Biomimetic hybrid Liposome–Exosome nanoparticle: Shining a light on Theranostic agents in Breast cancer — A Systematic Review

Technical Summary: Biomimetic Hybrid Liposome–Exosome Nanoparticles for Breast Cancer Theranostics

Problem Statement
Conventional chemotherapy for breast cancer is frequently limited by systemic toxicity, poor tumor specificity, and uneven drug distribution. While traditional synthetic nanocarriers like liposomes offer improved drug loading and stability, they often suffer from rapid immune clearance, limited biocompatibility, and a lack of intrinsic targeting mechanisms. Conversely, exosomes possess natural biocompatibility, low immunogenicity, and inherent tumor-targeting capabilities; however, they are hindered by low drug-loading capacity, difficult scalability, and instability during storage. The integration of these two systems into a hybrid platform aims to synergize the structural versatility and high cargo capacity of liposomes with the biological functionality and targeting precision of exosomes.

Methodology
This study is a systematic review conducted in accordance with PRISMA guidelines. The authors searched the Web of Science, PubMed, and Scopus databases (as of July 31, 2025) using the query "exosomes" AND "liposome" AND "hybrid" AND "breast cancer."

• Selection Criteria: The review included only original research articles published in English that reported both in vitro and in vivo data regarding exosome-liposome hybrids for breast cancer therapy. Reviews, letters, and non-English articles were excluded.
• Data Extraction: Ten studies met the inclusion criteria. Data were extracted regarding study design, exosome sources (donor cells, isolation methods), liposome composition (lipid ratios, synthesis methods), hybridization techniques, cargo loading, characterization methods, and therapeutic outcomes.
• Quality Assessment: The risk of bias in the included in vivo studies was evaluated using the SYRCLE (Systematic Review Centre for Laboratory Animal Experimentation) risk of bias tool, assessing domains such as selection, performance, detection, attrition, and reporting bias.

Key Contributions and Results
The review analyzed ten studies (published between 2021 and 2025) involving various hybrid formulations (e.g., REV@SR780Fe@LEV-RS17, P-I@M1E/AAL, TEX-Liposome-PTX).

1. Hybrid Design and Fabrication:

   • Sources: Exosomes were derived from M1 macrophages, tumor cells (4T1, MDA-MB-231), platelets, and human plasma.
   • Synthesis: The predominant hybridization method was membrane fusion, utilizing techniques such as sonication, freeze-thaw cycles, and extrusion. A minority of studies used thin-film hydration where exosomes were incorporated during liposome formation.
   • Ratios: Most studies utilized a 1:1 ratio (by volume, weight, or particle number), though some explored variable protein-to-phospholipid ratios to optimize targeting.
   • Cargoes: Theranostic agents included chemotherapeutics (Doxorubicin, Paclitaxel, Docetaxel), photothermal/photodynamic agents (IR780, ICG, methylene blue), and immunomodulators. Loading strategies varied, including passive encapsulation, remote loading via pH gradients, and post-insertion.

2. Therapeutic Efficacy:

   • Mechanisms: The hybrids demonstrated enhanced cellular uptake, improved lysosomal escape, and the ability to induce immunogenic cell death (ICD). Several studies reported the repolarization of tumor-associated macrophages from an M2 (pro-tumor) to an M1 (anti-tumor) phenotype.
   • In Vivo Outcomes: In mouse models (primarily 4T1 tumor-bearing Balb/C mice), the hybrid systems consistently showed superior tumor growth suppression, prolonged survival rates, reduced metastasis, and lower systemic toxicity compared to free drugs or non-hybrid controls.
   • Safety: Most studies reported favorable biosafety profiles with no significant body weight loss or major organ damage.

3. Quality and Bias Assessment:

   • While the studies reported essential animal model details, significant methodological weaknesses were identified.
   • Selection Bias: Allocation concealment was not reported in any study, resulting in an "unclear" risk rating. Random sequence generation was unclear in two studies.
   • Performance Bias: Random housing and blinding of investigators were not reported in any study, leading to an "unclear" risk rating.
   • Detection Bias: Blinding of outcome assessors was reported in only one study; the rest were rated as unclear.
   • Other Biases: Three studies were rated as high risk due to reported conflicts of interest.

Significance and Limitations
The paper concludes that exosome-liposome hybrid nanovesicles represent a biologically synergistic and versatile platform for breast cancer treatment, effectively combining the targeting and biocompatibility of exosomes with the stability and loading capacity of liposomes. The review highlights that these systems can support multimodal therapeutic effects, including chemotherapy, phototherapy, and immunomodulation.

However, the authors emphasize that the translation of these systems to clinical practice is currently hindered by:

• Methodological Gaps: Inconsistent reporting of experimental controls, lack of randomization and blinding in preclinical studies, and poor reporting of hybridization protocols.
• Technical Challenges: Lack of long-term stability data, inconsistent cargo-loading efficiency, and the absence of scalable manufacturing processes compliant with Good Manufacturing Practice (GMP) standards.
• Clinical Translation: There is a distinct lack of clinical trials and standardized protocols required to move from preclinical success to clinical application.

The paper asserts that while the preclinical data is promising, advancing these systems requires rigorous bias control, standardized methods, and comprehensive pharmacokinetic and immunological studies.