DC Court Says that Stem Cells are Drugs

On the 23rd of July, 2012, the US District Court in Washington DC acknowledged the right of the Food and Drug Administration (FDA) to regulate clinical therapies that are made from the patient’s own processed stem cells. This case answered the question, “Does the court agree with the FDA that stem cells are drugs?”

According to the judge, the FDA is right and stem cells cultured outside the body are drugs. This ruling upholds the injunction brought by the FDA against Regenerative Sciences, the Broomfield, Colorado-based clinic that offers the Regenexx stem cell treatment procedure.

The Regenexx procedure uses mesenchymal stem cells that are isolated from patients’ bone marrow. These stem cells are then processed and injected back into the patients to treat joint pain. The FDA has labeled this procedure the “manufacturing, holding for sale, and distribution of an unapproved biological drug product.” In August 2010, the FDA ordered Regenerative Sciences to stop offering the treatment, since they were offering a drug without FDA approval

According Nature magazine science reporter, David Cyanoski, investigations by the FDA that led to the injunction showed that there were flaws in the cell processing protocol that violated the FDA’s regulations that refer to “adulteration.” These regulations are meant to ensure the safety of patients who receive the therapy.

Not surprisingly, academics are praising the decision and a shot across the bow of any enterprising physician who wants to offer stem cell treatments. For example, Jeanne Loring, a regenerative-medicine scientist at the Scripps Research Institute in La Jolla, California, has said that this court decision will send a warning to others who want to offer unapproved stem-cell treatments. In her words: “So many people want to start these companies. They say, ‘FDA? What FDA?’.”

Chris Centeno, the medical director of Regenerative Sciences and one of two majority shareholders, told Nature that he plans to appeal against the ruling. Centeno has replied to the ruling in an internet book entitled “The Stem Cells They Do Not Want You To Have.” Centeno’s main objection during the trial was that the ‘Regenexx’ procedure does not significantly modify the mesenchymal stem cells before they are reinjected into the patient. Therefore, the procedure should be considered a routine medical procedure. The company also argued that because all the processing work is done in Colorado, the procedure should be subject to state law, rather than to regulation by the FDA.

Unfortunately for Centeno, the Ninth Circuit court disagreed with both arguments. According to the court: “the biological characteristics of the cells change during the process.” This and other considerations mean that the cells are more than “minimally manipulated,” which makes them a drug a subject to regulation by the FDA. .

University of Minnesota bioethicist Leigh Turner, agrees with the court on this one. Turner noted: “It is much too simplistic to think that stem cells are removed from the body and then returned to the body without a ‘manufacturing process’ that includes risk of transmission of communicable diseases,” he says. “Maintaining the FDA’s role as watchdog and regulatory authority is imperative.”

The FDA injunction only applies to one of the Regenexx stem-cell products; the Regenexx-C procedure. In this procedure, the bone marrow mesenchymal stem cells are processed for 4–6 weeks. The Regenexx-C procedure will still be available, since after the 2010 injunction, the company moved its treatment location to an affiliated Cayman Island clinic.

Centeno plans to continue providing the other three procedures; Regenexx-SD, Regenexx-AD, and Regenexx-SCP, for joint pain, in the United States. In those treatments, the cells are reinjected within one-two days. Centeno claims that those cells are “minimally manipulated”, and that the FDA sees them as the “practice of medicine” and “has no issues” with them.

According the Nature’s David Cyanoski, until July 25th of this year, a graphic on the Regenerative Sciences website claimed that these three other procedures were “FDA approved.” However, the FDA has not approved these three procedures, and Centeno was not able to provide documentation to support his claims that the agency views the three treatments as outside its purview. This graphic was removed from the Regenexx website after Nature’s enquiries.

Stem-cell ethics and regulation expert, Doug Sipp, who is at the RIKEN Centre for Developmental Biology in Kobe, Japan, is concerned that this ruling will simply drive entrepreneurs to move their stem cell clinics outside the United States to avoid regulation. Indeed, Regenerative Sciences has done just that by setting up their Regenexx-C procedure in the Cayman Islands. According to Sipp, “Other US stem-cell outfits have close ties with partner clinics in Mexico and other neighboring countries, which are traditionally regulatory havens for other forms of fringe medicine as well. I suppose it will be business as usual in such places,”
We will have more to say about this in the days to come, but for now, this is it.

