OBJECTIVETo optimize the best concentration of neuraminidase (Neu) that enhances the migration of neuraminidase (Neu)-treated donor bone marrow cells (dBMCs) to the liver, and observe the influence of short-term cyclosporin A(CsA) application combined with intravenous injection (i.v.) of Ne treated dBMCs on the survival of skin allografts.

METHODSThe experiment consisted of two parts. For selection of an appropriate concentration of Neu, 26 female Wistar rats were randomly divided into four groups. The dBMCs were prepared by routine method and treated with four concentrations (0, 0.5, 1.0, 2.0 U/ml) of Neu at 37 degrees C for 30 min. The untreated and Neu-treated dBMCs were labeled by 99mTc, and injected via the tail veins to female Wistar rats in each group, respectively. After five hours, the radioactivity of various organs collected from sacrificed rats was measured by a gamma counter, and the values were expressed as percentage of total radioactivity of all organs from the same rat. To observe the survival of skin allograft, 23 male Wistar rats were randomly divided into control group, untreated dBMCs group and Neu-treated dBMCs group. All rats in each group were grafted with skin allografts from male Sprague-Dawley (SD) rats. The dBMCs from the same donor without and with Neu treatment by the concentration selected from the above experiment were injected via the tail veins of female Wistar rats in untreated dBMCs group and Neu-treated dBMCs group, respectively. Rats in untreated dBMCs group and Neu-treated dBMCs group received CsA (10 mg/kg) through intraperitoneal injection (i.p.) at 2 and 5 days post-grafting. Neither dBMCs or CsA were given in the control group. The survival of allograft skin in each group was checked and photographed daily after 5 days post operation.

RESULTSWhen the concentration of Neu was 1.0 U/ml, the percentage of dBMCs in liver was (75.3 +/- 9.8) %, which was obviously higher than that in 0 U/ml group [(58.9 +/- 4.2%)], (P < 0.01), indicating that the optimal concentration of Neu was 1.0 U/ml. The survival time of skin allografts in rats of Neu-treated dBMCs group was prolonged significantly in comparison with that of the rats in dBMCs group without Neu treatment (P < 0.01). The survival time in both dBMCs group and Neu-treated dBMCs group was longer that of control group (P < 0.01), and it was prolonged in Neu-treated dBMCs group compared with that in dBMC group.

CONCLUSIONAdministration of proper concentration of Neu can increase the affinity of dBMCs to the liver, and promote the Neu-treated dBMCs to migrate to liver. The intravenous injection of Neu-treated dBMCs combined with short-term CsA administration can delay the rejection of skin allografts in rats.