Homing Profiles Of Mesenchymal Stem Cells In Mouse Models And Metastasis And Therapy Efficiency In Prostate Cancer Models

Malignant tumor is one of fatal diseases that threaten human life.According to the estimation from Cancer Society found that hepatocarcinoma ranks fifth among all tumors and occupies the forth leading cause of cancer mortality in China.Meanwhile prostate cancer is the most common cancer expected to occur in men,with accounting for 1 in 5 new diagnoses,and the second leading cause of cancer-related death in the United States.Searching for effective treatment,especially specific target to tumor therapy,which decrease side effect to healthy tissues has become a hotspot in oncology research.Recently,several studies suggest that mesenchymal stem cells(MSC)have relation to tumor progress.Here,we studied the tumor tropism of MSC in different tumor models in this thesis.In the first chapter,the ability to specifically tropic to tumor tissue and differentiate as a potential source of cancer-associated fibroblast with periadventitial cells,including pericytes,vascular smooth muscle cells,endothelial cells and infiltrating immune cells,to create a favorite niche that promote carcinogenic progression by paracrine secretion to increase metastatic abilities.Systemically infused ectogenic MSC localize within injured,inflamed,and cancerous tissues,suggesting that MSC could serve as a cellular drug delivery system for multiple applications.However,the mechanisms underlying the homing process and the homing time and efficiency are poorly studied.In vivo flow cytometry(IVFC)can be used to quantify fluorescencelabeled cells in the circulation without extracting blood samples,allowing non-invasive and continuous detection of larger blood volumes than ex vivo flow cytometry.Here,we use in vivo flow cytometry to study the homing time course and fate of fluorescence-labeled MSC after systemic delivery into healthy mice and hepatocellular carcinoma mouse models.In addition,we dynamically monitored the process of prostate cancer growth,development and metastasis by IVFC and in vivo animal ultrasonic imaging.We compare tumor behaviors in both orthotopic and subcutaneous tumor model.Then we assess the curative effect of androgen deprivation therapy(ADT)in two kinds of mouse tumor models.In the second chapter,we use surgery or tumor cells injection to establish EGFP-transfected orthotopic HCCLM3 models,subcutaneous tumor models,and lung metastasis tumor models.MSC isolated from mouse bone marrow exhibited the growth of colonies with spindle-shape morphology in tissue culture.We found that DiD labeled MSC have long circulation time and rebound peak in specific time points after i.v.injection by IVFC.Combined with blood sampling test by conventional flow cytometry and in vitro co-culture exam,we found that neutrophil could attach apoptotic DiD labeled MSC,and bring the DiD dye to neutrophil during the phagocytosis process.After removal neutrophil by i.v.injection neutralizing antibody for 24 hours later,we found that the rebound peak of systemic infused DiD-MSC disappeared during 30-48 hours by IVFC.We suggest that the rebound peak of DiD-MSC in blood circulation related to the removing of apoptotic MSC by neutrophil.Moreover some parts of low level DiD positive signals,which detected by IVFC in long circulation time,may leaded by the neutrophil.In the third chapter,we investigated the dynamic homing profiles of systemically infused MSC,which transfected with adenovirus to express EGFP,in healthy mice and three types of tumor mouse models.The circulation times of MSC in healthy mice and mice with subcutaneous tumors,orthotopically transplanted liver tumors,or metastatic lung tumors were 30,24,18,and 12 hours,respectively.Our results support the idea that the homing of MSC to tumor microenvironments involves both passive mechanical trapping and active tumor tropism.MSC infiltrated into hepatocellular carcinoma sites and preferentially engrafted to micrometastatic regions both in vivo and in vitro.The expression of EGF,CXCL9,CCL25,and MMP-9 by hepatocellular carcinoma cells differed between primary tumor sites and metastatic regions.By characterizing the homing profiles of systemically perfused MSC under physiological and cancerous conditions,these findings increase our understanding of the migration of MSC from the circulation to tumor sites and constitute a basis for developing MSC-based anti-cancer therapeutic strategies.In the fourth chapter,we use high metastatic PC3 cell line,transfected by lentiviral to stably express green fluorescence protein(GFP),to establish subcutaneous tumor models and prostate orthotopically transplanted tumor models.We used IVFC and in vivo animal ultrasonic imaging to dynamically monitor the process of prostate cancer growth,development and metastasis.We found that the number of circulating tumor cells(CTC)in orthotopic tumor models was higher than in subcutaneous tumor models.The CTC number in orthotopic tumor models was burst growth,while the metastatic tumor cell number in subcutaneous tumor models showed gradually increase with the growth of tumor size.And the mice with subcutaneous tumor have longer survival time than with orthotopically transplanted prostate tumor.After androgen deprivation therapy by extracting testicular seven days later,we constructed GFP-PC3 subcutaneous tumor models and orthotopic tumor models.Then we found that the CTC number dramatically decreased,relieved the symptoms caused by tumor,and significantly prolonged the survival time after extracting testicular in orthotopically transplanted prostate tumor models,while the carcinogenesis process and metastases were not influence by ADT therapy in subcutaneous tumor models.Thus,orthotopic tumor model is better to assess the tumor growth,development and metastasis characteristics under clinically relevant conditions.ADT treatment can restrict tumor growth,significant decrease the CTC number and distant invasion through inhibiting tumor proliferation and tumor angiogenesis in prostate orthotopically implanted tumor models.