Exploring the critical therapeutic window: Dose-frequency optimization of human umbilical cord mesenchymal stem cells for preclinical asthma treatment.

Background: Current drugs primarily target inflammation control but do not reverse tissue remodeling changes for asthma. Human mesenchymal stem cells are known for their anti-inflammatory and tissue remodeling capabilities. However, limited research has explored the therapeutic impact of varying doses and frequencies of human umbilical cord blood-derived mesenchymal stem cells (HUC-MSCs) on established airway remodeling in experimental asthma.

Aim: To explore and optimize the dosage and administration frequency of HUC-MSCs in experimental models of ovalbumin (OVA)-induced asthma.

Methods: BALB/c mice underwent sensitization and were challenged using OVA. Control animals were administered a saline solution following the same protocol. HUC-MSCs were identified using flow cytometry. HUC-MSCs at incremental dosages (1 × 10⁵, 2 × 10⁵, 4 × 10⁵) were injected via tail veins on day 30 (the second after the final stimulation). After comparing each group and determining the optimal dose, supplement the optimal dose twice on day 30 and day 33 (the second and fifth day after the final stimulation). Bronchoalveolar lavage fluid (BALF) and serum were harvested for analysis of concentrations of interleukin-4 (IL-4), IL-13, immunoglobulin E and interferon-gamma (IFN-γ) by enzyme-linked immunosorbent assay. Pharmacology of airways and lung functions were also evaluated to identify the optimal group.

Results: The study shows that HUC-MSC transplantation ameliorates OVA-induced asthma by significantly reducing airway inflammation and obstruction in preclinical models. This effect is associated with decreased Th2 cytokines IL-4 and IL-13, and increased Th1 cytokine IFN-γ. The optimal dose of 2 × 10⁵ cells/mouse was identified as the most effective in reducing local asthmatic airway inflammation and changing levels of IL-4, IL-13, and IFN-γ in serum and BALF compared to other single doses of HUC-MSC. Multiple treatments with the medium dose (2 × 10⁵ cells) of HUC-MSCs on days 30 and 33 yield the best pathological and lung function outcomes. However, double treatments do not reduce IL-4 and IL-13 expression or enhance IFN-γ production in serum or BALF more effectively than a single medium dose.

Conclusion: HUC-MSCs effectively regulate pro-inflammatory mediators in serum and BALF, modulating airway remodeling and lung function. In this acute mouse asthma model, a single dosage of 2 × 10⁵ is optimal, with more significant effects of decreasing airway obstruction requiring repeated administration.