Researchers presented the results of the first clinical trial for treating Huntington's disease using neural stem cells derived from pluripotent stem cells at the annual meeting of the International Society for Stem Cell Research in 2026. This marks an early step in testing a regenerative medicine approach against a neurodegenerative disease for which no disease-modifying treatment currently exists.

The trial, named REGEN4HD, is a two-phase study. Its first phase aims to evaluate the safety and tolerability of the treatment through gradual dose escalation, before moving to a later phase to determine the maximum tolerated dose.

Huntington's disease progressively affects the brain, causing deterioration in movement, cognitive abilities, and mental state. The disease is caused by a genetic defect that gradually damages neurons, particularly in brain regions involved in motor control, behavior, and cognitive functions.

Important milestone

The new approach aims to use neural stem cells derived from pluripotent stem cells to influence the disease environment in the brain, potentially supporting damaged neurons or compensating for some cell loss. However, researchers emphasized that the trial is still in its early stages, and questions about slowing disease progression or improving symptoms can only be answered after careful, step-by-step clinical evaluation.

The study enrolls patients with relatively early symptoms of Huntington's disease, aged between 18 and 65. According to the University of California, Irvine, the treatment, known as hNSC-01, is delivered directly to a deep brain region through an image-guided surgical procedure. This region is associated with the disease's effects on movement, decision-making, and motivation.

The study's lead author, Leslie Thompson, who has worked in Huntington's research for over 35 years, said that reaching the launch of the first trial of a product derived from pluripotent stem cells for Huntington's disease represents an 'important milestone' for the field, after years of preclinical research, safety studies, and regulatory discussions with the U.S. Food and Drug Administration.

She added that the initial goal of the study is to demonstrate safety, noting that if later studies show that a single-dose cell therapy can slow disease progression, it would have a major impact on patients. However, she emphasized that this hypothesis still requires careful clinical testing.

Scientific challenge

Developing a regenerative treatment for Huntington's disease poses a major scientific challenge because the disease progresses slowly over years, and targeting the brain requires precision in selecting the cell type, mechanism of action, delivery location, and method of measuring effects. Moreover, any cell therapy within the brain must undergo strict monitoring for short- and long-term safety risks.

The first patient received the treatment last May, and no serious adverse events related to the procedure were reported. A second patient is scheduled for treatment this month. These early results do not mean the treatment is effective, but they provide a first step in a long path to test whether regenerative medicine can offer a new option for Huntington's patients.

The researchers believe that the trial could open the door to larger studies if the early phases demonstrate that the treatment is safe and feasible. Exploratory measurements in the study will focus on detecting any biological or clinical signals that could guide the design of future trials, without being considered definitive evidence of efficacy at this stage.