137 - Human Extremely Preterm Umbilical Cord Derived Mesenchymal Stem Cells Exposed to Extremes of Oxygen Conditions

Poster Number: 137
Publication Number: 137.436

Meaghan Neary, University of California, Irvine, School of Medicine, Orange, CA, United States; Shayan R. Ahmad, University of California, Irvine, School of Medicine, Orange, CA, United States; Fayez Bany-Mohammed, University of California, Irvine, School of Medicine, Orange, CA, United States; Cherry Uy, University of California, Irvine, School of Medicine, Orange, CA, United States; Muhammad Aslam, University of California, Irvine, School of Medicine, Orange, CA, United States

Background: Our studies using human umbilical cord derived mesenchymal stem cells (MSCs) and their conditioned medium (MSC-CM) have shown promising results in Bronchopulmonary dysplasia (BPD). BPD is a chronic debilitating disease of extremely preterm infants resulting from oxygen toxicity (prolonged hyperoxia with periods of intermittent hypoxia), inflammation, and ventilator use leading to arrested alveolar development. We hypothesized that extremely preterm MSCs harvested from 22-24 weeks’ gestational age (GA) infants will have altered growth and mitochondrial function when exposed to experimental BPD conditions (persistent hyperoxia as well as prolonged hyperoxic conditions with intermittent hypoxia).

Objective: Our aims included generation of MSCs from preterm 22-24 weeks’ GA umbilical cords, culture of MSCs in extremes of oxygen conditions, and assessment of endogenous MSC mitochondrial bioenergetics, proliferation, and survival analysis.

Design/Methods: The study was approved by the Institutional IRB. The umbilical cord Wharton’s jelly plastic adherent cells harvested from extremely preterm 22-24 weeks’ GA cords, propagated, and immunodepleted to obtain MSCs. MSCs cultured for 48-hours under extremes of oxygen conditions as follows:
Group A: 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
Endogenous MSC mitochondrial bioenergetics, proliferation, and survival analysis assessed using commercial kits and published protocols.

Results: Flow cytometry apoptosis assay showed 13% apoptosis in control MSCs in normoxia (group A). Experimental BPD groups (B and D) showed statistically significantly higher apoptosis compared with control group A. Group B with persistent hyperoxia showed 47% apoptosis whereas group D with hyperoxia with intermittent hypoxia showed 63% apoptosis. Group C with hypoxia showed 18% apoptosis which was not statistically significant compared to control group A. Like severe apoptosis, groups B and D also showed highest mitochondrial dysfunction with increased oxidative stress as well as decreased mitophagy when compared with control group A. Group C with hypoxia showed minimal mitochondrial dysfunction which was not statistically significant compared with control group A.

Conclusion(s): Clinical BPD conditions (Hyperoxia as well as hyperoxia alternating with hypoxia) lead to faster apoptosis and worsening mitochondrial dysfunction in extremely preterm human umbilical cord derived MSCs.