Dose-Dependent Effects of Prolotherapy Dextrose on Neuronal Cells: A Systematic Review of in Vitro Evidence

Abstract

Introduction
Dextrose prolotherapy is increasingly investigated for neuropathic conditions due to its potential regenerative and anti-inflammatory effects. However, the optimal concentration for neuronal applications remains unclear, as in vitro studies demonstrate both protective and cytotoxic effects depending on glucose levels.

Objective
To determine the optimal dextrose concentration for prolotherapy in neuronal models based on in vitro evidence.

Methods
A systematic review was conducted following PRISMA principles using a semantic search platform (2016–2026). A total of 1,000 articles were identified, 66 were screened by abstract, and 20 studies were included after full-text review. Eligible studies involved neuronal cell cultures exposed to defined glucose concentrations with quantitative outcomes, including cell viability, apoptosis, oxidative stress, and inflammatory markers.

Results
Moderate glucose supplementation (12.5–25 mM above baseline) demonstrated neuroprotective effects, particularly in TNF-α-induced neuronal injury models. A concentration of 12.5 mM improved cell survival and reduced reactive oxygen species, while 25 mM more effectively suppressed inflammatory mediators such as IL-6, IL-1β, NF-κB, and COX-2. In contrast, higher concentrations (>30–45 mM) consistently induced neurotoxicity, characterized by oxidative stress, mitochondrial dysfunction, apoptosis, and impaired neurite outgrowth. Glucose deprivation also reduced neuronal viability. Overall, a biphasic (hormetic) response was observed.

Conclusion
Dextrose exerts concentration-dependent effects on neuronal cells within a narrow therapeutic window. No universal optimal concentration can be defined, as outcomes depend on cellular context and experimental conditions. These findings highlight limitations in clinical translation and the need for further physiologically relevant studies.