In May 2026, Cell & Gene Therapy Insights published a major review systematically examining the current state of human induced pluripotent stem cell (hiPSC) applications in neurodegenerative disease modeling. This article distills the review's core findings and maps the key recombinant protein raw materials involved in this field.

01 Why hiPSC Matters

Research into neurodegenerative diseases — Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and others — has long been constrained by model systems. Animal models lack human physiological relevance, and post-mortem tissue can only provide static snapshots of end-stage disease. hiPSCs — pluripotent stem cells obtained by reprogramming somatic cells — resolve this dilemma: they are rapidly expandable, can differentiate into any neural cell type, and can carry patient-specific mutations. Since Yamanaka's lab first established iPSC technology in 2006, hiPSCs have become a standard platform for neurodegenerative disease research.

02 Two Main Approaches to Generating Neuronal Models

Generating neurons from hiPSCs currently follows two technical routes.

The first is the dual SMAD inhibition method. By using small molecules SB431542 and LDN193189 to inhibit TGF-β and BMP signaling pathways respectively, neural ectoderm differentiation is induced, yielding highly expandable neural progenitor cells (NPCs). NPCs can be further regionally patterned using molecules such as SHH, the Wnt agonist CHIR99021, and retinoic acid to generate neuron subtypes of specific brain regions — such as ventral midbrain dopaminergic neurons (a key model for PD research) or cervical spinal motor neurons (ALS models). This method offers strong expandability, but with higher cell population heterogeneity.

The second is the NGN2 overexpression method. By inserting a doxycycline-inducible NGN2 expression cassette into hiPSCs via gene editing, activation rapidly yields a uniform population of pure neurons. This approach is simple and easy to standardize, but limited in expandability.

Each route has its appropriate application scenarios, and researchers must weigh the trade-offs based on experimental objectives.

03 Disease-Specific Models Now Cover Major Neurodegenerative Diseases

Alzheimer's Disease (AD) Models: hiPSC-derived cortical neurons carrying APP gene duplications, PSEN1 mutations, or APOE4 risk alleles recapitulate pathological features including abnormal Aβ production, Tau phosphorylation, and endosomal enlargement. The 4R-P301S Tau overexpression model has revealed prion-like propagation mechanisms of Tau protein.

Parkinson's Disease (PD) Models: hiPSC-derived ventral midbrain dopaminergic neurons carrying SNCA triplication or LRRK2 G2019S mutations exhibit α-Synuclein accumulation, autophagy defects, and neuronal degeneration.

ALS/FTD Models: hiPSC-derived motor neurons and astrocytes carrying TDP-43 mutations or C9ORF72 repeat expansions recapitulate RNA metabolism abnormalities and neuroinflammation features.

Drug screening has already yielded clinical outputs. Risdiplam — an SMA therapeutic discovered through phenotypic screening of stem cell cultures — was approved for marketing in the EU in 2021. Bromocriptine for AD is currently in clinical trials.

04 Glial Cells: From Supporting Players to Disease Drivers

The most important conceptual shift of the past decade is the recognition that neurodegenerative diseases are not solely neuronal problems. Astrocytes and microglia are active participants in the pathological process.

Astrocytes: The APOE ε4 allele is the strongest risk factor for late-onset AD. APOE4 astrocytes display disrupted cholesterol metabolism, increased pro-inflammatory cytokine secretion, and impaired Aβ clearance capacity — collectively, these phenotypes directly drive AD pathology progression. hiPSC-derived astrocyte generation depends on JAK/STAT pathway activation (commonly using CNTF, LIF) and BMP signaling (BMP2/4), combined with FGF2 and EGF to promote NPC proliferation. SOX9/NFiB transcription factor overexpression can shorten differentiation time to 21 days.

Microglia: As the CNS's resident immune cells, microglia mediate chronic inflammation in neurodegeneration. LRRK2 G2019S mutant microglia directly induce dopaminergic neuron degeneration in co-culture. Microglial differentiation depends on M-CSF, IL-34, and TGF-β1. Transient overexpression of the PU.1 transcription factor alone can induce microglial fate.

05 From 2D to 3D: Co-Culture and Organoids

Single-cell-type cultures cannot recapitulate the complexity of the brain. Recently, a neuron-astrocyte-microglia triple culture system was established for the first time, with single-cell RNA sequencing revealing dramatic transcriptomic differences between co-culture and mono-culture conditions. hiPSC-derived 3D neural organoids go a step further, recapitulating regional spatial organization, axonal connectivity, and neuromelanin expression — features entirely absent in 2D culture.

06 Key Recombinant Proteins at a Glance

A summary of core recombinant proteins involved in this field:

Application

Key Proteins

07 SciproTech Relevant Products

Many recombinant proteins commonly used in hiPSC neural modeling are available in the SciproTech product line:

All products are manufactured under animal-origin-free conditions with high batch-to-batch consistency, suitable for establishing serum-free hiPSC-derived neural culture systems.

Conclusion

In less than two decades since iPSC technology was first reported in 2006, hiPSCs have evolved from a laboratory novelty into a mainstream platform for neurodegenerative disease research. The reevaluation of glial cell roles, the rise of 3D organoids, and the maturation of gene-editing tools are pushing this field to new heights. And none of these advances would be possible without a common foundation — high-quality, chemically defined recombinant protein raw materials.

Reference

Alliband DM, Willoughby LJ, Lane JD, Crompton LA. Human iPSC models of neurodegenerative disease: from application to therapy. Cell & Gene Therapy Insights 2026; 12(3), 326–354.