Stem cell therapies, and cell therapies in general, have tremendous promise in treating age-related conditions, particularly those that lead to structural damage in the body, such as degenerative disc disease. While animal studies have produced very interesting results, these therapies have yet to achieve more than initial goals in clinical practice, however. Hematopoietic stem cell transplants work well for the uses they are put to, albeit while being a comparatively stressful, higher risk procedure. Immunotherapies based on cell transplants are quite well advanced in the cancer field. First generation mesenchymal stem cell transplants are quite good at suppressing chronic inflammation for a time, but increased regeneration is an unreliable outcome at best. In general, regeneration through cell therapy remains an elusive goal in the clinic.
In part, this is likely because it is hard to manage cells in culture. Small differences in implementation of a protocol for sourcing and growing cells used in therapy can cause large differences in the quality of the cells. Two clinicians performing the same work, with the same protocol, in different clinics may produce widely varying outcomes for patients. This has been very evident in the delivery of mesenchymal stem cell therapies.
Beyond first generation therapies, delivery of cells that are more specialized to the target tissue has produced promising results in animal studies. Thymic regrowth can be engineered by injection of suitable cells, while numerous different approaches to delivering cardiomyocyte cells or their progenitors have produced heart regeneration. Clinical trials of numerous varieties of the more sophisticated forms of cell therapy have been undertaken. Certainly, cell therapies in animals have produced good results in models of disc degeneration. But it seems there is a way to go yet before this sort of therapy is widely used in the clinic. The regulators make stringent quality and reliability demands on developers, and these are not easy goals to reach at present.
With the acceleration of population aging, the incidence of spinal degenerative diseases has increased significantly, and the main sign is chronic low back pain, which seriously affects patients' quality of life and increases the economic burden on their family and society. Although the aetiologies of spinal degenerative diseases are varied and complex, intervertebral disc degeneration (IDD) is recognized as one of the most important causes. Degenerative disc diseases (DDDs) arising from IDD comprise a series of painful spinal diseases that include discogenic low back pain and lumbar disc herniation. At present, most patients use rest or conservative treatment for pain relief, as well as a variety of drugs such as steroids, local anaesthetics, and other blocking agents. When these methods are ineffective, surgery is often performed to relieve symptoms and improve quality of life. Surgical treatments can also solve pain problems, but have disadvantages such as inability to replace decreased nucleus pulposus (NP) cells, inability to reverse the pathological state of the intervertebral disc (IVD), and potential to cause various intraoperative and postoperative complications.
In recent years, with the rapid development of stem cell technologies that have been effectively applied in haematology, circulation, orthopaedics, and other fields, stem cells have attracted the attention of researchers and clinicians. With in-depth studies on the IVD and IDD as well as its mechanism, many teams have found that combination of stem cell technology and treatment for IDD can not only maintain the normal physiological function and structure of the IVD, but even reverse the IDD cascade. Organic combination of the IVD and stem cell technology has outstanding advantages for IDD treatment and recovery, but remains controversial.
Although cell therapy appears to have great potential for IVD regeneration, there remains a lack of relevant evidence regarding safety, long-term complications, effectiveness in different patient populations, and surgical cost-effectiveness. Further development of stem cell technology and in-depth exploration of IDD in the medical community will determine the future development direction of the organic combination of stem cells and IDD research. First, we need to further explore the interactions between stem cell repair mechanisms and target cells, and strive to identify more targets that promote differentiation. Second, we need to find ways to improve the harsh microenvironment in IDD to provide a better living environment for loaded stem cells. Third, we need to establish methods that can induce and differentiate stem cells from different sources more efficiently and stably, thereby improving the safety of stem cell application. Last, but not the least, it is necessary to optimize the performance of stem cell carrier materials to avoid secondary damage during implantation and further enhance the repair ability of stem cells.