| Up to now, there were no effective therapies for nerve cellsdied by the cerebrovascular disease.As a usual disease in nervous system, ischemiccerebrovascular disease always cause no reverted nerve functionalimpairment which brought great distress to the patients.These days, international researchers are trying to use severalkinds of therapy from thrombolysis to intervention therapy torehabilitate ischemic region and protect neuron impairment.But, because of the restriction of "time window", there were fewpatients could accept thrombolysis in time. Prothrombolysis orother therapy couldn't block the occurrence of brain damage andregenerate it.Transplantation of neuron stem cell to treat nervous centralsystem disease brought more and more attention from world widemedical researchers. It could substitute neuron function impairmentto "no sequel" which is ultimate therapy.The discovery of neuron stem cell changed people's opinionabout regeneration of neuron and axon shouldn't happen innervous central system. It brought new possibility to treat manykinds of nervous system diseases.Formerly, neuron stem cell was collected from embryo andadult nervous system. It made some problems to obtainment, ethic,and immunologic rejection after transplantation, and places apremium on tumor. It was restricted usefulness inclinical in deed.Blood from umbilical cord is another main source of neuronstem cell. But, it also has a greatdisadvantage, i.e. heterology,which needs long term treatment with immunosuppressant to avoidimmunologic rejection. Human mesenchymal stem cell (hMSC) hassome benefits derived from its wide source, easiness to obtain,easiness to catch from ex vitro growth, free from ethic problem, autologous transplantation, avoidance of immunoreactions. Butthere have some disputation whether hMSC integrate into receptortissue and differentiate into neuronal and astroglial cells or it inducethe growth of endogenous progenitor cells.In this research, neural functional test was done for all theanimals after intravenous injection of hMSC who have focalischemic stroke. We give the point for the region of cerebralinfarction, living ratio of hMSC after it arrive the region of ischemicnervous, the degree of differentiation from tansplantment cell,progenitor cell exist in around ischemic region, subependymalregion and corpus striatum to demonstrate some mechanism aboutthe action of transplanted hMSC neural system.There were several kinds of technique for transplantation,which include the directory injection according to the solidlocalization, injection throw cerebrospinal fluid, and intravenousinjection. Because of the side-effect, former two techniques weredifficult to use in clinical treatment and they were substituted byintravenous injection.There were some bifurcations about the amount of injectionamong the researchers. A few amount of injection couldn't lethMSC arrive central nervous system, most of them stayed in lungand lien, and a great lot should derive embolism. In recent days, itis recommended to use (1—6)×10~6.In this study, we used 1×10~6 and gained a quite approvingresult.First, healthy volunteers were selected to aspirate 10ml ofbone marrow from iliac crest; centrifuge was done for separation ofhMSC and labeled with fluorescent dye PKH26 after incubation for2 weeks.We divided into sham operation group (group A, shamoperation + intravenous injection of saline throw caudal vein),ischemia and reperfusion group (group B, middle cerebral artery infarction + intravenous injection of saline throw caudal vein), bonemarrow stem cell group (group C, middle cerebral artery infarction+ intravenous injection of hMSC throw caudal vein), the amount ofhMSC used in this study was 1×10~6.Rat model which has focal ischemic cerebrovascular diseasewas made with suture infarction method, and intravenous injectionwith PKH26 labeled hMSC was done after 24 hours later. Allanimals received daily intraperitoneal injection withbromodeoxyuridine (BrdU) to label growth progenitor neural cell.We performed neural functional test at 1, 7 and 14 days. All theanimals were killed at 14 days since infarction.Immunohistochemistry was done to measure the region of cerebralinfarction, quantitative PHK26 labeled and NuMA labeled hMSC,evaluate the degree of differentiation, and compare the degree ofdifferentiation from progenitor neural cells in subependymal aroundhomolateral cerebral cavities.As a result, neurological function was improved aftertransplantation of hMSC: region of cerebral infarction wasdecreased(P＜0.05); we also found PKH26 labeled hMSC aroundischemic cerebral region at 14 days later. Accrementition ofprogenitor neural cells was happened in group B and C found insubependymal and the latter has more significant than former (P＜0.01). Astroglial cells and neuron differentiated from BrdU labeledcells could be observed but couldn't from NuMA labeled cells.According to this study, we get some conclusion. 1) hMSC canarrive and be alive near to the ischemic region after intravenousinjection throw caudal vein, and it can restore injury tissue only afterit arrive ischemic region. We demonstrated that injection with1×10~6 hMSC was enough as the opinion comes from some otherresearchers. 2)We can observe significant reinstatement ofneurological function and decrease region of cerebral infarction after transplantation of hMSC.The score of Motor tests, Sensory test, Modified NeurologicalSeverity Score (mNSS) given at 1, 7, 14 days in group C hassignificant difference from group B, which showed improvementfrom 3rd day and maximum was 14th day. 3) Transplanted hMSCdoes not differentiate into neuron and astroglial cells after it arriveto the region of ischemic cerebra. Because there were nomorphological change happened in hMSC, we considered theimprovement of neurological function is not come from integrationof neuron derived from transplanted hMSC. 4) After hMSC wastransplanted, progenitor neural cells which were around ischemicregion, subependymal region and corpus striatum reproduce anddifferentiate to neuron and astroglial cells, finally courseimprovement from ischemic cerebral impairment. And, what kindsof effects the transplanted hMSN has?Maybe, it is reasonable for that the protein synthesized fromthe transplanted hMSC should increase plasticity of host cerebraltissue, change the microenvironment around ischemic region, wakeup sleeping progenitor neural cells existed before. All of thesereasons show wide possibility in rehabilitate and treatment centralnervous system disease in future.Although transplantation of hMSC got some evolvement, thebasic biological feature and immunological feature to hMSC has notbeen completely identified, it needs further research to find efficienttransplanting method, needs to can monitor transplanting course invivo about electrophysiology feature, synapses connection, signalconduction and liberation functions.It will be laid the foundations to use hMSC in clinical treatmentthat improvement of living time of transplanted hMSC in vivo, safety,optimized condition to growth ex vitro and investigating theconnection between hMSC and nerve growth factor, and to finddifferentiate hMSC key point gene. It is only a start step to transplantation and gene therapy. Inorder to increase therapeutic efficiency, it is necessary to fartherinvestigate to realize the action of hMSC in the differentiation anddevelopment.
|
PDF Full Text Request