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Dual-Targeting of Tumor Cells and Neovasculature for Synergistic Photoimmunotherapy: A CD105 Nanobody-Driven Nanoplatform Reprograms the Immune Microenvironment

This study presents a CD105 nanobody-functionalized layered double hydroxide nanoplatform that delivers indocyanine green for synergistic photodynamic/photothermal therapy, effectively reprogramming the tumor immune microenvironment by inducing immunogenic cell death and robust T-cell responses to suppress tumor growth and angiogenesis.

Original authors: Xuandong Lin, Sandar Moe Moe Sint, Qing Huang, Shuai Li, Xueling Ma, Liji Mo, Hao Zhang, Jindong Long, Xintong Xie, Fangfang Xie, Xiaomei Yang, Hongbing Liao

Published 2026-06-26

📖 5 min read🧠 Deep dive

CC BY 4.0

Original authors: Xuandong Lin, Sandar Moe Moe Sint, Qing Huang, Shuai Li, Xueling Ma, Liji Mo, Hao Zhang, Jindong Long, Xintong Xie, Fangfang Xie, Xiaomei Yang, Hongbing Liao

Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). ✨ This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer

Imagine you are trying to destroy a fortress (a tumor) that is hiding deep inside a city. The problem with traditional methods is that they are like throwing a net over the whole city; they catch some bad guys, but they miss the ones hiding in the back alleys, and they often accidentally hurt the innocent civilians (healthy tissue) nearby.

This research paper describes a new, high-tech "smart missile" designed to solve these problems. Here is how it works, broken down into simple steps:

1. The Target: A "Name Tag" on the Enemy

The researchers found that the enemy fortress (the tumor) and the roads leading to it (the blood vessels feeding the tumor) both wear a specific "name tag" called CD105. Healthy roads and buildings in the city usually don't have this tag.

The Problem: Old drugs are like blindfolded soldiers; they wander around hoping to bump into the enemy.
The Solution: The team created a tiny "smart seeker" called a Nanobody. Think of a Nanobody as a super-accurate GPS tracker that is much smaller and more agile than a regular antibody. It is programmed to lock onto that specific "CD105" name tag and ignore everything else.

2. The Vehicle: A "Smart Truck"

They needed a vehicle to carry the weapon to the target. They chose a Layered Double Hydroxide (LDH).

The Analogy: Imagine a microscopic, flat, sandwich-like truck. This truck is special because it is biocompatible (safe for the body) and has a "smart release" feature. It stays closed while driving through the body, but when it hits the tumor's acidic environment (like a secret password), it opens up to release its cargo.

3. The Weapon: A "Double-Strike" Bomb

Inside this smart truck, they loaded a dye called ICG. This isn't just any dye; it's a dual-purpose weapon:

Strike A (Heat): When hit by a specific laser light (Near-Infrared), it turns into a heater, cooking the tumor cells from the inside out (Photothermal Therapy).
Strike B (Poison): The same laser light makes the dye create toxic "oxygen bubbles" (Reactive Oxygen Species) that shred the cells from the inside (Photodynamic Therapy).

Why combine them? The heat from Strike A opens up the blood vessels, letting more oxygen in, which makes Strike B (the poison) work even harder. It's a 1+1=3 effect.

4. The Mission: How It Plays Out

Here is the step-by-step story of the experiment described in the paper:

The Delivery: The "Smart Truck" (CD105 Nb-LIN) is injected into the bloodstream. Because it has the GPS tracker (Nanobody) on its side, it ignores healthy tissues and zooms straight to the tumor and its blood supply, sticking to the CD105 name tags.
The Trigger: Once the truck is parked at the tumor, the doctors shine a special laser on the area.
The Explosion: The laser wakes up the truck. It releases the dye, which immediately starts cooking the cells and creating toxic oxygen bubbles.
The "Wake Up" Call (Immune System): This is the clever part. When the tumor cells die this specific way, they don't just vanish quietly. They scream for help. They release "distress signals" (molecules like ATP and HMGB1).
- The Analogy: It's like the fortress blowing its own whistle to alert the police. These signals wake up the body's immune system (specifically the "Dendritic Cells" and "T-Cells").
- The Result: The immune system realizes, "Oh, there's a tumor here!" and sends in its own elite soldiers (CD8+ T-cells) to finish the job and hunt down any remaining bad cells.

