title: The interplay of T1- and T2-relaxation on T1-weighted MRI of hMSCs induced by Gd-DOTA-peptides.
abstract: Three Gd-DOTA-peptide complexes with different peptide sequence are synthesized and used as T1 contrast agent to label human mesenchymal stem cells (hMSCs) for magnetic resonance imaging study. The peptides include a universal cell penetrating peptide TAT, a linear MSC-specific peptide EM7, and a cyclic MSC-specific peptide CC9. A significant difference in labeling efficacy is observed between the Gd-DOTA-peptides as well as a control Dotarem. All Gd-DOTA-peptides as well as Dotarem induce significant increase in T1 relaxation rate which is in favor of T1-weighted MR imaging. Gd-DOTA-CC9 yields the maximum labeling efficacy but poor T1 contrast enhancement. Gd-DOTA-EM7 yields the minimum labeling efficacy but better T1 contrast enhancement. Gd-DOTA-TAT yields a similar labeling efficacy as Gd-DOTA-CC9 and similar T1 contrast enhancement as Gd-DOTA-EM7. The underlying mechanism that governs T1 contrast enhancement effect is discussed. Our results suggest that T1 contrast enhancement induced by Gd-DOTA-peptides depends not only on the introduced cellular Gd content, but more importantly on the effect that Gd-DOTA-peptides exert on the T1-relaxation and T2-relaxation processes/rates. Both T1 and particularly T2 relaxation rate have to be taken into account to interpret T1 contrast enhancement. In addition, the interpretation has to be based on cellular instead of aqueous longitudinal and transverse relaxivities of Gd-DOTA-peptides.
authors.affiliation: Division of Nanobionics, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, PR China; University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049, PR China.
authors.forename: Limin
authors.initials: L
authors.lastname: Cao
authors.affiliation: Division of Nanobionics, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, PR China; University of Science and Technology of China, 19 Ren'ai Road, Suzhou 215123, PR China.
authors.forename: Binbin
authors.initials: B
authors.lastname: Li
authors.affiliation: Division of Nanobionics, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, PR China.
authors.forename: Peiwei
authors.initials: P
authors.lastname: Yi
authors.affiliation: Division of Nanobionics, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, PR China.
authors.forename: Hailu
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Division of Nanobiomedicine, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, PR China; State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100190, PR China.
authors.forename: Jianwu
authors.initials: J
authors.lastname: Dai
authors.affiliation: Division of Nanobionics, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, PR China. Electronic address: btan2012@sinano.ac.cn.
authors.forename: Bo
authors.initials: B
authors.lastname: Tan
authors.affiliation: Division of Nanobionics, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, PR China. Electronic address: zwdeng2007@sinano.ac.cn.
authors.forename: Zongwu
authors.initials: Z
authors.lastname: Deng
mesh_terms: D003287:Contrast Media / Q000737:chemistry*; D006571:Heterocyclic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D059630:Mesenchymal Stem Cells / Q000473:pathology; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*
chemical_list: D003287:Contrast Media; D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; C050823:gadolinium 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetate
keywords: Gd-DOTA-peptides; MRI; Relaxivity; T(1) enhancement; hMSCs