Scientists Identify the Stem Cells From Which Sweat Glands Grow

Sweat glands control our body temperatures, but little is known about how they develop and the cells that give rise to them. However, researchers from Rockefeller University have now identified in mice the stem cell population from which sweat glands originally develop and the stem cells that regenerate adult sweat glands.

In this study, scientists from the laboratory of Elaine Fuchs invented a strategy to purify and molecularly characterize the different kinds of stem cell populations that make up the complex sweat duct and glands found in mammalian skin. Afterwards, they examined how these different stem cell populations respond to normal tissue homeostasis and to different types of skin injuries. They also found how sweat glands differ from their close cousins, the mammary glands.

Elaine Fuchs, who is an investigator at the Howard Hughes Medical Institute, said: “Mammary gland stem cells respond to hormonal induction by greatly expanding glandular tissue to increase milk production. In contrast, during a marathon race, sweat gland stem cells remain largely dormant,and glandular output rather than tissue expansion accounts for the 3 liters of sweat our body needs. These fascinating differences in stem cell activity and tissue production are likely at the root why breast cancers are so frequent, while sweat gland cancers are rare.”

These findings from Fuchs’ lab might someday help improve treatment strategies for burn patients and to develop topical treatments for people who sweat too much, or too little.

“For now, the study represents a baby step towards these clinical goals, but a giant leap forward in our understanding of sweat glands,” said the study’s lead author, Catherine P. Lu, a postdoctoral researcher in Fuchs’s laboratory.

Each one of us has millions of sweat glands but they have rarely been extensively studied, and much of this has to do with the difficulty of gathering enough of the tiny organs to research in a lab. Mice are traditionally used as a model for human sweat gland studies. Therefore, for this study, Lu and colleagues laboriously extracted sweat glands from the tiny paw pads of mice, the only place they are found in these and most other mammals. The goal was to determine if the different cells that make up the sweat gland and duct contained stem (progenitor) cells that can repair damaged adult glands.

According to Lu, “We didn’t know if sweat stem cells exist at all, and if they do, where they are and how they behave.” The last major studies on the proliferative potential within sweat glands and sweat ducts were conducted in the early 1950s before modern biomedical techniques were used to understand fundamental biomedical science.

Fuchs’ team determined that just before birth, the nascent sweat duct forms as a down-growth from progenitor cells in the epidermis, the same master cells that at different body sites give rise to mammary glands, hair follicles and many other epithelial appendages. As each duct grows deeper into the skin, a sweat gland emerges from its base.

Lu then led the effort to look for stem cells in the adult sweat gland. Sweat glands are composed of two layers: an inner layer of luminal cells that produce the sweat and an outer layer of myoepithelial cells that squeeze the duct to discharge the sweat.

Lu devised a strategy to fluorescently tag and sort the different populations of ductal and glandular cells. The Fuchs team then injected each population of purified cells into different body areas of female host recipient mice to see what the cells would do.

When introduced into the mammary fat pads, the sweat gland myoepithelial cells generated fluorescent sweat gland-like structures. “Each fluorescent gland had the proper polarized distribution of myoepithelial and luminal cells, and they also produced sodium-potassium channel proteins that are normally expressed in adult sweat glands but not mammary glands,” Lu said.

When the host mice became pregnant, some of the fluorescent sweat glands began to express milk, even though they still retained some sweat gland features as well. Sweat gland myoepithelial cells produced epidermis when engrafted to the back skin of the mice.

“Taken together, these findings tell us that adult glandular stem cells have certain intrinsic features that enable them to remember who they are in some environments, but adopt new identities in other environments,” Fuchs said. “To test the possible clinical implications of our findings, we would need to determine how long these foreign tissues made by the stem cells will last, unless it is long-term, a short-term “fix” might only be useful as a temporary bandage for regenerative medicine purposes,” Fuchs said.

The findings can now be used to explore the roots of some genetic disorders that affect sweat glands, as well as ways to potential ways to treat them.

“We have just laid down some critical fundamentals of sweat gland and sweat duct biology,” Lu said. “Our study not only illustrates how sweat glands develop and how their cells respond to injury, but also identifies the stem cells within the sweat glands and sweat ducts and begins to explore their potential for making tissues for the first time.”

