Acid ceramidase expression in human cumulus cells post-retrieval may be used to assess oocyte quality

Abstract

OBJECTIVE: Acid Ceramidase (AC) is an enzyme that regulates an important lipid second messenger inducing programmed cell death (apoptosis). Cumulus cells form a multilayered cell mass that support oocyte maturation in vivo. AC levels in the cumulus cells could potentially influence oocyte development. We evaluated AC activity levels in human cumulus cells post-retrieval as a method to assess oocyte quality.DESIGN: HPLC chromatography.MATERIALS AND METHODS: Human cumulus cells were obtained from 33 IVF patients who gave consent to use of discarded materials. Cumulus cells from each patient were collected, centrifuged and frozen. Protein extracts were prepared on thawed cumulus cells with CelLyticM total cell lysis buffer (Sigma), according to manufacturer protocol. Wilcoxon signed-rank test was used for statistical analysis.RESULTS: Average patient age was 35.7±4.3 and the number of retrieved oocytes was 15.2±7.5. AC activity was detected in 24 samples (73%). The mean activity level was 273.2±168.5 pmol/μl (range: 34.5-593.5 pmol/μl). We detected a positive correlation with the level of AC in the post-retrieval cumulus cells and number of oocytes retrieved. The AC results were consistent for the total number of oocytes collected and the number of mature oocytes per patient (p<0.0001, p=0.0005, respectively). AC level was significantly associated with peak serum estradiol values and positive pregnancy test (p<0.0001, p<0.003, respectively). An inverse association between AC activity per oocyte and patient age was noted (p<0.0001).CONCLUSIONS: This is the first report of AC activity in human post-retrieval cumulus cells. The results suggested that high AC activity may correlate with oocyte developmental potential and subsequent fertilization and pregnancy. AC may have a protective effect on cumulus cells and may stimulate secretion of estradiol preventing apoptosis. Our study revealed that AC is one of the essential factors required to support oocytes during maturation in vivo. OBJECTIVE: Acid Ceramidase (AC) is an enzyme that regulates an important lipid second messenger inducing programmed cell death (apoptosis). Cumulus cells form a multilayered cell mass that support oocyte maturation in vivo. AC levels in the cumulus cells could potentially influence oocyte development. We evaluated AC activity levels in human cumulus cells post-retrieval as a method to assess oocyte quality. DESIGN: HPLC chromatography. MATERIALS AND METHODS: Human cumulus cells were obtained from 33 IVF patients who gave consent to use of discarded materials. Cumulus cells from each patient were collected, centrifuged and frozen. Protein extracts were prepared on thawed cumulus cells with CelLyticM total cell lysis buffer (Sigma), according to manufacturer protocol. Wilcoxon signed-rank test was used for statistical analysis. RESULTS: Average patient age was 35.7±4.3 and the number of retrieved oocytes was 15.2±7.5. AC activity was detected in 24 samples (73%). The mean activity level was 273.2±168.5 pmol/μl (range: 34.5-593.5 pmol/μl). We detected a positive correlation with the level of AC in the post-retrieval cumulus cells and number of oocytes retrieved. The AC results were consistent for the total number of oocytes collected and the number of mature oocytes per patient (p<0.0001, p=0.0005, respectively). AC level was significantly associated with peak serum estradiol values and positive pregnancy test (p<0.0001, p<0.003, respectively). An inverse association between AC activity per oocyte and patient age was noted (p<0.0001). CONCLUSIONS: This is the first report of AC activity in human post-retrieval cumulus cells. The results suggested that high AC activity may correlate with oocyte developmental potential and subsequent fertilization and pregnancy. AC may have a protective effect on cumulus cells and may stimulate secretion of estradiol preventing apoptosis. Our study revealed that AC is one of the essential factors required to support oocytes during maturation in vivo.