VEGF-transfected hBMSCs Aggravate Early Brain Edema in Cerebral Hemorrhage Rats

  Objective  To investigate the effects of human bone marrow mesenchymal stem cells/vascular endothelial growth factor (hBMSCs/VEGF) transplantation on early brain edema in rats with cerebral hemorrhage.

  Methods  Cultured the hBMSCs in vitro, transducted the cells with VEGF recombinant lentivirus vector to abtain the hBMSCs/VEGF cells. Intracerebral hemorrhage (ICH) rat model was established by injection of type Ⅰ collagenase and heparin into the caudate putamen. 2 h after the operation, the rats were evaluated with modified nerve function defect (mNSS) score to ensure whether the model was successfully established. At the third day after the injection, SD rats were randomly divided into sham group (only injected with empty needle), cerebral hemorrhage group, saline group, hBMSCs group and hBMSCs/VEGF group. Saline group, hBMSCs group and hBMSCs/VEGF group mice were injected with normal saline, hBMSCs (2×10⁶ cells/kg body mass) and hBMSCs/VEGF (2×10⁶ cells/kg body mass) respectively; sham group and model group did not perform intervention. On day 3 and 7 after injection, the rats were evaluated with modified neurological function score (mNSS). Then rats were sacrificed, and brain tissue specimens from the right caudate putamen area were separated. The wet and dry weighing method was used to measure the water content, and HE staining was used to evaluate pathological and functional changes. The expressions of VEGF, matrix metalloproteinase 9 (MMP-9) and aquaporin 4 (AQP-4) proteins were detected by immunofluorescence and Western blot.

  Results  2 h after injection, compared with rats in sham operation group, mNSS scores of rats in model group were increased, indicating that the models have successfully established. 3 d and 7 d after intervention, the mNSS score, the content of brain water, the expression level of VEGF, MMP-9 and AQP-4 proteins in model group and NS group were significantly higher than those of sham group (P<0.05), while the above values in hBMSCs group were significantly lower than those in saline group and model group (P<0.001), and the above values in hBMSCs/VEGF group were significantly higher than those of hBMSCs group (P<0.05). There were obvious hemorrhage and infarction in the brain tissue in the model group and NS group rats observed under the light microscope. Besides, the brain tissue developed loose structure and edema change. However, the bleeding and infarction in the brain tissue of hBMSCs group mice were reduced. Compared with the hBMSCs group mice, the brain tissue of hBMSCs/VEGF group mice was looser, more vacuoles occurred, and many neurons showed apoptosis changes such as nuclear deflation.

  Conclusion  hBMSCs transplantation could improve neurological function and relieve brain edema. But hBMSCs/VEGF will increase the vascular permeability and then aggravate the early cerebral edema in rats with cerebral hemorrhage.