Cardiopulmonary Bypass in a Mouse Model: A Novel Approach

Summary

This paper describes how to perform cardiopulmonary bypass in mice. This novel model will facilitate the investigation of the molecular mechanisms involved in organ damage.

Abstract

As prolonged cardiopulmonary bypass becomes more essential during cardiac interventions, an increasing clinical demand arises for procedure optimization and for minimizing organ damage resulting from prolonged extracorporal circulation. The goal of this paper was to demonstrate a fully functional and clinically relevant model of cardiopulmonary bypass in a mouse. We report on the device design, perfusion circuit optimization, and microsurgical techniques. This model is an acute model, which is not compatible with survival due to the need for multiple blood drawings. Because of the range of tools available for mice (e.g., markers, knockouts, etc.), this model will facilitate investigation into the molecular mechanisms of organ damage and the effect of cardiopulmonary bypass in relation to other comorbidities.

Introduction

Since the introduction of cardiopulmonary bypass (CPB) into the clinic, it has played an essential role in cardiac surgery¹. In modern cardiac surgery, prolonged CPB time is essential to perform extensive aortic reconstructions and combined procedures. Although technological advances have been tremendous, the use of extracorporal circulation is associated with intra- and postoperative systemic and local organ damage^2,3.

Large animal models have been developed to investigate the role of CPB on physiological processes^4,

Protocol

All animal experiments were performed in compliance with the German Animal Protection Law (TierSchG) and were approved by the local animal welfare committee (Lower Saxony State Office for Consumer Protection and Food Safety, Protocol TSA 14/1556). The minimal weight of mouse suitable for this model is 25 g.

1. Preoperative Preparations

NOTE: All procedures are carried out under clean, non-sterile conditions, with autoclaved instruments.

1. Place 50-60 8-cm long propylene hollow fibers in parallel in a tube and connect with a T-adapter on both sides. Fill the space between the hollow fibers and th....

Results

This protocol describes the perfusion circuit, surgical procedures, and monitoring of physiological parameters during CPB of a mouse. When performed by an adequately skilled microsurgeon, the results are consistently and reproducibly obtained.

To maintain adequate tissue perfusion, the mean arterial pressure is always kept between 40 and 60 mmHg by adjusting the CPB blood flow and adding of extra volume. Depending on the weight .......

Discussion

We have developed a fully-functioning clinically-relevant model of CPB in a mouse. With more than thirty strains of mice having cardiovascular diseases, our model could be a starting point for development of new prospective protocols related to CPB. Moreover, due to the plethora of mouse-specific reagents and knockout-out mice, this model can not only replace the current rat model of CPB but will facilitate dissection of the molecular mechanisms involved in CPB-related organ damage. To date, CPB has not been applied in m.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Sterofundin	B.Braun Petzold GmbH	PZN:8609189	priming volume, 1:1 with Tetraspan
Tetraspan 6% HES Solution	B. Braun Melsungen AG	PZN: 05565416	priming volume, 1:1 with Sterofundin
Heparin Natrium 25.000	Ratiopharm GmbH	PZN: 3029843	2.5 IU per ml of priming solution
NaHCO3 8,4% Solution	B. Braun Melsungen AG	PZN: 1579775	3% in priming solution
KCL 7.45 % Solution	B. Braun Melsungen AG	PZN: 2418577	0.1 mL for cardioplegia
Carprofen	Zoetis Inc., USA	PZN:00289615 08859153	5 mg/kg/BW
1 Fr PU Catheter	Instechlabs INC., USA	C10PU-MCA1301	carotid artery
2 Fr PU Catheter	Instechlabs INC., USA	C20PU-MJV1302	jugular vein
Vasofix Safety catheter 20G	B.Braun Medical	4268113S-01	orotracheal intubation
8-0 Silk suture braided	Ashaway Line & Twine Mfg. Co., USA	75290	ligature
Isoflurane	Piramal Critical Care Deutschland GmbH	PZN:9714675	narcosis
CLINITUBES blood capillaries	Radiomed GmbH	51750132	blood sampling 60 - 95 microliter
Spring Scissors - 6mm Blades	Fine Science Tools GmbH	15020-15	instruments
Spring Scissors - 2mm Blades	Fine Science Tools GmbH	15000-03	instruments
Halsted-Mosquito Hemostat	Fine Science Tools GmbH	13009-12	instruments
Dumont #55 Forceps	Fine Science Tools GmbH	11295-51	instruments
Castroviejo Micro Needle Holder - 9cm	Fine Science Tools GmbH	12060-02	instruments
Micro Serrefines	Fine Science Tools GmbH	18555-01	instruments
Bulldog Serrefine	Fine Science Tools GmbH	18050-28	instruments
MiniVent Ventilator for Mice (Model 845)	Harvard Apparatus	73-0044	mechanical ventilation
Isoflurane Vaporizer Drager 19.1	Drägerwerk AG & Co. KGaA		anesthesia 1.3 - 2.5%
PowerLab data acquisition device 4/35	ADInstruments Ltd, New Zealand	PL3504	invasive pressure, ECG, temperature
ABL 800 Flex	Radiometer GmbH		blood gas analysis
NMRI mice	Charles River Laboratories	Crl:NMRI(Han)	male, 30 - 35 g, 12 weeks old, housed at least 1 week before the experiment