Parabiosis in Mice: A Detailed Protocol

Parabiotic joining of two organisms leads to the development of a shared circulatory system. In this protocol, we describe the surgical steps to form a parabiotic connection between a wild-type mouse and a constitutive GFP-expressing mouse.

Parabiosis is a surgical union of two organisms allowing sharing of the blood circulation. Attaching the skin of two animals promotes formation of microvasculature at the site of inflammation. Parabiotic partners share their circulating antigens and thus are free of adverse immune reaction. First described by Paul Bert in 1864¹, the parabiosis surgery was refined by Bunster and Meyer in 1933 to improve animal survival². In the current protocol, two mice are surgically joined following a modification of the Bunster and Meyer technique. Animals are connected through the elbow and knee joints followed by attachment of the skin allowing firm support that prevents strain on the sutured skin. Herein, we describe in detail the parabiotic joining of a ubiquitous GFP expressing mouse to a wild type (WT) mouse. Two weeks after the procedure, the pair is separated and GFP positive cells can be detected by flow cytometric analysis in the blood circulation of the WT mouse. The blood chimerism allows one to examine the contribution of the circulating cells from one animal in the other.

Parabiosis, the surgical joining of two organisms, was first described in 1864 by Paul Bert as a way to develop a model to study shared circulatory systems and consisted of the joining of the skin and muscular walls of two rats¹. Parabiosis promotes formation of microvasculature at the site of inflammation³ and has had several applications in physiological studies, such as the hormonal communication between the pituitary gland and gonads as well as the role of the kidney in hypertension⁴. It has been further employed to investigate the recruitment and integration of progenitor cells in neovascularization⁵, migration of hemat....

All animal studies were performed according to the guidelines of UCLA's animal care and use committee and the National Institutes of Health Guide for the Care and Use of Laboratory Animals. The duration of the procedure described below is approximately 45-60 min from beginning to end.

1. Preparation of Surgical Field

1. Perform procedure in a clean animal surgery room.
2. Equipment: isoflurane Vaporizer, Gaymer T Pump with heating pad.
3. Sterile tools: two curved forceps, fine scissors, needle holder.
4. Sterile gloves must be used during the entire procedure.

2. Preparatio....

The anticipated outcome of parabiosis of two organisms is the equal contribution of each animal's circulatory system to a common blood circulation (Figure 2). One can easily verify the successful equilibration of the blood of the parabiosed WT and GFP positive mice by flow cytometric analysis. Here, venous blood was obtained from the tails of both parabionts at 2 weeks after the surgery and was fractionated for peripheral blood cells (to exclude erythrocytes). The fractionated hematopoietic-derived cell .......

The parabiosis method discussed here presents minimal technical difficulties and results in low mortality rates. The attachment of knee and elbow joints is a significant improvement of the Bunster and Meyer technique. However, the procedure remains invasive thus maintenance of sterile conditions throughout the surgery is imperative. To further prevent infection of the surgical site, it is important that the parabiosed animals receive a combination of antibiotics and be monitored regularly. To ensure firm support and prev.......

The authors have no competing financial interests.

The authors would like to thank Adriane Mosley and Libuse Jerabek (Stanford) for assistance with the surgical technique.