Types of Neurodegenerative Disease: Which Ones Are Being Studied With Stem Cell Therapy?

What This Article Covers

"Neurodegenerative disease" is not one condition but a family of them, and stem cell research has not moved into that family evenly. Some subtypes — Parkinson's disease chief among them — now have transplanted, lab-grown neurons sitting in human brains with early safety data in hand. Others, including Alzheimer's disease and multiple system atrophy (MSA), have real but much smaller and earlier trials whose signals are encouraging but far from proof. Still others, like frontotemporal dementia (FTD) and Lewy body dementia, have barely reached the human-trial stage at all. This overview maps where each major subtype actually stands today — not as a ranking of hope, but as an honest reading of trial phase, sponsor, and evidence quality — so readers can tell a Phase 1 safety signal apart from an approved treatment, because right now, none of what follows is either.

Why This Category Looks So Uneven

Cell therapies are built around a specific loss: a population of neurons that dies off in a fairly predictable pattern. That structure is why Parkinson's — where dopamine-producing neurons in one small brain region die — became the proving ground: scientists can replace one defined cell type in one defined location. Alzheimer's, FTD, and Lewy body dementia involve more diffuse, more molecularly tangled damage (amyloid, tau, alpha-synuclein, TDP-43, spread across whole cortical networks), which is harder to address by dropping in replacement cells. That single structural difference explains much of the gap in trial maturity below.

Parkinson's Disease: The Most Advanced Cell-Therapy Pipeline

Parkinson's has the deepest bench of active programs. The academic STEM-PD trial, running at Skåne University Hospital in Sweden since February 2023, has already transplanted lab-grown, stem cell-derived dopamine neurons into patients' brains in a Phase 1 study; safety data has been maturing, and the program (now under Cellular Intelligence after Novo Nordisk's involvement) has a Phase 2 trial planned for late 2026 into 2027 (ReNEW/University of Copenhagen, 2026). Parallel programs, including autologous iPSC-derived dopamine neuron transplants and BlueRock Therapeutics' bemdaneprocel, are running similar early-phase human trials. No program has reported a cure, and dyskinesia and immune-suppression risks remain real concerns — but Parkinson's is unambiguously the furthest along of any neurodegenerative disease.

Huntington's Disease: A First-in-Human Milestone

Huntington's disease, caused by a known single-gene mutation, has just entered a genuine human-trial era. The REGEN4HD trial at UC Irvine — a Phase 1b/2a study backed by the California Institute for Regenerative Medicine — has dosed its first participant with neural stem cells (hNSC-01) implanted directly into the striatum, the brain region hit earliest in Huntington's (UCI Health, 2025; HDBuzz, 2026). A separate first-in-human study is also testing dental pulp-derived stem cells given intravenously. These are safety-focused, small-enrollment trials years from any efficacy verdict, but the "first patient dosed" milestone is a real and meaningful step.

ALS: Hard Lessons and a Second Try

ALS's stem cell story is a useful reminder that early promise doesn't guarantee later success. BrainStorm Cell Therapeutics' NurOwn (autologous mesenchymal stem cells engineered to secrete neurotrophic factors) showed encouraging signals in Phase 2 but failed to meet its primary endpoint in a completed Phase 3 trial, and the FDA concluded the data didn't demonstrate benefit (ALS News Today, 2021). Rather than folding, BrainStorm is now advancing under an FDA Special Protocol Assessment agreement into ENDURANCE, a new ~200-patient Phase 3b confirmatory trial (SEC filing, 2025). That is the honest state of ALS cell therapy: one rigorous trial that didn't pan out, and one more underway to find out if a different population or protocol does better.

Alzheimer's Disease: Encouraging Early Signals, Still Thin Evidence

Alzheimer's has the thinnest stem cell evidence base of any well-known subtype, but not a nonexistent one. A Phase 1 trial from Regeneration Biomedical, using patients' own adipose-derived stem cells delivered directly into the brain's ventricles, reported that a majority of participants showed improved cognitive scores and biomarker shifts (reduced phosphorylated tau, improved amyloid PET readings) at 12 weeks (NeurologyLive, 2025). That's genuinely worth watching, and a roughly 115-person Phase 2 trial is now planned. But this remains a single small, open-label study — the kind of result that needs a controlled trial to hold up, not evidence of a working treatment.

Multiple System Atrophy: Small Trials Asking Big Questions

MSA, a rarer and faster-progressing Parkinson's-related disorder, has been tested with intrathecal (spinal-fluid) mesenchymal stem cell injections in dose-escalation safety trials, including an NIH/NINDS-supported study and earlier controlled work suggesting a possible slowing of decline. These trials are explicitly framed around safety and tolerability first; MSA's rapid course makes it an attractive but high-risk area to study, and results so far are preliminary.

Frontotemporal and Lewy Body Dementia: Barely Off the Ground

FTD has a handful of very early efforts — a CIRM-funded project developing iPSC-derived microglia, and small early trials of stem cell-derived or exosome-based products — but nothing yet at the scale of the trials above. Lewy body dementia has essentially no dedicated stem cell trials in progress. For both, "being studied" currently means laboratory and earliest human-safety work, not anything a patient could realistically access as an established option.

Bottom Line

Stem cell research for neurodegenerative disease is real, active, and in places genuinely encouraging — but it is not one story. Parkinson's disease has the most mature pipeline, with human transplants and a path toward Phase 2 efficacy testing. Huntington's just reached its first-in-human milestone. ALS shows how a promising early signal can fail a rigorous Phase 3 and still deserve a second, better-designed attempt. Alzheimer's and MSA have real but small, early trials that need replication before they mean much. Frontotemporal and Lewy body dementia remain largely preclinical. None of this is FDA-approved as a treatment or cure for any of these conditions — it is investigational science at different stages of a long process, and trial phase is the single most useful number for telling those stages apart.