Mouse Model of Surgically-induced Endometriosis by Auto-transplantation of Uterine Tissue

Summary

A description of the surgical induction of endometriosis in mice and rats by auto-transplantation of uterine tissue to the arterial cascade of the intestinal mesentery.

Abstract

Endometriosis is a chronic, painful disease whose etiology remains unknown. Furthermore, treatment of endometriosis can require laparoscopic removal of lesions, and/or chronic pharmaceutical management of pain and infertility symptoms. The cost associated with endometriosis has been estimated at 22 billion dollars per year in the United States¹. To further our understanding of mechanisms underlying this enigmatic disease, animal models have been employed. Primates spontaneously develop endometriosis and therefore primate models most closely resemble the disease in women. Rodent models, however, are more cost effective and readily available². The model that we describe here involves an autologous transfer of uterine tissue to the intestinal mesentery (Figure 1) and was first developed in the rat³ and later transferred to the mouse⁴. The goal of the autologous rodent model of surgically-induced endometriosis is to mimic the disease in women. We and others have previously shown that the altered gene expression pattern observed in endometriotic lesions from mice or rats mirrors that observed in women with the disease^5,6. One advantage of performing the surgery in the mouse is that the abundance of transgenic mouse strains available can aid researchers in determining the role of specific components important in the establishment and growth of endometriosis. An alternative model in which excised human endometrial fragments are introduced to the peritoneum of immunocompromised mice is also widely used but is limited by the lack of a normal immune system which is thought to be important in endometriosis^2,7. Importantly, the mouse model of surgically induced endometriosis is a versatile model that has been used to study how the immune system⁸, hormones^9,10 and environmental factors^11,12 affect endometriosis as well as the effects of endometriosis on fertility¹³ and pain¹⁴.

Protocol

1. Planning for live-animal surgery

1. Ensure that appropriate approval has been received to work with laboratory animals.
2. Order mice and allow at least one week of acclimation to their new environment.
3. Female mice housed in the absence of exposure to male pheromones can stop cycling, a phenomenon referred to as the Whitten effect^15,16. To keep mice cycling transfer urine-soaked male bedding to the female cage every five days. Alternatively, if open-top cages are used, place the female cage between two cages of males to keep the females cycling regularly.
4. Ensure that mice are cycling by analyzing vaginal cytology daily....

Discussion

There are several critical parameters that should be noted while performing the surgical induction of endometriosis in mice. First, endometriosis is an estrogen dependent disease and as such this surgery should be performed in intact animals or alternatively in ovariectomized animals supplemented with estrogens²⁰. Second, suturing the endometrial biopsies to the arterial cascade must be performed with extreme care. We have found that using only two relatively loose knots with one throw each keeps the biopsy in.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Wax pencil	Fisher Scientific	NC9954135
Glass slide	Fisher Scientific	12-550-433
Eyedropper	Fisher Scientific	S79383
Standard light microscope for evaluating vaginal cytology smears
Buprenorphine HCL c3 (CARJET) 10X1ml	Butler Animal Health Supply	022891
Sterile phosphate buffered saline (PBS)	GIBCO, by Life Technologies	14040-117
10,000U/ml Penicillin, 10,000μg/ml Streptomycin in 0.85% NaCl	Hyclone	SV30010
Isoflurane	Abbott Laboratories	05260-05
Isoflurane non-rebreathing anesthetic system
Recirculating hot water heating pad
30 ml syringe sheath	Fisher Scientific	14-823-16G
Powder free sterile gloves	Fisher Scientific	19020558
Ophthalmic ointment	Major Pharmaceuticals	10033691
Small electrical clippers	Wahl Clipper Corp.	9861-600
Chlorhexidine scrub	Fisher Scientific	NC9863042
70% Ethanol
Polylined sterile field	Busse Hospital Disposables	696
Size 3 scalpel	Fisher Scientific	22-079-657
Number 10 scalpel blades	Fisher Scientific	22-079-681
Small surgical scissors	Roboz Surgical Instruments Co.	RS-5850
Small serrated semi-curved forceps	Roboz Surgical Instruments Co.	RS-5135
5-0 black braided silk suture	Ethicon Inc.	K870H
Sterilized pyrex glass Petri dishes	Corning	70160-101
2 mm biopsy punch	Miltex Inc.	33-31
Sterile gauze	Kendall	1806
6-0 black monofilament ethilon nylon suture	Ethicon Inc.	697G
Needle drivers (optional)	World Precision Instruments, Inc.	500023
5-0 undyed braided coated vicryl suture	Ethicon Inc.	J490G
9mm Autoclip wound clips	BD Biosciences	427631
Autoclip applier & remover	BD Biosciences	427630
23G needle	BD Biosciences	305193
1cc syringe	BD Biosciences	301025
5X magnifying glass stand (optional)	Fisher Scientific	14-648-23
10% Buffered formalin	Fisher Scientific	SF100-4
Calipers	Roboz Surgical Instruments Co.	RS-6466
Processing/embedding cassettes	Fisher Scientific	15-197-700A
Biopsy foam pads	Fisher Scientific	22-038-222
RNAqueous RNA isolation kit	Ambion	AM1912
Liquid nitrogen
Snap cap microcentrifuge flat top tube	Fisher Scientific	02-681-240
Ketamine (optional)	Sigma-Aldrich	K4138
Domitor (medetomidine hydrochloride) (optional)	Tocris Bioscience	2023
Antisedan (atipamezole) (optional)	Sigma-Aldrich	A9611