Tag Archives: rabbit

The new face of transplant surgery, thanks to animal research

Yesterday the University of Maryland Medical Center (UMM) announced most extensive full face transplant completed to date, including both jaws, teeth, and tongue. In a marathon 36-hour operation the surgical team led by Professor Eduardo Rodriguez were able to transplant a face of an anonymous donor onto their patient Richard Lee Norris, who had been injured in a gun accident 15 years ago.  The operation was the culmination of years of clinical and animal research undertaken at UMM under the leadership of Professor Stephen Bartlett, and funded by the Department of Defense and  Office of Naval Research due to its potential to help war veterans who have received serious facial injuries.

This successful operation, termed a vascularized composite allograft, was made possible not only by the selflessness of the family of the anonymous donor, but also by the years of animal research undertaken by Professors Rodriguez and Bartlett and colleagues. For example, a key factor in the success of this operation was that they transplanted high amounts of vascularized bone marrow (VBM), which came inside the transplanted jaw, a technique that was developed by the team after observing that tissue rejection following composite tissue allotransplantation in a cynomolgus monkeys was greatly reduced when VBM was included in the transplant. This discovery will also help to reduce the amount of immunosuppression that Mr. Norris and future patients require following facial transplants.

Of course this is far from the first contribution that animal research has made to transplant surgery, from the development of the techniques of kidney transplant through research in dogs by Joseph Murray and colleagues, to the careful experiments in dogs conducted by Norman Schumway and Richard Lower that led to the first successful heart transplants, to the studies in mice and rats that identified the immunosuppressive properties of the drug cyclosporin that transformed the transplantation field in the 1980’s, animal research has made a crucial contribution to this field. Indeed, in his 1990 Nobel Lecture Edward Donnall Thomas stressed the importance of animal research to his Nobel prize winning discoveries concerning bone marrow transplantation.

Finally, it should be noted that marrow grafting could not have reached clinical application without animal research, first in inbred rodents and then in outbred species, particularly the dog.”

Animal research continues to make key contributions to transplant science, and we have had several opportunities to discuss its role in the development of lab-engineered tissues for transplant, such as the artificial bladder, on this blog.

Yesterday’s news from the University of Maryland is another reminder that animal research is still crucial to advances in transplant surgery. It is also worth remembering that when animal rights groups attack animal research conducted by the Department of Defense, it is work such as that which led to yesterday’s breakthrough that they are attacking.

Paul Browne

Bob Edwards wins 2010 Nobel Prize for developing IVF: Thank the mice, rabbits, hamsters…

Professor Robert G. Edwards of the University of Cambridge has long been recognized as one of the pioneers of reproductive medicine. His most famous accomplishment, along with surgeon Patrick Steptoe*, came in 1978 with the birth of Louise Joy Brown, the first baby born through in-vitro fertilization.  This achievement has now been recognized by the Nobel Assembly who awarded him the Nobel Prize in Physiology or Medicine 2010 for “the development of in vitro fertilization”.

As Dario discussed in an article for this blog a few months ago the development of IVF by Bob Edwards depended on basic and applied research undertaken in rabbits and hamsters by pioneers including Gregory Pincus and Min Chueh Chang, who identified the essential conditions required for IVF.

In advanced information accompanying today’s announcement the Nobel Assembly notes the importance of this research in laying the foundations for the development of human IVF by Bob Edwards and Patrick Steptoe, and also discusses how Bob Edwards’ own extensive research on the reproductive biology of mice – and animal research he and his colleagues conducted in a variety of species while working on IVF – aided progress. In particular the Nobel Assembly highlights how his experience with mice in enabled Bob Edwards to solve a critical problem that was preventing successful IVF, by developing a way to harvest human egg cells at the optimal stage of their maturation prior to in vitro fertilization.

Professor Robert Edwards, Nobel Laureate and IVF pioneer

Without the decades of careful animal research undertaken by Bob Edwards, Gregory Pincus, Min Chueh Chang, and scores of their colleagues it is unlikely that IVF would ever have become a reality.

We heartily congratulate Professor Edwards on his Nobel Prize, an award that recognizes his outstanding contribution to a medical advance that has brought joy to hundreds of thousands of families around the world.

* Sadly Patrick Steptoe died in 1988 and therefore could not share the Nobel Prize with Robert Edwards.

Paul Browne

Heart failure breakthrough: animal research paved the way!

