Stabilized Window for Intravital Imaging of the Murine Pancreas

Summary

We present a protocol for the surgical implantation of a stabilized indwelling optical window for subcellular-resolution imaging of the murine pancreas, allowing serial and longitudinal studies of the healthy and diseased pancreas.

Abstract

The physiology and pathophysiology of the pancreas are complex. Diseases of the pancreas, such as pancreatitis and pancreatic adenocarcinoma (PDAC) have high morbidity and mortality. Intravital imaging (IVI) is a powerful technique enabling the high-resolution imaging of tissues in both healthy and diseased states, allowing for real-time observation of cell dynamics. IVI of the murine pancreas presents significant challenges due to the deep visceral and compliant nature of the organ, which make it highly prone to damage and motion artifacts.

Described here is the process of implantation of the Stabilized Window for Intravital imaging of the murine Pancreas (SWIP). The SWIP allows IVI of the murine pancreas in normal healthy states, during the transformation from the healthy pancreas to acute pancreatitis induced by cerulein, and in malignant states such as pancreatic tumors. In conjunction with genetically labeled cells or the administration of fluorescent dyes, the SWIP enables the measurement of single-cell and subcellular dynamics (including single-cell and collective migration) as well as serial imaging of the same region of interest over multiple days.

The ability to capture tumor cell migration is of particular importance as the primary cause of cancer-related mortality in PDAC is the overwhelming metastatic burden. Understanding the physiological dynamics of metastasis in PDAC is a critical unmet need and crucial for improving patient prognosis. Overall, the SWIP provides improved imaging stability and expands the application of IVI in the healthy pancreas and malignant pancreas diseases.

Introduction

Benign and malignant pancreatic diseases are potentially life-threatening, with considerable gaps in the understanding of their pathophysiology. Pancreatitis-inflammation of the pancreas-is the third major cause of gastrointestinal disease-related hospital admissions and readmissions in the US and is associated with substantial morbidity, mortality, and socioeconomic burden¹. Ranked as the third leading cause of cancer-related death², pancreatic ductal adenocarcinoma (PDAC) accounts for most pancreatic malignancies³ and portends a poor 5-year survival rate of only 11%². The....

Protocol

All procedures described in this protocol have been performed in accordance with guidelines and regulations for the use of vertebrate animals, including prior approval by the Albert Einstein College of Medicine Institutional Animal Care and Use Committee (IACUC).

1. Passivation of windows

NOTE: Passivation of stainless steel cleans the metal of contaminants and creates a thin oxide layer that greatly increases the metal's biocompatibility with sof.......

Discussion

The SWIP protocol described here provides an improved method of pancreas tissue stabilization by utilizing a cross-stitch basket technique. Early abdominal imaging windows (AIWs) enabled intravital imaging (IVI) of internal organs of the abdomen but did not adequately limit the movement of soft tissues such as the pancreas. In response, Park et al. developed a pancreas imaging window (PIW) that incorporates a horizontal metal shelf and allows improved stabilization of the pancreas tissue while maintaining contact with th.......

Materials

Name	Company	Catalog Number	Comments
1% (w/v) solution of enzyme-active detergent	Alconox Inc	NA	Concentrated, anionic detergent with protease enzymes for manual and ultrasonic cleaning
5% (w/v) solution of sodium hydroxide	Sigma-Aldrich	S8045	Passivation reagent
5 mm cover glass	Electron Microscopy Sciences	72296-05	Round Glass Coverslips
7% (w/v) solution of citric acid	Sigma-Aldrich	251275	Passivation reagent
28G 1 mL BD Insulin Syringe	BD	329410	Syringe for cell injection
Baytril 100 (enrofloxacin)	Bayer (Santa Cruz Biotechnology)	sc-362890Rx	Antibiotic
Bench Mount Heat Lamp	McMaster-Carr	3349K51	Heat lamp
Buprenorphine 0.3 mg/mL	Covetrus North America	059122	Buprenorphine Analgesia
Castroviejo Curved Scissors	World Precision Instruments	WP2220	Scissor for cutting tissue
C57BL/6J Mouse	Jackson Laboratory	000664	C57BL/6J Mouse
Chlorhexidine solution	Durvet	7-45801-10258-3	Chlorhexidine Disinfectant Solution
Compressed air canister	Falcon	DPSJB-12	Compressed air for drying tissue
Cyano acrylate - Gel Superglue	Staples	234790-6	Skin Glue
Cyano acrylate - Liquid Superglue	Staples	LOC1647358	Coverslip Glue
DPBS 1x	Corning	21-031-CV	DPBS for cerulein/cell injections
Gemini Cautery Kit	Harvard Apparatus	726067	Cautery Pen
Germinator 500	CellPoint Scientific	GER 5287-120V	Bead Sterilizer
Graefe Micro Dissecting Forceps; Serrated; Slight Curve; 0.8 mm Tip Width; 4" Length	Roboz Surgical	RS-5135	Graefe Micro Dissecting Forceps
Imaging microscope	NA	NA	See Entenberg et al. 2011 [27]
Imaging software	NA	NA	See Entenberg et al. 2011 [27]
Isoethesia (isoflurane)	Henry Schein Animal Health	50033	Isoflurane Anesthesia
Kim Wipes	Fisher Scientific	06-666-A	Kim Wipes
Laboratory tape	Fisher Scientific	159015R	Laboratory Tape
Mouse Dissecting Kit	World Precision Instruments	MOUSEKIT	Surgical Instruments
Mouse Paw Pulse Oximeter Sensor	Kent Scientific Corpo	MSTAT Sensor-MSE	Pulse Oximeter
Mouse Surgisuite	Kent Scientific	SURGI-M04	Heated platform
Nair Hair Removal Lotion	Amazon	B001RVMR7K	Depilatory Lotion
Oxygen	TechAir	OX TM	Oxygen
PERMA-HAND Black Braided Silk Sutures, ETHICON Size 5-0	VWR	95056-872	Silk Suture
Phosphate Buffered Saline 1x	Life Technologies	10010-023	PBS
PhysioSuite System	Kent Scientific	PhysioSuite	Heated Platform Controller
Puralube	Henry Schein Animal Health	008897	Eye Lubricant
Puritan Nonsterile Cotton-Tipped Swabs	Fisher Scientific	867WCNOGLUE	Cotton Swabs
SHARP Precision Barrier Tips, For P-100, 100 µL	Denville Scientific Inc.	P1125	100 µL Pipet Tips
Tetramethylrhodamine isothiocyanate–Dextran	Sigma-Aldrich	T1287-500MG	Vascular Label
Window-fixturing plate	NA	NA	Custom made plate for window placement on microscope stage. Plate is made of 0.008 in stainless steel shim stock. For dimensions of plate see Entenberg et al., 2018 [8].
Window Frame	NA	NA	The window is composed of a steel frame with a central aperture that accepts a 5 mm coverslip. A groove of 1.75 mm around the circumference of the frame provides space for the peritoneal muscle and skin layers to adhere to. See Entenberg et al., 2018 [8].