In recent times much has been said about the promise of stem cells to heal and improve the quality of life of patients. As individuals grow older and lead more active lifestyles, orthopaedic surgeons are increasingly being called on to use their surgical techniques to improve patients’ quality of life. Earlier solutions to orthopaedic disorders required the use of metals and plastics to improve the mechanical environment for orthopaedic tissues. Newer research has aimed to improve the biologic environment for healing. One area that has shown a promising future is the use of stem cells to regenerate or repair tissues.
Stem cells or Pluripotent Stem Cells (PSCs) in broad terms, are cells that can self-replicate and differentiate into any cell line in the body. In this country, stem cells are usually taken from the patient (Adult Stem Cells) or from the umbilical cord (cord blood cells).
Mesenchymal stem cells (MSCs) are a subset of PSCs which are already committed to differentiating into muscle, bone, ligaments or tendons. Most orthopaedic research has been conducted using adult MSCs.
Fracture healing occurs through an organized process by which bone cells lay down bone. In certain traumatic situations, the defects are extensive and cannot be healed via the normal biologic process.
Several researchers have been able to isolate and purify MSCs from bone marrow and use them to heal these defects.
Disorders of the back and back pain result in significant morbidity and loss of productivity to our society. Most therapeutic solutions rely on conservative or nonsurgical treatment. In certain situations, removal of the degenerated intervertebral disc (IVD) and fusion can lead to a successful result.
Understanding the causes of degeneration and developing treatments to regenerate the IVD may help prevent these problems. When autologous MSCs were transplanted into a rabbit model of degenerative disc disease, the treated rabbits improved and achieved 91 per cent of the height of their discs 24 weeks after transplantation. However, research in using this technology in humans has been limited.
Injuries related to disruption or inflammation of ligaments or tendons are common and can result in significant morbidity to the active individual. When these tissues heal, the resulting scar tissue is of inferior quality. Cell-based therapy is actively being investigated as a new method of treating these injuries. MSCs have also been studied in the repair of meniscal injuries. Tears in the inner third region of the meniscus have a limited capability to heal due to the lack of blood supply. A recent study found that MSCs transplanted into this region of the meniscus in an animal model can result in tissue with better bonding capabilities. New studies are beginning to examine whether these same techniques can be used to improve the results of human meniscal repair.
The treatment of early stage arthritis or damaged cartilage and bone with MSCs has received a lot of interest in recent times. In fact, a paper from Stanford University (2011) showed that stem cells reside in multiple tissues in the body and participate in the repair of damaged tissue. These cells are replenished from the bone marrow and are transported to the injury site when needed. Therefore a promising strategy that we use is to reinforce the inherent healing capacity of the body by delivering MSCs harvested from the patients own body to the site of injury. These extra cells provide an added ‘boost’ to the healing process and support our concept of instant stem cell therapy.
As we orthopaedic surgeons attempt to improve patients’ quality of life, we will need to expand the techniques we use. In the past, surgeons used a combination of instrumentation and surgical technique to maximize results. As we improve our understanding of the biology of degenerative processes, we may turn to newer agents and more sophisticated techniques to improve quality of life.