Heart failure, where the heart is unable to maintain a sufficient blood flow to supply the body’s needs, is a leading cause of death, especially among the over 65’s. Half of all chronic heart failure patients die within four years of diagnosis. It can have a number of causes, for example damage to heart tissue after a heart attack, and leads to a variety of problems in patients. Fatigue and muscle weakness are common as the muscles receive insufficient oxygen, and because waste products cannot be removed from tissues quickly enough fluid can build up in the lungs and other parts of the body, often the legs and abdomen. The extra strain placed on the heart as it tries to maintain adequate blood pressure can lead to further damage to the heart and ultimately cardiac arrest.

Ivabradine can lower the heart rate while maintaining a normal blood pressure - good news for heart failure patients. Image courtesy of the CDC Public Health Image Library.

In heart failure the rate at which the heart beats is often increased, and group of scientists led by Karl Svedberg and Michael Komajda set up the SHIfT study, to evaluate whether a drug called Ivabradine, which lowers the heart rate, could reduce risk of death or hospitalization in a group of patients who had heart failure accompanied by an elevated resting heart rate.  Significantly fewer patients taking Ivabradine in addition to their existing treatments required hospital admission during the course of the study, compared to a control group who were given a placebo in addition to their existing treatment. The most striking outcome was that Ivabradine cut the risk of death by 26%.

So what is Ivabradine, and where does it come from?

Ivabradine slows the heart rate by inhibiting an electrical current known as the If current* which is a major regulator of the activity of the sinoatrial node – better known as the pacemaker. Inhibiting the If current slows the generation of the electrical impulses by the sinoatrial node that trigger heart contraction, and therefore slows the heart rate itself. Ivabradine, then known as S16257, was first developed in the early 1990’s when it was found to be able to block the If current in-vitro in sinoatrial node tissue from rabbits and guinea pigs, and slowed the generation of electrical impulses in a manner that was safer than other bradycardic drugs (1). Ivabradine was then evaluated in live rats and dogs, where it safely reduced the heart rate, and moreover did so without reducing the blood pressure (2,3). While beta-blockers such as Propranolol can reduce the heart rate they also lower the blood pressure – indeed they are used to treat hypertension – and hence are not suitable for many patients, so the development of a drug that could reduce heart rate without affecting blood pressure was very welcome.

Following the successful animal studies Ivabradine entered human clinical trials and in 2005 was approved for the treatment of angina pectoris. In angina pectoris the heart muscle receives too little oxygen, a problem exacerbated by a fast heart beat that increases the need for oxygen, so lowering of the heart rate by Ivabradine reduced oxygen demand and prevents angina attacks. The success of Ivabradine in the treatment of angina pectoris in turn led to its evaluation in heart failure.

The successful outcome of SHIfT study is a major boost to the development of better treatment regimes for heart failure, and if it is confirmed by further clinical trials will improve and prolong the lives of many heart failure patients.

* Hence the name of the SHIfT study – Systolic Heart failure treatment with the If inhibitor ivabradine Trial

Paul Browne

1) Thollon C. et al. “Electrophysiological effects of S 16257, a novel sino-atrial node modulator, on rabbit and guinea-pig cardiac preparations: comparison with UL-FS 49.” Br J Pharmacol. Volume 112(1), Pages 37-42 (1994) PubMedCentral:PMC1910295

2) Gardiner S.M. et al. “Acute and chronic cardiac and regional haemodynamic effects of the novel bradycardic agent, S16257, in conscious rats.”  Br J Pharmacol. Volume 115(4):579-586 (1995) PubMedCentral:PMC1908496

3) Simon L. et al. “Coronary and hemodynamic effects of S 16257, a new bradycardic agent, in resting and exercising conscious dogs.”  J Pharmacol Exp Ther. Volume 275(2), Pages 659-666 (1995) PubMed:7473152

Hopping rabbits herald breakthrough in tissue engineering

A team of NIH-funded scientists and veterinarians at Columbia University, the University of Missouri, Clemson University, and the Medical University of South Carolina, have this week announced a significant advance in tissue engineering, for the first time they have used cutting–edge tissue engineering technology to produced a moving joint, in this case the hip, in rabbits.  A press release on the NIH website discusses the work in some detail, and those with a subscription can read the original research article in the Lancet.  This is not the first paper to describe the production of bone or cartilage using tissue engineering, but it is the first time that the two tissues have been regenerated together to produce a moveable joint, and represents a significant step forward in terms of the complexity of tissue that can now be engineered.

