Clinical neurotransplantation: core assessment protocol rather than sham surgery as control

Sham surgical procedures for pain intervention result in significant improvements in pain: systematic review and meta-analysis

OBJECTIVE

To perform a systematic review and meta-analysis to study the magnitude of the placebo effect associated with sham surgery procedures.

STUDY DESIGN AND SETTING

We conducted a systematic search for randomized controlled clinical trials comparing any type of surgery to a corresponding sham placebo group and compared improvements in the sham treatment arms in subjective, objective, categorical, and continuous outcomes, as well as complication rates and mortality. Effect sizes were reported as standardized mean differences (SMDs). This is a systematic review and meta-analysis.

RESULTS

The overall effect size for pain improvement after sham surgery was SMD = 0.22 (95% confidence interval [CI] = 0.08-0.35) with improvement most marked at 1 month (SMD = 0.34, 95% CI = 0.26-0.43). There was a higher rate of improvement in subjective outcomes compared to objective outcomes for both dichotomized (number of patients with improvement) (42.8% compared to 27.1%) and continuous outcomes (SMD = 0.12, 95% CI = -0.05, 0.30 vs. SMD = -0.01, 95% CI = -0.05, 0.03). There were no deaths in the sham treatment arms and major complications were very rare (0.2%, 95% CI = 0.0-0.6%).

CONCLUSION

Sham surgery is associated with a large improvement in pain and other subjective patient-reported outcomes but with relatively small effect on objective outcomes. Sham surgeries are overwhelmingly safe. The magnitude of this effect should be used when planning future sham-controlled surgery trials.

Placebo in Surgical Research: A Case-Based Ethical Analysis and Practical Consequences

Placebo is a form of simulated medical treatment intended to deceive the patient/subject who believes that he/she received an active therapy. In clinical medicine, the use of placebo is allowed in particular circumstances to assure a patient that he is taken care of and that he/she receives an active drug, even if this is not the case. In clinical research placebo is widely used, as it allows a baseline comparison for the active intervention. If the use of placebo is highly regulated in pharmacological trials, surgery studies have a series of particularities that make its use extremely problematic and regarded less favorably. The purpose of this paper is to present three famous cases of placebo use in surgical trials and to perform an ethical analysis of their acceptability using the Declaration of Helsinki as a main regulatory source.

The long-term safety and efficacy of bilateral transplantation of human fetal striatal tissue in patients with mild to moderate Huntington's disease

Huntington's disease (HD) is a fatal autosomal dominant neurodegenerative disease involving progressive motor, cognitive and behavioural decline, leading to death approximately 20 years after motor onset. The disease is characterised pathologically by an early and progressive striatal neuronal cell loss and atrophy, which has provided the rationale for first clinical trials of neural repair using fetal striatal cell transplantation. Between 2000 and 2003, the 'NEST-UK' consortium carried out bilateral striatal transplants of human fetal striatal tissue in five HD patients. This paper describes the long-term follow up over a 3-10-year postoperative period of the patients, grafted and non-grafted, recruited to this cohort using the 'Core assessment program for intracerebral transplantations-HD' assessment protocol. No significant differences were found over time between the patients, grafted and non-grafted, on any subscore of the Unified Huntington's Disease Rating Scale, nor on the Mini Mental State Examination. There was a trend towards a slowing of progression on some timed motor tasks in four of the five patients with transplants, but overall, the trial showed no significant benefit of striatal allografts in comparison with a reference cohort of patients without grafts. Importantly, no significant adverse or placebo effects were seen. Notably, the raclopride positron emission tomography (PET) signal in individuals with transplants, indicated that there was no obvious surviving striatal graft tissue. This study concludes that fetal striatal allografting in HD is safe. While no sustained functional benefit was seen, we conclude that this may relate to the small amount of tissue that was grafted in this safety study compared with other reports of more successful transplants in patients with HD.