5. The Results: What Happened in the Lab?

The researchers tested this on mice with liver and pancreatic tumors:

Precision: The smart trucks piled up only at the tumor, not in the liver or kidneys (where drugs usually get stuck).
Effectiveness: The tumors were almost completely wiped out. The "Smart Truck" + Laser combo worked much better than just the laser or just the truck alone.
Safety: The mice didn't get sick, lose weight, or suffer organ damage. The "truck" is safe, and the "bomb" only goes off where the laser is pointed.
Immune Boost: In a special test using human immune cells, the treatment didn't just kill the tumor; it turned the tumor area into a "training ground" where the body's own immune cells learned to attack the cancer.

Summary

The paper claims to have built a smart, dual-targeting nanoplatform. It uses a tiny, agile tracker (Nanobody) to deliver a heat-and-poison bomb (ICG in LDH) directly to tumor cells and their blood supply. When activated by a laser, it destroys the tumor and simultaneously sounds an alarm to wake up the body's immune system to help fight the cancer.

Key Takeaway: It's a "targeted delivery + double attack + immune wake-up call" strategy that the authors say works very well in mice without hurting the rest of the body.

Technical Summary: Dual-Targeting of Tumor Cells and Neovasculature for Synergistic Photoimmunotherapy

Problem Statement
The clinical translation of combined photodynamic therapy (PDT) and photothermal therapy (PTT) for solid tumors is currently hindered by three primary limitations: insufficient intratumoral accumulation of therapeutic agents, lack of targeting specificity, and weak activation of antitumor immunity. Conventional nanotherapeutic systems rely heavily on the enhanced permeability and retention (EPR) effect, which is often unreliable in early-stage tumors with intact vasculature and leads to non-specific accumulation in healthy organs (e.g., liver, spleen). Furthermore, traditional antibody-based targeting strategies suffer from large molecular weights, poor tissue penetration, and potential immunogenicity, limiting their efficacy in deep tumor cores. There is a critical need for a precision delivery system that can simultaneously target tumor cells and neovasculature, penetrate dense tumor matrices, and reprogram the immunosuppressive tumor microenvironment (TME).

Methodology
To address these challenges, the authors engineered a CD105 nanobody (Nb)-functionalized layered double hydroxide (LDH) nanoplatform, designated as CD105 Nb-LIN.

Nanoplatform Construction: The system utilizes biocompatible LDH nanosheets as a carrier. Indocyanine green (ICG), a photosensitizer capable of both ROS generation and photothermal conversion, was intercalated into the LDH layers to form LI. Subsequently, a CD105-specific nanobody (Nb), screened for high affinity and thermostability, was conjugated to the surface of the LI nanoparticles via non-covalent modification.
Targeting Mechanism: CD105 (endoglin) is a co-receptor in the TGF-β pathway, selectively overexpressed on tumor neovascular endothelial cells and certain malignant cells, while minimally expressed in normal tissues. The CD105 Nb enables active dual-targeting of both tumor cells and the tumor vasculature.
Therapeutic Strategy: The nanoplatform is designed for synergistic PDT/PTT. Upon near-infrared (NIR) irradiation (808 nm), the system generates singlet oxygen ( $^1O_2$ ) and heat. Crucially, the LDH carrier exhibits pH responsiveness, facilitating controlled release and enhanced ROS generation in the acidic tumor microenvironment (pH < 6.5).
Immune Modulation: The study investigates the induction of immunogenic cell death (ICD), characterized by the secretion of damage-associated molecular patterns (DAMPs) such as ATP, calreticulin (CRT), and HMGB1. This is hypothesized to drive dendritic cell (DC) maturation and subsequent CD8+ cytotoxic T lymphocyte (CTL) infiltration.
Experimental Models: The efficacy was evaluated using:
- In vitro: Various cell lines including HepG2 (hepatocellular carcinoma), PANC-1 (pancreatic cancer), HUVECs, and HemECs.
- In vivo: Subcutaneous HepG2 tumor models in BALB/c nude mice for direct antitumor efficacy and biosafety.
- Humanized Models: NOD/SCID mice reconstituted with human PBMCs and intratumorally injected with THP-1-derived immature DCs to evaluate adaptive immune responses in a human immune context.

