The ex vivo tissue perfusion system, as an important experimental technique, plays an irreplaceable role in biomedical research. This system can simulate the in vivo environment in vitro, maintain the physiological functions of tissues and organs, and provide an ideal platform for studying tissue metabolism, drug action mechanisms, and toxic effects. With the deepening of biomedical research, the requirements for ex vivo tissue perfusion systems are becoming increasingly high, making system design optimization and performance evaluation particularly important.
The technology of ex vivo tissue perfusion originated in the early 20th century and has evolved from simple single organ perfusion to complex multi organ combined perfusion systems after more than a century of development. At present, the system has been widely used in the research of various organs such as the liver, heart, and kidneys, providing important tools for new drug development, disease mechanism research, and optimization of clinical treatment plans.
1、 Design principles
The core design goal of ex vivo tissue perfusion system is to simulate the internal environment as much as possible and maintain the normal physiological function of tissues. The system mainly consists of a perfusion liquid circulation device, an oxygenation device, a temperature control system, a monitoring device, etc. The perfusion fluid circulation device usually includes a storage bottle, a peristaltic pump, a piping system, and a collection device to ensure that the perfusion fluid can flow continuously and stably through the tissue.
The selection and preparation of infusion fluid are key steps in system design. Commonly used perfusion fluids include Krebs Henneleit buffer, Tyrode's solution, etc., and their composition needs to be adjusted according to specific tissue types. The ideal perfusion fluid should contain appropriate electrolytes, nutrients, and oxygen, with a pH value maintained between 7.35-7.45 and an osmotic pressure of approximately 290-310mOsm/L. In addition, necessary energy substrates such as glucose and fatty acids need to be added.
Temperature and pH control are crucial for maintaining tissue activity. The system usually uses water bath circulation or electric heating to maintain a constant temperature of 37 ℃, and the pH value is controlled by adjusting the concentration of bicarbonate in the perfusion solution or introducing an appropriate proportion of CO2/O2 mixed gas. The advanced system is also equipped with real-time monitoring devices that can continuously record temperature pH、 Parameters such as oxygen partial pressure.
2、 System performance evaluation indicators and methods
The stability of perfusion fluid flow rate is the primary indicator for evaluating system performance. The ideal perfusion system should be able to provide a stable and low pulsation perfusion fluid flow, with a flow rate fluctuation range not exceeding ± 5% of the set value. The evaluation methods include directly measuring the volume of fluid poured per unit time, or continuous monitoring through flow sensors.
The ability to maintain organizational activity is a core indicator of system performance. It can be evaluated by measuring biochemical indicators such as tissue ATP content, lactate dehydrogenase release, and oxygen consumption rate. Morphological examinations such as light and electron microscopy can also visually reflect the integrity of tissue structure. In addition, tissue-specific functional indicators such as the liver's urea synthesis ability and the heart's contractility can directly reflect the performance of the system.
The efficiency of metabolite exchange reflects the system's ability to simulate the in vivo environment. It can be calculated by measuring the consumption of nutrients and the generation of metabolites at the inlet and outlet of the infusion solution. For example, glucose uptake rate, lactate production rate, and urea secretion are commonly used evaluation indicators. Advanced systems can also integrate analytical techniques such as mass spectrometry or high-performance liquid chromatography to achieve real-time monitoring of multiple metabolites.
3、 Application Status and Development Trends
Currently, the system has been widely applied in multiple research fields. In drug development, this system can be used to evaluate drug metabolism, toxicity, and tissue-specific distribution; In disease research, tissue reactions under pathological conditions can be simulated; In transplant medicine, it can be used to evaluate the quality of organ preservation. The liver perfusion system is also used as a transitional therapy for the clinical treatment of acute liver failure.
The future development trend is mainly reflected in three aspects: firstly, miniaturization and automation, achieving more precise environmental control through microfluidic technology and intelligent control systems; The second is to integrate multiple organs and establish a model of inter organ interactions that is closer to the in vivo environment; The third is the combination of imaging technology and omics technology to achieve multidimensional data acquisition and analysis. These developments will greatly expand the application scope and scientific research value of ex vivo tissue perfusion systems.