Umbilical Mesenchymal Stem Cells Improve the Symptoms of Patients With Decompensated Liver Cirrhosis

One of the most central organs for the body’s metabolism is the liver. When the gastrointestinal tract absorbs food molecules, the first stop for most of these molecules is the liver. The liver makes many blood-specific proteins, detoxifies foreign molecules to make them more water-soluble so that the body can excrete them, and stores energy reserves in the form of glycogen. Consequently, damage to the liver from chronic liver infections (e.g., hepatitis B & C, bilharzia or schistosomiasis, illegal drug use, etc.), alcoholism, or exposure to liver-damaging chemicals (carbon tetrachloride, chloroform, etc.) seriously compromises the capacity of the body to store energy, process food molecules, make blood specific proteins (which include clotting factors), and process and synthesize metabolic wastes. Repeated damage to the liver causes extensive scarring and deposition of fatty tissues, and such a condition is called “cirrhosis.”

Cirrhosis ultimately leads to liver failure, and tough scar tissue with nodules replaces once healthy liver tissue. There are two main types of cirrhosis. Compensated cirrhosis of the liver refers to early liver damage in which the body functions well despite the damaged liver tissue. Even though liver function is decreases, the body still operates within normal parameters, and the patient often shows no symptoms of disease. Even though people with compensated liver cirrhosis are often asymptomatic, they may display symptoms of weakness, fatigue, loss of appetite, vomiting, weight loss and easy bruising. Liver function tests may reveal increased levels of certain liver enzymes. Liver damage is not reversible, but treating the underlying cause can prevent further damage. Additionally, constant monitoring is required for the early detection of loss of liver function that leads to life-threatening complications.

Decompensated liver cirrhosis is a life-threatening complication of chronic liver disease, and it is also one of the major indications for liver transplantation. The symptoms of decompensated cirrhosis are internal bleeding from the esophagus (bleeding varices), fluid in the belly (ascites), confusion (encephalopathy), yellowing of the eyes and skin (jaundice). When someone becomes this sick, there is little to be done, but receive a liver transplant.

Can stem cells help patients with decompensated liver cirrhosis? Perhaps they can. A paper from the Journal of Gastroenterology and Hepatology (2012; 27 Suppl 2:112-20) has examined the ability of human umbilical cord mesenchymal stem cells to improve symptoms in patients with decompensated liver cirrhosis (DLC). The paper’s first author is Z. Zhang and the title of the paper is “Human Umbilical Cord Mesenchymal Stem Cells Improve Liver Function and Ascites in Decompensated Liver Cirrhosis Patients.” These authors are from the Research Center for Biological Therapy at the Beijing 302 Hospital, in Beijing, China.

In this study, the safety and efficacy of umbilical cord-derived MSCs (UC-MSC) were infused into in patients with DCL. They used a total of 45 chronic hepatitis B patients, all of whom were diagnosed with DCL. 30 patients received transfusions of UC-MSCs, and another 15 patients were given saline as the control. After transfusions, all 45 patients were followed for a 1-year follow-up period.

In none of the 45 patients who were infused, were any significant side-effects observed. Also, there were no significant complications were observed in either group. As to the symptoms suffered by the patients, those who had received the UC-MSC transfusion showed a significant reduction in the volume of ascites in comparison to those patients who had received the control saline transfusions. When liver function parameters were examined, UC-MSC therapy also significantly increased of serum albumin levels (albumin is made by the liver), decreased in total serum bilirubin levels (bilirubin is a waste that is processed by the liver), and stabilized the sodium levels for patients (patients with cirrhosis have low blood sodium levels).

Further follow-up of these patients is clearly warranted, but for the year follow-up. It seems clear that UC-MSC transfusions are clinically safe. Furthermore, when compared to controls, they also seem to improve liver function and reduce the volume of belly fluid in patients with DCL. UC-MSC transfusions might represent a novel therapeutic approach for patients with DCL.

What is the Best Way to Deliver Stem Cells to the Heart?

Three main techniques have been used to deliver stem cells to the heart. The simplest technique to introduce stem cells intravenously and hope that they will home to the heart and stay there. A more technically demanding way to introduce stem cells to the heart is to inject them into the wall of the heart. This method is called transendocardial cell injection, and it requires electromechanical mapping guidance (NOGA) in order to direct the surgeon to the site where the stem cells should be injected. Finally, stem cells are introduced to hearts by means of intracoronary delivery. Intracoronary delivery takes advantage of angioplasty technology to deliver stem cells through the coronary arteries where they move across the blood vessels and enter the heart.