Rabbits are a popular experimental model for the study of bone repair and regeneration; the structure of their bones is very similar to that seen in larger animals including humans, for example unlike some smaller rodents they have structures known as  Haversian canals that affect bone growth and repair, while their size allows more complex surgery than is possible with smaller rodents.

Tissue engineering techniques we have discussed previously, such as the artificial lung, involved seeding a scaffold, were created by stripping cells from donor tissue, seeding with stem cells, and then allowing the cells to grow in vitro to produce a functioning organ. The technique reported this week differs in that the scaffold was made from an artificial bio-polymer, and rather than implant stem cells into the scaffold and growing the tissue in vitro, they coated the scaffolds with the growth factor known as TGFβ3 and then implanted it into the rabbits. TGFβ3 attracts bone and cartilage precursor cells to the scaffold, where they multiply and after a few weeks have formed a functioning joint.  When they compared scaffolds coated with TGFβ3 to bare scaffolds, they observed that more precursor cells were recruited to the scaffold when TGFβ3 was present, and that the rabbits transplanted with TGFβ3-coated scaffolds moved more easily when assessed one to two months after surgery, indeed the joints were able to support the weight of the rabbits without any limping.

Rabbits play an important role in medical research. Image courtesy of Understanding Animal Research.

This technique is significantly simpler than those approaches that require stem cell seeding and in vitro growth prior to transplant, and might be especially useful for younger hip transplant patients, individuals aged 65 or younger. Younger patients would be expected to recover more quickly, have fewer co-morbidities that would be aggravated by staying in bed for a prolonged time to allow the tissue to regenerate, and would benefit more from not having to have hip operations every 10-15 years as is currently the case with metal hip joints.  For more elderly patients metal hip joints are likely to remain the best option.

So does this technique replace that used in the tissue engineering studies we have previously discussed? Well, the answer is no, for some applications either approach might work, but for others, for example the artery and lung transplants, the tissue needs to be capable of functioning immediately following transplant. One aspect that is being evaluated elsewhere is the use of biopolymer scaffolds, which are being used with stem cells to produce replacement blood vessels, and may provide a more flexible and reliable alternative to the use of decellularized tissue.

It’s an interesting development, and one that again highlights how quickly things are happening in the field of tissue engineering. Of course it will be some time before clinical trials in humans start, before then this technique must be evaluated in a larger animal, probably a pig, to determine whether tissue regeneration on the scaffold is rapid and effective enough in a model of comparable sizes to humans. Only if these tests are successful will this technique warrant evaluation in a human clinical trial.

Paul Browne

Animal Research Benefits Mom and Baby Alike

The contributions of animal research to human health are many.

In response to blanket statement that animal research “does not work” I wanted to provide three examples of how animal research has directly benefited the health of women and their babies: in-vitro fertilization, oral contraceptives and neonatal intensive care.

Do you or any of your friends conceived with help of in-vitro fertilization?  Do you know how the method was developed?

It turns out that rabbits played a central role in the development of in-vitro fertilization.   As far abck as 1891 Walter Heape in England reported the first known case of embryo transplantation from one rabbit species to another, thereby showing that it was possible to transfer the embryos to a gestational carrier without adverse effects.  In 1934 Dr. Gregory Pincus at Harvard achieved in-vitro fertilization in rabbits for the first time, and he made very detailed studies in animals of the effects of hormones on ovulation and early embryonic development.  Being ahead of his time brought him much negative reputation and was described by the media a modern “Dr. Frankestein” (in fact, he was denied tenure due to these experiments.)   In 1958 Dr. Min Chueh Chang demonstrated conclusively that IVF was possible by implanting black rabbit embryos conceived in the lab into a white rabbit.  His studies in rabbits, rats, mice and hamsters during the 1950’s, 60’s, and 70’s, identified key conditions for IVF to be successful, such as the need for sperm capacitation.  These findings paved the way for the development of in-vitro fertilization in humans by Dr. Robert Edwards and Dr. Patrick Steptoe, which allows families to have a children overcoming many obstacles to pregnancy, both in cases of female and male infertility.  Approximately 60,000 infants are born with the help of IVF in the US every year…   Thank the rabbits.

Have you ever asked yourself where oral contraceptives come from?