Key Results

Material Characterization: The CD105 Nb-LIN nanoparticles (~112 nm) exhibited successful intercalation of ICG and surface conjugation of the Nb. The system demonstrated pH-responsive singlet oxygen generation (enhanced at pH 5.0) and superior photothermal stability compared to free ICG, maintaining efficacy over multiple laser cycles.
Targeting and Internalization: Flow cytometry and confocal microscopy confirmed that CD105 Nb-LIN achieved significantly higher binding and internalization in CD105-positive cells (HepG2, PANC-1, HemECs) compared to non-targeted controls. The targeting was specific, as evidenced by reduced binding in CD105-negative cells and when the Nb was blocked by recombinant CD105 protein.
Synergistic Cytotoxicity: In vitro assays revealed that CD105 Nb-LIN combined with NIR irradiation induced potent dose-dependent cytotoxicity and apoptosis (via mitochondrial damage and oxidative stress) in tumor cells and endothelial cells, with an IC50 significantly lower than free ICG or non-targeted LI.
Transcriptomic Insights: RNA sequencing of treated HepG2 cells revealed upregulation of stress-response genes (FOS, JUN, AP-1) and activation of apoptosis pathways (IL-17, TNF, MAPK signaling). Notably, the heat shock protein gene HSPG2 was significantly downregulated, suggesting a disruption of survival mechanisms under combined thermal and oxidative stress.
Immune Activation (In Vitro): Treatment with CD105 Nb-LIN triggered ICD, leading to the maturation of THP-1-derived DCs (increased CD80/CD86 expression) and robust proliferation of CD8+ CTLs in co-culture systems.
In Vivo Antitumor Efficacy: In BALB/c nude mice, CD105 Nb-LIN + NIR irradiation resulted in near-complete tumor ablation and significant suppression of angiogenesis (reduced CD31+ vessels) without systemic toxicity. Histology confirmed extensive necrosis and high CRT expression (an "eat-me" signal).
Humanized Model Findings: In NOD/SCID mice with human immune systems, the treatment promoted the maturation of intratumorally injected DCs and significantly increased the infiltration of human CD8+ CTLs within the tumor. Interestingly, while DCs did not migrate to lymph nodes (likely due to vascular/lymphatic damage from therapy), they activated T cells in situ. This was accompanied by elevated levels of pro-inflammatory cytokines (hTNF-α, hIFN-γ, hIL-2), indicating a shift from a "cold" to a "hot" TME.

Significance and Claims
The paper claims to establish an integrated therapeutic paradigm of "targeted delivery–synergistic PDT/PTT–immune activation" for CD105-overexpressing solid tumors.

Dual-Targeting Precision: The study demonstrates that CD105 nanobodies overcome the limitations of traditional antibodies by enabling deep tissue penetration and simultaneous targeting of both tumor cells and the neovasculature, effectively addressing the "off-target" and "insufficient accumulation" problems.
Synergistic Mechanism: The work provides mechanistic evidence that the LDH carrier not only enhances the stability and efficacy of ICG but also facilitates pH-responsive ROS generation, creating a synergistic effect that lowers the ablation threshold for tumor cells.
In Situ Immune Activation: A key contribution is the demonstration that this nanoplatform can reprogram the TME by inducing ICD and activating CD8+ T cells directly within the tumor site, independent of lymph node trafficking. This offers a novel strategy to circumvent DC migration barriers and convert immunologically cold tumors into hot ones.
Safety and Translation: The system exhibits favorable biosafety profiles in both nude and humanized mouse models, with no significant organ toxicity or systemic weight loss, supporting its potential as a low-toxicity, precision photoimmunotherapy strategy.

The authors conclude that this nanoplatform provides a robust experimental foundation for Nb-mediated tumor-targeted photoimmunotherapy, offering a promising avenue for treating solid malignancies that rely on CD105 expression.