Stem cell delivery by means of intravenous introduction has been shown in several studies to be extremely inefficient. The vast majority of the stem cells end up in the lungs, liver and the spleen and only a tiny, insignificant fraction goes to the heart.

The transendocardial injection method is the most difficult of the three methods, but it is also the most direct, since it deposits the stem cells directly into the cardiac muscle . This method requires special equipment and also increases the risk of rupture of the heart wall.

The intracoronary method was adapted from the same procedure that cardiologists use to implant stents. This procedure, known as percutaneous infusion (PCI), uses an over-the-wire technique to inflate the coronary artery nearest the damage, and then deposits the stem cells into the artery (see this video here). Because PCI has been used so much recently and because the technique has been greatly refined, stem cell delivery with this technology is second nature to many cardiologists. However, it does have some risk of causing narrowing of the artery (stenosis).

Which technique is better, transendocardial injection or intracoronary delivery? While some papers have compared the two procedures, there has been no randomized comparison with blinded endpoint analysis of the two techniques; until now.

In a paper published in the Journal of Cellular and Molecular Medicine by a Dutch lab at the University of Utrecht in the Netherlands, these two techniques were used to deliver stem cells to the hearts of pigs that had suffered heart attacks. The number of stem cells delivered in both cases were exactly the same, and the outcomes were compared and statistically compared. The stem cells were also labeled with a low-energy radioactive isotope so that they could be easily visualized in imaging experiments.

The results showed that both sets of pigs, which were given the stem cell treatments four weeks after the heart attack, improved about the same. Also the retention of stem cells in the heart was the same for both groups. The only difference was that the cells delivered by transendocardial injection tended to be clustered near the border of the infarct, but in the case of intracoronary delivery, the cells were spread throughout the heart muscle.

Also the safety profiles of both techniques were about the same, with the exception that the intracoronary delivery technique was easier and did not show the variation of the transendocardial technique, which is a much more difficult technique.

The authors conclude that both of these delivery techniques are feasible and safe. Furthermore, the conditions and cost of the techniques should determine which is used, since the safety and efficacy of the two is essentially the same.

Slow Adhering Skeletal Muscle Cells Improve Function of Sick Hearts

Skeletal muscles consist of cells that have fused together to form a so-called “myotube.” Myotubes, upon closer examination, are filled with contractile proteins that help them contract. These rows of contractile proteins are organized into stripes, and for this reason, skeletal muscle is often called “striated muscle” because of its stripped appearance under the microscope. Skeletal muscles are collections of these myotubes all bound together, and attached to bones by means of tendons.

Skeletal muscles also contain a stem cell population called muscle satellite cells. Muscle satellite cells divide and form new muscle in response to increase demand on the muscles. Muscle satellite cells are responsible for the increase in muscle size when you lift heavy weights.

Because muscle satellite cells are easily isolated from patients, and they resist the hostile conditions of a heart that has had a heart attack, they were one of the first stem cells used to treat heart attack patients. Preclinical work on laboratory animals produced hopeful results. The implanted satellite cells did not become heart muscle cells (Reinecke H, Poppa V, Murry CE (2002) J Mol Cell Cardiol. 34(2):241-9). However, the hearts that had received satellite transplants after a heart attack showed functional improvements and no deterioration in comparison to the control animals (rats – CE Murray, et al., J. Clin. Invest. 98(11): 2512–2523; rabbits – Blatt A,, et al., Eur J Heart Fail. 2003 Dec;5(6):751-7). These positive results were the impetus for the first human clinical trials that used a patient’s own satellite muscle stem cells as a treatment for acute heart attacks.

Early trials were quite small but the implanted patients seemed to improve. Unfortunately, these early studies were not controlled terribly well, and the results somewhat hopeful, but not completely conclusive (Siminiak T., et al., Am Heart J. 2004;148(3):531-7). More controlled clinical trials, the MAGIC and MYSTAR trials, however, revealed a problem with satellite cells. They had a tendency to not connect with the resident heart muscle cells, and were, therefore, functionally isolated from the rest of the heart (Léobon B, et al., Proc Natl Acad Sci USA. 2003;100:7808–7811). Such isolation had a tendency to cause implanted hearts to beat irregularly, and for this reason, muscle satellite clinical trials have been tabled for the time being (Menasché P, et al., Circulation. 2008;117(9):1189-200).

