ABSTRACT: This study aimed to establish the expression profile of circulating microRNAs (miRNAs) during nerve allotransplantation. Experimental design Male Balb/c and C57BL/6 mice (age, 10M-bM-^@M-^S12 weeks; weight, 30M-bM-^@M-^S35 g) were purchased from BioLasco (Yi-Lan, Taiwan). The Balb/c mice served as sciatic nerve allograft donors. The C57BL/6 mice were randomized into the group of nerve allograft transplantation with FK506 treatment and the group without FK506 treatment. These species of mice were selected on the basis of disparity at the MHC locus and prior experience with reciprocal rejection of grafts between these murine strains [18]. The mice were anesthetized by intraperitoneal injection of an anesthetic cocktail consisting of 0.1 mg/g ketamine and 0.01 mg/g xylazine. The anesthetized mice were restrained in a supine position on a heated pad to maintain the body temperature at 37M-BM-0C. Under aseptic conditions, with sterile povidone/iodine preparation and 70% ethanol and sterile instruments and drapes, the skin over the proximal right hindlimb was incised, and the underlying biceps femoris muscle was bluntly dissected to expose the sciatic nerve. An established mouse sciatic nerve allotransplantation model was used. In brief, 1-cm Balb/c donor sciatic nerve grafts were transplanted in reverse orientation into 0.5-cm sciatic nerve gaps created in the recipient Balb/c mice. Tension-free repair was then performed under an operating microscope with three 11M-bM-^@M-^S0 nylon (Ethicon Inc., Somerville, NJ) interrupted epineurial sutures under 40X magnification. The muscle was closed with 5M-bM-^@M-^S0 vicryl sutures, and the skin with interrupted 5M-bM-^@M-^S0 nylon sutures. The animals were monitored to ensure appropriate feeding and diet after surgery. FK506 was administered subcutaneously at 1 mg/(kg-d) throughout the experimental course. At 3, 7, and 14 d after initial surgery (n = 3 animals per group at each time point), the whole blood samples were collected at the indicated times in tubes containing anticoagulant. (F)3d, (F)7d and (F)14d were used to indicate the serum samples of allotransplantation mice with FK506 immunosuppression for 3, 7, and 14 d, respectively. (N)3d, (N)7d and (N)14d were used to indicate the serum samples of allotransplantation mice without FK506 immunosuppression and sacrificed at postoperative 3, 7, and 14 d, respectively. After the whole blood samples were incubated at room temperature for 15 min, they were centrifuged at 3,000 M-CM-^Wg for 10 min, white blood cells were slowly removed from the corresponding layers, and the serum was extracted and stored at M-bM-^@M-^S80M-BM-0C before processing for RNA analyses. Small RNA libraries generated from the serum of mice of above groups were analyzed using an Illumina HiSeq2000 Sequencer.
