**Paper:** [Impact of high-power short-duration atrial fibrillation ablation technique on the incidence of silent cerebral embolism: a prospective randomized controlled study](https://doi.org/10.1186/s12916-023-03180-3)

**Authors:** Wei-Jie Chen, Chun-Xia Gan, Yang-Wei Cai, Yang-Yang Liu, et al.

**Journal:** BMC Medicine, 2023

**Why it matters:** Even when catheter ablation successfully restores heart rhythm, microscopic clots can silently lodge in the brain — and this trial tests whether a next-generation cooling catheter actually reduces that hidden risk.

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**Summary**

Catheter ablation for atrial fibrillation (AF) — where radiofrequency energy is used to scar the tissue driving abnormal electrical signals — is highly effective, but the heat applied to actively circulating blood can generate micro-emboli (tiny clots and gaseous particles) that travel to the brain. These "silent cerebral embolisms" (SCEs) produce no immediate symptoms yet show up as new lesions on sensitive imaging in a substantial fraction of patients. This trial asked whether a high-power short-duration (HPSD) strategy, delivering 50 W through a Smart Touch Surround Flow (STSF) catheter — which features 56 circumferential irrigation holes designed to aggressively cool the electrode-tissue interface — reduces SCE incidence compared to the conventional 30–35 W approach using a standard Smart Touch (ST) catheter.

One hundred AF patients were randomized 1:1. High-resolution diffusion-weighted MRI (1 mm slice thickness on a 3.0 T scanner) was performed before and 24–72 hours after ablation to detect new lesions, with cognitive function assessed by the Montreal Cognitive Assessment (MoCA) at baseline, immediately post-procedure, and at three months. The HPSD technique was procedurally faster and required less irrigation fluid, confirming it delivered on its engineering promise. However, SCE rates were nearly identical: 44% in the HPSD group versus 40% in the conventional group (p = 0.685), with no significant differences in lesion count, maximum diameter, or total lesion volume.

Multivariable regression identified persistent AF and a high CHA₂DS₂-VASc score (a validated stroke-risk metric) as the only independent predictors of SCE — not the catheter type or ablation duration. The finding suggests that sluggish, turbulent blood flow in a structurally remodeled, dilated left atrium overwhelms any cooling advantage the hardware provides. Reassuringly, patients who developed SCEs showed no detectable cognitive decline at three months compared to those with clean scans. A key limitation is the relatively small sample of 100 patients, which may have been underpowered to detect modest differences.

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**Three takeaways**

1. The HPSD/STSF approach produced SCEs in 44% of patients versus 40% with conventional ablation — a difference that was not statistically significant (p = 0.685), meaning the advanced cooling catheter conferred no measurable brain protection.

2. Multivariable regression showed that persistent AF and CHA₂DS₂-VASc score — markers of adverse cardiac remodeling and baseline thrombotic risk — were the only independent predictors of SCE, with catheter type and ablation duration eliminated as predictors.

3. Despite 106 new lesions detected across 42 patients (92% in the telencephalon), MoCA scores were stable at both the immediate post-procedure and three-month assessments, suggesting micro-lesions of this scale do not translate to detectable short-term cognitive decline.

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**Read the paper:** [https://doi.org/10.1186/s12916-023-03180-3](https://doi.org/10.1186/s12916-023-03180-3)

**Paper:** [Improving mitochondria and ER stability helps eliminate upper motor neuron degeneration that occurs due to mSOD1 toxicity and TDP‐43 pathology](https://doi.org/10.1002/ctm2.336)

**Authors:** Barış Genç, Mukesh Gautam, Öge Gözütok, Ina Dervishi, Santana Sanchez, et al.

**Journal:** Clinical and Translational Medicine, 2021

**Why it matters:** NU-9 is the first compound shown to halt upper motor neuron degeneration — the cortical neurons whose loss defines ALS, primary lateral sclerosis, and hereditary spastic paraplegia — by physically restoring the structural integrity of mitochondria and the endoplasmic reticulum in living animals.

**Summary**

Upper motor neurons (UMNs), the cortical cells that issue commands for voluntary movement, degenerate in ALS, primary lateral sclerosis (PLS), and hereditary spastic paraplegia (HSP), yet have been largely overlooked in drug development because they are difficult to isolate and monitor in vivo. To address this, the researchers crossed disease mouse models — one driven by misfolded SOD1 protein (mSOD1) toxicity, another by TDP-43 pathology — with a UCHL1-eGFP reporter line that labels UMNs with green fluorescent protein, enabling direct visualization and quantification of these specific neurons during treatment. Electron microscopy revealed that both genetic triggers, despite operating through distinct molecular pathways, converge on the same organelle-level destruction: mitochondria lose their cristae (the inner membrane folds essential for energy production), the endoplasmic reticulum (ER) cisternae fracture and detach from ribosomes, and the apical dendrite — the neuron's primary signal-receiving antenna — becomes riddled with vacuoles. Critically, this pattern of damage was also observed in postmortem tissue from human ALS patients, validating the mouse model at the ultrastructural level.

