title: Intranasal delivery of stem cells to the brain.
abstract: BACKGROUND
  Stem cell-based therapy has proved to be a promising treatment option for neurological disorders. However, there are difficulties in successfully administrating these stem cells. For example, the brain-blood barrier impedes the entrance of stem cells into the CNS after systemic administration. Direct transplantation or injection may result in brain injury, and these strategies are clinically less feasible. Intranasal administration is a non-invasive and effective alternative for the delivery of drugs, vector-encoded viruses or even phages to the CNS. Recent studies have in fact demonstrated that stem cells may enter the CNS after intranasal administration. These results suggest that intranasal delivery may provide an alternative strategy for stem cell-based therapy.
  
  
  METHODS
  This review summarizes current studies that have applied the intranasal delivery of stem cells into the brain. In addition, the distribution and fate of stem cells in the brain and the potential opportunities as well as challenges of intranasal stem cell delivery are also discussed.
  
  
  CONCLUSIONS
  Intranasal delivery of stem cells is a new method with great potential for the transplantation of stem cells into the brain, and it may provide an extraordinary approach to overcoming the existing barriers of stem cell delivery for the treatment of many neurological disorders. This potential benefit emphasizes the importance of future research into intranasal delivery of stem cells.
authors.affiliation: Nanjing University School of Medicine, Jinling Hospital, Department of Neurology, Nanjing, Jiangsu Province, China.
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Jiang
authors.forename: Juehua
authors.initials: J
authors.lastname: Zhu
authors.forename: Gelin
authors.initials: G
authors.lastname: Xu
authors.forename: Xinfeng
authors.initials: X
authors.lastname: Liu
mesh_terms: D000281:Administration, Intranasal; D001921:Brain / Q000187:drug effects; D002986:Clinical Trials as Topic; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D006801:Humans; D009422:Nervous System Diseases / Q000628:therapy*; D058953:Neural Stem Cells / Q000637:transplantation; D009666:Nose; D033581:Stem Cell Transplantation / Q000379:methods*; D013234:Stem Cells / Q000502:physiology*