Copyright 2019 - Clinical Commissioning Groups Association

Development of novel stem cell therapies for chronic diseases - Professor Søren Paludan Sheikh MD PhD

The regenerative capacity of stem cells is widely accepted, however in reality not many stem cell therapies have become standard treatments in the clinic beyond rare diseases including bone marrow transplantation. To address the high expectations of stem cell therapy, it will be necessary to test the safety and efficacy of different types of stem cells to extend the regenerative approach to major diseases and conditions. This is especially important since current medical treatments for many chronic diseases are mainly symptomatic and palliative while stem cell therapy has the potential to be curative by repairing damaged cells. Developing curative therapies for chronic diseases would reduce the burden on the public health system and improve life quality for the patients. Therefore, understanding the underlying cellular mechanisms and molecular circuits in the human regenerative response including stem cell therapy and adopting novel insight into standard patient care is at the core of modern health care.

Stem cells possess a unique dual ability: they can undergo symmetric division (to increase their own numbers) and they can differentiate into multiple other cell types. Stem cells ensures maintenance of homeostasis in our tissues and body. Since approx. 106 cells are lost in our body every second, we would not last long without stem cells. In the adult, especially the so-called mesenchymal stem cells (MSC’s) including progenitor/stem cells isolated from adult adipose tissue, perinatal sources or bone marrow, have attracted attention as a cell source for clinical treatment. Adipose-derived regenerative cells (ADRCs) have strong regenerative capacity and have proven safe for human use1,2. A systematic review of 70 studies including 1474 patients and another review including 600 patients suggest MSC/ADRC treatment2,3 does not give rise to clinically important adverse effects. These cells work as site-regulated ‘drugstores’ in vivo by secreting molecules that facilitate repair. Our goal is to develop and implement novel stem cell therapies, understand the mode of action of stem cells and help to transform modern medicine. For this to happen, the regulatory bodies in different countries would need strong data to approve novel stem cell therapies for public use for the benefit of patients. To this end, it will be necessary to perform clinical trials in several different countries using the same method for stem cell isolation and the same design of the clinical trials. The data from all the trials could be pooled resulting in a higher power. This design can potentially help shape the view on stem cell treatment by reducing the barriers including public skepticism and regulatory approval. We are performing multicenter double-blind randomized, placebo controlled phase 2 clinical trials analyzing safety and efficacy of autologous (the patient’s own cells) ADRCs to correct erectile dysfunction (ED)4,5 and alleviate Breast cancer-related lymphedema (BRCL)6 and treat hip and knee pain (HJP) at key hospitals in multiple countries.

There is a large unmet need for all these three chronic diseases. It is estimated that around 40% of European men between the age of 40 and 79 suffer from ED. Taking into account the limitation and dropout rate of current medical treatment, stem cell treatment is in reality the best treatment option. For breast cancer alone there is app. 4500 new patients pr. year in Denmark alone, and app. 25% of these (=1.214) patients will eventually suffer from BCRL. Current compression treatment and physiotherapy has only marginal effect. Osteoarthritis (OS) is the main reason for chronic pain worldwide. This causes a significant impact to the public health system, since OS affects every eights person. We treat the patients with autologous fat stem cells (cells from the patient him-/her-self) in a one-day procedure, where the patient is first subjected to an abdominal liposuction under anesthesia. Next, we isolate the multipotent ADRC’s using a semi-automatic enzyme-based and GMP-compliant system, followed by injection into the patient. The ADRC’s are used freshly isolated and thus no tissue culture of the stem cells is necessary. Besides these three diseases, different types of mesenchymal stem/progenitor cells are being tested for safety and efficacy in multiple other conditions worldwide including cardiovascular diseases such as heart failure and critical limp ischemia, diabetes, liver and kidney diseases, inflammation and autoimmune conditions, graft-versus-host disease, wound healing, oncology, neurodegenerative diseases and spinal cord injury.

