Encapsulation of Mesenchymal Stem Cells by Bioscaffolds Protects Cell Survival and Attenuates Neuroinflammatory Reaction in Injured Brain Tissue after Transplantation

Abstract

Since the brain is naturally inefficient in regenerating functional tissue after injury or disease, novel restorative strategies including stem cell transplantation and tissue engineering have to be considered. We have investigated the use of such strategies in order to achieve better functional repair outcomes. One of the fundamental challenges of successful transplantation is the delivery of cells to the injured site while maintaining cell viability. Classical cell delivery methods of intravenous or intraparenchymal injections are plagued by low engraftment and poor survival of transplanted stem cells. Novel implantable devices such as 3D bioactive scaffolds can provide the physical and metabolic support required for successful progenitor cell engraftment, proliferation, and maturation. In this study, we performed in situ analysis of laminin-linked dextran and gelatin macroporous scaffolds. We revealed the protective action of gelatin–laminin (GL) scaffolds seeded with mesenchymal stem cells derived from donated human Wharton's jelly (hUCMSCs) against neuroinflammatory reactions of injured mammalian brain tissue. These bioscaffolds have been implanted into (i) intact and (ii) ischemic rat hippocampal organotypic slices and into the striatum of (iii) normal and (iv) focally injured brains of adult Wistar rats. We found that transplantation of hUCMSCs encapsulated in GL scaffolds had a significant impact on the prevention of glial scar formation (low glial acidic fibrillary protein) and in the reduction of neuroinflammation (low interleukin-6 and the microglial markers ED1 and Iba1) in the recipient tissue. Moreover, implantation of hUCMSCs encapsulated within GL scaffolds induced matrix metalloproteinase-2 and -9 proteolytic activities in the surrounding brain tissue. This facilitated scaffold biodegradation while leaving the remaining grafted hUCMSCs untouched. In conclusion, transplanting GL scaffolds preseeded with hUCMSCs into mammalian brain tissue escaped the host's immune system and protected neural tissue from neuroinflammatory injury. This manuscript is published as part of the International Association of Neurorestoratology (IANR) supplement issue of Cell Transplantation.