Microvascular Perfusion Monitored by Laser Speckle Contrast Imaging during Renal Ischemia-Reperfusion Injury in Mice

Summary

A laser speckle contrast imaging system was used to monitor the changes in renal microvascular blood flow during unilateral renal ischemia-reperfusion after the resection of the right kidney in mice.

Abstract

Laser speckle contrast imaging (LSCI) is a non-invasive technique for measuring superficial blood perfusion over large areas. With its high spatiotemporal resolution, LSCI semi-quantifies heterogeneous blood flow changes across different regions within the imaged area. Here, we demonstrate the technique of LSCI to record blood flow during unilateral renal ischemia-reperfusion injury (IRI) in mice. Following right nephrectomy, the position of the mouse and the focal point of the objective of the LSCI system were adjusted to ensure the left kidney was in the field of view. LSCI scans were performed before, during, and after the ischemia of the kidney. Furthermore, by selecting regions of interest (ROIs), blood flow in the regions was simultaneously monitored. The method of LSCI visualizes microvascular perfusion of the kidney and allows for a real-time mapping of blood flow. It may be utilized to monitor the microvascular blood flow and evaluate the effect of an intervention on the reperfusion kinetics and spatial homogeneity during mouse renal IRI or other similar animal models.

Introduction

Ischemia-reperfusion injury (IRI) is among the leading causes of acute kidney injury (AKI), which is associated with high morbidity and high mortality in patients^1,2. The change of renal hemodynamics is one of the critical factors of IR-induced AKI¹. IR-evoked microcirculatory dysfunction is a major reason for the development of injury, leading to oxygen deprivation and mitochondrial dysfunction of cells^3,4. Therefore, monitoring blood flow changes in real time is an effective method for ensuring the successful ischemia or reper....

Protocol

All animal procedures complied with the NIH Guide for the Care and Use of Laboratory Animals and the Guide for the Care and Use of Laboratory Animals, and were approved by the Institutional Animal Care and Use Committee of Shantou University Medical College. To eliminate gender and strain-based differences in IRI effects, only male C57BL/6N mice were used in the study. All mice were matched in age and weight to produce comparable results. A sample size of n = 5 was used, consistent with prior methodological studies utilizing LSCI for technical validation²¹. The animals received humane care and were euthanized after the experiments by CO₂

Results

This article aimed to detect changes in renal blood flow during IR-induced AKI. Therefore, we employed a common mouse model that involves right nephrectomy (Figure 1A) followed by an IR procedure on the contralateral kidney (Figure 1B). Because real-time monitoring of blood flow during IRI was required, all manipulations on the mice were performed at the instrument region throughout the entire process (Figure 1C).

Discussion

This work describes the application of an LSCI system for the real-time, high-resolution visualization of renal microvascular blood flow dynamics during IRI in mice. The protocol offers a significant advantage over traditional endpoint measurements or methods with limited spatial resolution, such as LDF, by providing a two-dimensional perfusion map that captures regional heterogeneity within the kidney microcirculation. The efficiency and usability of LSCI for intraoperative real-time monitoring are key strengths of this.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Absorber canister (for anesthesia)	Shenzhen Laiyue Biotech Co., Ltd, China	10-0210
Alcohol, medical (75%)	HENGLIYA, Xinjiang, China	N/A	Skin disinfectant
Anesthetic vaporizer	Midmark	https://www.midmark.com/animal-health/products/anesthesia/detail/matrx-vip-3000-veterinary-vaporizer
Cotton swabs	Qingdao Hainuo Biological Engineering Co., Ltd, China	https://www.hainuocn.com/index/detail/448.html
Depilatory cream	VEET	https://www.veet.com.cn/jingchun/whx
Gauze bandage	Winner Medical Co., Ltd, Shenzhen, China	https://www.winnermedical.com/gauze-bandage.html
Heating pad	Renqiu Dingsheng Heating Equipment Co., Ltd, China	HD-1902	For maintaining body temperature
Iodophor solution	Taixinkang, Jinxian, China	https://www.11467.com/nanchang/co/120661.htm	Skin antiseptic
Isoflurane	RWD Life Science Co., Ltd, China	R510-22-10	Inhalation anesthetic
Laser speckle contrast imaging (LSCI) system	Hubei Xunwei Optoelectronic Technology Co., Ltd, China	SIM BFI HR PRO	MoorFLPI-2 equivalent system
Meloxicam	Qilu Animal Health Products Co., Ltd, China	https://en.qiludb.com/companion_animal/500.html	0.2 mg per kg of body weight; analgesic
Micro-clamp	Shanghai Medical Instrument(Group) Co., Ltd, China	W40140	Vascular clamp
Normal saline (0.9% sodium chloride)	Cisen Pharmaceutical Co., Ltd, China	https://www.cisen-pharma.com/index/shows?catid=42&id=62
Silk braided suture (6-0)	Yangzhou Fuda Medical Devices Co., Ltd, China	http://www.fdma.com.cn/products_detail/12.html	For vessel ligation
Silk braided suture (7-0)	Wego Terumo (Weihai) Medical Products Co., Ltd, China	https://www.weigaoholding.com/	For wound closure, non-absorbable surgical sutures with the curved needle
Syringe (1 mL)	Shandong Ande Healthcare Apparatus Co., Ltd, China	https://www.andehealthcare.com/html/chanpinzhanshi/Medication-Delivery/syringes/131.html	With 26 G needle
Tribromoethanol	Sigma-Aldrich	T48402-100G	2.5% solution; injectable anesthetic