Initial results of clinical application of mesenchymal stromal stem cell-derived extracellular microvesicles after abdominal delivery

The last decade has been marked by a radical change in priorities for primary cesarean births because of the utmost importance of a post-cesarean uterine scar. In this context, there is a need for new methods to improve myometrium repair after surgery so that 2–3 years after cesarean birth, a woman could give birth naturally. Over the recent 15 years, cell technologies have been successfully used in clinical medicine to improve tissue regeneration [1–3]. Nevertheless, there are specific difficulties for their widespread implementation [4–7]. One of the interesting mechanisms of stem cells' action can be their ability to communicate and exchange functional proteins and genetic material through the secretion of microvesicles, which can improve tissue repair, since they can transfer intercellular information and work as a modulator [8–13].

Based on the above, we assume that extracellular microvesicles (EMV) will improve the postoperative course and allow patients with a post-cesarean uterine scar to give birth naturally, thus reducing the cesarean birth rate. Moreover, the experimental studies on the cesarean birth model using an inbred line of Wag rats showed that both in intact animals and after a cesarean section, exosomes remain in the myometrium for at least eight days (Fig. 1–3) [14, 15 ].

The study aimed to investigate the tolerability of the injection of EMV of placenta-derived mesenchymal stromal cells (MSC) during abdominal delivery and assess the postoperative course.

Materials and methods

The study included 53 puerperal women after cesarean birth, who were divided into two groups. Patients in the study group (n=23) during abdominal delivery received an injection of 500 μl EMV MSC obtained in the laboratory of cell technologies of V.I. Kulakov NMRC for OG&P into the incision area and had continuous closure of the low transverse uterine incision with vicryl suture. Patients in the control group (n=30) underwent traditional continuous single-layer closure of uterine incision with vicryl suture.

The age characteristics of the study participants are presented in the Table 1.

As shown in the table, the patients were young, and the age in the study groups did not differ significantly.

Comorbidities among the study participants are presented in Table 2. There were no significant differences between the study groups regarding the rates of non-obstetric diseases. Almost every second patient had chronic tonsillitis (from 50 to 56.5%). More than 40% were diagnosed with chronic inflammation of the kidneys and 17% of the bronchi.

The infectious index (the ratio of the total number of infectious diseases to the number of patients) in the study and control groups was 1.3 and 1.2, respectively (Table 2).

In terms of socioeconomic status, almost half of pregnant women who had a cesarean birth (46.6% to 47.8%0 did not work and were engaged in housekeeping (Table 3).

Outcomes of previous pregnancies of the control group patients are presented in Table 4.

It is noteworthy that 6 (26.1%) and 7 (23.3%) in the study and control group had a history of voluntary induced termination of pregnancy, which could subsequently provoke spontaneous termination of pregnancy in 4 (17.4%) and 6 (20%) women from groups I and II, respectively.

Many abortions were directly related to the low level of contraceptive education of the study participants. Only every tenth patient (8.7%), who received 500 μL of exosomes during cesarean birth, used contraceptive methods. In the control group, the indicator did not fundamentally differ – 3 (10%).

The age at menarche in the patients was standard for Russian women and averaged 13 years (Table 5), not differing significantly from the control group (p > 0.05). There was a high rate of inflammatory diseases (Table 6), which was reported by almost every eighth pregnant woman in the study [3 (13.1%)] and every tenth [3 (10%)] in the control group.

Therefore, therewerenosignificantdifferencesbetween the study groups regarding clinical characteristics.

Statistical analysis

Statistical analysis was performed using Microsoft Excel spreadsheets and the GraphPad Prism 6 software (GraphPad Software, USA). Quantitative variables showing normal distribution were expressed as means (M) and standard deviation (SD). Statistical comparisons were performed using the paired Student's t-test (for paired samples). Differences were considered significant at p <0.05.

Results and discussion

The vast majority of patients in the study group [21 (91.3%)] administered intraoperatively with 500 μl of EMV were primiparous without a complicated obstetric history, wishing vaginal birth after cesarean within 2–3 years. Ten women (43.5%) underwent a planned cesarean section due to mixed breech presentation. In two cases (8.7%), the operation was performed for the marginal placenta previa.

An emergency cesarean section was performed in 13 (56.5%) women in labor due to acute intrauterine fetal hypoxia (30.4%), labor dystocia not amenable to drug correction (21.7%), and in one case due to the loss of umbilical cord loops during prelabor rupture of membranes (Table 7).

In all women, the cesarean section was performed under epidural anesthesia with intraoperative antibiotic prophylaxis.

Among patients undergoing emergency abdominal delivery, there were no between-group differences in operative time, total intraoperative blood loss, and duration of the first stage of labor (Table 8).

The present comparative study revealed significant differences between puerperal women in the study and control groups in duration of ruptured membranes (Table 8), which in the patients of the control group was 7.75 (0.48) hours and was shorter than in patients who received 500 μl EMV (p=0.041). Significant differences were also observed in the duration of the postoperative hospital stay [(4.26 (0.09) in group I vs. 5.33 (0.38) in group II (p=0.02)]. A similar dynamics were observed in leukocyte counts at discharge, which in the group with the intraoperative injection of exosomes was 11.18 (0.48) x 109/l, which was was significantly lower than in the control group [13.04 (0.33) x 109/l (p=0.02)]. Patients of the study group had no postpartum inflammatory complications, while in the control group, there was two endometritis (6.7%) and one lochiometra (3.3%).

Conclusion

The study findings suggest a good tolerability profile and higher effectiveness of intraoperative EMV administration than traditional postpartum management. Initial results of the clinical application of exosomes open up new horizons for their use. It may help improve myometrium repair and predict future spontaneous delivery for patients with post-cesarean uterine scars.