The “pill” was first introduced in the 60s based on synthetic hormones that mimic the way progesterone works to prevent ovulation.  In 1919 Dr Ludwig Haberlandt and colleagues first demonstrated that transplantation of ovaries of pregnant rabbits into fertile female rabbits suppressed their ovulation.   Shortly before his death Haberlandt was able to prevent pregnancy in mice through the oral administration of an extract from the ovaries. It later was discovered that this was caused by the hormone progesteroneMargaret Sanger, the famous American birth control activist,  asked Dr. Gregory Pincus (the same one that developed IFV) to think of new methods of contraception and, building on these results, he showed that repeated injections of progesterone indeed could stop ovulation in rabbits.   This key finding, along with the development of a synthetic version of progesterone, led the first clinical trials of “the pill” in Puerto Rico.   Identifying effective synthetic progesterones was not an easy task, Dr. Pincus and Dr. Chang screened over 200 candidates before identifying three that prevented ovulation in laboratory animals.  The subsequent clinical trials of one of these synthetic progesterones were successful and Enovid was approved by the FDA in 1957.   Thank the rabbits again…

Dr Gregory Pincus and Dr Min Chueh Chang, pictured alongside artificial insemination pioneer Sir John Hammond. Courtesy of Mrs. F. Hammond.

Have you any of your friends had a premature baby in the intensive care unit?   Do you know why survival rates are now much higher than in the past?

The rate of premature birth has increased by 36% since the 80s (1).  Most babies born before 37 weeks of pregnancy are premature and are at risk of many complications.  In the USA alone, about 12.8% of babies are born prematurely and will spend their first few days of their lives in the neonatal intensive care unit.  Among babies born before the 34th week, 23,000 a year of them suffer from respiratory distress syndrome (RDS).  Such babies lack a protein in their lungs (called surfactants) that keep the air sacs in the lungs from collapsing.

Surfactants were discovered and their chemical composition analyzed using dogs in biomedical research and through research on rabbits and lambs surfactant therapy, initially using surfactant from cows and later synthetic surfactant, was developed.  The fruits of this research were translated into the treatments using surfactants in the 90s, which reduced the death of babies from RDS by about 50% (2).  In other words, slightly more than 10,000 babies are saved every year just in the US alone due to surfactant-replacement therapy.

That’s more than one baby per hour just in the US… Saved.  Thanks to animal research.

And this work goes on, for example in recent posts Paul has discussed the use of brain cooling and xenon gas to protect babies who have suffered oxygen starvation during birth from brain damage.

So when animal rights activists and the medical wing of their movement state that animal research “does not work”, what they really mean is that it does not work… for them.

Yet, they cannot deny these facts with books full of half-truths and out-of-context citations.

Anyone can walk into the nearest neonatal ICU and face the babies and their parents.  Face the facts.

Dario Ringach

References:

(1) Martin, J.A., et al. Births: Final Data for 2006. National Vital Statistics Reports, volume 57, number 7, January 7, 2008.

(2) Engle, W.A., and the Committee on Fetus and Newborn. Surfactant-Replacement Therapy for Respiratory Distress in the Preterm and Term Neonate. Pediatrics, volume 121, number 2, February 2008, pages 419-428

Protecting a broken heart: the discovery of remote ischemic preconditioning.

After a couple of weeks dominated by dialogue with moderate animal rights activists, and subsequently the response of the scientific community to threats by animal rights extremists,  it is refreshing to be able to turn again to an example of how research on rabbits and dogs is furthering medical progress.

The prospects of surviving a heart attack have improved greatly over the past few decades, and thanks  to the development of surgical techniques such as coronary artery bypass and clot-busting thrombolytic drugs many patients go on to live long and healthy lives who would previously have faced an early grave.  Despite this progress doctors and scientists are still looking for ways to further reduce the toll of death and infirmity that results from heart attacks; now a report on the BBC suggests that another important advance is in progress.

Figure A is an overview of a heart and coronary artery showing damage (dead heart muscle) caused by a heart attack. Figure B is a cross-section of the coronary artery with plaque buildup and a blood clot. Image displayed courtesy of the National Heart, Lung and Blood Institute.

A team led by Professor Hans Botker of Aarhus University Hospital in Denmark reported a clinical trial of over 300 patients where a novel technique known as remote ischaemic preconditioning (rIPC) safely reduced the amount of damage suffered by the heart during ischemia, when its blood and oxygen supply is cut off during a heart attack (1).  rIPC is a phenomenon whereby short periods of ischemia in one tissue can protect a distant tissue or organ from longer periods of ischemia. In this trial the blood supply to muscles in the arm was cut off using a blood pressure cuff for brief periods in heart attack victims on their journey to hospital, and it was used in addition to established treatments.

