Performing Human Skeletal Muscle Xenografts in Immunodeficient Mice

Summary

Complex human diseases can be challenging to model in traditional laboratory model systems. Here, we describe a surgical approach to model human muscle disease through the transplantation of human skeletal muscle biopsies into immunodeficient mice.

Abstract

Treatment effects observed in animal studies often fail to be recapitulated in clinical trials. While this problem is multifaceted, one reason for this failure is the use of inadequate laboratory models. It is challenging to model complex human diseases in traditional laboratory organisms, but this issue can be circumvented through the study of human xenografts. The surgical method we describe here allows for the creation of human skeletal muscle xenografts, which can be used to model muscle disease and to carry out preclinical therapeutic testing. Under an Institutional Review Board (IRB)-approved protocol, skeletal muscle specimens are acquired from patients and then transplanted into NOD-Rag1^null IL2rγ^null (NRG) host mice. These mice are ideal hosts for transplantation studies due to their inability to make mature lymphocytes and are thus unable to develop cell-mediated and humoral adaptive immune responses. Host mice are anaesthetized with isoflurane, and the mouse tibialis anterior and extensor digitorum longus muscles are removed. A piece of human muscle is then placed in the empty tibial compartment and sutured to the proximal and distal tendons of the peroneus longus muscle. The xenografted muscle is spontaneously vascularized and innervated by the mouse host, resulting in robustly regenerated human muscle that can serve as a model for preclinical studies.

Introduction

It has been reported that only 13.8% of all drug development programs undergoing clinical trials are successful and lead to approved therapies¹. While this success rate is higher than the 10.4% previously reported², there is still significant room for improvement. One approach to increase the success rate of clinical trials is to improve laboratory models used in preclinical research. The Food and Drug Administration (FDA) requires animal studies to show treatment efficacy and assess toxicity prior to Phase 1 clinical trials. However, there is often limited concordance in treatment outcomes between animal studies and cli....

Protocol

All use of research specimens from human subjects was approved by the Johns Hopkins Institutional Review Board (IRB) to protect the rights and welfare of the participants. All animal experiments were approved by the Johns Hopkins University Institutional Animal Care and Use Committee (IACUC) in accordance with the National Institutes of Health (NIH) Guide for the Care and Use of Laboratory Animals. Male NOD-Rag1^null IL2rγ^null (NRG) host mice (8-12 weeks old) .......

Discussion

Patient-derived xenografts are an innovative way to model muscle disease and carry out preclinical studies. The method described here to create skeletal muscle xenografts is rapid, straightforward, and reproducible. Unilateral surgeries can be performed in 15 to 25 minutes, or bilaterally in 30 to 40 minutes. Bilateral xenografts can provide additional experimental flexibility. For instance, researchers can perform localized treatment of one xenograft, with the other left as a control. The NRG mice are resistant to surgi.......

Materials

Name	Company	Catalog Number	Comments
100 mm x 15 mm Petri dish	Fisher Scientific	FB0875712
2-Methylbutane	Fisher	O3551-4
20 x 30 mm micro cover glass	VWR	48393-151
Animal Weighing Scale	Kent Scientific	SCL- 1015
Antibiotic-Antimycotic Solution	Corning, Cellgro	30-004-CI
AutoClip System	F.S.T	12020-00
Castroviejo Needle Holder	F.S.T	12565-14
Chick embryo extract	Accurate	CE650TL
CM1860 UV cryostat	Leica Biosystems	CM1860UV
Coplin staining jar	Thermo Scientific	19-4
Dissection Pins	Fisher Scientific	S13976
Dry Ice - pellet	Fisher Scientific	NC9584462
Embryonic Myosin antibody	DSHB	F1.652	recommended concentration 1:10
Ethanol	Fisher Scientific	459836
Fetal Bovine Serum	GE Healthcare Life Sciences	SH30071.01
Fiber-Lite MI-150	Dolan-Jenner	Mi-150
Forceps	F.S.T	11295-20
Goat anti-mouse IgG1, Alexa Fluor 488	Invitrogen	A-21121	recommended concentration 1:500
Goat anti-mouse IgG2b, AlexaFluor 594	Invitrogen	A-21145	recommended concentration 1:500
Gum tragacanth	Sigma	G1128
Hams F-10 Medium	Corning	10-070-CV
Histoacryl Blue Topical Skin Adhesive	Tissue seal	TS1050044FP
Human specific lamin A/C antibody	Abcam	ab40567	recommended concentration 1:50-1:100
Human specific spectrin antibody	Leica Biosystems	NCLSPEC1	recommended concentration 1:20-1:100
Induction Chamber	VetEquip	941444
Iris Forceps	F.S.T	11066-07
Irradiated Global 2018 (Uniprim 4100 ppm)	Envigo	TD.06596	Antibiotic rodent diet to protect again respiratory infections
Isoflurane	MWI Veterinary Supply	502017
Kimwipes	Kimberly-Clark	34155	surgical wipes
Mapleson E Breathing Circuit	VetEquip	921412
Methanol	Fisher Scientific	A412
Mobile Anesthesia Machine	VetEquip	901805
Mouse on Mouse Basic Kit	Vector Laboratories	BMK-2202	mouse IgG blocking reagent
Nail Polish	Electron Microscopy Sciences	72180
NAIR Hair remover lotion/oil	Fisher Scientific	NC0132811
NOD-Rag1null IL2rg null (NRG) mice	The Jackson Laboratory	007799	2 to 3 months old
O.C.T. Compound	Fisher Scientific	23-730-571
Oxygen	Airgas	OX USPEA
PBS (phosphate buffered saline) buffer	Fisher Scientific	4870500
Povidone Iodine Prep Solution	Dynarex	1415
ProLong™ Gold Antifade Mountant	Fisher Scientific	P10144 (no DAPI); P36935 (with DAPI)
Puralube Ophthalmic Ointment	Dechra	17033-211-38
Rimadyl (carprofen) injectable	Patterson Veterinary	10000319	surgical analgesic, administered subcutaneously at a dose of 5mg/kg
Scalpel Blades - #11	F.S.T	10011-00
Scalpel Handle - #3	F.S.T	10003-12
Stereo Microscope	Accu-scope	3075
Superfrost Plus Microscope Slides	Fisher Scientific	12-550-15
Suture, Synthetic, Non-Absorbable, 30 inches long, CV-11 needle	Covidien	VP-706-X
1ml Syringe (26 gauge, 3/8 inch needle)	BD Biosciences	329412
Trimmer	Kent Scientific	CL9990-KIT
Vannas Spring Scissors, 8.0 mm cutting edge	F.S.T	15009-08
VaporGaurd Activated Charcoal Filter	VetEquip	931401
Wound clips, 9 mm	F.S.T	12022-09