May 9, 2006
There has been much debate in the recent scientific literature as well as in the media about recent research findings suggesting a potential new cure for type 1, autoimmune diabetes. Original reports from Dr. Denise Faustman at Harvard University suggested that diabetes-prone mice could be cured of their diabetes, after mice had become diabetic, using a complex therapeutic scheme possibly resulting in the regeneration of insulin-producing cells.
Many people have contacted the Diabetes Research Institute Foundation asking for clarifications and guidance, as many are confused by the controversy. The information provided below is meant to provide a balanced and unbiased view of the subject matter.
First, we will explain the therapeutic scheme developed by Dr. Faustman and its three critical components. This scheme is based on:
- the injection of Complete Freund's Adjuvant (CFA);
- the transplantation of pancreatic islet cells from identical mice;
- the infusion of donor spleen cells from non-identical mice.
CFA: The first component of the treatment scheme involves the administration of CFA, a potent pro-inflammatory compound. This compound is based on mineral oils and killed bacteria that normally cause tuberculosis (mycobacterium tuberculosis). CFA is normally used to stimulate the immune system responses in experimental mice. It provokes inflammation and lesions at the site of injection, and its use is even restricted in experimental mice because of the inflammation, lesions and pain it causes. It is believed that the injection of CFA may inhibit or block the autoimmune attack that causes diabetes. This was indeed shown by original studies performed in 1990, when it was demonstrated the CFA prevents the spontaneous development of diabetes in mice.
Islet transplantation: The second component involves transplantation of islets from mice identical to the diabetic mice. The transplanted islets are used to restore insulin production and normalize blood sugar, allowing mice to survive. Because islets are from identical mice, the islets are not rejected by the immune system as a transplant from non-related person normally would.
Infusion of spleen cells: The third component involves the infusion of spleen cells from mice that are not identical to the diabetic mice. According to Dr. Faustman the spleen cells include progenitor or “stem cells” capable of promoting regeneration of the insulin-producing cells in the pancreas of the diabetic mouse.
What has been found? What does this mean? In April 2006, research papers from three independent groups of scientists have recently been published in the journal Science. All three papers refute the major claim of Dr. Faustman's research, that the cure of diabetes in her experiments was due to regeneration of the insulin-producing cells in the pancreas of the mice, which originated from stem cells contained in the spleen cell infusion. Actually, there was evidence that the spleen cells from the non-identical donor mice were rejected, as one would predict. Some media, as well as Internet websites supporting Dr. Faustman, have acknowledged the above and yet maintain that the validity of Dr. Faustman's therapeutic approach has been, in essence, verified and validated.
We feel it is useful to provide the following clarifications and simple, unbiased explanations of the published findings:
- None of these papers provided direct evidence for regeneration of insulin-producing cells. Regeneration means the formation of new beta cells. True regeneration would produce brand new islets and brand new beta cells and should correct for the loss of islets caused by the autoimmunity. Rather, there was evidence that islets were still present in the diabetic mice although in much reduced numbers.
- The papers reported evidence for functional recovery, meaning that beta cells that were impaired in their insulin producing function by inflammation recovered their ability to secrete insulin.
- There was evidence for expansion of the islets. In the treated mice, islets grew bigger. The authors suggested that the enlarged (hypertrophic islets) were explained by the division or replication (not formally proven, and not technically equal to regeneration) of existing beta cells. Hypertrophic islets are often seen in untreated NOD mice, possibly an adaptive response to the autoimmune process and the loss of beta cells. Ultimately, there is no direct or convincing evidence for regeneration in any of the papers. Again, functional recovery and some expansion (or hypertrophy) as shown by the bigger islets does not equate to regeneration. Critically, these papers fail to confirm the original claim that there was regeneration and this was due to the presence of stem cells that were infused with the spleen cells.
All three research groups failed to reproduce the high rates of cure observed in mice by Dr. Faustman, reporting that that only a minority of mice were actually cured. In fact, after the islet transplants were removed, a minority of mice showed persisting insulin secretion. From the available data it would appear that the functional recovery and hypertrophy was the explanation for the curative effect. There may be several explanations for the different efficacy of the treatment in the different studies, including experimental variability, some associated with the CFA itself.
Thus, it appears that Dr. Faustman has devised a treatment protocol that can reverse diabetes at least in a small percentage of mice by preserving residual beta cells and favoring recovery and expansion. Dr. Faustman has shown that inducing normoglycemia and interfering with autoimmunity soon after diabetes symptoms develop may be beneficial and perhaps preserve sufficient pancreatic beta cells to reverse diabetes symptoms for a long period of time, maybe permanently if the autoimmune attack is permanently halted. Although the transplanted islets were not rejected and were not attacked by autoimmune cells, experiments showed that immune cells were still surrounding the islets in the pancreas and those transplanted in the kidney. Experiments also showed that the mice were not immunologically tolerant to the islets, in other words the root cause of diabetes, loss of immunological tolerance to islet cells, had not been corrected. Thus, it cannot be excluded that diabetes may return in the treated mice with longer follow-up, possibly as a reactivation of the autoimmune attack or as a failure and loss of the islets that recovered after the treatment.
