Patients in the Netherlands have been warned against having controversial stem cell treatment for conditions such as multiple sclerosis and spinal chord injuries.

The Dutch Health Care Inspectorate issued the warning before the end of an investigation into two private clinics that offer such treatment because of “media attention.” The clinics are the Preventive Medicine Clinic in Rotterdam and Cells4Health, based near Zutphen.

These clinics claim to have had successful results with the techniques, for which the Health Care Inspectorate says there is “no scientific proof.” Such treatment is banned in the United Kingdom but not in the Netherlands.

The investigation follows complaints from leading Dutch neurologists. …