New treatments are emerging that are still in the beginning clinical trial phases. Glucosamine injections may offer pain relief for some without precluding the use of more aggressive treatment options. In the US, artificial disc replacement is viewed cautiously as a possible alternative to fusion in carefully selected patients, yet it is widely used in a broader range of cases in Europe, where multi-level disc replacement of the cervical and lumbar spine is common. Adult stem cell or cell transplantation therapies for disc regeneration are in their infancy of development, but initial clinical trials have shown cell transplantation to be safe and initial observations suggest some beneficial effects for associated pain and disability. An optimal cell type, transplantation method, cell density, carrier, or patient indication remains to be determined. Investigation into mesenchymal stem cell therapy knife-less fusion of vertebrae in the United States began in 2006 and a DiscGenics nucleus pulposus progenitor cell transplantation clinical trial has started as of 2018 in the USA and Japan.