Neural tissue transplantation, repair, and rehabilitation

Transplants of cells and tissues to the central nervous system of adult mammals can, under appropriate conditions, survive, integrate, and function. In particular, the grafted cells can sustain functional recovery in animal models of a range of neurodegenerative conditions including genetic and idiopathic neurodegenerative diseases of adulthood and aging, ischemic stroke, and brain and spinal cord trauma. In a restricted subset of such conditions, cell transplantation has progressed to application in humans in early-stage clinical trials. At the present stage of play, there is clear evidence of clinical efficacy of fetal cell transplants in Parkinson disease (notwithstanding a range of technical difficulties still to be fully resolved), and preliminary claims of promising outcomes in several other severe neurodegenerative conditions, including Huntington disease and stroke. Moreover, the experimental literature is increasingly suggesting that the experience and training of the graft recipient materially affects the functional outcome. For example, environmental enrichment, behavioral activity, and specific training can enhance the recovery process to maximize functional recovery. There are even circumstances where the grafted cells have been demonstrated to restore the neural substrate for new learning. Consequently, it is not sufficient to replace lost cells anatomically; rather, for the grafts to be effective, they need to be integrated functionally into the host circuitry, and the host animal requires training and rehabilitation to maximize function of the reconstructed graft-host circuitry. Such observations require reconsideration of the design of the next generation of clinical trials and subsequent service delivery, to include physiotherapists, cognitive therapists, and rehabilitation experts as core members of the transplant team, along with the neurologists and neurosurgeons that have conventionally led the field.

Clinical trials of neural transplantation in Huntington's disease

Clinical neural transplantation in Huntington's disease has moved forward as a series of small studies, which have provided some preliminary proof of principle that neural transplantation can provide benefit. However, to date, such benefits have not been robust, and there are a number of important issues that need to be addressed. These include defining the optimum donor tissue conditions and host characteristics in order to produce reliable benefit in transplant recipients, and whether, and for how long, immunosuppression is needed. Further clinical studies will be required to address these, and other issues, in order to better understand the processes leading to a properly functioning neural graft. Such studies will pave the way for future clinical trials of renewable donor sources, in particular, stem cell-derived neuronal progenitor grafts.

Cell transplantation for Huntington’s disease: practical and clinical considerations

Huntington’s disease is a dominantly inherited neurodegenerative disorder, usually starting in mid-life and leading to progressive disability and early death. There are currently no disease-modifying treatments available. Cell transplantation is being considered as a potential therapy, following proof of principle that cell transplantation can improve outcomes in another basal ganglia disorder, namely Parkinson’s disease. The principle aim is to replace the striatal medium spiny neurons lost in Huntington’s disease with new cells that are able to take over their function and reconnect the circuitry. This article reviews the experimental background and evidence from clinical studies that suggest that cell transplantation may improve function in Huntington’s disease, reviews the current status of the field and considers the current challenges to taking this experimental strategy forward to becoming a reliable therapeutic option.

Potential cellular and regenerative approaches for the treatment of Parkinson's disease

Parkinson's disease is most commonly treated with a range of pharmacotherapeutics, with the more recent introduction of surgical techniques including deep-brain stimulation. These have limited capabilities to improve symptoms of the disease in more advanced stages, thus new therapeutic strategies including the use of viral vectors and stem cells are in development. Providing a continuous supply of dopamine to the striatum in an attempt to improve the treatment of motor symptoms using enzymes in the dopamine synthesis and machinery is one approach. Alternatively, there are tools which may serve to both protect and encourage outgrowth of surviving neurons using growth factors or to directly replace lost innervation by transplantation of primary tissue or stem cell-derived dopaminergic neurons. We summarize some of the potential therapeutic approaches and also consider the recent EU directives on practical aspects of handling viral vectors, cells and tissues, and in the running of clinical trials in Europe which impact on their development.

Placebo-controlled procedural trials for neurological conditions

Neurological disease has been a central focus in the ongoing ethical debate over the use of invasive placebo controls, especially sham surgery. The risk to research subjects and necessary use of deception involved in these procedures must be balanced against the methodological need to control for bias and the placebo effect. We review a framework formulated for the ethical assessment of sham surgery in the context of research evaluating novel procedures for neurological conditions. Special issues raised include the growing evidence of expectation and conditioning effects in a number of neurological diseases, the escalating scale of risk from different types of invasive placebo interventions, and the increasing use of cross-over designs, which allow a switch from placebo to active intervention without additional procedures.

A critical analysis of evidence for using sham surgery in Parkinson's disease: implications for public health

Sham surgery was introduced as a means for improving the methodological quality of surgical research and evaluation. The development of cellular-based surgical therapies for the treatment of Parkinson's disease provides an opportunity to carefully analyse the alleged methodological benefits of sham surgery. However, detailed analysis of the evidence does not support these hypothesised advantages. In this paper, we argue that sham surgery is a public health concern as vulnerable individuals are exposed to unnecessary and costly surgical procedures that have no benefits for ensuring rigorous health research.

