title: In vivo tracking of human placenta derived mesenchymal stem cells in nude mice via ¹⁴C-TdR labeling.
abstract: BACKGROUND
  In order to shed light on the regenerative mechanism of mesenchymal stem cells (MSCs) in vivo, the bio-distribution profile of implanted cells using a stable and long-term tracking method is needed. We herein investigated the bio-distribution of human placental deciduas basalis derived MSCs (termed as PDB-MSCs) in nude mice after intravenous injection by carbon radioisotope labeling thymidine ((14)C-TdR), which is able to incorporate into new DNA strands during cell replication.
  
  
  RESULTS
  The proliferation rate and radioactive emission of human PDB-MSCs after labeled with different concentrations of (14)C-TdR were measured. PDB-MSCs labeled with 1 μCi possessed high radioactivity, and the biological characteristics (i.e. morphology, colony forming ability, differentiation capabilities, karyotype and cell cycle) showed no significant changes after labeling. Thus, 1 μCi was the optimal concentration in this experimental design. In nude mice, 1 × 10(6) (14)C-TdR-labeled PDB-MSCs were injected intravenously and the organs were collected at days 1, 2, 3, 5, 30 and 180 after injection, respectively. Radiolabeled PDB-MSCs were found mainly in the lung, liver, spleen, stomach and left femur of the recipient nude mice at the whole observation period.
  
  
  CONCLUSIONS
  This work provided solid evidence that (14)C-TdR labeling did not alter the biological characteristics of human placental MSCs, and that this labeling method has potential to decrease the signal from non-infused or dead cells for cell tracking. Therefore, this labeling technique can be utilized to quantify the infused cells after long-term follow-up in pre-clinical studies.
authors.affiliation: Laboratory of Stem Cell and Tissue Engineering, Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu, People's Republic of China. chengguang1989@foxmail.com.
authors.forename: Cheng-Guang
authors.initials: CG
authors.lastname: Wu
authors.affiliation: Laboratory of Stem Cell and Tissue Engineering, Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu, People's Republic of China. 929976776@qq.com.
authors.forename: Ji-Chun
authors.initials: JC
authors.lastname: Zhang
authors.affiliation: Laboratory of Stem Cell and Tissue Engineering, Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu, People's Republic of China. 578510232@qq.com.
authors.forename: Cheng-Quan
authors.initials: CQ
authors.lastname: Xie
authors.affiliation: Centro di Ricerca E.Menni, Fondazione Poliambulanza, Brescia, Italy. ornella.parolini@poliambulanza.it.
authors.forename: Ornella
authors.initials: O
authors.lastname: Parolini
authors.affiliation: Centro di Ricerca E.Menni, Fondazione Poliambulanza, Brescia, Italy. antonietta.silini@poliambulanza.it.
authors.forename: Antonietta
authors.initials: A
authors.lastname: Silini
authors.affiliation: Laboratory of Stem Cell and Tissue Engineering, Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu, People's Republic of China. 934044952@qq.com.
authors.forename: Yi-Zhou
authors.initials: YZ
authors.lastname: Huang
authors.affiliation: West China School of Pharmacy, Sichuan University, Chengdu, People's Republic of China. 373011236@qq.com.
authors.forename: Bing
authors.initials: B
authors.lastname: Lian
authors.affiliation: Center Laboratory For Isotopy, West China Hospital, Sichuan University, Chengdu, People's Republic of China. tws189@189.cn.
authors.forename: Min
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Department of Orthopaedics and Traumatology, The University of Hong Kong, Hong Kong, SAR, People's Republic of China. y.c.huang@connect.hku.hk.
authors.forename: Yong-Can
authors.initials: YC
authors.lastname: Huang
authors.affiliation: Laboratory of Stem Cell and Tissue Engineering, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, People's Republic of China. dengli2000@gmail.com.
authors.forename: Li
authors.initials: L
authors.lastname: Deng
mesh_terms: D000818:Animals; D002250:Carbon Radioisotopes / Q000737:chemistry / Q000493:pharmacokinetics*; D058948:Cell Tracking / Q000379:methods*; D005260:Female; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000737:chemistry* / Q000166:cytology* / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D010920:Placenta / Q000166:cytology*; D011247:Pregnancy; D013936:Thymidine / Q000737:chemistry / Q000493:pharmacokinetics*; D014018:Tissue Distribution
chemical_list: D002250:Carbon Radioisotopes; D013936:Thymidine