Inclusion criteria
Women who received IVF merely because infertility caused by male factors in the First Affiliated Hospital of Soochow University, Jiangsu Province, China from January 2021 to February 2022.
Exclusion criteria
①The body mass index (BMI) less than 18.5 kg/m2 or greater than 23.9 kg/m2; ②In the past 3 months, used drugs that are prohibited or with caution in pregnant women, such as anti-psychotic, anti-epileptic, anti-tubercular, anti-tumor drugs, etc.; ③In the past 6 months, received allogeneic blood transfusion, transplantation, stem cell therapy and immunotherapy; ④Patients with ovarian diseases or abnormalities, such as polycystic ovarian syndrome, premature ovarian failure/premature ovarian insufficiency, ovulatory dysfunction, luteinized unruptured follicle syndrome, etc.; ⑤Patients with uterine diseases or abnormalities, such as endometriosis, adenomyosis, hysteromyoma, endometrial polyps, thin endometrium, etc.; ⑥Patients with tubal or pelvic diseases, abnormalities or inflammation, such as hydrosalpinx, salpingemphraxis, salpingitis, pelvic inflammatory disease, etc.; ⑦Chromosome number and/or structural abnormalities in one of the spouses; ⑧Patients with cancer; ⑨Patients with ovarian hyperstimulation syndrome (OHSS) during controlled ovarian stimulation (COS); ⑩Incomplete information.
COS protocols and IVF
Selection of COS protocols and collection of follicular aspirates were performed strictly according to the latest China expert consensus and guide. Briefly, women under-went individualized COS according to age, AFC and FSH levels. Leuprolide acetate or cetrorelix acetate are used to block estrogen feedback to the hypothalamus, leaving the body at a high estrogen level. Recombinant FSH and/or highly purified human urinary gonadotropin are used for ovarian stimulation at step-down doses starting with 225 to 300 IU, followed by ultrasound monitorization. When at least one dominant follicle up to 18 mm or two up to 17 mm in diameter is found, recombinant human chorionic gonadotrophin (r-hCG) 250 μg by intramuscular injection. Follicles were aspirated about 35h after hCG injection and the oocytes were identified in a culture dishusing a stereomicroscope. Insemination was performed by conventional IVF or ICSI, based on the presence and location of two pronuclei, and then oocyte fertilization was assessed after 18–20 h. According to the current cleavage-stage scoring criteria for embryo morphology, the features of cell number, degree of fragmentation, equality of size and shape of blastomeres and multinucleationsize were observed under high magnification (×200) on the third day after insemination, and then that were classified as transplantable embryos and high-quality embryos.
Collect the clear, yellowish and bloodless follicular fluid for the first puncture, that from follicles 18-22 mm in diameter and the oocyte retrieval successful. Immediately centrifuge at 4 ℃ for 3,000 r/min for 15min, and then use ELISA or test kit from Jiangsu Meimian Industrial Co.,Ltd. (Jiangsu, China) to determine the levels of RAS components, inflammation and oxidative stress indexes, sex hormone. Including renin, ACE, ACE2, AngⅡ, Ang(1-7), IL-6, IL-10, ROS, MDA, SOD and GSH. At the same time, information was collected for research from medical records that does not contain personal identification. The information includes ①General clinical data: age, duration of infertility, BMI, dosage of gonadotropins (Gn) used, length of stimulation; ②Basic serum sex hormone level: E2, FSH, LH, P, PRL, T; ③AMH; ④AFC; ⑤IVF laboratory outcomes: the number of oocyte retrieval count and the rate of metaphase Ⅱ oocyte maturation, 2 pronucleus embryos, transplantable embryos, high-quality embryos.
