Murine Fecal Isolation and Microbiota Transplantation

Summary

The goal here is to outline a protocol to investigate the mechanisms of dysbiosis in cardiovascular disease. This paper discusses how to aseptically collect and transplant murine fecal samples, isolate intestines, and use the "Swiss-roll" method, followed by immunostaining techniques to interrogate changes in the gastrointestinal tract.

Abstract

Gut microbiota dysbiosis plays a role in the pathophysiology of cardiovascular and metabolic disorders, but the mechanisms are not well understood. Fecal microbiota transplantation (FMT) is a valuable approach to delineating a direct role of the total microbiota or isolated species in disease pathophysiology. It is a safe treatment option for patients with recurrent Clostridium difficile infection. Preclinical studies demonstrate that manipulating the gut microbiota is a useful tool to study the mechanistic link between dysbiosis and disease. Fecal microbiota transplantation may help elucidate novel gut microbiota-targeted therapeutics for the management and treatment of cardiometabolic disease. Despite a high success rate in rodents, there remains translational changes associated with the transplantation. The goal here is to provide guidance in studying the effects of gut microbiome in experimental cardiovascular disease. In this study, a detailed protocol for the collection, handling, processing, and transplantation of fecal microbiota in murine studies is described. The collection and processing steps are described for both human and rodent donors. Lastly, we describe using a combination of the Swiss-rolling and immunostaining techniques to assess gut-specific morphology and integrity changes in cardiovascular disease and related gut microbiota mechanisms.

Introduction

Cardiometabolic disorders, including heart disease and stroke, are the leading global causes of death¹. Physical inactivity, poor nutrition, advancing age, and genetics modulate the pathophysiology of these disorders. Accumulating evidence supports the concept that gut microbiota affect cardiovascular and metabolic disorders, including type 2 diabetes², obesity³, and hypertension⁴, which may hold a key to the development of new therapeutic approaches for these diseases.

The exact mechanisms by which the microbiota cause diseases are still unknown....

Protocol

Vanderbilt University's Institutional Animal Care and Use Committee approved all procedures described in this manuscript. C57B1/6 male mice at 3 months of age, purchased from The Jackson Laboratory, were housed and cared for in accordance with the Guide for the Care and Use of Laboratory Animals.

1. Collection, storage, and processing of human fecal samples

1. Collect a stool sample, using a sterile container if the subject is in the clinic. Refrigerate the stool samples at 4 °C within 36 h of collection until ready for processing. Alternatively, collect stool samples using a commercially available tool fo....

Results

The steps described above are summarized in Figure 1. Mouse cecal contents or human feces are resuspended in sterile saline to prepare a slurry to give to germ-free mice (100 µL) by gavage, first for 3 consecutive days, then once every 3 days. At the end of the protocol, blood pressure is measured by the tail-cuff method, mice are euthanized, and tissues are harvested for assessment of changes in the gut microbiota and cardiovascular and metabolic changes.

A key s.......

Discussion

A valuable approach to studying the causal role of gut microbiota in cardiovascular and metabolic disease is to transfer the total microbiota or select species of interest into germ-free mice. Here, we describe protocols to collect fecal samples from humans and conventionally housed mice into germ-free mice to study the role of gut microbiota in hypertensive disorders.

In mice, we use aseptically collected cecal contents processed in an aerobic chamber, and in humans, collect feces. FMT can be.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Alexa Fluor 488 Tyamide SuperBoost	ThermoFisher	B40932
Anaerobic chamber	COY	7150220
Apolipoprotein AI	Novus Biologicals	NBP2-52979
Artery Scissors - Ball Tip	Fine Science Tools	14086-09
Bleach solution	Fisher Scientific	14-412-53
Bovine Serum Albumin	Fisher Scientific	B14
CD3 antibody	ThermoFisher	14-0032-82
CD68 monoclonal antibody	ThermoFisher	14-0681-82
Centrifuge	Fisher Scientific	75-004-221
CODA high throughput monitor	Kent Scientic Corporation	CODA-HT8
Cryogenic vials	Fisher Scientific	10-500-26
Disposable graduate transfer pipettes	Fisher Scientific	137119AM
Disposable syringes	Fisher Scientific	14-823-2A
Ethanol	Fisher Scientific	AA33361M1
Feeding Needle	Fine Science Tools	18061-38
Filter paper sheet	Fisher Scientific	09-802
Formalin (10%)	Fisher Scientific	23-730-581
High salt diet	Teklad	TD.03142
OMNIgene.GUT	DNAgenotek	OM-200+ACP102
Osmotic mini-pumps	Alzet	MODEL 2002
PAP Pen	Millipore Sigma	Z377821-1EA
Petri dish	Fisher Scientific	AS4050
Pipette tips	Fisher Scientific	21-236-18C
Pipettes	Fisher Scientific	14-388-100
Serile Phosphate-buffered saline	Fisher Scientific	AAJ61196AP
Smart spatula	Fisher Scientific	NC0133733
Stool collection device	Fisher Scientific	50-203-7255
TBS Buffer	Fisher Scientific	R017R.0000
Triton X-100	Millipore Sigma	9036-19-5
Varimix platform rocker	Fisher Scientific	09047113Q
Vortex mixer	Fisher Scientific	02-215-41
Xylene	Fisher Scientific	1330-20-7, 100-41-4