Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325000, China.
Department of Pharmaceutical Sciences, University of North Texas Health Science Center, Fort Worth, TX, 76107, USA.
Stem Cell Res Ther. 2019 Mar 15;10(1):96. doi: 10.1186/s13287-019-1210-4.
Studies have shown that transplantation of bone marrow-derived mesenchymal stem cells (BMSCs) protects against brain damage. However, the low survival number of transplanted BMSCs remains a pertinent challenge and can be attributed to the unfavorable microenvironment of the injured brain. It is well known that calpain activation plays a critical role in traumatic brain injury (TBI)-mediated inflammation and cell death; previous studies showed that inhibiting calpain activation is neuroprotective after TBI. Thus, we investigated whether preconditioning with the calpain inhibitor, MDL28170, could enhance the survival of BMSCs transplanted at 24 h post TBI to improve neurological function.
TBI rat model was induced by the weight-drop method, using the gravitational forces of a free falling weight to produce a focal brain injury. MDL28170 was injected intracranially at the lesion site at 30 min post TBI, and the secretion levels of neuroinflammatory factors were assessed 24 h later. BMSCs labeled with green fluorescent protein (GFP) were locally administrated into the lesion site of TBI rat brains at 24 h post TBI. Immunofluorescence and histopathology were performed to evaluate the BMSC survival and the TBI lesion volume. Modified neurological severity scores were chosen to evaluate the functional recovery. The potential mechanisms by which MDL28170 is involved in the regulation of inflammation signaling pathway and cell apoptosis were determined by western blot and immunofluorescence staining.
Overall, we found that a single dose of MDL28170 at acute phase of TBI improved the microenvironment by inhibiting the inflammation, facilitated the survival of grafted GFP-BMSCs, and reduced the grafted cell apoptosis, leading to the reduction of lesion cavity. Furthermore, a significant neurological function improvement was observed when BMSCs were transplanted into a MDL28170-preconditioned TBI brains compared with the one without MDL28170-precondition group.
Taken together, our data suggest that MDL28170 improves BMSC transplantation microenvironment and enhances the neurological function restoration after TBI via increased survival rate of BMSCs. We suggest that the calpain inhibitor, MDL28170, could be pursued as a new combination therapeutic strategy to advance the effects of transplanted BMSCs in cell-based regenerative medicine.
研究表明，骨髓间充质干细胞（BMSCs）的移植可减轻脑损伤。然而，移植的 BMSCs 存活率低仍然是一个挑战，这可归因于受损大脑的不利微环境。众所周知，钙蛋白酶激活在创伤性脑损伤（TBI）介导的炎症和细胞死亡中起着关键作用；先前的研究表明，TBI 后抑制钙蛋白酶的激活具有神经保护作用。因此，我们研究了 TBI 后 24 小时预先用钙蛋白酶抑制剂 MDL28170 预处理是否可以提高 BMSCs 的存活率，从而改善神经功能。
采用落体法诱导 TBI 大鼠模型，利用自由落体的重力产生局灶性脑损伤。TBI 后 30 分钟，将 MDL28170 注入损伤部位的颅内，24 小时后评估神经炎症因子的分泌水平。TBI 大鼠脑损伤部位在 TBI 后 24 小时局部给予绿色荧光蛋白（GFP）标记的 BMSCs。通过免疫荧光和组织病理学评估 BMSC 的存活和 TBI 损伤体积。采用改良神经严重程度评分来评估功能恢复。通过 Western blot 和免疫荧光染色确定 MDL28170 参与炎症信号通路和细胞凋亡调节的潜在机制。
总的来说，我们发现 TBI 急性期单次给予 MDL28170 可通过抑制炎症改善微环境，促进移植 GFP-BMSCs 的存活，并减少移植细胞凋亡，从而减少损伤腔。此外，与未用 MDL28170 预处理的 TBI 脑相比，将 BMSCs 移植到 MDL28170 预处理的 TBI 脑中可显著改善神经功能。
综上所述，我们的数据表明，MDL28170 通过提高 BMSCs 的存活率改善 BMSC 移植的微环境，并增强 TBI 后的神经功能恢复。我们建议，钙蛋白酶抑制剂 MDL28170 可作为一种新的联合治疗策略，以提高细胞再生医学中移植 BMSCs 的效果。