Isolation, culture and identification of MSCs
MSCs isolation: The full-length umbilical cords from healthy full-term pregnant women who underwent cesarean sections were selected and placed in a biosecure transport box for transportation at a low temperature of 2~8 ℃. The umbilical cord was sectioned into small segments of approximately 5~8 cm in length, thoroughly rinsed with PBS buffer, and two umbilical arteries and one umbilical vein were excised, followed by the separation of the epidermis. The tissues were cut into fragments of about 1 cm3 in size and cultured in DMEM/Low Glucose culture medium supplemented with 10% FBS and 1% Penicillin-Streptomycin under the conditions of 37 ℃ and 5% CO2. The culture medium was replaced every 3~4 d, with continuous monitoring of cell growth.
Identification of cellular immunophenotype: 0.25% trypsin digestion, centrifugation at 800-1000 rpm, and resuspension in PBS to achieve a concentration of 5~10 ×106 cells/cm2. 100 μl of the cell suspension was dispensed into flow tubes, to which about 5 μl of each of the antibodies CD29, CD44, CD90, CD14, CD34, and HLA-DR were added. The cells were then incubated at ambient temperature, protected from light, for 15~30 min. Following this, the cells were washed 2~3 times with PBS buffer, collected by centrifugation, and finally resuspended in 500 μl of PBS.
Osteogenic-induced differentiation: Cells were collected using the same trypsinization method as described above and then seeded in gelatin-coated six-well plates at a density of 2×104 cells/cm2. After this, 2 ml of osteogenic induction medium was added, and the fluid was changed every 3~4 d. Calcium nodules were closely monitored, and alizarin red staining was performed after approximately 2~4 weeks.
Adipogenic-induced differentiation: Cells were collected using the same trypsinization method as described above and then seeded in gelatin-coated six-well plates at a density of 2×104 cells/cm2. The cells were cultured in DMEM/Low Glucose medium until they reached 100% confluence or over-confluence under the microscope. At this point, the medium was replaced with lipidogenic induction medium solution A. After 3 d, the medium was replaced with solution B and then after a further 24 hours, it was returned to solution A. This cycle of alternating induction was repeated 3-5 times. Cell culture was then continued with solution B for 4~7 d before being stained with Oil Red O.
MSCs transplantation
Using the same trypsinization method as described above, cells were collected. Mice were then intravenously injected in the tail vein with a cell suspension containing 1×106 of hUC-MSCs. This transplantation was carried out in four separate passages, each separated by 1 week.
Animals
A total of 24 inbred SPF grade female C57BL/6 mice were used, including 8 at 6 weeks of age (17~19 g) and 16 at 40 weeks of age (26~30 g). The above experimental animals were purchased from Hangzhou Ziyuan Experimental Animal Technology Co., Ltd. (Zhejiang, China), with license No. SCXK (Zhejiang) 2019-0004 and certificate of conformity No. 20210802Abzz0105000375. The animals were housed in the SPF grade laboratory animal room of Soochow University, Jiangsu Province, China with the indoor temperature ranging from 20 to 26 ℃, the daily temperature difference less than 4 ℃, the relative humidity maintained at 40~70%, the noise less than 60 dB, and the light time from 8:00 to 20:00. The mice had free access to water and were fed with standard mouse chow, ensuring an adequate water supply and changing the bedding every 2 to 3 days. This experiment meets the requirements and conditions of SPF grade animal feeding management.
Acquisition of mouse serum and ovarian tissue
The animals were weighed on an electronic balance and the weights were recorded. After the mice were executed and placed on ice, the left and right ovarian tissues were rapidly dissected and removed. Connective tissues such as fat and fascia were removed on filter paper moistened with PBS buffer, then the tissues were rinsed 2~3 times with PBS and blotted dry. The weight of each ovarian tissue was measured on a microbalance and recorded.