It is important to note here that Faustman's experiments as well as the studies from the other three groups all lacked two fundamental controls: mice not receiving CFA and mice not receiving islet transplants. Normoglycemia may be critical to allow the beta cells in the pancreas to become metabolically less active, less susceptible to immune attack (which was also inhibited by the CFA, as originally shown in 1990), and more likely to recover functionally and adapt with hypertrophy. It is conceivable that CFA prevented an autoimmune attack against the transplanted islets, as shown in original experiments by Dr. Rajotte in the early 1990s. Thus, these studies did not address which elements of the treatment strategy, the CFA or the islet transplants, were critical to its success in the cured mice or whether CFA alone could be sufficient to reverse diabetes without the islet transplant. This is a fundamental question, particularly since Dr. Faustman is planning to launch a clinical trial which does not involve islet transplantation.
In actuality, of three key elements in the Faustman's strategy, none may be used in clinical trials. CFA it too toxic and cannot be administered to humans. Islet cell transplants from an identical individual cannot be practically performed in humans. The infusion of donor spleen cells was shown to be inconsequential. Thus, it appears that this treatment protocol, as used to treat mice, has no direct applicability for treating human disease.
The new trial proposed by Dr. Faustman is based on the administration of BCG, or Bacille Calmette-Guerin, a vaccine preparation against tuberculosis that might possibly mimic the effects of CFA, but unlike CFA can be administered to humans. However, there are no direct data supporting the rationale for a clinical trial based on the administration of BCG from the Faustman's studies. Literature data show that BCG may stimulate TNF production, eliminate autoreactive immune cells (T cells) and in turn antagonize islet autoimmunity in mice. However, the mice used in diabetes research are laboratory animals living in germ-free conditions. The model most commonly used, the NOD mouse, is highly sensitive to manipulation. Many treatments that work in the NOD mouse don't work in humans. The response to an "environmental-like" stimulus, such as BCG, may not have the same effects in humans as we are routinely exposed to many environmental factors. So far, BCG has not been shown to work in human diabetes, as earlier studies with BCG at diabetes onset suggest that BCG is not effective. Some studies suggest that children receiving BCG within the first 3 months of age may progress to overt diabetes faster, although there was no clear evidence that BCG increased disease incidence. One may attempt to modify doses and regimens, but then there are other trials that are being done with a much more solid scientific rationale. Obviously there may be different opinions about whether another trial with BCG is justified, or necessary, or what its priority may be compared to other intervention modalities. In the design of clinical trials, scientists must balance therapeutic potential and safety and prioritize the conduct of these trials based on these and several other factors. The design and conduct of clinical trials for type 1 diabetes poses critical ethical issues, which are particularly important given that the health and possible chances of recovery of our children are at stake.
Building on the treatment goals identified by Faustman, diabetes research foundations could support studies to device alternative ways to obtain similar effects but using an approach with clinical applicability. Insulin therapy could induce normoglycemia (it was also used in some of the Faustman experiments) and many other agents can interfere with the autoimmune process at onset. Perhaps a study with other immunomodulators and insulin could be designed, and if successful in mice could be more easily translated to clinical trials.
November 22, 2010
Later in 2008 Dr. Faustman published a paper reporting that autoreactive CD8 T cells could be eliminated by TNF agonists. This study provides some additional support to the idea that BCG (by stimulating TNF) could be of potential benefit in antagonizing islet autoimmunity. According to the clinicaltrials.gov site, a study to determine whether BCG alters autoreactive T cells has been open for recruitment during the last few months. This study would determine if there are effects on the immune system that could interfere with the autoimmune responses. Importantly, the results of this study will inform decisions about future clinical trials based on the administration of BCG.
Clarifications from Dr. Faustman, December 2010
Clarifications and updated information to Dr. Pugliese's 2006 commentary provided by Dr. Faustman on November 30 2010, including information that became known after May 2006:
- The contribution of spleen stem cells to regeneration was not a major claim of the original Faustman studies, and the spleen stem cells were not an absolute requirement for diabetes reversal, although it could accelerate reversal. Rather, the major claim is the targeted disease reversal in mice with established diabetes.
- Other groups have since shown the existence and potential of spleen stem cells, at least when these stem cells are from mice of the same kind, in other words cells that would not be rejected by the immune system. Clinical trials to test this therapy will not utilize spleen stem cells.
- Additional studies have reported beta cell regeneration in mice, and identified additional varieties of stem cells.
- There are a number of technical explanations for why not all groups have obtained cure rates as good as the original studies, and other groups have reported higher diabetes reversal rates.
- Therapeutic effects on the permanent reversal of autoimmunity were supported by the inability of lymphocytes from cured mice to transfer disease in other mice.
- Experiments indicating that such effects were due to CFA treatment, although not included in the later papers, were included in Dr. Faustman's paper published in the Journal of Clinical Investigation in 2001.
- In clinical trials, insulin therapy will be used instead of islet transplantation to control blood sugars and favor the response to therapy.
- While CFA, a veterinarian preparation of the BCG organism cannot be administered to people, BCG has a similar but not identical composition and should elicit in people similar effects to those seen in mice treated with CFA.
- BCG vaccination has proven safe and this has been confirmed in the Phase I clinical trial run by Dr. Faustman in patients with type 1 diabetes.
- Dr. Faustman has created a method to track the therapeutic effects of BCG, including measuring the effects on autoaggressive lymphocytes associated with the development of diabetes, which will help in the design and conduct of future trials.
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Alberto Pugliese, MD |
