Experimental study of secondary osteoporosis of spinal cord injured rats / 中国组织工程研究

ABSTRACT

BACKGROUND: Osteoporosis is one of the complications of spinal cord injury, but its mechanism is unclear, different scholars have different points about whether all bones above and below the level of trauma are affected after spinal cord injury (SCI).OBJECTIVE: To observe the ultrastructure of bone tissue of secondary osteoporosis after spinal cord injury and the change of serum biochemical indexes, to analyze the suffered condition and injured degree of the bones above and below the level of the trauma.DESIGN: Randomized controlled experimentSETTING: Laboratory of Animals, and Department of Laboratory Medicine of the Second Clinical Hospital of Jilin University; Transmission Electron Microscope Center, Norman Bethune Division of Medical Sciences of Jilin UniversityMATERIALS This experiment was conducted at the Laboratory of Animals, Second Clinical Hospital of Jilin University from May 2002 to May 2003. Totally 110 male Wistar rats, aged 4 to 5 month-old, with the body mass of (300 -320)g were involved.METHODS: Ten rats were randomly chosen from 110 male Wistar rats and were set as 0 week blank control group, the ther rats were randomly divided into experimental group and control group, there were 10 rats in week 1, 2, 3, 7 and 11 control group and experimental group separately.1 mL/L of pentobarbital natrium was intraperitoneal injected to perform anesthesia, in the control group, lamina with dura intact of rats were removed only, without spinal cord injury at the level of tenth thoracic vertebrae. In the experimental group, lamina of rats was also removed, the spinal cord injury model of the rats were made by the method of Allen's.4 mL venous blood was collected from the animals at the end of postoperative week 0, week 1, week 2, week 3, week 7 and week 11, then the animals were put to death, perform blood centrifuging .We observe the change of serum concentration of calcium, phosphorus and alkaline phophatase (ALP) with 7170A HITACHI auto-biochemistry analyzer. Right side humerus, tibia in week 0 blank control group, week 7 experimental group and week 11 experimental group were chosen, then 25 mL/L ethylene dinitrilotetraacetic acid was used for decalcium for 1 month for preparingthe sections. We observe the change of ultrastructure of osteocytes at the sites of tibial plateau and the surgical neck of the humerus after stained by uranyl acetate and lead citrate under transmission electron microscope.biochemistry detection the level of phosphorus at week 2 of the experiment was significantly lower in the control group than experiment group [(1.54±0.21),(2.76±0.16)mmol/L, (P ＜ 0.01)]; the level of calcium at week 3 in the experiment group was significantly higher than in the control group [(2.52±0.06),(2.35±0.12)mmol/L, (P ＜ 0.01)];the level of alkaline phophatase at week 7 in the experiment group was significantly higher than in the control group [(155.86±20.42), (129.25±7.30)Nμ/mg,operative week 7, the tibia sample showed that the osteocyte separated from the osseous lacuna, the nucleus showed anomaly, fluffed materials appeared. Mitochondrion swelled, rough endoplasmic hollowed; At week 11, osteocyte separated from the osseous lacuna. At postoperative 7 week,the humerus sample showed that osteocyte separated from osseous lacuna,some nucleus pycnosis and rough endoplasmic hollowed; At postoperative week 11, the above changes still were seen, but the degree of cellular swelling and hollowing were lighten.CONCLUSION: At the early stage of spinal cord injury, the activity of osteoclast is increased and the activity of osteoblast is decreased, which leads to the increase of bone absorption, the bone formation is largely weakened. The bones above and below the level of trauma are both affected after spinal cord injury, but different extents of osteoporosis can be seen in different bones .The change of ultrastructure of osteocytes is remarkable when osteoporosis has happened.