Hematoxylin-eosin staining
Mouse ovarian tissues were completely immersed in 4% polymerized formaldehyde solution and fixed for 24 h. Gradient alcohol dehydration was performed:
75% C2H5OH
|
1 h (35 ℃)
|
85% C2H5OH
|
1 h (35 ℃)
|
95% C2H5OH Ⅰ
|
1 h (35 ℃)
|
95% C2H5OH Ⅱ
|
1 h (35 ℃)
|
100% C2H5OH Ⅰ
|
30 min (35 ℃)
|
100% C2H5OH Ⅱ
|
30 min (35 ℃)
|
Xylene transparent was performed:
C8H10 Ⅰ
|
20 min (35 ℃)
|
C8H10 Ⅱ
|
20 min (35 ℃)
|
Tissues are dipped in wax for 3-5 hours and then paraffin embedded and sectioned. Dewaxing was performed:
C8H10 Ⅰ
|
15 min
|
C8H10 Ⅱ
|
15 min
|
Rehydration was performed:
100% C2H5OH Ⅰ
|
5 min
|
100% C2H5OH Ⅱ
|
5 min
|
95% C2H5OH Ⅰ
|
5 min
|
95% C2H5OH Ⅱ
|
5 min
|
85% C2H5OH
|
5 min
|
75% C2H5OH
|
5 min
|
H2O
|
3-5 min
|
Hematoxylin staining for 5-10 min, hydrochloric acid alcohol differentiation for 3-5 s, eosin staining for 2-3 min. Dehydration and sealing were performed:
75% C2H5OH
|
5 min
|
85% C2H5OH
|
5 min
|
95% C2H5OH Ⅰ
|
5 min
|
95% C2H5OH Ⅱ
|
5 min
|
100% C2H5OH Ⅰ
|
5 min
|
100% C2H5OH Ⅱ
|
5 min
|
C8H10 Ⅰ
|
5-10 min
|
C8H10 Ⅱ
|
5-10 min
|
Neutral mounting medium to seal the slide
|
Long-term preservation
|
The morphology of the tissue was visualized microscopically and all levels of follicles were counted, including primordial, primary, secondary, antral/mature and atretic follicles.
qRT-PCR
Mouse ovary tissue RNA was extracted and reverse transcribed to cDNA. Primers were designed as follows:
TARGET GENE
|
PRIMER
|
NUCLEOTIDE SEQUENCE
|
m-Renin
|
F
|
GCCCTCTGCCACCCAGTAA
|
R
|
CAAAGCCAGACAAAATGGCCC
|
m-Agt
|
F
|
GGTCTCTTTCTACCTTGGATCC
|
R
|
GACCTTGTGTCCATCTAGTCG
|
m-Ace
|
F
|
CTACCCCCAAGCATCTATACAG
|
R
|
CCACTCCTGGTTATAGTTCTCC
|
m-Ace2
|
F
|
GTGTACAAAGGTCACAATGGAC
|
R
|
CTTCATTGGCTCCGTTTCTTAG
|
m-Agtr1a
|
F
|
CACTGTTTGCGCTTTTCATTAC
|
R
|
AGCCTTCTTTAGAGCTTTCCAT
|
m-Agtr1b
|
F
|
CCCTGGCTGATTTATGCTTTTT
|
R
|
GCGATCTTACATAGGTGATTGC
|
m-Agtr2
|
F
|
CTGTCTCAAAGAAGGAATCCCT
|
R
|
ATGTTGGCAATGAGGATAGACA
|
m-Mas
|
F
|
CCACTTGTCCATTGCTGATATC
|
R
|
GTCACCGATAATGTCACGATTG
|
m-Gapdh
|
F
|
AAAATGGTGAAGGTCGGTGTG
|
R
|
TGAGGTCAATGAAGGGGTCGT
|
The Power Up SYBR Green Master Mix premix, forward primer, reverse primer and ddH2O were added in the proportions shown in the table below:
COMPONENTS
|
10 μl SYSTEM
|
2× Power Up SYBR Green Master Mix
|
5 μl
|
Forward primer
|
0.5 μl
|
Reverse primer
|
0.5 μl
|
cDNA
|
1 μl
|
ddH2O
|
Make up to 3 μl
|
Add 9 μl of reaction solution and 1 μl of sample cDNA to each well of the 96-well plate, and do 3 replicates for each sample. The PCR instrument parameters were set according to the table below:
NAME
|
TEMPERATURE
|
TIME (min:sec)
|
REMARK
|
Holding
|
95 ℃
|
5:00
|
|
Cycling
(40 cycles)
|
95 ℃
|
0:10
|
Record
|
60 ℃
|
0:30
|
Melt curve stage
|
95 ℃
|
0:15
|
Record
|
60 ℃
|
1:00
|
95 ℃
|
0:15
|
The program was run, the data was exported when it was finished and a record of the experiment was kept.
