341 - Human Preterm Umbilical Cord Mesenchymal Stem Cells Prevent Fetal Neural Stem Cell Injury in vitro under Extremes of Oxygen Exposure

Poster Number: 341
Publication Number: 341.2866

Background: Preterm infants are at increased risk of neuronal injury with poor neurodevelopment outcomes resulting from extremes of oxygen exposure (hyperoxia, hypoxia, or hyperoxia alternating with hypoxia) while being cared in the NICU. Neural stem cells (NSCs) reside in neuronal niche and have capabilities of differentiating into mature neurons to repair brain injury. How NSCs function under extremes of oxygen conditions in preterm infants is largely unknown. Our work using human preterm umbilical cord derived mesenchymal stem cells (MSCs) have shown their protective role in cell injury and repair during extremes of oxygen conditions in experimental injury models.

Objective: We hypothesized that NSC growth and differentiation is disrupted during extremes of oxygen exposure and that human preterm umbilical cord MSCs will prevent it via regulation of NSC growth and prevention of apoptosis.

Design/Methods: Human fetal NSCs were harvested from cadaver brains using our published protocols. Human umbilical cord MSCs harvested from extremely preterm 22-24 weeks’ GA cords and cultured to obtain MSC-conditioned medium (MSC-CM). Human dermal fibroblast conditioned medium (HDF-CM) used as control for MSC-CM. NSCs were cultured alone, with MSC-CM, and HDF-CM for 48-hours under extremes of oxygen conditions and their growth assessed via apoptosis assays. We divided experiments as four groups as follows.
Group A: Control cells in Normoxia (21% O2)
Group B: Hyperoxia (90% O2)
Group C: Hypoxia (5% O2)
Group D: Hyperoxia (90% O2) with intermittent hypoxia (5% O2) for one hour every 6 hours

Results: The results are shown in Table 1. Flow cytometry apoptosis assay showed minimal apoptosis in control group A where NSCs cultured in Normoxia. Group D where NSCs cultured in hyperoxia with periods of hypoxia showed highest apoptosis when cultured alone (63%) or in HDF-CM (59%). Co-culture with MSC-CM prevented apoptosis in group D (23%) but not completely to Normoxia level of group A (10%). Groups B and C also showed higher apoptosis compared with control group A. Group B with persistent hyperoxia showed 51% apoptosis whereas group C with hypoxia showed 39% apoptosis. Co-culture with MSC-CM prevented apoptosis in group B (17%) and D (13%). All these results were statistically significant.

Conclusion(s): Extremes of oxygen conditions lead to faster NSCs apoptosis with lack of brain injury repair. MSC-CM prevented NSCs apoptosis and can be used as an effective modality to prevent and treat neuronal injury in preterm infants.