Cell therapy using ADRC’s is currently at the epicenter of regenerative medicine. The multipotent autologous ADRC’s have the ability to differentiate into novel cells belonging to bone, cartilage, skin, blood vessels, lymphatic vessels, neurons, and liver. As opposed to many clinical trials that use cultured cells isolated from bone marrow, we recommend using freshly isolated stem/progenitor cells from adipose tissue. Adipose tissue is so rich in ADRC’s (also called stromal vascular fraction) that we do not need to culture the cells to increase cell number. This reduces the cost of treatment since GMP culturing is expensive, time consuming and requires an advanced laboratory and regulatory permits. It is important to stress that the ARDC’s is a heterogeneous mixture of different cell types including stem cells (mesenchymal stromal cells, hematopoetic stem cells, pericytes and supra-adventicial cells), progenitor cells (endothelial and vascular progenitor cells, preadipocytes and hematopoetic progenitors) and mature cells (adipocytes, fibroblasts, endothelial cells, and blood cells including monocytes and macrophages)7. At this stage of the game, this may be an advantage since more than one cell types likely contribute to the clinical effects in different diseases. However, the heterogeneity also presents a problem since we do not currently understand the mechanism of action. Thus, it is not known which of these cells are responsible for the clinical effect, but it is likely that they are not all involved. It is known that the ADRC’s modulate the immune system to induce a regenerative response in the damaged tissue8,9. In addition, the ADRC’s contain a host of molecules that facilitate repair and reduce inflammation including growth factors, hormones, cytokines and different forms of DNA and RNA molecules. Since transplanted ADRC’s do not remain long in the host organism, it is thought that the therapeutic effects of stem cells are mediated by the aforementioned soluble mediators that change the balance in the immune system and promotes regeneration while reducing inflammatory processes by several mechanisms including inhibition of macrophage activation. The molecules may be delivered to damaged tissues in extracellular vesicles or by transport in microtubules. In addition, cell-to-cell contacts between stem cells and damaged cells may also play a role in the tissue regeneration.

Erectile dysfunction is defined as the inability to attain or maintain a penile erection satisfactory for sexual intercourse10. As mentioned, it is a prevalent disease, and existing treatments have major problems including lack of efficiency, numerous side effects, decreased libido because of ED and the reduced spontaneous element in the sexual behaviour11. In addition, ED is often considered a general indicator of decreased male health. The success rate of current treatment for ED after radical prostatectomy is estimated to be 14-53% for oral PDE-5 inhibitors (such as Cialis), 49-75% for the urethral pellets that delivers prostaglandin E1 (PGE1) also called ‘Medicated System for Erection’ (MUSE), and 47-80% for penile injections with PGE1 (alprostadil) alone or in combination with papaverine and phentolamine. Finally, patients can be treated quite successfully by getting a penile prosthesis implanted. However, this requires a sophisticated operation with placement of three different mechanical parts. The rationale for using ADRC’s to treat ED is based on these progenitors cells ability to stimulate repair of epithelial cells, vascular smooth muscle cells and neurons. The mechanism behind penile erection is that blood fills the penile sinusoids by relaxation of vascular smooth muscle cells induced by release of nitric oxide (NO) from the cavernous nerves and endothelial cells. NO diffuses into the vascular muscle cells, activates guanosine cyclase to produce cGMP, which in turn reduces Ca2+ levels and induces relaxation10. At Odense University Hospital in Denmark, we are currently enrolling 70 patients in a prospective, randomized, placebo-controlled and double-blinded phase 3 clinical trial using autologous ADRC’s for erectile dysfunction after prostate cancer. Accordingly, 35 men receive ADRC’s while 35 men are injected with saline. Prostate cancer is the most common cancer in men, and 16-60% experience ED after radical prostatectomy. The Danish regulatory bodies have approved the current trial based on preliminary data from our phase 1 study that describes a stem cell therapy that appears safe and potentially can correct ED after prostatectomy4. Briefly, we treated 17 men with no recovery using conventional therapy including PDE-5 or PGE-1 analogs. All subjects were sexually active before the operation, and were prostatectomized 5-18 months before stem cell treatment. All men underwent a liposuction performed by a plastic surgeon, followed by ADRC isolation and intracavernous injection of 4 x 1 ml ADRC’s. The men received between 8.4 and 37.2 million ADRC’s immediately after cell isolation. Interestingly, with a one year follow up period, 8 out 11 urinary continent men recovered their erectile function and were able to accomplish sexual intercourse as assessed by extensive self-reporting questionnaires dubbed International Index of Erectile Function (IIEF) and Erection Hardness Score (EHS). In contrast, none of the 6 incontinent men regained erectile function. Importantly, the procedure was safe and well tolerated, since only minor events including tenderness, redness and small bleedings related to the liposuction and injection sites was reported at the one-month evaluation. None of the men contacted a doctor for any side effect. Our study has limitations since we had no control group, it was an un-blinded investigation, we had no objective measurements for ED recovery and we do not know the mode of action of the stem cells. Finally, the treatment did not work in all patients. Nevertheless, we conclude that ADRC treatment is a promising interventional therapy for erectile dysfunction following prostatectomy. By extension, it is likely that the ADRC therapy would also work for other ED due to other common causes including diabetes, age, atherosclerosis and neural diseases. ED after prostatectomy is a severe form due to severed nerves followed by hypoxia and fibrosis in the penile tissue.