Western blot
Protein lysate was prepared by mixing RIPA with PMSF (100 mM) at a ratio of 100:1. Then, 20 μl of the protein lysate was added to 1 mg of tissue for grinding. The lysate was kept on ice for 30 min and centrifuged at 15,000 rpm for 10~15 min at 4 °C. The supernatant was collected. SDS loading buffer was added and the system was metal bathed at 100 °C for 15~20 min. The gel was dispensed and the electrophoresis tank was assembled with the prepared protein samples. Electrophoresis was performed at 80 V for 30~50 min, followed by a change to 100~120 V for 2 h. The wet transfer system was then assembled and electrified at 200 mA at a constant current for 2 h. The membrane was blocked in a solution of 5-10% skimmed milk on a shaking bed for 1~2 h at ambient temperature, followed by incubation with the primary antibody at ambient temperature for 12 h with shaking. Depending on the properties of the primary antibody, the membrane was then incubated with the corresponding secondary antibody for 1 h at ambient temperature with shaking. Protein bands on the membrane were visualized using an ECL luminescent agent in a dark room.
Cell counting kit-8
The cells were collected using the same trypsinization method as described above, and inoculated into 96-well plates at a density of 2000 cells/100 μl/well. They were then incubated at 37 ℃ in a 5% CO2 environment for 12 hours. Media with a gradient concentration of AngⅡ or Ang(1-7) were added to the wells and incubated at 37 ℃ and 5% CO2 for varying durations, as per the experimental design. Each incubation time was repeated five times. Each well was then incubated with 10 μl of CCK-8 solution for 0.5~4 h. The absorbance at 450 nm (OD) was detected by an enzyme counter and recorded.
Enzyme linked immunosorbent assay
The standard was diluted according to the table below:
HUMAN
|
STANDARD 1
|
STANDARD 2
|
STANDARD 3
|
STANDARD 4
|
STANDARD 5
|
Renin (pg/ml)
|
10
|
20
|
40
|
80
|
160
|
ACE (ng/L)
|
20
|
40
|
80
|
160
|
320
|
ACE2 (ng/L)
|
4
|
8
|
16
|
32
|
64
|
AngⅡ (ng/L)
|
2.5
|
5
|
10
|
20
|
40
|
Ang(1-7) (ng/L)
|
3
|
6
|
12
|
24
|
48
|
E2 (pmol/L)
|
3
|
6
|
12
|
24
|
48
|
P (pmol/L)
|
100
|
200
|
400
|
800
|
1600
|
MOUSE
|
STANDARD 1
|
STANDARD 2
|
STANDARD 3
|
STANDARD 4
|
STANDARD 5
|
E2 (pmol/L)
|
12.5
|
25
|
50
|
100
|
200
|
FSH (IU/L)
|
1
|
2
|
4
|
8
|
16
|
LH (pg/ml)
|
150
|
300
|
600
|
1200
|
2400
|
AMH (pg/ml)
|
11.25
|
22.5
|
45
|
90
|
180
|
Renin (pg/ml)
|
15
|
30
|
60
|
120
|
240
|
ACE (ng/L)
|
10
|
20
|
40
|
80
|
160
|
ACE2 (ng/L)
|
5
|
10
|
20
|
40
|
80
|
AngⅡ (ng/L)
|
30
|
60
|
120
|
240
|
480
|
Ang(1-7) (ng/L)
|
22.5
|
45
|
90
|
180
|
360
|
Blank control wells were prepared without any sample or standard. In the standard wells, 50 μl of each standard 1~5 was added respectively. 10 μl of each group of samples was added to the test wells, with at least 3 replicates created for each sample. They were then incubated at 37 ℃ for 30 min and subsequently washed 3-5 times. After 50 μl of enzyme reagent was added to each well, they were again incubated at 37 ℃ for 30 min, followed by another wash. 50 μl each of colorants A and B were added to every well, and after incubating in the dark for 10 min at 37 ℃, 50 μl of termination solution was added. The zero point was set using the blank wells, and the absorbance (OD) of each well at 450 nm was measured and recorded.
