CAR‑Astrocyte Therapy: Single‑Injection Amyloid Clearance Reported in Mice

A report on CAR-astrocytes describes a preclinical approach in a mouse model of amyloid pathology. Investigators report peripheral, noninvasive AAV delivery to target CNS astrocytes with an anti–amyloid-β (Aβ) chimeric antigen receptor (CAR).

A single systemic administration is described as supporting broad brain expression and as being associated with prevention of Aβ accumulation and early plaque deposition when delivered before plaque onset, and a significant reduction of established amyloid burden when delivered after plaques were present. The report frames these outcomes as arising from engineered resident glia rather than transplanted cells, and the findings are presented as single-dose, mouse-only observations.

The abstract describes creating CAR-expressing astrocytes (CAR-A) by fusing an anti-Aβ single-chain variable fragment (scFv) to intracellular domains of selected phagocytic receptors to enable recognition, phagocytosis, and degradation of Aβ42 oligomers. For CNS targeting, investigators report systemic delivery with AAV-PHP.eB-GFAP to drive astrocyte expression broadly across the brain. This strategy is presented as a way to leverage an abundant glial population and as a platform whose intracellular signaling can be tuned, described as conceptually complementary to other Aβ clearance approaches. The delivery approach and promoter choice are described as enabling CNS-wide astrocyte transduction following peripheral administration.

The abstract reports two timing scenarios for in vivo evaluation. When administered before plaque onset, it describes prevention of Aβ accumulation and early plaque deposition with associated pathology for 2.5 months. When administered after plaque formation, it reports a significant reduction in amyloid burden within three months, accompanied by reduced neuritic dystrophy. These tissue-pathology readouts are presented in relation to when CAR-A delivery occurred relative to plaque development.

For construct selection, the abstract reports generating four FcRγ-independent anti-Aβ CAR designs and evaluating them in vitro, with two constructs selected for in vivo CNS delivery. One selected construct, Cre-Megf10, is described as a crenezumab-derived scFv linked to the phagocytic domain of MEGF10; the second (Adu-Dectin1) is described as an aducanumab-derived scFv linked to the phagocytic domain of Dectin1. The abstract notes that these constructs were examined with single-nucleus RNA sequencing and immunostaining to characterize glial responses in vivo, and it emphasizes these two CAR designs as the in vivo exemplars.

For cellular-state readouts, the abstract reports that both CAR designs induced disease-associated astrocyte states, while microglia shifted toward more homeostatic signatures with reduced exhaustion signatures, with shared glial signatures including disease-associated astrocytes and activated microglial populations. It also reports partially divergent downstream programs, describing Cre-Megf10 as acting mainly on astrocytic states and Adu-Dectin1 as additionally engaging microglial activation through astrocyte–microglia communication. As a caveat and forward-looking statement, the abstract notes that continued optimization will be needed to maximize amyloid clearance while preserving neuronal integrity and minimizing off-target effects.

Key Takeaways:

• The abstract reports peripheral, noninvasive AAV-PHP.eB-GFAP delivery to drive CNS-wide astrocyte expression of anti-Aβ CAR constructs in mice.
• Investigators describe prevention of Aβ accumulation and early plaque deposition with early delivery and a significant reduction in established amyloid pathology with post-plaque delivery over the reported follow-up periods.
• Single-nucleus RNA sequencing and immunostaining are reported to show disease-associated astrocyte states and shifts in microglial signatures toward more homeostatic states with reduced exhaustion signatures, alongside construct-dependent downstream programs.