Macrophage depletion and Schwann cell transplantation reduce cyst size after rat contusive spinal cord injury

Schwann cell transplantation is a promising therapy for the treatment of spinal cord injury（SCI） and is currently in clinical trials.In our continuing efforts to improve Schwann cell transplantation strategies,we sought to determine the combined effects of Schwann cell transplantation with macrophage depletion.Since macrophages are major inflammatory contributors to the acute spinal cord injury,and are the major phagocytic cells,we hypothesized that transplanting Schwann cells after macrophage depletion will improve cell survival and integration with host tissue after SCI.To test this hypothesis,rat models of contusive SCI at thoracic level 8 were randomly subjected to macrophage depletion or not.In rat subjected to macrophage depletion,liposomes filled with clodronate were intraperitoneally injected at 1,3,6,11,and 18 days post injury.Rats not subjected to macrophage depletion were intraperitoneally injected with liposomes filled with phosphate buffered saline.Schwann cells were transplanted 1 week post injury in all rats.Biotinylated dextran amine（BDA） was injected at thoracic level 5 to evalute axon regeneration.The Basso,Beattie,and Bresnahan locomotor test,Gridwalk test,and sensory test using von Frey filaments were performed to assess functional recovery.Immunohistochemistry was used to detect glial fibrillary acidic protein,neurofilament,and green fluorescent protein（GFP）,and also to visulize BDA-labelled axons.The GFP labeled Schwann cell and cyst and lesion volumes were quantified using stained slides.The numbers of BDA-positive axons were also quantified.At 8 weeks after Schwann cell transplantation,there was a significant reduction in cyst and lesion volumes in the combined treatment group compared to Schwann cell transplantation alone.These changes were not associated,however,with improved Schwann cell survival,axon growth,or locomotor recovery.Although combining Schwann cell transplantation with macrophage depletion does improve histopathology of the injury site,the effect on axon growth and behavioral recovery appears no better than what can be achieved with Schwann cell transplants alone.

Liposome Immunoassay for Determination of Phenytoin

Homogeneous liposome immunoassay for the determination of phenytoin was studied.Liposomes were prepared from cholesterol (CH) and phospholipids including dipalmitoyl phosphatidyl ethanolamine (DPPE) tbr conjugation with thiol-containing antibodies. Hemin chloride was entrapped in the liposome and antibody was modified by reaction with 3' (2-pyndyl-dithio) propionyl N-hydroxysuccinimide ester (SPDP) to introduce thiol groups for efficient coupling. Antibody-coupled liposomes (immunoliposomes) were incubated with phenytoin and complement, and then with hemin substrate. The amount of hemin released from immunoliposomes, which increases with concentration increase of phenytoin, can be detected rapidly by determining the fluorescence with its substrate p-hydroxyphenyl propionic acid (HPPA)and hydrogen peroxide.