Reactive oxygen species by DCFH-DA assay
he DCFH-DA staining solution was prepared and added in the dark to the six-well plate inoculated cells. The plate was then incubated at 37 ℃ with 5% CO2 for 20 min. After incubation, the wells were washed 2-3 times in the dark using FBS-Free medium and then observed under a fluorescence microscope in the dark. Images were taken from three randomly selected, non-overlapping fields of view in each quadrant of each well.
Senescence and acid β-galactosidase staining
The fixative was added to the six-well plate inoculated with cells and fixed at ambient temperature for 15 min, then washed three times with PBS buffer. The Acid-β-Gal staining solution was prepared according to the following table:
Acid β-Gal staining A
|
10 μl
|
Acid β-Gal staining B
|
10 μl
|
Acid β-Gal staining C
|
930 μl
|
X-Gal staining
|
50 μl
|
The SA-β-Gal staining solution was prepared according to the following table:
Senescence-Associated β-Gal staining A
|
10 μl
|
Senescence-Associated β-Gal staining B
|
10 μl
|
Senescence-Associated β-Gal staining C
|
930 μl
|
X-Gal staining
|
50 μl
|
According to the experimental design, 1~2 ml of Acid-β-Gal staining solution or SA-β-Gal staining solution was added to each well, and incubated at 37 ℃ for 12 h. Observations were made under an ordinary light microscope, and images were taken from three randomly selected, non-overlapping fields of view in each quadrant of each well.
Mitochondrial membrane potential by JC-1 assay
JC-1 staining solution was prepared, added in the dark to the six-well plate inoculated with cells, and incubated at 37 ℃ with 5% CO2 for 20 min. Then, JC-1 staining buffer was added in the dark and the plate was washed 2-3 times. After that, the plate was observed under a fluorescence microscope in the dark. Images were taken from three randomly selected, non-overlapping fields of view in each quadrant of each well.
Quantification and statistical analysis
The correlation between hFF-RAS and age was analyzed by simple linear regression, and multivariate linear regression was used to further analyze the correlation between hFF-RAS and ovarian function, inflammation, oxidative stress indexes and IVF laboratory outcomes. General clinical data did not obey normal distribution and were statistically described in quartiles (p25, median, p75).
The organ coefficient of ovaries = ovarian weight (mg) / body weight (g). The formula for analyzing the qRT-PCR results of mRNA transcription levels can be referred to as follows: 2-△△ct=2- [(Average ct value of the target gene in the test group)-(Average ct value of the reference gene in the test group)]- [(Average ct value of the target gene in the control group)-( Average ct value of the reference gene in the control group)]. The Western blot results for protein translation levels were analyzed using Image J software to measure the grayscale values. The CCK-8 detection results were statistically analyzed using the reference formula: The cell proliferation rate = [(Experimental well absorbance - Blank well absorbance) / (Control well absorbance - Blank well absorbance) × 100%. The average fluorescence intensity of Immunofluorescence images was analyzed by Image J software. The positive cell count for β-Gal staining was performed using Image J software. Data that followed a normal distribution were described statistically as mean ± standard deviation (x ± s). For data that followed a normal distribution and had homogeneous variances, a one-way analysis of variance (ANOVA) was used for between-group comparisons, and the least significant difference (LSD) method was applied for multiple comparisons. If the data did not have homogeneous variances, Tamhane's T2 method in a nonparametric test was chosen. A p-value less than 0.05 indicated a statistical difference, while a p-value less than 0.01 indicated a statistically significant difference.