ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 pathogenesis of many malignancies and has been reported to influ- ence response to anti PD-L1 targeted therapy. Methods: Expression of PD-L1 and MLH1, MSH2, MSH6 and PMS2 was assessed by immunohistochemistry (IHC) on 50 resected cases of epithelial ovarian carcinomas (EOCs). Results: Mismatch repair deficiency was noted in 15 cases (30% of the cases). PD-L1 expression was noted in 20% of the cases (10 cases) in tumour cells and in 14% of the cases (7 cases) in the tumour infiltrating lymphocytes (TILs). A statistically significant inverse correlation was noted between PD-L1 expres- sion in TILs and PD-L1 expression in tumour cells with extra- ovarian spread of tumour, and between TILs and lymphovascu- lar invasion. There was no statistically significant association between MMR deficiency and PD-L1 expression in tumour cells or PD-L1 expression in TILs. Conclusion: Approximately one third cases of EOCs showed MMR deficiency and PD-L1 expression was noted in only one sixth to one fifth of the cases. There was no statistically significant asso- ciation between MMR deficiency and PD-L1 expression in the current study. However, more studies on a larger sample size are required to study relation between MMR status and PD-L1 expres- sion in EOCs. PS-08-008 Oct-4 expression as a pluripotency factor and changes of apop- tosis in the uterus during spontaneous and immune-dependent abortions in mice P. Vishnyakova*, K. Artem’eva, I. Stepanova, I. Bogdanova, M. Boltovskaya, N. Yaglova, S. Obernikhi, E. Ponomarenko *National Medical Research Center for Obstetrics, Gynaecology and Perinatology named after Academician V.I. Kulakov, Russia Background & objectives: The balance of apoptosis and pro- liferation plays an important role in maintaining pregnancy. The aim: to study Oct-4, Bax and Bcl-2 expression in the uterus during spontaneous and immune-dependent abortions in mice. Methods: 18 mice formed three identical groups. Сontrol- ♀ CBA/ Lacx ♂ BALB/c, spontaneous abortions(SA)- ♀ CBA/Lacx ♂ DBA/2J; immune-dependent abortions(IDA)- ♀ CBA/Lacx ♂ BALB/c with intraperitoneal administration of β-heptyl glycoside muramyl dipeptide in dose of ≈1 mg/kg on days 5 and 7 of gestation (DG). Mice were taken out of the experiment on the 8 DG. The uterus were excised and immunohistochemically stained with antibodies to Bax(Δ21), Bcl-2, Oct-4. Results: The level of embryos resorption in control was 12.5%, in SA- 34.8%, in IDA- 46.7%. Bax(Δ21) expression was detected in the decidua. Staining intensity varied from weak to moderate in control and from moderate to strong in SA and IDA. Bcl-2 was localized in the stromal part of the endometrium in control (intensity staining) and in IDA group (very weak staining), but no staining in SA. Oct4+ cells with nuclear or cytoplasmic staining are localized in the myome- trium and perimetrium. The percentage of Oct-4+ nuclei in SA and IDA groups was less than in the control, with negative correlation between Oct-4+ nuclear staining and the level of embryo resorption (r=-0.99,95CI(-0.99;-0.88);p=0.0003) Conclusion: Thus, the negative correlation between the level of embryo resorption and the percentage of Oct-4+ cells in the myo- metrium and perimetrium in SA and IDA is probably due to an insufficient increase in the volume of the fetoplacental unit under conditions of enhanced apoptosis. Funding: The study was carried out within the framework of State Assignment No. 122030200534-4 PS-08-009 The effect of a mesenchymal stem cell conditioned medium fraction on uterine healing after full-thickness surgical incision P. Vishnyakova*, N. Tikhonova, A. Milovanov, V. Alexankina, T. Fokina, A. Alexankin, M. Boltovskaya, N. Nizyaeva, A. Sklifas, A. Temnov *National Medical Research Center for Obstetrics, Gynaecology and Perinatology named after Academician V.I. Kulakov, Russia Background & objectives: The mechanism of cesarean scar defect development is unclarified. Treatment of that complication is an important obstetric task. We assessed the effect of the conditioned medium obtained by culturing mesenchymal stem cells with low oxygen content (10%) on uterine healing. Methods: Component from MSCs was used to treat uterine wound of Sprague Dawley rats (treated group=15, without treatment=11). Histologic examination was performed 5 and 15 days after surgi- cal operation with Mallory staining and monoclonal antibodies to aSMA and CD34. The healing area between damage myome- trium and the area of the blood vessels in the healing zone were calculated. Results: By the 5th day, there was a complete closure of the uterine wall. The area between the separated muscle layers in the treated group was (p<0.05) smaller compared to the control in 5 (p<0.05) and 15 (p<0.05) days. In the control group, the healing area from the 5th to the 15th day increased unreliable (p>0.05). The area of the vessels in the healing zone of treated group was significantly lower compared to control in 5 (p<0.05) and 15 days (p<0.05). Blood vessel area of treated group decreased to 15th day in damage myometrium zone (p<0.05) but not damage perimetrium. Conclusion: Protein composition obtained by culturing the cells under a reduced content of O2 (10%), significantly influences on size and vascularization of healing area between damage myometrium and peri- metrium in uterine wall after full-thickness surgical incision. Area of connective tissue and fibrosis in healing uterine wall after treating the composition decreased that seems to improve uterine wall healing. PS-08-010 Morphological features of the placenta in women with con- firmed SARS-CoV-2 infection P. Vishnyakova*, N. Nizyaeva, E. Dolgopolova, N. Lomova, R. Shmakov, V. Frankevich *National Medical Research Center for Obstetrics, Gynaecology and Perinatology named after Academician V.I. Kulakov, Russia Background & objectives: It`s known that angiogenesis with vascular branching failure is characteristic of chronic intrauterine hypoxia. The aim was to assess the morphological features of the placenta in women with SARS-CoV-2+ infection, children whom have suffered from acute hypoxia in labour. Methods: The main group of the study was women with positive test of SARS-CoV-2 gave birth to a live born children (n=42), and control group (n=40) with negative test to SARS-CoV-2. We performed histological(H&E staining) and immunohistochemical study on the placenta with antibodies to CD34. Results: It was revealed that in 8.3% there was acute foetal hypoxia in second stage of the labour, which required operative delivery. We observed a higher percentage of infarctions, the presence of throm- bosis of the chorionic vessels, intervillous and subamniotic hema- tomas in the main study group as compared to the control group (p<0,05). Histological examination revealed angiogenesis with a predominance of vascular branching (more than 10 blood vessels in one terminal villus, comparison 3-7 as normally) (p<0,05). Intrau- terine hypoxia and depletion of compensation mechanisms, even with even week exposure (uterine contractile activity, umbilical S108