# Hesperetin modulates osteoprogenitor cells and macrophages under zoledronic acid and inflammatory stress

## TL;DR

Hesperetin helps bone cells and reduces inflammation in stressed cells affected by zoledronic acid and inflammatory conditions.

## Contribution

Hesperetin is shown to modulate both osteoprogenitor cells and macrophages under zoledronic acid and inflammatory stress.

## Key findings

- Hesperetin enhances mineralization in alveolar bone-derived mesenchymal stem cells and partially restores it after zoledronic acid exposure.
- Hesperetin reduces pro-inflammatory cytokine production in M1 macrophages without affecting their viability.
- In co-cultures, hesperetin preserves cell viability, increases matrix deposition, and reduces cytokine release under inflammatory conditions.

## Abstract

To investigate the osteogenic and immunomodulatory effects of hesperetin (HT) on alveolar bone-derived mesenchymal stem cells (aBMSCs) and macrophages under zoledronic acid (ZA) and inflammatory stress.

aBMSCs were exposed to ZA (0–10 μM) for 3 days, followed by HT (0–1000 μM) for 3 days. Cell viability was assessed for 3 days of treatments, and osteogenic activity was evaluated by alizarin red quantification at 14 and 21 days. THP-1-derived macrophages were polarized to M1 using lipopolysaccharides (LPS, 1 μg/mL) and treated with HT (1–50 μM) to evaluate cell viability and synthesis of cytokines (ELISA). A co-culture system of aBMSCs and macrophages (1:1 ratio) was established under inflammatory stimulation (LPS ± 20 μM HT) to assess cell viability, cytokine release and mineralized matrix formation. Data were analyzed by ANOVA/post-hoc tests (α = 5 %).

ZA significantly reduced aBMSCs viability and mineralization in a dose-dependent manner. HT (5–50 μM) enhanced mineralization in healthy aBMSCs and partially restored it after ZA exposure. In M1 macrophages, HT (5–20 μM) decreased TNF-α, IL-1α, and IL-6 synthesis without affecting viability. In inflammatory co-cultures, HT (20 μM) preserved cell viability, increased mineralized matrix deposition, and reduced cytokine release compared to LPS-only controls.

This study evidenced that HT can concurrently stimulate osteogenic differentiation and suppress inflammatory responses under ZA- and LPS-induced stress. HT emerges as a promising osteoimmunomodulatory adjuvant to enhance bone regeneration and mitigate bisphosphonate-related osteonecrosis.