Effect of human cord blood mononuclear cells transplantation on the ability of learning and memory of newborn rats with hypoxic-ischemic brain damage

Abstract

Objective To explore the effect of human cord blood mononuclear cells (HCMNCs) transplantation on the ability of learning and memory of neonatal rats with hypoxic-ischemic brain damage(HIBD) and its correlation. Methods Sixty 7-day-old neonatal SD rats were divided into 3 groups randomly.A modified newborn rat model that had a combined hypoxic and ischemic brain damage as described by Rice was used.After 24 h, in the HIBD+ HCMNCs group intraperitoneal injection with 1×107 HCMNCs was given; HIBD+ 9 g/L saline group received intrape-ritoneal injection with the equal 9 g/L saline, and a control group was also established.The brain MRI was done to eva-luate the recovery from brain damage 10 d and 67 d after birth.The Morris water maze was used to evaluate the ability of learning and memory 35 d after birth.Then they were beheaded for the brain samples, and morphological grading roughly to mouse, transmission electron microscope were used to evaluate the neurons synaptic ultrastructure changes in each mouse brains injury.At last, correlation analysis was made among groups. Results Compared with HIBD+ HCMNCs group and blank control group, in Morris water maze, from the second day, the HIBD+ 9 g/L saline showed longer escape latency from the 2nd day[the second day: (61.17±6.22) s vs (53.09±7.41) s vs (53.53±5.28) s, the third day: (57.26±14.98) s vs (49.76±9.40) s vs (47.11±7.36) s, the fourth day: (52.10±6.17) s vs (44.16±5.74) s, (41.96±8.97) s], the times through the platform reduced[(2.12±1.05) times vs (3.06±1.16) times vs (3.70±1.17) times], the total movement distance was reduced [(16.68±3.76) nm vs (22.00±3.32) nm vs (23.80±2.25) nm], the average speed was reduced [(0.28±0.06) cm/s vs (0.37±0.06) cm/s vs (0.40±0.04) cm/s], the movement time was reduced [(22.75±4.85) s vs (27.88±3.81) s, (28.02±4.09) s](all P 0.05). On the the fourth day in Morris water maze, high correlation existed between the escape latency and the synaptic cleft(r=0.788, P<0.05). Conclusion HCMNCs intraperitoneal transplantation significantly promoted the recovery of injured brain and the ability of learning and memory. Key words: Hypoxic-ischemic, brain; Cord blood stem cell transplantation; Learning; Memory