(952) Immature myeloid cells involvement in human placental angiogenesis stratified by parity.

To evaluate Immature Myeloid Cells (IMCs) maturation to Mature Myeloid Cells (MMCs) and angiogenesis potential in human placentas following term deliveries in low-risk multipara as compared to nullipara women.

Study Design:

Forty-four human placentas were collected from low-risk multipara (n=29) and nullipara (n=15) following term uncomplicated vaginal deliveries. IMCs were enriched by mechanical and enzymatic digestion followed by Ficoll buffer gradient filtration and magnetic cell separation. Immunostaining of IMCs and MMCs was performed with fluorochrome-labeled monoclonal antibodies and analyzed by flow cytometry using FACS. IMCs were defined as CD11b+CD45+LIN2+CD14+HLADR-. MMCs were defined as CD45+CD11c+HLADR+. Furthermore, RNA was extracted from MMC, reverse transcribed into cDNA, and analyzed by real-time PCR for expression of selected anti-angiogenic cytokines including - ADAMTS1, THBS1, and CXCL9, and pro-angiogenic cytokines including MMP9 and CCL3.

Results: Utilizing fluorochrome-labeled monoclonal antibodies staining, MMCs were statistically significantly more prevalent in multiparas placentas ((24.75% vs. 10.78%, P< 0.05). Analyzing the cytokine expression level, we found that the RNA expression of ADAMTS1 was 3.4- fold higher (SD ±1.8, P< 0.05) in nullipara compared to multipara placentas and that the RNA expression of CCL3 was 4.5-fold higher (SD ±5.7, P=0.05) in multipara compared to nullipara placentas. There was no significant difference in RNA expression of THBS1, CXCL9 and MMP9 between groups.

Conclusion:

Our study suggests a higher transition rate of IMCs to MMCs in multipara placentas compared to nullipara placentas, following term uncomplicated vaginal deliveries. In addition, a higher RNA expression of anti-angiogenic cytokines in nullipara placentas compared to a higher RNA expression of pro-angiogenic cytokines in multipara placentas, may explain the favorable outcome in subsequent pregnancies.