Amniotic fluid embolism (AFE) is a serious complication of labor in which amniotic fluid suddenly enters the maternal circulation during delivery causing acute pulmonary embolism, anaphylactic shock, disseminated intravascular coagulation, renal failure, or sudden death, and the mechanism is not yet understood. Currently, animal models are obtained by injecting autologous, allogeneic, or human amniotic fluid, fecal-contaminated amniotic fluid, or a mixture of amniotic fluid and placental extract into the circulation of the animal. Commonly used animals include goats, rabbits, rats, dogs, miniature pigs, cats, etc., while rhesus monkeys have been shown to be unsuitable for animal models of amniotic fluid embolism.
Operation method
Animal model of amniotic fluid embolism
Principle
The basic principle of amniotic fluid embolism animal model is that the tangible substances in the contaminated amniotic fluid (fetal cui hair, keratinized epithelium, fetal lipids, fetal feces) can cause mechanical embolism, activation, consumption of a large number of complement, activation and cleavage of fragments, the cells are further activated to produce and release a number of toxic oxygen radicals, arachidonic acid and cytokines, which directly or indirectly lead to the damage of the organism's own tissues.
Materials and Instruments
Experimental material: amniotic fluid samples. Move The basic process of amniotic fluid embolism can be divided into the following steps: Caveat Fecal-stained amniotic fluid or amniotic fluid containing placental extract can | cause more pronounced or severe pathophysiologic changes when injected relative to the original amniotic fluid or amniotic fluid filtrate. For more product details, please visit Aladdin Scientific website.
A. Collection and preparation of amniotic fluid samples
(1) Original amniotic fluid collection
1) Human amniotic fluid collection: It can be extracted during cesarean section of pregnant women with full-term pregnancy.
2) Amniotic fluid collection from rats: Take rats with a gestational age of 19~21 days, and fast for 12 hours before the operation, and drink water without any restriction. The pregnant rats were anesthetized, fixed on the operating table, sterilized, and the abdominal cavity was opened along the lower abdominal incision to expose the uterus, which was washed with saline and then underwent subtotal hysterectomy, and the abdomen was closed. The amniotic fluid was extracted from the amniotic cavity with a syringe and stored in a water bath at 37 ℃.
3) Collection of amniotic fluid from goats: Goats at 120-150 days of gestation were fasted for 12 hours before the operation, and water intake was not restricted. The animals were fixed on the operating table after intravenous anesthesia. Auscultation confirmed that the lung fields were clear, and the anesthesia level was maintained at a level that allowed the animal to breathe spontaneously, but without voluntary movement or coughing. The abdominal cavity was opened along the median abdominal incision to expose the uterus, which was washed with warm physiological water and then incised to expose the amniotic membranes, the amniotic fluid was aspirated with a syringe, the fetal lamb and placenta were delivered, and the uterus and abdominal wall were closed. Animals without cesarean section can be extracted by direct puncture to extract amniotic fluid.
(2) Preparation of filtered amniotic fluid: Raw amniotic fluid is filtered through a 5 μm filter.
(3) Preparation of feces-stained amniotic fluid: small animals such as mice and rabbits, etc., cut open the abdominal wall of the fetus, remove the large intestine, and gently squeeze out the feces, or flush the intestinal lumen with the original amniotic fluid, and then obtain the amniotic fluid mixed with feces, or mix the feces with the amniotic fluid according to the required proportion, and generally formulate the amniotic fluid containing 1% to 4% of the feces.
(4) Preparation of amniotic fluid containing placental extract: take placental tissue homogenate, centrifuge it at 3000 r/min for 10 minutes, take the supernatant, and mix it with autologous amniotic fluid at 1:40.
B. Amniotic fluid is usually used within 1 hour after preparation. Raw or filtered amniotic fluid or a mixture of prepared amniotic fluid is rapidly injected into the jugular or femoral vein of the animal at a dose of 2.5 ml/kg, as required. Rabbits are usually injected through the marginal ear vein.