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The Optimization of Self-Assembled Coacervate Drug Delivery Systems to Enhance Uptake by Macrophages and Their Polarization Towards an Anti-Inflammatory Phenotype

Delzendeh Rooy, Alireza | 2025

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 58274 (07)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Safari, Hanieh; Mashayekhan, Shohreh
  7. Abstract:
  8. Macrophages play a crucial role in the healing process of chronic wounds in diabetic patients. These cells polarize from a pro-inflammatory M1 phenotype to an anti-inflammatory M2 phenotype, guiding the initial inflammation toward tissue repair and regeneration. In diabetic patients, physiological disturbances impair this polarization, resulting in persistent, chronic, and inflamed wounds. Glucocorticoid anti-inflammatory drugs are commonly used but have serious side effects, necessitating targeted delivery systems. This study aims to design and optimize self-assembled complex coacervate drug delivery system composed of gelatin and sodium alginate (GA/SA CCA) that can selectively uptake by macrophages and modulate inflammation. In this study, the different ratios of gelatin to sodium alginate (1:0.5, 1:1, 1:2, 1:4) of coacervates was characterized and their effect on cellular uptake by RAW264.7 macrophages was evaluated. Fluorescent staining and confocal imaging were used to assess internalization, complemented by fluorescence intensity measurement. Furthermore, the influence of various compositions (GA:SA ratios) on macrophage polarization and the expression of M1 and M2 markers at 4 and 48 hours was investigated. Additionally, the uptake of dexamethasone sodium phosphate (Dex), as a glucocorticoid anti-inflammatory drug, by GA/SA CCA carrier with different ratios and free solution drug was quantified to assess delivery efficiency via HPLC. Quantitative analysis showed that GA/SA CCA with a 1:4 gelatin-to-sodium alginate ratio exhibited the highest uptake, with over 80% internalization by macrophages. In contrast, pure sodium alginate and free drug displayed minimal uptake (less than 5%). Flow cytometry indicated that the percentage of CD86+ (M1 marker) cells at 4 hours was around 40% in high SA ratio groups, higher than other groups (<20%). However, at 48 hours, the proportion of CD206+ (M2 marker) cells increased significantly, exceeding 70% in the 1:4 ratio group, while other groups reached approximately 50%. These findings suggest that higher SA content accelerates macrophage polarization toward the anti-inflammatory phenotype over time. The uptake of Dex via the 1:4 GA/SA CCA was approximately 1.5 times higher than in other ratios and free drug, with over 70% of the drug internalized in this group versus 30% in free form. This demonstrates that GA/SA carriers with higher SA concentrations facilitate targeted and rapid drug delivery, reducing off-target effects. Our findings indicate that self-assembled GA/SA CCA, especially at a 1:4 ratio, exhibit high potential for targeted drug delivery and promoting macrophage polarization toward the M2 phenotype. Increasing the SA proportion accelerates both drug uptake and macrophage phenotypic shift, making this system a promising targeted delivery platform for treating chronic diabetic wounds. This approach can reduce side effects associated with glucocorticoids and improve therapeutic efficacy in controlling inflammation and tissue regeneration.
  9. Keywords:
  10. Targeted Druy Delivery ; Sodium Alginate ; Macrophage Polarization ; Macrophage Cells ; Diabetic Wound ; Gelatin Type A ; Coacervate Drug Carrier

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