Non-erythroid hemoglobin promotes human cumulus cell viability and the developmental capacity of the human oocyte by Reeva B Makhijani

F S Sci. 2023 Mar 16:S2666-335X(23)00013-7. doi: 10.1016/j.xfss.2023.03.003. Online ahead of print.

ABSTRACT

OBJECTIVE: To determine the relationship between the levels of cumulus cell hemoglobin mRNA and the developmental potential of the associated oocyte and if hemoglobin protects the cumulus cells from oxidative stress-induced apoptosis.

DESIGN: Laboratory based study.

SUBJECTS: Cumulus cells from oocytes of patients undergoing in vitro fertilization with intracytoplasmic sperm injection with and without preimplantation genetic testing between 2018-2020.

SETTING: University laboratory and university-affiliated IVF center.

EXPOSURE: Studies on individual and pooled cumulus cells collected at the time of oocyte retrieval or cultured under 20% or 5% O2. MAIN OUTCOME MEASURES: Quantitative PCR analysis of individual and pooled patient cumulus cell samples were used to monitor hemoglobin mRNA levels. RT-PCR arrays were used to assess genes that regulate oxidative stress in cumulus cells associated with aneuploid and euploid blastocysts. Studies were conducted to assess the effect of oxidative stress on the rate of apoptosis, the level of reactive oxygen species and gene expression in cumulus cells in vitro.

RESULTS: Compared to cumulus cells associated with arrested and aneuploid blastocysts the mRNA levels encoding the alpha and beta chains of hemoglobin were increased 2.9 and 2.3-fold in cumulus cells associated with euploid blastocysts, respectively (p<0.01). mRNAs encoding alpha and beta chains of hemoglobin were also increased by 3.8 and 4.5-fold in cumulus cells cultured under 5% O2 vs. 20% O2, respectively (p<0.01) and multiple regulators of oxidative stress were overexpressed in cells cultured under 20% O2 compared to 5% O2. However, the rate of apoptosis and the amount of mitochondrial reactive oxidative species were increased by 1.25 fold in cumulus cultured under 20% O2 compared to 5% O2 (p<0.01). Variable amounts of the alpha and beta chains of hemoglobin were also detected within the zona pellucida and oocytes.

CONCLUSION: Higher levels of non-erythroid hemoglobin in cumulus cells are associated with oocytes that result in euploid blastocysts. Hemoglobin may protect cumulus cells from oxidative stress-induced apoptosis, which may enhance cumulus-oocyte interactions. Moreover, cumulus cell derived hemoglobin may be transferred to the oocytes and protect it from the adverse effects of oxidative stress that occurs in vivo and in vitro.

PMID:36933864 | DOI:10.1016/j.xfss.2023.03.003