Cell transplantation for Huntington's disease

Cell transplantation for Huntington's disease has developed over the last decade to clinical application in pilot trials in the USA, France and the UK. Although the procedures are feasible, and under appropriate conditions safe, evidence for efficacy is still limited, which has led to some calls that further development should be discontinued. We review the background of striatal cell transplantation in experimental animal models of Huntington's disease and the rationale for applying similar strategies in the human disease, and we survey the present status of the preliminary studies that have so far been undertaken in patients. When we consider the variety of parameters and principles that remain poorly defined -- such as the optimal source, age, dissection, preparation, implantation, immunoprotection and assessment protocols -- it is not surprising that clinical efficacy is still unreliable. However, since these protocols are all tractable to experimental refinement, we consider that the potential for cell transplantation in Huntington's disease is greater than has yet been realised, and remains a therapeutic strategy worthy of investigation and pursuit.

Pharmaceutical, cellular and genetic therapies for Huntington's disease

HD (Huntington's disease) is a devastating neurodegenerative disorder caused by a polyglutamine expansion in the gene encoding the huntingtin protein. Presently, there is no known cure for HD and existing symptomatic treatments are limited. However, recent advances have identified multiple pathological mechanisms involved in HD, some of which have now become the focus of therapeutic intervention. In this review, we consider progress made towards developing safe and effective pharmaceutical-, cell- and genetic-based therapies, and discuss the extent to which some of these therapies have been successfully translated into clinical trials. These new prospects offer hope for delaying and possibly halting this debilitating disease.

Ethics, methodology and the use of placebo controls in surgical trials

There is an emergent view among North American researchers and bioethicists that not only is the use of sham surgery ethical, but that it should also be mandatory when conducting trials to evaluate surgical procedures such as neural grafting. This view is based on erroneous assumptions concerning the magnitude of the placebo effects associated with surgery. A detailed analysis of four recent clinical trials failed to provide consistent evidence for pronounced and long term improvements in sham operated patients. There was no evidence that the results of the placebo control groups were necessary for identifying unsafe and ineffectual surgical procedures. We contend that the advancement of clinical science and the protection of individual patients are best guaranteed by adopting the principles of evidence-based medicine.

[Research ethics and the use of placebo: status of the debate in Canada]

The question of the use of the placebo is one of the most controversial in the field of the ethics of research today. The use of the placebo remains the standard practice of biomedical research in spite of the fact that various revisions of the Helsinki Declaration have sought to limit its use. In Canada, the Tri-council policy statement: Ethical conduct for research involving humans adopted a very restrictive position with respect to the use of placebos, precisely defining the situations in which its use would meet the demands of ethical research. The positions taken by the various ethical decision-making bodies are, however, hardly shared by regulatory bodies such as the Food and drug administration (FDA), the Council for international organization of medical sciences (CIOMS) or the European agency for the evaluation of medicinal products (EMEA). This divergence of opinions reveals two quite different conceptions of what constitutes the ethical. In the case of decision-making bodies in the ethical field, it is clearly medicine's Hippocratic Oath which explains their reluctance to use placebos. The first responsibility of the doctor is to "do no harm" to his or her patient. This duty is inherent to the medical profession and as such is not grounded in the view of medicine as a contract for care. In the case of regulatory bodies, it is the vision of "medicine as contract" which is in view; and it is this notion that justifies the use of placebos once free and informed consent has been obtained. It is also worth noting that these regulatory bodies make frequent use of arguments based on utilitarian ends. In an unprecedented move, the World medical association published in October 2001 a clarification note about the use of placebos. An analysis of this text raises the question about its real meaning: clarification or concession?

Making and repairing the mammalian brain--in vitro production of dopaminergic neurons

Midbrain dopamine (DA) neurons play an essential role in modulating motor control, and their degeneration is the hallmark feature of Parkinson's disease (PD). In vitro production of DA neurons provides insight into the mechanisms that control cell fate choice, and offers an alternative to the use of fetal tissue for experimental cell replacement in PD. Here we will review the advantages and disadvantages of the various renewable cell sources and protocols tested, and discuss their relevance for basic studies and for cell therapy.