Replantation is the surgical reattachment by microsurgical techniques of a body part (finger, hand, or an arm) that has been completely cut from the body. With the continuous advancement of clinical surgical techniques, the replantation of various anatomical parts has become possible [1, 2]. As the opportunities for replanting increase, it becomes more and more important to preserve the body parts for longer and in better conditions. To date, studies have shown that through experiments on preservation and retransplantation of rat limbs, it has been found that the cold ischemic time of limbs should not exceed 12–24 h [3]. Although, in subsequent experiments, studies have found that after wrapping the limb with saline-moistened gauze, sealing it in a plastic bag, and keeping it on ice for 94 h, the finger can still be successfully replanted. However, in order to ensure the success of the operation, it is still recommended that the separated limbs be retransplanted within 12–24 h [4, 5].
The development of cryopreservation technology began when the British biologist Christopher Polge discovered in 1949 that sperm treated with glycerol can survive cryopreservation, and it has been widely used in clinical medicine [6]. Subsequently, Jason G et al. [7] revealed that the ovarian cortical tissue strips of human were preserved using cryopreservation technology, and was transplanted with successful reproductive function after thawing. Yin et al. [8] reported that the rat ovaries were successful cryopreservation and replantation, and not disrupt the function of the ovaries. In addition, Tanaka et al. [9] reported that the cryopreserved tracheal allografts was successful transplanted in rabbit models. Therefore, it further clarified that the limbs can survive after cryopreservation in vitro. Low-temperature storage can be divided into two categories: one is conventional low-temperature storage at a storage temperature of 4 °C, and the other is deep-low temperature storage, that is, storage in a 80 °C low-temperature refrigerator or liquid nitrogen (-196 °C) [10–12]. Generally, cryoprotectants are added to preserve the limbs while cryopreserving to maintain the biological integrity of the tissues. Cryopreservation is usually used to preserve homogeneous cell populations and monolayer tissues [13]. The purpose of cryopreservation is to keep the tissue in a suspended state, in which the biological process is suspended, and the final temperature is usually the temperature of liquid nitrogen. In addition, bones can be frozen and stored without using cryoprotectants, usually at a temperature not lower than − 80 °C [14]. Although various types of tissues can be cryopreserved, the preserved specimens can be thawed and the physiological functions of the limbs can be restored, progress is being made in the cryopreservation of whole organs [14]. However, the optimal parameters for cryopreservation vary for different tissue types [15]. Composite tissues (such as limbs) are composed of multiple tissue types, including skin, muscles, blood vessels, nerves, and bones. Therefore, although cryopreservation of composite tissue is technically challenging, it is still expected to improve the quality of life of many people [16, 17].
Therefore, the purpose of this study is to provide experimental basis for exploring suitable storage methods for amputated fingers (limbs), the effects of rat limbs preserved for 72 h and 7 days under different storage conditions on the survival of limbs after transplantation was observed. Provide methodological reference and corresponding theoretical support for future clinical practice, and provide more guidance cases for the establishment of a limb bank and completion of allogeneic limb replantation in the future, which can more effectively reduce the disability rate of patients and replant the original limbs.