Our findings may open a new treatment paradigm in organic male impotence in general and including novel possibilities for a large group of men with ED due to late complication of type 1 and 2 diabetes. In further work, it will be necessary to design experiments to unravel the underlying molecular and cellular mechanisms of ADRC action, establish the optimal delivery mode including stem cell dose number, timing and administration route. It will also be important to lower costs of the treatment and develop methods to identify the patients that will respond to ADRC treatment or recover by standard treatment. In addition, considering the heterogeneous nature of ADRC’s, different methods of isolation and preparation yield different and often inconsistent results regarding relative amounts of stem/progenitor cells and mature cells. On top of that, most researchers employ expanded cells cultured under different conditions including media, addition of growth factors and passage numbers. Therefore, it is important that we develop better markers of the cells that are important for the clinical effect, and use standard methods to characterize the cells. Lastly, we need to increase efficiency of ADRC isolation. In addition, the literature is full of case reports and reports with very small numbers of patients treated with poorly defined stem/progenitor cells. Finally, there have been concerns that these progenitor cells could increase the risk of malignancies. We may never see stem cell therapy reach its full potential unless the field solves these problems and provides compelling evidence from adequately powered and controlled clinical trials that meet regulatory standards. Human regeneration is viewed as the most important biological process for managing repair for the chronic diseases in an ageing population. Thus, regenerative medicine is going to change the way we think about treatments of especially chronic diseases. A vision would be to develop standard stem cell treatments based upon scientific evidence regarding the molecular events underlying regeneration with the goal to offer the treatments as standard ‘packages’ including high technology to hospitals and professional clinics worldwide, thus making stem cell science immediately applicable for the patients.

References

  1. Zuk PA, Zhu M, Ashjian P, et al. Human adipose tissue is a source of multipotent stem cells. Molecular biology of the cell 2002; 13(12): 4279-95.
  2. Toyserkani NM, Jorgensen MG, Tabatabaeifar S, Jensen CH, Sheikh SP, Sorensen JA. Concise Review: A Safety Assessment of Adipose-Derived Cell Therapy in Clinical Trials: A Systematic Review of Reported Adverse Events. Stem cells translational medicine 2017; 6(9): 1786-94.
  3. Casiraghi F, Remuzzi G, Abbate M, Perico N. Multipotent mesenchymal stromal cell therapy and risk of malignancies. Stem Cell Rev 2013; 9(1): 65-79.
  4. Haahr MK, Jensen CH, Toyserkani NM, et al. Safety and Potential Effect of a Single Intracavernous Injection of Autologous Adipose-Derived Regenerative Cells in Patients with Erectile Dysfunction Following Radical Prostatectomy: An Open-Label Phase I Clinical Trial. EBioMedicine 2016; 5: 204-10.
  5. Lin CS, Xin Z, Dai J, Huang YC, Lue TF. Stem-cell therapy for erectile dysfunction. Expert opinion on biological therapy 2013; 13(11): 1585-97.
  6. Toyserkani NM, Jensen CH, Andersen DC, Sheikh SP, Sorensen JA. Treatment of Breast Cancer-Related Lymphedema with Adipose-Derived Regenerative Cells and Fat Grafts: A Feasibility and Safety Study. Stem cells translational medicine 2017; 6(8): 1666-72.
  7. Dominici M, Le Blanc K, Mueller I, et al. Minimal criteria for defining multipotent mesenchymal stromal cells. The International Society for Cellular Therapy position statement. Cytotherapy 2006; 8(4): 315-7.
  8. Aggarwal S, Pittenger MF. Human mesenchymal stem cells modulate allogeneic immune cell responses. Blood 2005; 105(4): 1815-22.
  9. Yagi H, Soto-Gutierrez A, Parekkadan B, et al. Mesenchymal stem cells: Mechanisms of immunomodulation and homing. Cell Transplant 2010; 19(6): 667-79.
  10. Reed-Maldonado AB, Lue TF. The Current Status of Stem-Cell Therapy in Erectile Dysfunction: A Review. World J Mens Health 2016; 34(3): 155-64.
  11. Carvalheira AA, Pereira NM, Maroco J, Forjaz V. Dropout in the treatment of erectile dysfunction with PDE5: a study on predictors and a qualitative analysis of reasons for discontinuation. The journal of sexual medicine 2012; 9(9): 2361-9.

Content provided by Professor Søren Paludan Sheikh 
Dept. Head, MD, PhD
Dept. for Clinical Biochemistry & Pharmacology
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OUH
Odense Universitetshospital
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