However, skeletal muscles possess several distinct cell types and some of these are probably better candidates for heart treatments (Winitsky SO, et al., PLoS Biol. 2005;3:e87). To that end, Johnny Huard’s laboratory at the University of Pittsburgh has characterized a population of cells that show superior therapeutic possibilities from skeletal muscle.

Masaho Okada was the lead author of this paper, and he and his colleagues observed that most of the cells in skeletal muscle adhere very readily to the culture flasks after the muscle tissue was pulled apart. They designated these fast adhering cells as RACs or rapidly-adhering cells. A minority population of cells were slow-adhering cells or SACs.

Comparisons of SACs and RACs showed that the SACs were more resistant to cellular stresses than their RAC counterparts. SACs also more readily formed myotubes that RACs. The gene expression profiles of the two cell populations were also sufficiently different to confirm that even though these two cell populations were clearly derived from skeletal muscle, they were distinct populations.

Finally, transplantation of SACs into the heart of laboratory animals that had suffered heart attacks showed definitively, that SACs improved cardiac function better than RACs. Also, SACs decreased the quantity of scar tissue in the heart and increased the number of blood vessels that had formed since the heart attack. There was also less cell death in the SAC-implanted hearts as opposed to the RAC-implanted hearts.

From these data, it seems clear that the SAC population more effectively improves heart function than the RAC population. If such a population exists in the skeletal muscles of adult humans, then such cells might prove more effective for cardiac treatments than muscle satellite cells. The only caveat is that such cells may not exist in humans, since searches for such cells have not turned up anything useful to date (see Susanne Proksch, et al., Mol Ther. 2009; 17(4): 733–741).

Stem Cells From Burnt Tissue May Augment Burn Treatment

Researchers from the Netherlands have discovered that cells from the non-viable tissue that remains after burn injuries, which are normally removed by debridement, to prevent infection, are a potential source of mesenchymal cells that can be used for tissue engineering. In this study, the research team of Magda Ulrich compared cells isolated from burn eschars (dry scabs or sloughs formed on the skin as a result of a burn or by the action of a corrosive or caustic substance) with fat-derived stem cells and dermal fibroblasts, and determined how well they conform to those criteria established for multipotent mesenchymal stromal cells.

According the Dr. Ulrich, who is member of the Association of Dutch Burn Centers in the Netherlands: “In this study we used mouse models to investigate whether eschar-derived cells fulfill all the criteria for multipotent mesenchymal stromal cells as formulated by the International Society for Cellular Therapy (ISCT). The study also assessed the differentiation potential of MSCs isolated from normal skin tissue and adipose tissue and compared them to cells derived from burn eschar.”

Burn treatment advances have increased the percentage of patients who survive severe burn injuries. This growing survival rate has also increased the number of people who are left with burn scars, and these scars cause skin problems, such as contracture (shortening and hardening of muscles, tendons, or other tissues that leads to deformity and rigidity of joints), and the social and psychological aspects of disfigurement.

Tissue engineering attempts to rebuild the skin are some of the most promising approaches to addressing these problems. Unfortunately, two shortcomings with this approach include finding a viable source of stem cells for the therapy and designing the scaffold that produces a suitable microenvironment to guide the stem cells toward those behaviors that engender tissue regeneration.

“The choice of cells for skin tissue engineering is vital to the outcome of the healing process,” Ulrich said. “This study used mouse models and eschar tissues excised between 11 and 26 days after burn injury. The delay allowed time for partial thickness burns to heal, a process that is a regular treatment option in the Netherlands and rest of Europe.”

Since elevated levels of MSCs have been detected in the blood of burn victims, Ulrich and her co-workers suspected that shortly after being burned, the severely damaged tissues attract stem cells from the surrounding tissues,.

“MSCs can only be beneficial to tissue regeneration if they differentiate into types locally required in the wound environment,” Ulrich said. “We concluded that eschar-derived MSCs represent a population of multipotent stem cells. The origin of the cells remains unclear, but their resemblance to adipose-derived stem cells could be cause for speculation that in deep burns the subcutaneous adipose tissue might be an important stem cell source for wound healing.”

Further work is needed to properly identify the origins of the stem cells found in the burn eschar, and how their function is influenced by the wound environment.