So how does it work? Well the answer is that we still don’t know. Research in animals indicates that the tissue exposed to brief periods of ischemia release factors that then travel through the bloodstream to other organs where they alter the metabolism in that organ to make it more resistant to damage from oxygen starvation, but the identity of these factors had not yet been confirmed (2).  This raises an obvious question, if the mechanism is so poorly understood how was this phenomenon identified? After all without this knowledge  in vitro or computational studies could not have identified it, and doctors could hardly go around stopping the blood flow in the arms of heart attack victims without having a very good reason for doing so!

This story starts in the mid 1980’s when scientists studying heart attacks in dogs observed that while blocking a major coronary artery for an extended period resulted in the same damage seen in heart attacks in humans, brief blockage of blood flow did not result in this damage, even if repeated several times.  In fact they observed that the energy use in the heart was slower in later periods of transient ischemia than in the first period, reducing its need for oxygen, and postulated that multiple brief periods of ischemia in the heart might prevent it from damage in a subsequent longer period of ischemia. When they tested this in dogs they found that was indeed the case, four 5 minute periods of ischemia did indeed reduce the heart damage seen after a sustained 40 minute period of ischemia (3).  Subsequent experiments confirmed this finding, and in later clinical trials the technique was found to be beneficial for patients undergoing heart surgery where the supply of blood to the heart is cut off.  Despite this utility the technique of directly preconditioning the heart has been restricted to situations where it is possible to operate on the patient before the supply of blood to the heart muscle is cut off for a prolonged period, and it is not a viable option with heart attack victims.

At this point further analysis of the studies undertaken in dogs suggested a way to widen the clinical use of this technique, as it was noticed that preconditioning one area of heart tissue protected other areas from subsequent damage. Might it be possible to protect the heart by inducing transient ischemia in other tissues? Initial studies in animals and subsequent human trials examined transient ischemia of the mesentery and kidney, discovering that it could reduce damage to the heart. However inducing transient ischemia in the mesentery and kidney still required surgery and was hardly ideal for emergency situations. The breakthrough came with the demonstration by Yochai Birnbaum and colleagues at the Good Samaritan Hospital that inducing transient skeletal muscle ischemia in a rabbit model of heart attack substantially reduced the damage to the heart (4), a result subsequently confirmed by other scientists studying heart attack in rats and rabbits.  The significance of this discovery is that it is possible to block the blood flow to skeletal muscle through the use of a standard blood-pressure cuff, avoiding the necessity for additional surgery.

Thanks to pioneering work of Yochai Birnbaum and other animal researchers successful clinical trials of the blood pressure cuff to induce transient ischemia in limb muscles have been reported in children undergoing heart surgery (5) and now in heart attack victims.  We hope that in years to come this exciting new technique will fulfill its early promise and help save many lives.

Paul Browne, PhD

1)      Botker H. E. et al. “Remote ischemic conditioning before hospital admission, as a complement to angioplasty, and effect on myocardial salvage in patients with acute myocardial infarction: a randomized trail” The Lancet Volume 375 (9716), Pages 727-734 (2010) DOI:10.1016/S0140-6736(09)62001-8

2)      Shimizu M. et al. “Transient limb ischemia remotely preconditions through a humoral mechanism acting directly on the myocardium: evidence suggesting cross-species protection” Clinical Science, Volume 117, Pages 191-200 (2009) DOI:10.1042/CS20080523

3)       Murry C.E., Jennings R.B., Reimer K.A. “Preconditioning with ischemia: a delay of lethal cell injury in ischemic myocardium.” Circulation Vol.74(5), Pages 1124-1136 (1986) PMID: 3769170

4)      Birnbaum Y., Hale S.L. Kloner R.A. “Ischemic preconditioning at a distance: reduction of myocardial infarct size by partial reduction of blood supply combined with rapid stimulation of the gastrocnemius muscle in the rabbit.” Circulation Vol. 96(5), Pages 1641-1646 (1997) PMID: 9315559

5)      Cheung M.M. et al. Randomized controlled trial of the effects of remote ischemic preconditioning on children undergoing cardiac surgery: first application in humans” J. Am. Coll. Cardiol. Volume 47(11), Pages 2277-2282 (2006) doi:10.1016/j.jacc.2006.01.066