood. MSCs have also been discovered in unexpected places, such as the eye. Now, however, stem cells with properties that are similar to MSCs have been extracted from dental pulp.

Researchers in Kaohsiung, Taiwan, in collaboration with scientists in the U.S., have used stromal cells derived from the dental pulp of Rhesus macaque monkeys to promote the formation of neural cells in mice. The DPSCs (dental pulp stem/stromal cells), which were extracted from the teeth of the monkeys, were found to be similar in their properties and behavior to MSCs that are derived from human bone marrow. Led by Dr. Anderson Hsien-Cheng Huang, of the Department of Oral Pathology at the Grace Dental Clinic at the School of Dentistry at Kaohsiung Medical University Hospital in Kaohsiung, Taiwan, a team of scientists implanted undifferentiated, untreated DPSCs into the hippocampus of mice, where the cells were found to stimulate the differentiation of pre-existing endogenous neural progenitor cells, as well as the recruitment of mature neurons to the site of the graft. According to the authors of the study, “Although the DPSC graft itself was short-term, it had long-term effects by promoting growth factor signaling.” Such growth factor signaling, which is a result of the high concentration of neurotrophic growth factors that the DPSCs released, plays a major role in the modulation of the neurophysiological microenvironment, which in turn is what directs the transformation of endogenous stem and progenitor cells into neural tissue.

The ability of stem cells that are derived from dental pulp to promote the proliferation and differentiation of neurological tissue should come as no surprise, since dental pulp is composed of odontoblast cells which originate in the neural crest during embryological development. A natural “affinity”, or tendency toward a specific type of differentiation, therefore exists between DPSCs and neural tissue.

Dr. Huang and his colleagues hope that the therapeutic properties of something as common as dental pulp, which is usually discarded in childhood, might allow for greater ease in the development of personalized stem cell therapies which could be custom tailored to the individual patient, using his or her own dental pulp.

At the Royal Melbourne Hospital in Victoria, Australia, 9 patients with severe leg fractures have been successfully treated with their own adult stem cells. The 5 men and 4 women had suffered the most serious types of fractures as a result of car accidents, which left many of the patients unable to walk, even after attempts at surgery, which in all cases were unsuccessful. Even over 3 years after the surgeries, the broken bones still had not healed, and it is not uncommon in such cases for these types of severe breaks in the leg bones to result in amputation. However, within 4 months of being treated with their own adult stem cells, the patients recovered, as their thigh and shin bones were found to have regrown and healed.

One such example is a 35-year-old male who had broken both his tibia and fibula in a motorcycle accident in 2005. Although he underwent surgery in which a rod was placed in his tibia, over a year later he was still unable to walk without crutches. Indeed, approximately 15% of all such fractures never fully heal. But the man was recruited into the stem cell trial, in which his own adult stem cells were harvested from his bone marrow with a minimally invasive needle that was inserted into his pelvis. The stem cells were then cultured in a laboratory and injected directly into the sites of his leg fractures, where new bone began to form. The man was able to walk the following day. He is now fully recovered, free of pain, and enjoys running and playing football again.

Such a procedure is now believed to offer a powerful therapy not only in the event of traumatic injury, but also in cases of more gradual injury, such as with age-related arthritic hips. In many cases, this type of adult stem cell therapy may eliminate the need for elective surgery altogether, since those patients who in the past were likely to find their names on long hospital waiting lists can instead be treated as outpatients with their own adult stem cells.

According to Dr. Richard de Steiger, the orthopedic surgeon who led the trial, “Most of the time you have to have a secondary operation on the hip bone and take some bone graft out, and that’s often more painful than the surgery for the actual fracture. All these patients have avoided the need for having a second operation to get bone from somewhere else in the body. Instead the bone’s just grown outside the body, in a lab. The potential for doing this kind of work is very exciting. If we could try to regrow cartilage it would mean we’d be able to help people with early arthritis of the knees and hips as a result of sporting trauma.”

Similar trials, with similar success, have already been conducted in the UK, but this was a first of its kind in Australia. The particular stem cell technology that was used in the therapy is licensed by the company Mesoblast, and is expected to be commonly available in hospitals within the next 3 to 5 years.

The South Australian company Vet Biotechnology, Ltd., has successfully treated the race horse known as Viz Vitae for a severe tendon injury. In the past, such an injury would have resulted in the immediate retirement of a race horse, but instead, Viz Vitae is now back on the race course, and winning races once again, after being treated with a stem cell therapy that used his own adult stem cells.

According to Vet Biotechnology managing director, David Brigland, “In the case of Viz Vitae, he would have been retired. When you have these injuries, the tendons fill with scar tissue, which is inflexible and the tendon no longer has its mechanical power-generating capacity. What we’re trying to do is return a fully functioning tendon by regrowing the tendon cells, and return it to its normal function.”

The procedure was developed by the Royal Veterinary College of London, and has been tested since July of 2005 by Vet Biotechnology in 50 race horses, 36 of which have returned to racing, and 18 of which have won races. The cost of the procedure is $5,500, which proved to be a good investment in the case of Viz Vitae, who, after receiving the stem cell therapy, went on to win $110,000 for his owners.

According to veterinarian Dr. Campbell Baker, “Early results to date in terms of returning injured horses to the racetrack have been nothing short of stunning. This horse suggests to us at Lindsay Park that no matter how severe the tendon injury, stem cells promise a complete regeneration of the damaged tissue.”

Although Vet Biotechnology currently specializes in tendon and ligament regeneration, it is gradually moving into the market for bone treatment. As Dr. Baker explains, “At this stage what we can say is the cells we were able to expand into massive doses have been proven to create bone and cartilage.”

Vet Biotechnology, Ltd., is traded in Australia on the Newcastle Stock Exchange.