Stem cells have been given the sobriquet ‘Mother of Regeneration’ for good reason. These building blocks of the human body hold tremendous promise in the understanding and treatment of a range of diseases, injuries and other health- related conditions.
Professor Michael Pepper, director of the South African Medical Research Council (SAMRC) extramural unit for Stem Cell research and therapy at the university of Pretoria, says, ‘Stem-cell therapy is changing the way we practise medicine.’
It’s a bold statement. So, what makes stem cells so extraordinary? They are our body’s natural healing and rejuvenation system, dividing regularly to repair and replace worn-out or damaged tissues. They are also unlike other cells in the body as, regardless of their source, they have three general properties: they are prolific (capable of dividing and renewing themselves indefinitely), unspecialised and can give rise to specialised cell types.
Although stem-cell therapy is not new, scientists have taken a leap forward in terms of researching and harvesting stem cells. Innovative applications for their use have also made headlines. Who can forget the heartbreaking story of Pippie Kruger of Limpopo who, at the age of three, sustained third-degree burns on 85 percent of her body in a freak accident? Pippie’s treatment crossed the frontier of cutting-edge medicine when a plastic-like skin, grown from a small sample of her own skin, was cultivated in a lab in Boston in the US. The sheets of delicate skin were flown with an escort to South Africa and skilfully grafted onto her body.
The revolutionary use of stem cells to grow skin for a badly burnt toddler naturally drew a great deal of attention, but scientists and medical professionals are applying stem-cell therapy in their disciplines around the world. It’s unsurprising that stem cells, with their unique attributes and inherent mechanisms for healing, have the potential to treat an enormous range of conditions that plague millions of people across the globe.
Close to Miraculous
According to Professor Pepper, ‘the two most commonly utilised forms of adult stem cells are hematopoietic stem cells (HSCs), used for bone-marrow transplantation, and mesenchymal stem cells (MSCs), currently being tested for a variety of conditions in clinical trials around the world. HSCs are derived from bone marrow, peripheral blood (after mobilisation from bone marrow) and umbilical cord blood. Three common sources of MSCs are bone marrow, adipose tissue and Wharton’s jelly from the umbilical cord.
‘However, there are restrictions in terms of the miraculous properties of adult stem cells,’ he says. ‘they are what is called multipotent, which means they can’t generate any cell or tissue on command but they can create certain subsets of cell types. This means they have to be carefully targeted in their application.’
Pluripotent stem cells, on the other hand, are able to turn themselves into all the different cell types in the body. A miracle? Close enough. especially since they are very rare and only found naturally within very early embryos.
Until 2007 that is…
During the course of 2006 and 2007, Professor Shinya Yamanaka and colleagues at the university of Kyoto in Japan discovered a method of converting skin cells to stem cells (called induced pluripotent stem cells). He and British developmental biologist Sir John Gurdon of the Gurdon Institute at the University of Cambridge in the UK were awarded the Nobel Prize in Physiology or Medicine in 2012 for this breakthrough. Dr Janine Scholefield, senior researcher at the Council for Scientific and Industrial research (CSIR) Biosciences in Pretoria says, ‘this was really significant because pluripotent cells can be guided to become almost any cell type in the body.
To the best of our knowledge, our lab was the first to create these types of cells in South Africa, which we use for modelling “disease-in-a-dish”,’ she adds. They hold great potential for future stem-cell research and therapeutics. researchers globally continue to do extensive safety testing, until deemed ready for therapeutic application.
Apart from growing stem cells in a Petri dish, the best place to harvest stem cells is, of course, from the original production plant – the patient’s own body (autologous) or a stem-cell donor (allogeneic).
As they say, ‘medicine is not a perfect science’ and there are risks in using stem cells from a donor as they may be rejected. to avoid this, patients are placed on immunosuppressive therapy for life. There is also the possibility of the reverse, namely graft-versus-host disease, which is a potentially serious complication of bone- marrow transplantation.
The ‘Fifth’ Pillar
One of the increasingly possible and life-changing applications for stem cells is in neurological diseases (motor neuron disease, multiple sclerosis, Alzheimer’s disease, Parkinson’s disease and spinal-cord injuries). But Professor Pepper points out, ‘as far as I know, there is no official work being done in these areas. Some clinics are using stem cells for these conditions but this is not part of a registered clinical trial or of mainstream medicine. That said, the possible applications for stem-cell therapy continues to expand. There are hundreds of clinical trials on stem cells underway all over the world.’
Other applications include orthopaedics (osteoarthritis and cartilage and bone repair), sports’ injuries (cartilage and ligament repair), respiratory system diseases (emphysema), cardiology (heart-muscle regenerations) and blood circulation (critical limb ischemia).
Professor Pepper believes the most significant breakthrough internationally is for cancer. The foundations of cancer treatment have always been surgery, chemotherapy and radiation therapy. But over the past few years, immunotherapy, which solicits and fortifies the power of a patient’s immune system, has emerged as the ‘fifth pillar’ of cancer treatment, as oncologists call it. CAR T-cell therapy involves T cells being collected from a patient and are then engineered to recognise an antigen on targeted tumour cells. these cells are infused back into the patient. CAR-T cell therapy is being used to treat previously untreatable cancers with success.
Like most of nature’s resources, as we age, the number of stem cells decreases and become less efficient, which is where the science helps. gerontologists too, believe stem-cell technology is one of the most fascinating areas of modern biology and one of the pioneering ingredients in medicine.