The compound NU-9, identified from a screen of over 50,000 candidates, was administered orally once daily from postnatal day 60 to day 120 in both disease models. At 100 mg/kg/day, NU-9 demonstrated 94% oral bioavailability, robust blood-brain barrier penetration, and no cardiac or systemic toxicity at therapeutic doses. Electron microscopy at end stage showed near-complete restoration of mitochondrial cristae (healthy mitochondria rising from 10% to 86% of the total pool), reassembly of intact ER cisternae with attached ribosomes, and clearance of apical dendrite vacuoles. UMN counts in treated disease mice matched those of healthy wild-type controls, and treated mice performed significantly better on the hanging wire test. One important caveat: NU-9 had no protective effect on lower motor neurons in the spinal cord, which continued to degenerate at the same rate as in untreated controls — underscoring that upper and lower motor neurons have fundamentally different cellular vulnerabilities.

**Three takeaways**

1. Mitochondrial cristae loss and ER fragmentation are convergent structural pathologies in UMNs regardless of whether the upstream trigger is mSOD1 toxicity or TDP-43 pathology, and the same damage pattern is seen in postmortem human ALS tissue.

2. NU-9 treatment at 100 mg/kg/day restored the proportion of structurally healthy mitochondria from ~10% to ~86%, fully reassembled ER cisternae, and cleared apical dendrite vacuoles — returning UMN architecture to wild-type baseline in vivo.

3. NU-9 preserved UMN populations at healthy control levels and improved motor behavior on the hanging wire test, but provided no protection to lower motor neurons, demonstrating that the two neuron populations have distinct survival requirements within the same motor circuit.

**Read the paper:** https://doi.org/10.1002/ctm2.336

**Paper:** [A trophoblast glycoprotein specific 5T4-Vδ2 bispecific T cell engager recruits Vγ9Vδ2-T cells for tumor-selective cytotoxicity across solid malignancies](https://doi.org/10.1016/j.clim.2026.110707)

**Authors:** Milon de Jong, Rok Žiberna, Myrthe Veth, Elisabetta Michielon, et al.

**Journal:** Clinical Immunology, 2026

**Why it matters:** Solid tumors have largely resisted bispecific T cell engager therapies due to on-target toxicity in healthy tissue, and this study presents a strategy using gamma-delta T cells that may sidestep that problem.

**Summary**

Bispecific T cell engagers (bsTCEs) are antibody-like molecules that physically link a tumor antigen to a T cell receptor, forcing immune cells into proximity with cancer cells. While highly effective in blood cancers, their use in solid tumors has been hampered by "on-target off-tumor" toxicity — damage to healthy tissues that express the same antigen being targeted. This study addresses that problem by focusing on two components: the tumor antigen 5T4 (trophoblast glycoprotein), an oncofetal protein broadly overexpressed across solid malignancies but largely absent from healthy adult tissue, and Vγ9Vδ2-T cells, a subset of gamma-delta T cells known for potent anti-tumor activity and an intrinsic capacity to discriminate between stressed tumor cells and normal tissue.

The researchers developed high-affinity VHHs — single-domain antibody fragments derived from camelid antibodies — specific to 5T4, and linked them to a VHH targeting the Vδ2 T cell receptor to create the 5T4-Vδ2 bsTCE. They validated 5T4 expression across a broad panel of solid tumor types and then tested the engager in both conventional 2D cell cultures and more clinically representative 3D patient-derived tumor models. In these systems, the bsTCE triggered robust Vγ9Vδ2-T cell activation, proinflammatory cytokine production, and tumor cell lysis. Critically, when the construct was tested against healthy tissues that do express 5T4 at low levels, Vγ9Vδ2-T cell cytotoxicity was not observed — suggesting that the gamma-delta T cell arm of the engager contributes an intrinsic selectivity that conventional alpha-beta T cell engagers lack. One caveat is that these remain preclinical findings, and whether the tumor-preferential activity holds in the more complex immunosuppressive environment of human tumors in vivo will require clinical investigation.

**Three takeaways**

1. The 5T4-Vδ2 bsTCE induced potent Vγ9Vδ2-T cell-mediated killing and cytokine production in both 2D and 3D patient-derived solid tumor models.

2. 5T4 protein was expressed across the majority of solid malignancies evaluated, supporting its utility as a broad-spectrum therapeutic target.

3. Despite low-level 5T4 expression on some healthy tissues, the bsTCE did not trigger Vγ9Vδ2-T cell cytotoxicity against those tissues, demonstrating tumor-preferential activity in preclinical testing.

**Read the paper:** https://doi.org/10.1016/j.clim.2026.110707

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